Towards benign synthesis of indenes from indanones: Zinc-mediated allylation of ketones in aqueous media as a source of substituted indenyl ligand precursors

FULL PAPER

Towards Benign Synthesis of Indenes from Indanones: Zinc-Mediated

Allylation of Ketones in Aqueous Media as a Source of Substituted Indenyl

Ligand Precursors

Satu Silver,^[a]Ann-Sofie Leppänen,^[a]Rainer Sjöholm,^[a]Antti Penninkangas,^[b]and

Reko Leino*^[a]

Keywords: Cyclopentadienyl ligands / Allylation / Zinc / Ketones / Hydrosilylation

Substituted indenes are valuable ligand precursors for transi-

tion-metal complexes. Previously, most of the methods em-

ployed for the preparation of alkyl-substituted indenes have

involved the use of air-sensitive organometallic lithium or

diating metal in THF/NH₄Cl_aqfollowed by acid-catalyzed

dehydration. The method described is applicable also for in-

danones containing unprotected halide- and hydroxyl sub-

stituents. As an example of extension of the approach, some

Grignard reagents, often in combination with expensive me- indenes have been further hydrosilylated with achiral silanes

tal catalysts. The present work evaluates an approach to the

synthesis of 2- and 3-allyl-substituted indenes by employing

a simple, environmentally benign organometallic zinc-medi-

ated Barbier-type allylation of 1- and 2-indanones in aqueous

media. A large series of new achiral and racemic indenyl li-

gand precursors have been prepared in variable yields by

and disilanes in the presence of Karstedt’s catalyst to provide

new silaalkyl-substituted indenes and bis(indenes). Hydro-

silylation with a chiral silane, (+)-(R)-methyl-1-naphthalenyl-

phenylsilane, provides access to new chirally substituted in-

denes.

reacting substituted and unsubstituted indanones with allyl-, Germany, 2005)

crotyl-, and cinnamyl halides using metallic zinc as the me-

of steric and electronic effects, which in turn are induced

Introduction

by the substitution pattern of the indenyl ligand. Thus, the

development of new, simple and versatile methods for the

synthesis of substituted indenes and indenyl ligand precur-

sors is nontrivial and of continuous topical interest, espe-

cially so, considering the often expensive and complicated

methods currently in use for their preparation. Previously,

a number of methods have been applied to synthesize 1-

and 2-silyl,^[10]1- (or 3-) and 2-alkyl/aryl,^[1a,11,12]as well as

various heteroatom-substituted indenes.^[13]Most of the ear-

lier approaches to the synthesis of alkyl-substituted indenes

have involved the use of air- and moisture-sensitive or-

ganometallic lithium or Grignard reagents, often in combi-

nation with expensive metal catalysts. Thus, there exists a

demand to develop safer and more economical approaches

for their synthesis.

Zinc- and indium-mediated Barbier-type allylations of

aldehydes and ketones in aqueous media are powerful

methods for creating new C–C bonds under mild and envi-

ronmentally benign reaction conditions.^[14]Typically, zinc

powder is mixed with an allyl halide reagent and reacted

with a ketone or aldehyde in a mixture of THF and satu-

rated aqueous ammonium chloride to provide the corre-

sponding allylic alcohols in high yield. Indium, having a

lower first ionization potential can be used in nonacidic

aqueous solutions without additional proton sources.^[15]In

contrast to alkyllithium and Grignard reagents, both zinc

Substituted indenes and cyclopentadienes serve as versa-

tile ligand precursors for a broad range of transition-metal

complexes.^[1]In particular, group 4 bis(indenyl) metallo-

cenes are frequently employed catalyst precursors for stere-

ospecific polymerization of alkenes,^[2]and are being used as

reagents and catalysts for various stereo- and/or enantiose-

lective organic transformations.^[3]A remarkable example of

an organozirconium success story in organic synthesis is the

enantioselective carboalumination of alkenes catalyzed by

chiral zirconocene dichlorides,^[4]applied recently to the syn-

thesis of complex natural products.^[5]Other applications of

chiral zirconocenes in stereoselective synthesis include those

in enantioselective cyclopolymerization of nonconjugated

dienes,^[6]as well as applications in other carbon–carbon,^[7]

carbon–hydrogen,^[8]and carbon–oxygen^[9]bond forming re-

actions.

In general, the catalytic performance of group 4 bis(ind-

enyl)metallocene complexes is determined by a combination

[a] Department of Organic Chemistry Åbo Akademi University,

20500 Åbo, Finland

Fax: +358-2-215-4866

E-mail: reko.leino@abo.fi

[b] Laboratory of Polymer Technology Åbo Akademi University,

20500 Åbo, Finland

Supporting information for this article is available on the

WWW under http://ww w .eurjoc.org or from the author.

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DOI: 10.1002/ejoc.200400789

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and indium organometallics tolerate the presence of various bridged ansa-metallocenes by a photochemical [2+2] cyclo-

other functional groups in the molecule.

addition reaction.^[22]Further examples of developing func-

In two previous reports, allylation of 1-indanone with tional group chemistry on bent group 4 metallocene frame-

allyl bromide^[16]and 2-indanone with tetraallylstannane^[17]works have been collected in a recent review.^[23]

in dichloromethane resulted in the formation of the corre-

sponding 1- and 2-substituted allylhydroxyindanes in high

Results and Discussion

yields. Likewise, Bi(OTf)₃-catalyzed allylation of indene ox-

ide with tetraallylstannane^[18]and the indium(i) chloride

mediated allylation of indene oxide with allyl bromide cata-

lyzed by Pd^[19]has provided 2-allylhydroxyindane in 85 and

83% yields, respectively. These allylindanols in turn could

be easily envisioned to function as precursors to substituted

indenes after elimination of water. We became interested in

the applicability of the ketone allylation method in aqueous

media as a potential simple and environmentally benign

source of allylically substituted indenes, and describe here

its scope and application to the synthesis of a large series

of new substituted indenes and cyclopentadienes, suitable

as ligand precursors for transition-metal complexes.

Notably, bis(indenyl) group 4 metallocenes incorporating

double-bond containing ligand substituents are of current

interest as self-supporting olefin polymerization catalysts.

By this method, the homogeneous catalysts can be transfer-

red into a heterogeneous system without the use of inor-

ganic carriers.^[20]Also, in recent work, Erker and coworkers

As a starting point for the present work, various 1- and

2-indanones as well as some substituted cyclopentenones

were selected for the metal-mediated allylations in aqueous

media with allyl-, crotyl- and cinnamyl bromide as allylat-

ing reagents. While a number of metals have been reported

to mediate allylations of ketones and aldehydes under aque-

ous conditions, the efforts here were focused on metallic

zinc because of its superiority in terms of low cost and low

toxicity. A detailed description of the performed work fol-

lows. All of the isolated compounds have been fully charac-

1

terized by H and ¹³C NMR spectroscopic analysis and by

high resolution mass spectroscopy (for details, see the ex-

perimental section).

Allylation of 1-Indanones

The reactions of 1-indanone with allyl bromide, crotyl

have applied alkenyl-substituted metallocene complexes for bromide and cinnamyl bromide followed by acid-catalyzed

the preparation of novel bridged and bimolecular zir- dehydrations are summarized in Scheme 1. The zinc-medi-

conocene catalysts through use of the Grubbs ring-closing ated allylation of 1-indanone with allyl bromide yielded the

olefin metathesis reaction.^[21]Likewise, bis(2-alkenylind- desired allylindanol in good yield (88%) and as a racemic

enyl)zirconium dichlorides were recently converted into mixture of two enantiomers rac-1. Subsequent dehydration

Scheme 1. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Amberlyst 15, pentane. (iii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iv) Amberlyst 15,

pentane. (v) Cinnamyl chloride, Zn, NH₄Cl_aq/THF.

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of the rac-1 mixture with Amberlyst 15 in pentane gave an Amberlyst 15 in pentane (Scheme 2). The indenes 10 and

inseparable 1:1 mixture of the double-bond isomers 2 and 3 rac-15 were obtained in poor overall yields of 3% and 4%

resulting from non-regioselective water elimination in 33% over two steps, respectively, after purification by column

isolated yield. Various dehydration conditions and reagents chromatography. All attempts to react 2,4,7-trimethyl-1-in-

were investigated for compounds rac-1 (sulfuric acid, phos- danone with cinnamyl chloride failed. The total failure with

phorus oxychloride, oxalic acid, a mixture of sulfuric acid cinnamyl chloride, and the poor yields obtained with crotyl-

and acetic acid); however, none of the attempts resulted in and allylbromides are likely a result of the increased steric

the formation of a single product. In previous work, a mix- hindrance on the keto side of the indanone induced by the

ture of 1- and 3-allylindenes was prepared in 69% yield by methyl substituents in the 2- and 7-positions, which is even

the conventional addition of allyl chloride to indenyllithi- more pronounced when the larger cinnamyl reagent is em-

um.^[12c,24]

When crotyl bromide was used instead of allyl bromide

ployed.

In order to further evaluate the influence of methyl sub-

in the allylation of 1-indanone, a 1:0.3 diastereomeric mix- stitution on the course of the allylation reaction, 2-methyl-

ture of two pairs of enantiomers (rac-4 versus rac-5) was 1-indanone was employed as starting material (Scheme 3).

1

obtained in 87% yield, as evidenced by H NMR spectro- The results obtained were similar to the case of 2,4,7-trime-

scopic analysis. While this mixture was stored at –20 °C thyl-1-indanone; thus, the zinc-mediated allylations of 2-

overnight, some spontaneous dehydration took place. In or- methyl-1-indanone with allyl bromide and crotyl bromide

der to drive the reaction to completion, the diastereomeric yielded a 1:0.2 diastereomeric mixture of the allylindanols

mixture was reacted with Amberlyst 15 in pentane to pro- rac-16/rac-17 in a satisfactory 67% yield and a dia-

vide the 3-(1-methylallyl)indene rac-6 in 65% yield based stereomeric mixture of rac-20/rac-21/rac-22/rac-23 in 73%

on a mixture of rac-4 and rac-5 and as a racemic mixture yield, respectively. Allylation using cinnamyl chloride failed.

of two enantiomers.

Apparently, the effect of the methyl substituent in position

The allylation of 1-indanone with cinnamyl chloride, 7 thus plays a greater role than the substituent in position

likewise, initially yielded a diastereomeric mixture of four 2 when steric hindrance towards the allylating reagent is

allylindanols, which, however, due to their high lability, considered. Dehydration of the mixtures of alcohols rac-16/

spontaneously eliminated water upon storage at –20 °C rac-17, and rac-20/rac-21/rac-22/rac-23 with Amberlyst 15

overnight to provide the 3-(1-phenylallyl)indene rac-7 in in pentane gave a 1:0.16 mixture of the dehydration prod-

28% isolated overall yield, again as a racemic mixture of ucts 18 and rac-19, and the enantiomeric mixture of the 2-

two enantiomers.

methyl-3-(1-methylallyl)indene rac-24 in 18% and 43%

Allylation of the sterically more congested 2,4,7-trime- yields, respectively.

thyl-1-indanone with allyl bromide and crotyl bromide

Next, in order to further broaden the usability of the

yielded the desired diastereomeric alcohols rac-8/rac-9, and method, a series of functionalized 1-indanones were investi-

rac-11/rac-12/rac-13/rac-14, respectively. However, these re- gated. The zinc-mediated allylation of 4-hydroxy-1-in-

actions could not be driven to completion, and the crude danone with allyl bromide yielded the desired allylindandiol

products were dehydrated without purification by using rac-25 in 67% yield, which upon dehydration, gave an in-

Scheme 2. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iii) Amberlyst 15, pentane.

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Scheme 3. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Amberlyst 15, pentane. (iii) Crotyl bromide, Zn, NH₄Cl_aq/THF.

Scheme 4. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) MgSO₄, toluene, reflux. (iii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iv) Cinnamyl

chloride, Zn, NH₄Cl_aq/THF.

separable 1:0.16 mixture of the double-bond isomers 26 and

The steric effect of the substituent in the 7-position of 1-

27 in 25% isolated yield (Scheme 4). Allylation of 4-hy- indanone and the electronic effect of a halogen substituent

droxy-1-indanone with crotyl bromide and cinnamyl chlo- were further investigated by allylating 4-chloro-7-methyl-1-

ride resulted in spontaneous dehydration upon allylation to indanone (containing 13% of 7-chloro-4-methyl-1-in-

give the enantiomeric mixtures of 4-hydroxyindenes rac-28 danone as an impurity) with allyl bromide, crotyl bromide

and rac-29 in 42% and 19% isolated yields, respectively.

and cinnamyl chloride (Scheme 5). Allylation of the chloro-

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Scheme 5. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iii) Amberlyst 15, pentane.

Scheme 6. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iii) Amberlyst 15, pentane.

indanone mixture with allyl bromide and crotyl bromide lylation of the chloroindanone mixture with cinnamyl chlo-

yielded mixtures of the halogenated indanol derivatives rac- ride failed, again probably due to the steric hindrance in-

30/rac-31 and rac-35/rac-36/rac-38/rac-39 in 87% and 86% duced by the 7-substituent. Thus, again it appears that of

yields respectively. Subsequent dehydration of these mix- the allylayting reagents employed, cinnamyl chloride is the

tures gave mixtures of the dehydration products 32/33/34 most sensitive towards steric hindrance in the keto sub-

and rac-37/rac-40 in 35% and 33% yields, respectively. Al- strate.

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Allylation of 7-bromo-4-methyl-1-indanone gave results

similar to those observed for the chlorinated analogue

(Scheme 6). Allylation with allyl bromide and crotyl bro-

mide thus yielded the expected indanol mixtures rac-41 and

rac-44/rac-45 in 85% and 77% yields, respectively, which

upon dehydration in the allyl bromide case provided a 1:0.9

mixture of the double bond isomers 42 and 43 in 27% yield,

and in the crotyl bromide case, the enantiomeric mixture

rac-46 in 36% yield.

Figure 1.Nitro- and amino-substituted 1-indanones yielding no re-

action with crotyl bromide/Zn and crotyl bromide/In.

Allylation of 2-bromo-1-indanone with allyl bromide

gave the indanol rac-1 in 48% yield (Scheme 7). The zinc-

mediated allylation reaction thus appears to cleave the bro-

mine at the sp³-hybridized carbon atom in position 2 but,

as expected, not the aromatic bromine in position 7 as ob-

served in Scheme 6.

Allylation of 2-Indanones

Allylation of 2-indanone with allyl bromide, crotyl bro-

mide and cinnamyl chloride yielded the expected allylindan-

ols 47, rac-49 and rac-51 in 84%, 88% and nearly quantita-

tive yields, respectively. Subsequent acid-catalyzed dehy-

drations in refluxing toluene gave the corresponding substi-

tuted indenes 48, rac-50 and rac-52 in 38%, 53% and 15%

yields, respectively (Scheme 8). In a previous work, Schum-

ann and coworkers prepared 2-allylindene by Pd-catalyzed

Grignard reaction of 2-bromoindene with allylmagnesium

chloride, a considerably more elaborate procedure, which

resulted in the formation of the target compound in 25%

yield.^[8c]Syntheses of 2-allylindene by Rh-catalyzed al-

Scheme 7. (i) Allyl bromide, Zn, NH₄Cl_aq/THF.

Finally, allylation of a series of 1-indanones bearing a lylation of indene with allyl tosylate in 19% yield^[25]and by

nitro- or an amino substituent in the six-membered ring, as reaction of 2-indanone with allylmagnesium bromide fol-

illustrated in Figure 1, was investigated with crotyl bromide lowed by subsequent dehydration with p-TsOH in 30–40%

in combination with both zinc and indium as the mediating overall yield^[26]have likewise been reported. The overall

metal. For reasons remaining unknown at present, no reac- yield here over two steps for 2-allylindene is 32% and thus

tion was observed for any of these compounds.

entirely satisfactory considering also that none of the ini-

Scheme 8. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iii) Cinnamyl chloride, Zn, NH₄Cl_aq/THF. (iv)

Prenyl bromide, Zn, NH₄Cl_aq/THF. (v) p-TSA, toluene, reflux. (vi) H₂SO₄, toluene, reflux. (vii) Amberlyst 15, pentane.

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Scheme 9. (i) Crotyl bromide, Zn, NH₄Cl_aq/THF. (ii) Amberlyst 15, pentane.

tially screened reaction conditions reported in this work 11% isolated yield after subsequent dehydration and purifi-

have been optimized to maximize the formation of the tar- cation by flash chromatography.

get compounds.

Finally, one substituted 2-indanone, 4,7-dimethyl-2-in-

In addition, the zinc-mediated allylation of 2-indanone danone, was allylated with crotyl bromide providing the al-

using prenyl bromide was investigated on a small scale. The lyl-substituted indanol rac-55 in 75% yield. Dehydration of

indanol 53 was obtained in 91% yield and the indene 54 in rac-55 with Amberlyst 15 in pentane gave the enantiomeric

Scheme 10. (i) Allyl bromide, Zn, NH₄Cl_aq/THF. (ii) Crotyl bromide, Zn, NH₄Cl_aq/THF. (iii) Cinnamyl chloride, Zn, NH₄Cl_aq/THF. (iv)

Amberlyst 15, pentane. (v) MgSO₄, toluene, reflux.

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mixture of the corresponding indene rac-56 in 13% yield Cyclopentadienes are prone to form Diels–Alder products,

(Scheme 9).

and we assume that the side products formed may consist

of such mixtures, although their exact structure remains un-

known. Instead, dehydration of the mixtures rac-60/rac-61

and rac-63/rac-64 with heat yielded the desired cyclopenta-

dienes rac-62 and a mixture of rac-65, -66, and -67 as main

products. Unfortunately, in addition to the desired com-

pounds, inseparable side products were also formed, and

the cyclopentadienes could not be obtained in analytically

pure form. Thus, at present, the applicability of the zinc-

mediated aqueous allylation to the synthesis of substituted

cyclopentadienes appears less attractive than its application

to the synthesis of substituted indenes.

Allylation of Cyclopentenones

In order to briefly investigate the applicability of the

method for the preparation of substituted cyclopentadienes,

some readily available cyclopentenones were screened as

starting material. Of these, the allylation of 3-methyl-2-cy-

clopenten-1-one with allyl bromide was attempted that re-

sulted in a complex mixture of unknown products, possibly

containing Diels–Alder adducts. When 3,4-diphenyl-cy-

clopent-2-enone was reacted with allyl bromide, crotyl bro-

mide and cinnamyl chloride, the cyclopentenol rac-57 and

the mixtures rac-60/rac-61 and rac-63/rac-64 were obtained

in 9%, 40%, and 51% yields, respectively (Scheme 10). The

cyclopentenol derivative rac-57 was dehydrated with Am-

berlyst 15 in pentane, and a 2:1 mixture of compounds 58

and 59 with exocyclic double bonds was obtained in 22%

yield. The dehydration of the diastereomeric mixtures rac-

60/rac-61 and rac-63/rac-64 in acidic environment yielded

only undesired side products with large molecular weights.

Group

4 bis(indenyl) ansa-zirconocenes containing

benzo-fused indenyl ligands are known to form highly

active and stereoselective catalysts for the isospecific poly-

merization of propylene.^[27]Thus, the zinc-mediated al-

lylation of 1,3-dihydro-cyclopenta[l]phenanthren-2-one

with allyl bromide was also investigated and provided the

alcohol 68 in poor (7%) yield (Scheme 11). When indium

was used instead of zinc as the mediating metal, a signifi-

cantly higher yield (40%) was obtained. Dehydration of 68

under acidic conditions was attempted with p-TsOH,

H₂SO₄and Amberlyst 15, and by refluxing in toluene. Un-

fortunately, none of these attempts provided the desired de-

hydration product.

Derivatization of the Allyl Group

A specific advantage of the allyl substituent is the large

variety of postmodifications that can be applied for its

derivatization. As an example, we briefly investigated the

Scheme 11. i) Allyl bromide, Zn, NH4Claq/THF. (ii) Allyl bromide,

In, water/THF.

Scheme 12. Karstedt’s catalyst in toluene with (i) triethoxysilane, (ii) triethylsilane, (iii) triphenylsilane, (iv) 1,2-bis(dimethylsilanyl)ethane,

and (v) (1H-inden-1-yl)dimethylsilane (containing about 10% of (3H-inden-1-yl)dimethylsilane as impurity).

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hydrosilylation of 2-allylindene (48) in the presence of Kar- 1H-indene (rac-52) were hydrosilylated with (+)-(R)-methyl-

stedt’s catalyst with triethoxysilane, triethylsilane, tri- 1-naphthalenylphenylsilane to yield the 1:1 diastereomeric

phenylsilane, 1,2-bis(dimethylsilanyl)ethane, and a 90:10 mixtures of 76/77 and 78/79 in 25% and 21% yields, respec-

mixture of the 1- and 3-indenyl isomers of indenyldimethyl- tively (Scheme 14). Unfortunately, none of the compounds

silane (Scheme 12). In addition, a readily available chiral proved to be crystalline and all preliminary attempts to

silane, (+)-(R)-methyl-1-naphthalenylphenylsilane, was used separate the diastereomers by flash chromatography failed.

for evaluating the applicability of the approach for the prep- Nevertheless, considering the simple procedure, the method

aration of enantiomerically pure chirally substituted in- may prove to be of value for preparation/resolution of other

denes (Scheme 13). Hydrosilylation with the achiral mono- chirally substituted indenes.

and disilanes thus provided the 2-silaalkyl-substituted in-

denes 69–71 in 48%, 29%, and 15% isolated yields, and the

Summary and Conclusions

bridged bis(indene) 72, in 13% isolated yield after purifica-

tion by flash chromatography. The bridged bis(indene) 73/

74 (a mixture of 1- and 3-indenyl) isomers were obtained in

3% isolated yield by hydrosilylation of 2-allylindene with

the 1- and 3-indenyldimethylsilane mixture followed by pu-

rification by flash chromatography.^[28]Finally, the chiral in-

dene 75 was obtained in 30% isolated yield by hydro-

silylation of 2-allylindene with (+)-(R)-methyl-1-naphtha-

lenylphenylsilane.^[29]The proposed stereochemistry around

the silicon atom, as depicted in Scheme 13, is based on the

expected retention of configuration of the chiral silicon

atom during the hydrosilylation reaction.^[30]

To summarize, in the present work, we have demon-

strated the applicability of metal-mediated allylation of

ketones in aqueous media to be a potential source of new

substituted indenyl ligand precursors. With limitations, the

method would appear to be suitable also for the preparation

of substituted cyclopentadienes. It should be borne in mind

that the yields and procedures reported in this preliminary

screening are by no means optimized. Yields of the zinc-

mediated allylations may be highly dependent on reaction

conditions, such as temperature, concentration, ammonium

chloride/THF mole ratio, and the allyl halide reagent (chlo-

ride versus bromide), which, during the course of this inves-

tigation, were not varied systematically. Also, as demon-

strated by allylation of the cyclopenta[l]phenanthren-2-one

derivative depicted in Scheme 11, higher yields may simply

be obtainable by changing the mediating metal from zinc

to indium.

Finally, for evaluating the potential use of the chiral si-

lane as a resolving agent, the enantiomeric mixtures of 2-

(1-methylallyl)-1H-indene (rac-50) and 2-(1-phenylallyl)-

As it stands, yields of the allylation step with allyl bro-

mide, crotyl bromide, and cinnamyl chloride are generally

good with the exception of highly substituted indanones,

especially when cinnamyl chloride is used. Problems are en-

countered in some of the dehydration steps, in particular

with the 1-allylindanols and allylcyclopentenols, which

upon dehydration tend to give mixtures of the desired 3-

allylindene or allylcyclopentadiene together with products

where water elimination has taken place in an exocyclic

fashion. Of some concern, considering the potential use of-

Scheme 13. (i) (+)-(R)-Methyl-1-naphthalenylphenylsilane, Kar-

stedt’s catalyst, toluene.

Scheme 14. (i) (+)-(R)-Methyl-1-naphthalenylphenylsilane, Karstedt’s catalyst, toluene.

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Scheme 15. Metallation of 2-substituted indenes.

the indenes prepared as ligand precursors for transition-me-

tal complexes, is also the fact that the 3-(1-methylallyl)- and

3-(1-phenylallyl)indenes obtained with crotyl and cinnamyl

reagents are racemic mixtures that bear a chiral indenyl

substituent, which potentially produces a large amount of

stereoisomers upon metallation of the 3-substituted indenyl

anions. An analogous situation of course exists also with

the corresponding 2-substituted indenes of which 2-(1-

methylallyl)indene and 2-(1-phenylallylindene) are racemic

mixtures. However, in contrast to 3-substituted indenes, the

two π faces of a 2-substituted indenyl ligand precursor are

equivalent, and thus for racemic 2-substituted indenes,

metallation with group 4 metal tetrahalides potentially re-

sults in only three stereoisomers, namely a racemic pair

Experimental Section

General Considerations: Commercially available solvents and rea-

gents were used without further purification. 2,4,7-Trimethyl-1-in-

danone,^[36]2-methyl-1-indanone,^[37]4-nitro-1-indanone,^[38]6-nitro-

1-indanone,^[38]6-amino-1-indanone,^[38]4,7-dimethyl-2-indanone,^[39]

3,4-diphenyl-cyclopent-2-enone,^[40]1,3-dihydro-cyclopenta[l]phen-

anthren-2-one,^[41]4-methyl-7-bromo-1-indanone,^[42]the 87:13 mix-

ture of 4-chloro-7-methyl-1-indanone and 4-methyl-7-chloro-1-in-

danone,^[43]dimethylsilylindene,^[44]and (+)-(R)-methyl-1-naphtha-

lenylphenylsilane^[45]were synthesized according to literature pro-

cedures. Flash chromatography was performed on silica gel 60 (40–

63 µm). Purification by preparative TLC was performed on a 1 mm

silica gel 60 (40–63 µm) plate containing F₂₅₄. NMR spectra were

recorded at 298 K with a Bruker Avance 600 (¹H NMR 600 MHz,

¹³C NMR 150.9 MHz), a Jeol L-400 (¹H NMR 400 MHz, ¹³C

100.6 MHz) or with a Bruker 250 MHz instrument (¹H NMR

250 MHz). ¹H NMR chemical shifts were referenced to residual ¹H

impurities in the solvent relative to TMS, and ¹³C NMR chemical

shifts, to the solvent signals. The NMR spectra were recorded (in δ

values) with deuterochloroform or [D₄]MeOH as the solvent. Mass

spectra were recorded with a high resolution mass spectrometer

(Fison’s ZapSpec) and an Agilent 1100 Series LC/MSD SL Trap

system.

(R,R) together with (S,S) and

a meso-form (R,S)

(Scheme 15),^[1a]a situation analogous to the preparation of

conventional bridged bis(indenyl) ansa-metallocenes.^[31]

These, in turn, are potentially separable into the pure rac-

and meso diastereomers by standard recrystallization tech-

niques.^[32]On the other hand, the racemic nature of some

of the ligand precursors reported here should be of less con-

cern when applied, for example, to the synthesis of mono-

(indenyl)titanium trichlorides for applications in syndios-

pecific styrene polymerization^[33]or for use in mixed ligand

bis(cyclopentadienyl) metallocene complexes in which one

of the ligands does not bear a chiral substituent.

Zinc-Mediated Allylation of a Ketone – General Procedure 1: A

solution of the ketone in THF (4 mL) was added dropwise to a

well-stirred mixture of zinc, saturated NH₄Cl_aq(40 mL) and THF

(8 mL). Allyl halide was dissolved in THF (4 mL) and slowly added

dropwise to the reaction mixture. The reaction was mildly exother-

mic, and the mixture began to reflux spontaneously. After refluxing

had ceased, the reaction mixture was stirred at room temperature

for 1–24 h. The slightly acidic reaction mixture was extracted with

Et₂O (3×50 mL) and the combined organic layers were dried with

Na₂SO₄, filtered, and evaporated to give the crude product.

Of particular interest may also prove to be allylations of

functionalized indenes − only preliminarily investigated in

this work − which may lead to simplified procedures to new

heteroatom-substituted indenyl ligands and metallocene

complexes.^[13]Also, a number of functionalized allylation

reagents, not evaluated in the present work, should be read-

ily available, providing simple access to further functionaliz-

ation of the indenyl substitution pattern. As a direct deriva-

tization of the allyl group, the hydrosilylation reaction pre-

liminarily evaluated here may likewise result in new valuable

chiral or achiral indenyl ligand precursors.^[34]For example,

compound 55 carrying a triethoxysilyl functionality may

provide access to immobilization of indenyl ligands and/or

metallocenes to silica supports.^[35]We thus believe that the

method described herein opens a versatile and simple access

to a library of valuable building blocks for organometallic

catalyst research. Application of selected ligand precursors

reported in this work for preparation of transition-metal

complexes is currently in progress in the authors’ laborato-

ries and will be reported in forthcoming papers.

Indium-Mediated Allylation of a Ketone – General Procedure 2: In-

dium powder and allyl halide were added dropwise to a suspension

of the ketone in a 1:1 mixture of THF and water (5 mL) at room

temperature. The resulting reaction mixture was stirred for 24 h

and diluted with dichloromethane (50 mL). The layers formed were

separated, and the organic phase was washed with brine (50 mL),

dried with Na₂SO₄, filtered, and evaporated to give the crude pro-

duct.

Dehydration with Amberlyst 15 – General Procedure 3: Amberlyst

15 was added to a solution of allyl indanol in pentane (5–35 mL).

The resulting reaction mixture was stirred at room temperature for

a period of 15 min–24 h. The solid catalyst was removed by fil-

tration, and the filtrate was evaporated to dryness. The crude pro-

duct was purified by silica gel column chromatography to yield the

desired dehydration product.

Eur. J. Org. Chem. 2005, 1058–1081

www.eurjoc.org

1067

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

Dehydration with p-TSA or Sulfuric Acid – General Procedure 4: p- CH), 123.71 (arom. CH), 120.33 (arom. CH), 119.15 (arom. CH),

FULL PAPER

TSA or sulfuric acid was added to a solution of allyl indanol in

toluene (30–200 mL), and the resulting reaction mixture was re-

fluxed for a period of 2–9.5 h. The solvent was removed under re-

duced pressure, and the residue was dissolved in Et₂O (50 mL). The

organic layer was washed with saturated NH₄Cl_aq(50 mL), dried

with Na₂SO₄, and filtered, and the solvents, evaporated to dryness.

The crude product was purified by silica gel column chromatog-

raphy to yield the desired dehydration product.

118.78 (olefinic CH in chain in 3), 116.27 (olefinic CH₂in chain in

2 or 3), 115.92 (olefinic CH₂in chain in 2 or 3), 37.72 (aliphatic

CH₂in five-ring or chain in 2), 32.43 (aliphatic CH₂in five-ring or

chain in 2), 30.12 (aliphatic CH₂in five-ring in 3), 28.18 (aliphatic

CH₂in five-ring in 3) ppm. EIMS (30 eV): calcd. C₁₂H₁₂156.0939;

found 156.0941.

A Mixture of 1-(1-Methyl-allyl)-indan-1-ol (rac-4 and rac-5): By ap-

plying General Procedure 1, zinc (1.6945 g, 25.9 mmol), 1-indanone

(1.7007 g, 12.9 mmol), and crotyl bromide (3.1 mL, 30.1 mmol)

gave, after a 1-h reaction time, 2.1043 g (87%) of the title com-

pounds as yellow oils. The diastereomeric compounds were formed

in a 1:0.3 ratio. ¹H NMR (600 MHz, CDCl₃): δ = 7.37 (m, 4 H,

arom. CH in major and arom. CH in minor), 7.29 (m, 12 H, 6

arom. CH in major and 6 arom. CH in minor), 5.99 (ddd, J =

7.71 Hz, 10.79 Hz, 17.27 Hz, 2 H, olefinic CH in chain in minor),

5.80 (ddd, J = 7.09 Hz, 10.18 Hz, 17.27 Hz, 2 H, olefinic CH in

chain in major), 5.27 (dm, J = 17.27 Hz, 2 H, olefinic CH in chain

in minor), 5.21 (dm, J = 10.79 Hz, 2 H, olefinic CH in chain in

minor), 5.11 (dm, J = 17.27 Hz, 2 H, olefinic CH in chain in

major), 5.07 (dm, J = 10.18, 2 H, olefinic CH in chain in major),

3.01 (m, 4 H, aliphatic CH in five-ring in major and minor), 2.83

(m, 4 H, aliphatic CH in five-ring in major and minor), 2.76 (m, 4

H, aliphatic CH in chain in major and minor), 2.57 (br. s, 4 H, OH

in major and minor), 2.42 (m, 4 H, aliphatic CH in five-ring in

major and minor), 2.02 (m, 4 H, aliphatic CH in five-ring in major

and minor), 1.19 (d, J = 7.22 Hz, 6 H, CH₃in major), 0.95 (d, J =

7.22 Hz, 6 H, CH₃in minor) ppm. ¹³C NMR (150.9 MHz, CDCl₃):

δ = 146.42 (2 C_qin major), 145.94 (2 C_qin minor), 143.81 (2 C_q

in minor), 143.53 (2 C_qin major), 139.94 (4 C, olefinic CH in chain

in major and minor), 128.24 (2 arom. CH in minor), 128.10 (2

arom. CH in major), 126.57 (2 arom. CH in minor), 126.36 (2

arom. CH in major), 124.82 (2 arom. CH in major), 124.73 (2

arom. CH in minor), 123.74 (2 arom. CH in major), 123.49 (2

arom. CH in minor), 116.48 (2 olefinic CH₂in minor), 115.65 (2

olefinic CH₂in major), 85.38 (2 C-OH in minor), 85.33 (2 C-OH

in major), 47.42 (2 aliphatic CH in chain in minor), 46.20 (2 ali-

phatic CH in major), 36.96 (2 aliphatic CH₂in five-ring in major),

36.29 (2 aliphatic CH₂in five-ring in minor), 30.08 (2 aliphatic CH₂

in five-ring in minor), 29.83 (2 aliphatic CH₂in five-ring in major),

15.32 (2 CH₃in minor), 13.65 (2 CH₃in major) ppm. EIMS

(30 eV): calcd. C₁₃H₁₆O 188.1201; found 188.1188.

Dehydration with Heat – General Procedure 5: MgSO₄was added

to a solution of allyl cyclopentenol/allyl indandiol in toluene

(20 mL), and the resulting reaction mixture was refluxed for 1–2 h.

The reaction mixture was filtered, and the filtrate was concentrated

in vacuo. The crude product was purified by silica gel column

chromatography to yield the desired dehydration product.

Hydrosilylation of Substituted Indenes – General Procedure 6:

Karltedt’s catalyst (3 drops) was added to a solution of substituted

indene in toluene (5 mL). After the reaction mixture was stirred for

10 min, the silane was added. The resulting reaction mixture was

stirred at room temperature for 2–23 h, and the solvent was re-

moved under reduced pressure. The residue was purified by silica

gel column chromatography to yield the desired silaalkyl-substi-

tuted indene.

An Enantiomeric Mixture of 1-Allyl-indan-1-ol (rac-1): By applying

General Procedure 1, zinc (1.4092 g, 21.6 mmol), 1-indanone

(1.3777 g, 10.4 mmol), and allyl bromide (1.8 mL, 20.7 mmol) gave,

after a 1-h reaction time, 1.5859 g (88%) of the title compound as

a yellow oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.25 (m, 2 H, arom.

CH), 7.16 (m, 6 H, arom. CH), 5.77 (m, 2 H, olefinic CH in chain),

5.08 (m, 2 H, olefinic CH in chain), 5.06 (m, 2 H, olefinic CH in

chain), 2.93 (m, 2 H, aliphatic CH in five-ring), 2.73 (m, 2 H, ali-

phatic CH in five-ring), 2.56 (m, 2 H, aliphatic CH in chain), 2.43

(m, 2 H, aliphatic CH in chain), 2.25 (m, 2 H, aliphatic CH in five-

ring), 1.99 (m, 4 H, OH and aliphatic CH in five-ring) ppm. ¹³C

NMR (100.6 MHz, CDCl₃): δ = 146.99 (2 C_q), 142.95 (2 C_q),

133.73 (2 olefinic CH in chain), 128.22 (2 arom. CH), 126.62 (2

arom. CH), 124.89 (2 arom. CH), 122.85(2 arom. CH), 118.78 (2

olefinic CH₂in chain), 82.70 (2 C-OH), 44.94 (2 aliphatic CH₂in

chain), 39.62 (2 aliphatic CH₂in five-ring), 29.37 (2 aliphatic CH₂

in five-ring) ppm. EIMS (30 eV): calcd. C₁₂H₁₄O 174.1045; found

174.1036.

A Mixture of 3-Allyl-1H-indene (2) and 1-Allylidene-indane (3): By

applying General Procedure 3, 1-allyl-indan-1-ol (rac-1) (1.2457 g,

7.2 mmol) and Amberlyst 15 (1.0137 g) in pentane (30 mL) gave,

after a 30-min reaction time and column chromatography (hexane

as eluent), 0.3655 g (33%) of a 1:1 mixture of the title compounds

An Enantiomeric Mixture of 3-(1-Methyl-allyl)-1H-indene (rac-6):

By applying General Procedure 3, 1-(1-methyl-allyl)-indan-1-ol

(rac-4 and rac-5) (1.8795 g, 10.0 mmol) and Amberlyst 15 (1.45 g)

in pentane (35 mL) gave, after a 15-min reaction time, and column

chromatography (hexane as eluent), 1.0949 g (65%) of an enantio-

meric mixture of the title compounds as a yellow oil. ¹H NMR

1

as a pale yellow oil. H NMR (400 MHz, CDCl₃): δ = 7.51 (m, 2

H, arom. CH), 7.41 (m, 1 H, arom. CH), 7.33 (m, 1 H, arom. CH), (400 MHz, CDCl₃): δ = 7.51 (dm, J = 7.55 Hz, 2 H, arom. CH),

7.30 (m, 1 H, arom. CH), 7.24 (m, 3 H, arom. CH), 6.65 (m, 2 H, 7.46 (dm, J = 7.55 Hz, 2 H, arom. CH), 7.32 (tm, J = 7.55, 2 H,

olefinic CH in chain in 3), 6.28 (m, 1 H, aliphatic CH in five-ring

in 2), 6.05 (ddt, J = 6.33 Hz, 10.07 Hz, 17.09 Hz, 1 H, olefinic CH

in chain in 2), 5.32 (dm, J = 15.64 Hz, 1 H, olefinic CH in chain

in 3), 5.23 (dm, J = 17.09 Hz, 1 H, olefinic CH in chain in 2), 5.18

(dm, J = 6.56 Hz, 1 H, olefinic CH in chain in 3), 5.16 (dm, J =

10.07 Hz, 1 H, olefinic CH in chain in 2), 3.35 (m, 4 H, aliphatic

CH₂in chain in 2 and aliphatic CH₂in five-ring in 2), 3.06 (m, 2

H, aliphatic CH₂in five-ring in 3), 2.92 (m, 2 H, aliphatic CH₂in

five-ring in 3) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ = 146.88

arom. CH), 7.24 (tm, J = 7.55 Hz, 2 H, arom. CH), 6.29 (m, 2 H,

olefinic CH in five-ring), 6.07 (ddd, J = 6.79 Hz, 10.22 Hz,

17.24 Hz, 2 H, olefinic CH in chain), 5.18 (dt, J = 1.53 Hz,

17.24 Hz, 2 H, olefinic CH in chain), 5.10 (ddd, J = 1.22 Hz,

1.60 Hz, 10.22 Hz, 2 H, olefinic CH in chain), 3.57 (m, 2 H, ali-

phatic CH in chain), 3.38 (m, 4 H, aliphatic CH₂in five-ring), 1.44

(d, J = 7.02 Hz, 6 H, CH₃) ppm. ¹³C NMR (100.6 MHz, CDCl₃):

δ = 147.64 (2 C_q), 144.71 (2 C_q), 144.66 (2 C_q), 141.87 (2 olefinic

CH in chain), 127.27 (2 olefinic CH in five-ring), 125.83 (2 arom.

(C_q), 145.07 (2 C_q), 144.47 (C_q), 142.44 (C_q), 141.30 (C_q), 135.59 CH), 124.46 (2 arom. CH), 123.78 (2 arom. CH), 119.75 (2 arom.

(olefinic CH in chain in 2), 134.37 (olefinic CH in chain in 3),

128.89 (olefinic CH in five-ring in 2), 128.19 (arom. CH), 126.50

CH), 113.71 (2 olefinic CH₂in chain), 37.64 (2 aliphatic CH₂in

five-ring), 36.55 (2 aliphatic CH in chain), 19.06 (CH₃) ppm. EIMS

(arom. CH), 125.96 (arom. CH), 125.26 (arom. CH), 124.56 (arom. (70 eV): calcd. C₁₃H₁₄170.1096; found 170.1094.

Eur. J. Org. Chem. 2005, 1058–1081

Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

An Enantiomeric Mixture of 3-(1-Phenyl-allyl)-1H-indene (rac-7): 1-

indanone (2.1825 g, 16.5 mmol) in THF (4 mL) was added drop-

wise to a well-stirred mixture of zinc (2.1362 g, 32.7 mmol), satu-

rated NH₄Cl_aq(40 mL) and THF (8 mL). Cinnamyl chloride

(5.0195 g, 32.9 mmol) was dissolved in THF (4 mL) and slowly

added dropwise to the reaction mixture. The reaction mixture be-

gan to reflux spontaneously, and after refluxing had ceased, the

reaction mixture was stirred at room temperature for 1 h. The

slightly acidic (pH ~ 6) reaction mixture was extracted with diethyl

ether (3×50 mL), and the combined organic layers were dried with

Na₂SO₄and filtered, and the solvents, evaporated. The TLC analy-

sis (hexane as eluent) of the reaction product showed that a small

amount of the alcohol had spontaneously dehydrated. The reaction

product was stored at –20 °C overnight and analyzed with TLC

(hexane as eluent). The TLC analysis indicated complete dehy-

dration during storage. The reaction product was purified by silica

gel column chromatography with hexane as eluent and 1.077 g

(28%) of an enantiomeric mixture of the title compounds was ob-

tained as a colorless oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.52 (m,

2 H, arom. CH), 7.30 (m, 16 H, arom. CH), 6.35 (m, 4 H, aliphatic

CH in five-ring and olefinic CH in chain), 5.27 (dt, J = 1.30 Hz,

1.37 Hz, 10.15 Hz, 2 H, olefinic CH in chain), 5.11 (dt, J = 1.45 Hz,

1.53 Hz, 17.01 Hz, 2 H, olefinic CH in chain), 4.77 (m, 2 H, ali-

17.5 mmol), 2,4,7-trimethyl-indan-1-one (1.4956 g, 8.6 mmol), and

crotyl bromide (2.0 mL, 17.5 mmol) gave, after a 6-h reaction time,

1.4364 g of the mixture of 2,4,7-trimethyl-indan-1-one and 2,4,7-

trimethyl-1-(1-methyl-allyl)-indan-1-ol (rac-11, rac-12, rac-13 and

rac-14). The amount of the alcohol obtained was 40%. This crude

product was directly used in the dehydration step without further

purification or analysis. By applying General Procedure 3, the mix-

ture of 2,4,7-trimethyl-1-(1-methyl-allyl)-indan-1-ol (rac-11, rac-12,

rac-13 and rac-14) [0.1774 g, 0.77 mmol] and Amberlyst 15

(0.3022 g) in pentane (10 mL) gave, after a 2-h reaction time and

column chromatography (10% dichloromethane/90% hexane as

eluent), 0.0686 g (42%) of the enantiomeric mixture of the title

compounds as a pale slightly yellowish oil. The overall yield (over

1

two steps) was 4%. H NMR (400 MHz, CDCl₃): δ = 6.97 (d, J_AB

= 7.59 Hz, 2 H, arom. CH), 6.87 (d, J_AB= 7.59 Hz, 2 H, arom.

CH), 6.20 (ddd, J = 4.35 Hz, 10.43 Hz, 17.78 Hz, 2 H, olefinic CH

in chain), 5.13 (m, 2 H, olefinic CH in chain), 5.10 (m, 2 H, olefinic

CH in chain), 4.14 (m, 2 H, aliphatic CH in chain), 3.17 (m, 4 H,

aliphatic CH₂in five-ring), 2.58 (s, 6 H, CH₃attached to the aro-

matic ring), 2.32 (s, 6 H, CH₃attached to the aromatic ring), 2.14

(s, 6 H, CH₃attached to the five-ring), 1.44 (d, J = 7.17 Hz, 6 H,

CH₃attached to the aliphatic chain) ppm. ¹³C NMR (100.6 MHz,

CDCl₃): δ = 143.77 (2 C_q), 142.43 (2 olefinic CH in chain), 141.68

(2 C_q), 140.88 (2 C_q), 139.66 (2 C_q), 130.16 (2 arom. CH), 129.91

phatic CH in chain), 3.47 (m, 4 H, aliphatic CH₂in five-ring) ppm.

13

C NMR (100.6 MHz, CDCl₃): δ = 145.63 (2 C_q), 144.54 (2 C_q), (2 C_q), 126.92 (2 C_q), 124.66 (2 arom. CH), 112.44 (2 olefinic CH₂

in chain), 42.79 (2 aliphatic CH₂in five-ring), 34.96 (2 aliphatic

144.47 (2 C_q), 141.49 (2 C_q), 139.51 (2 olefinic CH in chain), 130.25

(2 olefinic CH in five-ring), 128.47 (4 arom. CH), 128.41 (4 arom. CH in chain), 20.98 (2 CH₃attached to the aromatic ring), 18.19

CH), 126.48 (2 arom. CH), 125.86 (2 arom. CH), 124.52 (2 arom. (2 CH₃attached to the aromatic ring), 18.16 (2 CH₃attached to

CH), 123.69 (2 arom. CH), 120.21 (2 arom. CH), 115.98 (2 olefinic

CH₂in chain), 48.87 (2 aliphatic CH in chain), 37.76 (2 five-ring

aliphatic CH₂) ppm. EIMS (70 eV): calcd. C₁₈H₁₈O 232.1252;

found 232.1248.

the aliphatic chain), 15.84 (2 CH₃attached to the five-ring) ppm.

EIMS (70 eV): calcd. C₁₆H₂₀212.1565; found 212.1560.

A Mixture of 1-Allyl-2-methyl-indan-1-ol (rac-16 and rac-17): By

applying General Procedure 1, zinc (0.7386 g, 11.3 mmol), 2-

methyl-indan-1-one (0.7838 g, 5.4 mmol), and allyl bromide

(940 µL, 10.7 mmol) gave, after a 2.5-h reaction time, 0.6743 g

(67%) of a mixture of the title compounds as a yellow oil. ¹H NMR

(600 MHz, CDCl₃): δ = 7.38 (m, 4 H, arom. CH in rac-16 and rac-

17), 7.26 (m, 12 H, arom. CH in rac-16 and rac-17), 5.94 (ddt, J =

5.87 Hz, 13.39 Hz, 16.01 Hz, 2 H, olefinic CH in chain in rac-16

or rac-17), 5.82 (ddt, J = 6.70 Hz, 9.38 Hz, 17.41 Hz, 2 H, olefinic

CH in chain in rac-16 or rac-17), 5.17 (dm, J = 17.41 Hz, 2 H,

olefinic CH in chain in rac-16 or rac-17), 5.16 (dm, J = 16.01 Hz,

2 H, olefinic CH in chain in rac-16 or rac-17), 5.12 (dm, J =

9.38 Hz, 2 H, olefinic CH in chain in rac-16 or rac-17), 5.04 (dm,

J = 13.39 Hz, 2 H, olefinic CH in chain in rac-16 or rac-17), 3.32

(s, 2 H, OH in rac-16 or rac-17), 3.02 (m, 4 H, aliphatic CH in five-

ring in rac-16 and rac-17), 2.74 (m, 2 H, aliphatic CH in five-ring

in rac-16 or rac-17), 2.65 (m, 12 H, aliphatic CH₂in chain in rac-

16 andrac-17 and aliphatic CH in five-ring in rac-16 and rac-17),

2.45 (m, 2 H, aliphatic CH in five-ring in rac-16 or rac-17), 2.10 (s,

2 H, OH in rac-16 or rac-17), 1.34 (d, J = 6.86 Hz, 6 H, CH₃in

rac-16 or rac-17), 1.12 (d, J = 6.86 Hz, 6 H, CH₃in rac-16 or rac-

17) ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 146.59 (2 C_qin rac-

16 or rac-17), 142.64 (2 C_qin rac-16 or rac-17), 139.55 (2 C_qin

rac-16 or rac-17), 136.49 (2 C_qin rac-16 or rac-17), 134.81 (2 ole-

finic CH in chain in rac-16 or rac-17), 134.29 (2 olefinic CH in

chain in rac-16 or rac-17), 128.41 (2 arom. CH in rac-16 or rac-

17), 127.50 (2 arom. CH in rac-16 or rac-17), 126.71 (2 arom. CH

in rac-16 or rac-17), 126.63 (2 arom. CH in rac-16 or rac-17),

125.11 (2 arom. CH in rac-16 or rac-17), 124.14 (2 arom. CH in

rac-16 or rac-17), 123.50 (2 arom. CH in rac-16 or rac-17), two

arom. CH in rac-16 or rac-17 are overlapping with other signals,

118.53 (2 olefinic CH₂in chain in rac-16 or rac-17), 115.41 (2 ole-

finic CH₂in chain in rac-16 or rac-17), 82.73 (2 C-OH in rac-16 or

3-Allyl-2,4,7-trimethyl-1H-indene (10): By applying General Pro-

cedure 1, zinc (1.1283 g, 17.3 mmol), 2,4,7-trimethyl-indan-1-one

(1.5230 g, 8.7 mmol), and allyl bromide (1.5 mL, 17.5 mmol) gave,

after a 5.5-h reaction time, 1.3694 g of the mixture of 2,4,7-trime-

thyl-indan-1-one and 1-allyl-2,4,7-trimethyl-indan-1-ol (rac-8 and

rac-9). The amount of the alcohol obtained was 27%. This crude

product was directly used in the dehydration step without further

purification or analysis. By applying General Procedure 3, a mix-

ture of 1-allyl-2,4,7-trimethyl-indan-1-ol (rac-8 and rac-9)

(0.1214 g, 0.56 mmol) and Amberlyst 15 (0.3398 g) in pentane

(10 mL) gave, after a 1.5-h reaction time and column chromatog-

raphy (10% dichloromethane/90% hexane as eluent), 0.0445 g

(40%) of the title compound as a yellow oil. The overall yield (over

1

two steps) was 3%. H NMR (400 MHz, CDCl₃): δ = 6.83 (d, J_AB

= 7.71 Hz, 1 H, arom. CH), 6.74 (d, J_AB= 7.71 Hz, 1 H, arom.

CH), 5.92 (ddt, J= 5.11 Hz, 10.22 Hz, 17.17 Hz, 1 H, olefinic CH

in chain), 4.94 (dq, J = 1.91 Hz, 10.18 Hz, 1 H, olefinic CH in

chain), 4.86 (dq, J = 1.99 Hz, 17.17 Hz, 1 H, olefinic CH in chain),

3.34 (m, 2 H, aliphatic CH₂in chain), 3.10 (m, 2 H, aliphatic CH₂

in five-ring), 2.43 (s, 3 H, CH₃attached to the aromatic ring), 2.21

(s, 3 H, CH₃attached to the aromatic ring), 1.98 (s, 3 H, CH₃

attached to the five-ring) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ

= 143.54 (C_q), 141.55 (C_q), 140.05 (C_q), 136.49 (olefinic CH in

chain), 135.52 (C_q), 129.87 (C_q), 129.76 (C_q), 129.45 (arom. CH),

124.78 (arom. CH), 115.00 (olefinic CH₂in chain), 41.51 (aliphatic

CH₂in five-ring), 30.75 (aliphatic CH₂in chain), 19.30 (CH₃at-

tached to the aromatic ring), 18.24 (CH₃attached to the aromatic

ring), 13.88 (CH₃attached to the five-ring) ppm. EIMS (70 eV):

calcd. C₁₅H₁₈198.1409; found 198.1409.

An Enantiomeric Mixture of 2,4,7-Trimethyl-3-(1-methyl-allyl)-1H-

indene (rac-15): By applying General Procedure 1, zinc (1.1470 g,

Eur. J. Org. Chem. 2005, 1058–1081

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1069

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

FULL PAPER

rac-17), 68.07 (2 C-OH in rac-16 or rac-17), 43.69 (4 C, aliphatic

CH₂in five-ring in rac-16 or rac-17 or aliphatic CH₂in chain in

rac-16 or rac-17), 42.06 (2 aliphatic CH in five-ring in rac-16 or

rac-17), 41.73 (2 aliphatic CH in five-ring in rac-16 or rac-17), 38.19

(4 aliphatic CH₂in five-ring in rac-16 or rac-17 or aliphatic CH₂

in chain in rac-16 or rac-17), 35.05 (4 aliphatic CH₂in five-ring in

rac-16 or rac-17 or aliphatic CH₂in chain in rac-16 or rac-17),

13.96 (4 C, CH₃in rac-16 and rac-17) ppm. EIMS (30 eV): calcd.

C₁₃H₁₆O 188.1201; found 188.1196.

20, rac-21, rac-22 and rac-23), 0.98 (d, J = 6.73 Hz, 3 H, CH₃

attached to the aliphatic chain in two compounds of rac-20, rac-

21, rac-22 and rac-23) ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ =

145.98 (6 C_qin six compounds of rac-20, rac-21, rac-22 and rac-

23), 145.63 (2 C_qin two compounds of rac-20, rac-21, rac-22 and

rac-23), 142.75 (2 C_qin two compounds of rac-20, rac-21, rac-22

and rac-23), 142.23 (6 C_qin six compounds of rac-20, rac-21, rac-

22 and rac-23), 140.30 (6 olefinic CH in chain in six compounds

of rac-20, rac-21, rac-22 and rac-23), 140,15 (2 olefinic CH in chain

in two compounds of rac-20, rac-21,rac-22 and rac-23), 128.30 (2

arom. CH in two compounds of rac-20, rac-21, rac-22 and rac-23),

128.15 (6 arom. CH in six compounds of rac-20, rac-21, rac-22 and

rac-23), 126.65 (2 arom. CH in two compounds of rac-20, rac-21,

rac-22 and rac-23), 126.42 (6 arom. CH in six compounds of rac-20,

rac-21, rac-22 and rac-23), 125.07 (6 arom. CH in six compounds

of rac-20, rac-21, rac-22 and rac-23), 124.84 (2 arom. CH in two

compounds of rac-20, rac-21, rac-22 and rac-23), 124.52 (6 arom.

CH in six compounds of rac-20, rac-21, rac-22 and rac-23), 124.01

(2 arom. CH in two compounds of rac-20, rac-21, rac-22 and rac-

23), 116.56 (2 olefinic CH₂in chain in two compounds of rac-20,

rac-21, rac-22 and rac-23), 115.83 (6 olefinic CH₂in chain in six

compounds of rac-20, rac-21, rac-22 and rac-23), 85.42 (6 C-OH in

six compounds of rac-20, rac-21, rac-22 and rac-23), 85.19 (2 C-

OH in two compounds of rac-20, rac-21, rac-22 and rac-23), 47.65

(2 aliphatic CH in chain in two compounds of rac-20, rac-21, rac-

22 and rac-23), 45.89 (6 aliphatic CH in chain in six compounds

of rac-20, rac-21, rac-22 and rac-23), 39.74 (6 C, aliphatic CH or

CH₂in five-ring in six compounds of rac-20, rac-21, rac-22 and

rac-23), 39.46 (2 C, aliphatic CH or CH₂in five-ring in two com-

pounds of rac-20, rac-21, rac-22 and rac-23), 38.88 (6C, aliphatic

CH or CH₂in five-ring in six compounds of rac-20, rac-21, rac-22

and rac-23), 38.18 (2 C, aliphatic CH or CH₂in five-ring in two

diastereomers of rac-20, rac-21, rac-22 and rac-23), 16.45 (2 C, CH₃

attached to the aliphatic chain or five-ring in two compounds of

rac-20, rac-21, rac-22 and rac-23), 15.93 (6C, CH₃attached to the

five-ring in six compounds of rac-20, rac-21, rac-22 and rac-23),

15.53 (2 C, CH₃attached to the aliphatic chain or five-ring in two

compounds of rac-20, rac-21, rac-22 and rac-23), 14.06 (6 C, CH₃

attached to the chain in six compounds of rac-20, rac-21, rac-22

and rac-23) ppm. EIMS (30 eV): calcd. C₁₄H₁₈O 202.1358; found

202.1368.

A Mixture of 3-Allyl-2-methyl-1H-indene (18) and 2-Methyl-1-prop-

2-en-(E)-ylidene-indane (rac-19): By applying General Procedure 3,

a

mixture of 1-allyl-2-methyl-indan-1-ol (rac-16 andrac-17)

(0.2479 g, 1.3 mmol) and Amberlyst 15 (0.1923 g) in pentane

(10 mL) gave, after a 1.5-h reaction time and column chromatog-

raphy (hexane as eluent), 0.0406 g (18%) of the mixture of the title

compounds as a colorless oil. ¹H NMR (600 MHz, CDCl₃): δ =

7.51 (m, 2 H, arom. CH in rac-19), 7.35 (m, 3 H, 1 arom. CH in

rac-19 and 1 arom. CH in 18), 7.24 (m, 4 H, 1 arom. CH in rac-19

and 2 arom. CH in 18), 7.13 (m, 3 H, 1 arom. CH in rac-19 and 1

arom. CH in 18), 6.46 (d, J= 16.33 Hz, 2 H, olefinic CH in chain

in rac-19), 6.23 (m, 2 H, olefinic CH in chain in rac-19), 5.91 (ddt,

J = 6.16 Hz, 10.15 Hz, 17.29 Hz, 1 H, olefinic CH in chain in 18),

5.10 (dm, J = 17.29 Hz, 1 H, olefinic CH in chain in 18), 5.03 (dm,

J = 10.15 Hz, 1 H, olefinic CH in chain in 18), 4 olefinic CH in

chain in rac-19 overlap with the corresponding signals from 18,

3.27 (m, 6 H, aliphatic CH₂in chain in 18, aliphatic CH₂in five-

ring in 18 and aliphatic CH in five-ring in rac-19), 2.13 (m, 4 H,

aliphatic CH₂in five-ring in rac-19), 2.05 (s, 3 H, CH₃in 18), 1.95

(d, J = 6.42 Hz, 6 H, CH₃in rac-19) ppm. ¹³C NMR (150.9 MHz,

CDCl₃): δ = 146.56 (C_qin 18), 145.42 (2 C_qin rac-19), 142.55 (C_q

in 18), 140.39 (2 C_qin rac-19), 139.37 (C_qin 18), 135.53 (olefinic

CH in chain in 18), 134.54 (2 C_qin rac-19), 134.46 (C_qin 18),

127.81 (2 olefinic CH in chain in rac-19), 126.15 (2 arom. CH in

rac-19), 126.09 (arom. CH in 18), 124.03 (2 arom. CH in rac-19 or

2 olefinic CH in chain in rac-19), 123.87 (2 arom. CH in rac-19 or

2 olefinic CH in chain in rac-19), 123.72 (arom. CH in 18), 123.33

(2 arom. CH in rac-19), 123.21 (arom. CH in 18), 119.47 (2 arom.

CH in rac-19), 118.56 (arom. CH in 18), 115.37 (3 C, olefinic CH₂

in chain in 18 and olefinic CH₂in chain in rac-19), 42.93 (2 ali-

phatic CH in five-ring in rac-19), 42.66 (aliphatic CH₂in chain in

18 or aliphatic CH₂in five-ring in 18), 31.76 (2 aliphatic CH₂in

five-ring in rac-19), 29.77 (aliphatic CH₂in chain in 18 or aliphatic

CH₂in five-ring in 18), 14.84 (2 CH₃in rac-19), 13.93 (CH₃in 18)

ppm. EIMS (70 eV): calcd. C₁₃H₁₄170.1096, found 170.1102.

An Enantiomeric Mixture of 2-Methyl-3-(1-methyl-allyl)-1H-indene

(rac-24): By applying General Procedure 3, a mixture of 2-methyl-

1-(1-methyl-allyl)-indan-1-ol (rac-20, rac-21, rac-22 and rac-23)

[0.2283 g, 1.1 mmol] and Amberlyst 15 (0.1822 g) in pentane

(10 mL) gave, after a 1.5-h reaction time and column chromatog-

raphy (hexane as eluent), 0.0888 g (43%) of the enantiomeric mix-

A Mixture of 2-Methyl-1-(1-methyl-allyl)-indan-1-ol (rac-20, rac-21,

rac-22 and rac-23): By applying General Procedure 1, zinc

(0.7949 g, 12.2 mmol), 2-methyl-1-indanone (0.8209 g, 5.6 mmol),

and crotyl bromide (1.4 mL, 11.5 mmol) gave, after a 2.5-h reaction

time, 0.8232 g (73%) of a mixture of the title compounds as a yel-

1

ture of the title compounds as a colorless oil. H NMR (600 MHz,

CDCl₃): δ = 7.25 (d, J = 7.92 Hz, 4 H, arom. CH), 7.10 (t, J =

7.92 Hz, 2 H, arom. CH), 6.99 (t, J = 7.92 Hz, 2 H, arom. CH),

6.04 (ddt, J = 5.08 Hz, 10.28 Hz, 17.05 Hz, 2 H, olefinic CH in

chain), 5.03 (dm, J = 17.05 Hz, 2 H, olefinic CH in chain), 4.98

(dm, J = 10.28 Hz, 2 H, olefinic CH in chain), 3.58 (m, 2 H, ali-

phatic CH in chain), 3.16 (m, 4 H, aliphatic CH₂in five-ring), 1.98

(s, 6 H, CH₃attached to the five-ring), 1.31 (d, J = 7.42 Hz, 6 H,

CH₃attached to the chain) ppm. ¹³C NMR (150.9 MHz, CDCl₃):

δ = 145.57 (2 C_q), 142.96 (2 C_q), 141.58 (2 olefinic CH in chain),

1

low oil. H NMR (600 MHz, CDCl₃): δ = 7.38 (m, 8 H, arom. CH

in rac-20, rac-21, rac-22 and rac-23), 7.26 (m, 24 H, arom. CH in

rac-20, rac-21, rac-22 and rac-23), 5.93 (m, 8 H, olefinic CH in

chain in rac-20, rac-21, rac-22 and rac-23), 5.16 (m, 16 H, olefinic

CH₂in chain in rac-20, rac-21, rac-22 and rac-23), 3.10 (m, 8 H,

aliphatic CH in five-ring in rac-20, rac-21, rac-22 and rac-23), 2.69

(m, 8 H, aliphatic CH in chain in rac-20, rac-21, rac-22 and rac-

23), 2.63 (m, 8 H, aliphatic CH in five-ring in rac-20, rac-21, rac- 139.20 (2 C_q), 138.36 (2 C_q), 125.86 (2 arom. CH), 123.48 (2 arom.

22 and rac-23), 2.59 (m, 8 H, aliphatic CH in five-ring in rac-20,

rac-21, rac-22 and rac-23), 1.92 (br. s, 8 H, C-OH in rac-20, rac-

21, rac-22 and rac-23), 1.16 (d, J = 6.73 Hz, 18 H, CH₃attached

to the aliphatic chain in six compounds of rac-20, rac-21, rac-22

and rac-23), 1.09 (m, 24 H, CH₃attached to the five-ring in rac-

CH), 120.03 (2 arom. CH), overlapping of two arom. CH, 113.59

(2 olefinic CH₂in chain), 43.10 (2 aliphatic CH₂in five-ring), 35.05

(2 aliphatic CH in chain), 18.44 (2 CH₃attached to the chain),

14.70 (2 CH₃attached to the five-ring) ppm. EIMS (70 eV): calcd.

C₁₄H₁₆184.1252; found 184.1255.

1070

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Eur. J. Org. Chem. 2005, 1058–1081

Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

An Enantiomeric Mixture of 1-Allyl-indan-1,4-diol (rac-25): By ap-

plying General Procedure 1, zinc (0.6556 g, 10.0 mmol), 4-hydroxy-

indan-1-one (0.7321 g, 5.0 mmol), and allyl bromide (870 µL,

chain), 5.12 (dt, J = 1.53 Hz, 17.17 Hz, 2 H, olefinic CH in chain),

5.04 (ddd, J = 1.18Hz, 1.56 Hz, 10.22 Hz, 2 H, olefinic CH in

chain), 4.73 (br. s, 2 H, OH), 3.49 (m, 2 H, aliphatic CH in chain),

9.9 mmol) gave, after a 1.5-h reaction time, 0.6185 g of a mixture 3.27 (m, 4 H, aliphatic CH₂in five-ring), 1.38 (d, J = 6.94 Hz, 6

of 4-hydroxy-1-indanone and the title compounds as white crystals.

The amount of the title compound was 67%. The yield from the

reaction was 43%. H NMR (400 MHz, CD₃OD): δ = 7.03 (m, 2

H, CH₃) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ = 151.12 (2 C_q),

147.96 (2 C_q), 147.06 (2 C_q), 141.82 (2 olefinic CH in chain), 129.14

(2 C_q), 127.78 (2 arom. CH), 127.01 (2 arom. CH), 113.72 (2 ole-

1

H, arom. CH), 6.84 (dm, J = 7.48 Hz, 2 H, arom. CH), 6.65 (dd, finic CH₂in chain), 113.21 (2 arom. CH), 111.90 (2 arom. CH),

J = 0.88 Hz, 7.89 Hz, 2 H, arom. CH), 5.74 (m, 2 H, olefinic CH 36.64 (2 aliphatic CH in chain), 34.18 (2 aliphatic CH₂in five-ring),

in chain), 5.04 (m, 4 H, olefinic CH₂in chain), 2.89 (m, 2 H, ali-

phatic CH in five-ring), 2.66 (m, 2 H, aliphatic CH in five-ring),

2.58 (ddt, J_AB= 1.07 Hz, 7.44 Hz,13.74 Hz, 2 H, aliphatic CH in

chain), 2.48 (ddt, J_AB= 1.22 Hz, 6.95 Hz, 13.74 Hz, 2 H, aliphatic

CH in chain), 2.28 (m, 2 H, aliphatic CH in five-ring), 2.02 (m, 2 H,

aliphatic CH in five-ring) ppm. ¹³C NMR (100.6 MHz, CD₃OD): δ

= 154.50 (2 C_q), 150.44 (2 C_q), 143.85 (2 C_q), 135.48 (2 olefinic CH

in chain), 128.95 (2 arom. CH), 118.07 (2 olefinic CH₂in chain),

115.35 (2 arom. CH), 115.08 (2 arom. CH), 84.22 (2 C-OH), 46.49

(2 aliphatic CH₂in chain), 39.63 (2 aliphatic CH₂in five-ring),

26.80 (2 aliphatic CH₂in five-ring) ppm. EIMS (70 eV): calcd.

C₁₂H₁₄O₂190.0994; found 190.0996.

19.12 (2 CH₃) ppm. EIMS (70 eV): calcd. C₁₃H₁₄O₁186.1045;

found 186.1043.

An Enantiomeric Mixture of 1-(1-Phenyl-allyl)-3H-inden-4-ol (rac-

29): By applying General Procedure 1, zinc (0.4575 g, 7.00 mmol),

4-hydroxy-1-indanone (0.4963 g, 3.35 mmol), and cinnamyl chlo-

ride (1.0336 g, 6.77 mmol) gave, after a 6-h reaction time and col-

umn chromatography (dichloromethane as eluent), 0.1576 g (19%)

of the enantiomeric mixture of the title compounds as a yellow oil.

¹H NMR (400 MHz, CDCl₃): δ = 7.19 (m, 10 H, arom. CH in

phenyl substituent), 6.98 (m, 2 H, arom. CH), 6.70 (dd, J =

0.76 Hz, 7.56 Hz, 2 H, arom. CH), 6.53 (dq, J = 0.38 Hz, 7.97 Hz,

2 H, arom. CH), 6.19 (m, 4 H, olefinic CH in chain and olefinic

CH in five-ring), 5.10 (ddd, J = 1.11 Hz, 1.56 Hz, 10.15 Hz, 2 H,

olefinic CH in chain), 4.97 (br. s, 2 H, OH), 4.95 (dt, J = 1.49 Hz,

A Mixture of 1-Allyl-3H-inden-4-ol (26) and 1-Prop-2-en-(E)-yli-

dene-indan-4-ol (27): By applying General Procedure 5, the enantio-

meric mixture of 1-allyl-indan-1,4-diol (rac-25) (0.5371 g; 17.09 Hz, 2 H, olefinic CH in chain), 4.59 (m, 2 H, aliphatic CH

2.8 mmol) and Mg₂SO₄in toluene (20 mL) gave, after refluxing

for 1.5 h and column chromatography (dichloromethane as eluent),

0.1188 g (25%) of a 1:0.16 mixture of the title compounds as a

yellow oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.19 (ddt, J = 0.53 Hz,

in chain), 3.24 (m, 4 H, aliphatic CH₂in chain) ppm. ¹³C NMR

(100.6 MHz, CDCl₃): δ = 151.06 (2 C_q), 146.81 (2 C_q), 145.85 (2

C_q), 141.47 (2 C_q), 139.48 (2 olefinic CH in chain), 130.00 (2 ole-

finic CH in five-ring), 128.44 and 128.40 (10 C, overlapping signals

7.48 Hz, 8.01 Hz, 1 H, arom. CH in 26), 7.09 (m, 1 H, arom. CH from arom. CH in phenyl), 127.75 (2 arom. CH), 126.49 (2 C_q),

in 27), 7.08 (m, 1 H, arom. CH in 27), 6.99 (dm, J = 7.48 Hz, 1 H,

arom. CH in 26), 6.67 (dm, J = 8.01 Hz, 1 H, arom. CH in 26),

6.66 (m, 1 H, arom. CH in 27), 6.58 (m, 2 H, olefinic CH in chain

in 27), 6.23 (m, 1 H, olefinic CH in five-ring in 26), 6.02 (ddt, J =

6.56 Hz, 10.07 Hz, 17.09 Hz, 1 H, olefinic CH in chain in 26), 5.29

(m, 1 H, olefinic CH in chain in 27), 5.25 (m, 1 H, olefinic CH in

chain in 27), 5.16 (ddd, J = 1.52 Hz, 3.43 Hz, 17.09 Hz, 1 H, ole-

finic CH in chain in 26), 5.10 (dm, J = 10.07 Hz, 1 H, olefinic CH

in chain in 26), 4.74 (br. s, 2 H, OH in 26 and OH in 27), 3.29 (m,

4 H, aliphatic CH₂in chain in 26 and five-ring aliphatic CH₂in

26), 2.93 (m, 4 H, five-ring aliphatic CH₂in 27) ppm. ¹³C NMR

(100.6 MHz, CDCl₃): δ = 151.09 (C_qin 26), 147.48 (C_qin 26),

142.74 (C_qin 26), 135.52 (olefinic CH in chain in 26), 134.22 (ole-

finic CH in 27), 128.88 (C_qin 26), 128.60 (olefinic CH in five-ring

in 26), 128.27 (arom. CH in 27), 127.92 (arom. CH in 26), 119.41

(olefinic CH in chain in 27), 116.32 (olefinic CH₂in chain in 26

and 27), 114.19 (arom. CH in 27), 113.06 (arom. CH in 27), 112.61

(arom. CH in 26), 112.07 (arom. CH in 26), 34.30 (aliphatic CH₂

in chain in 26 or aliphatic CH₂in five-ring in 26), 32.53 (aliphatic

CH₂in chain in 26 or aliphatic CH₂in five-ring in 26), 28.23 (ali-

phatic CH₂in five-ring in 27), 26.26 (aliphatic CH₂in five-ring in

27) ppm. The quaternary carbon atoms of the minor product could

not be detected in the carbon spectrum due to their low intensity.

EIMS (70 eV): calcd. C₁₂H₁₂O 172.0888; found 172.0886.

115.99 (2 olefinic CH₂in chain), 113.60 (2 arom. CH), 111.96 (2

arom. CH), 48.92 (2 aliphatic CH in chain), 34.39 (2 aliphatic CH₂

in five-ring) ppm. EIMS (70 eV): calcd. C₁₈H₁₆O₁248.1201; found

248.1198.

A Mixture of 1-Allyl-4-chloro-7-methyl-indan-1-ol (rac-30) and 1-

Allyl-7-chloro-4-methyl-indan-1-ol (rac-31): By applying General

Procedure 1, zinc (0.4379 g, 6.7 mmol), 4-chloro-7-methyl-indan-1-

one (containing 13% of 7-chloro-4-methyl-indan-1-one as impu-

rity) [0.5179 g, 2.9 mmol], and allyl bromide (500 µL, 5.7 mmol)

gave, after a 1.5-h reaction time, 0.5620 g (87%) of a mixture of

1

the title compounds as a yellow oil. H NMR (400 MHz, CDCl₃):

δ = 7.10 (d, J = 8.01 Hz, 2 H, arom. CH in rac-30), 7.05 (dm, J =

8,01 Hz, 2 H, arom. CH in rac-31), 6.97 (dm, J = 8,01 Hz, 2 H,

arom. CH in rac-31), 6.91 (dm, J = 8.01 Hz, 2 H, arom. CH in rac-

30), 5.71 (m, 4 H, olefinic CH in chain in rac-30 and olefinic CH

in chain in rac-31), 5.11 (m, 8 H, olefinic CH₂in chain in rac-30

and olefinic CH₂in chain in rac-31), 3.04–2.45 and 2.00–1.90 (m,

24 H, overlapping signals from aliphatic CH₂in chain in rac-30,

aliphatic CH₂in five-ring in rac-30, aliphatic CH₂in chain in rac-

31 and aliphatic CH₂in five-ring in rac-31), 2.43 (s, 12 H, CH₃

attached to the aromatic ring in rac-30 and CH₃attached to the

aromatic ring in rac-31), 2.19 (br. s, 4 H, OH in rac-30 and OH in

rac-31) ppm. The ratio between the enantiomeric mixture of 1-allyl-

4-chloro-7-methyl-indan-1-ol (rac-30) and the enantiomeric mix-

An Enantiomeric Mixture of 1-(1-Methyl-allyl)-3H-inden-4-ol (rac- ture of 1-allyl-7-chloro-4-methyl-indan-1-ol (rac-31) was approxi-

28): By applying General Procedure 1, zinc (0.5064 g, 7.74 mmol),

4-hydroxy-1-indanone (0.5660 g, 3.82 mmol), and crotyl bromide

(930 µL, 7.64 mmol) gave, after a 2-h reaction time and column

chromatography (dichloromethane as eluent), 0.2953 g (42%) of

the enantiomeric mixture of the title compounds as a yellow oil.

mately 83% of rac-30 and 17% of rac-31. ¹³C NMR (100.6 MHz,

CDCl₃): δ = 145.70 (2 C_qin rac-30), 144.33 (2 C_qin rac-31), 141.75

(2 C_qin rac-31), 140.69 (2 C_qin rac-30), 137.25 (2 C_qin rac-31),

132.54 (2 C_qin rac-31), overlapping of two C_qin rac-30 with other

signals, 133.29 (2 olefinic CH in chain in rac-30), 133.17 (2 olefinic

¹H NMR (400 MHz, CDCl₃): δ = 7.18 (tm, J = 7.75 Hz, 2 H, arom. CH in chain in rac-31), 130.94 (2 arom. CH in rac-30), 130.26 (2

CH), 7.04 (dd, J = 0.80 Hz, 7.75 Hz, 2 H, arom. CH), 6.66 (dm, J arom. CH in rac-31), 128.16 (2 C_qin rac-30), 127.85 (2 arom. CH

= 7.75 Hz, 2 H, arom. CH), 6.23 (m, 2 H, olefinic CH in five-ring),

5.99 (ddd, J = 6.79 Hz, 10.22 Hz, 17.17 Hz, 2 H, olefinic CH in

in rac-30), 127.98 (2 arom. CH in rac-31), 119.03 (2 olefinic CH₂

in chain in rac-30), 118.49 (2 olefinic CH₂in chain in rac-31), 85.25

Eur. J. Org. Chem. 2005, 1058–1081

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1071

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

FULL PAPER

(2 C-OH in rac-30), 84.88 (2 C-OH in rac-31), 44.35 (2 aliphatic

CH₂in five-ring or in chain in rac-31), 43.55 (2 aliphatic CH₂in

five-ring or in chain in rac-30), 39.58 (2 aliphatic CH₂in five-ring

or in chain in rac-30), 37.56 (2 aliphatic CH₂in five-ring or in chain

in rac-31), 28.33 (2 aliphatic CH₂in five-ring or in chain in rac-

30), 28.19 (2 aliphatic CH₂in five-ring or in chain in rac-31), 18.23

(2 CH₃attached to the aromatic ring in rac-31), 17.52 (2 CH₃at-

tached to the aromatic ring in rac-30) ppm. EIMS (30 eV): calcd.

C₁₃H₁₅OCl 222.0811; found 222.0815.

(rac-38 and rac-39): By applying General Procedure 1, zinc

(0.4321 g, 6.6 mmol), 4-chloro-7-methyl-indan-1-one (containing

13% of 7-chloro-4-methyl-indan-1-one as impurity) [0.5797 g,

3.2 mmol], and crotyl bromide (800 µL, 6.4 mmol) gave, after a 3-

h reaction time, 0.6539 g (86%) of a mixture of the title compound

as a yellow oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.10 (m, 4 H,

arom. CH in rac-35 and rac-36), 7.05 (m, 4 H, arom. CH in rac-38

and rac-39), 6.97 (m, 4 H, arom. CH in rac-38 and rac-39), 6.92

(m, 4 H, arom. CH in rac-35 and rac-36), 6.11 (m, 2 H, olefinic

CH in chain in rac-38 and rac-39), 6.01 (m, 2 H, olefinic CH in

chain in rac-35 and rac-36), 5.45 (ddd, J = 6.68 Hz, 10.53 Hz,

17.24 Hz, 2 H, olefinic CH in rac-35 and rac-36 and m, 2 H, ole-

finic CH in rac-38 and rac-39), 5.22 (m, 8 H, olefinic CH₂in chain

in rac-35 and rac-36 and olefinic CH₂in chain in rac-38 and rac-

39), 4.92 (dm, J = 17.24 Hz, 2 H, olefinic CH in chain in rac-35

and rac-36 and m, 2 H, olefinic CH in chain in rac-38 and rac-39),

4.86 (dm, J = 10.53 Hz, 2 H, olefinic CH in chain in rac-35 and

rac-36), 4.81 (ddd, J = 0.61 Hz, 1.22 Hz, 10.45 Hz, 2 H, olefinic

CH in chain in rac-38 and rac-39), 3.26 (m, 4 H, aliphatic CH in

chain in rac-38 and rac-39), 2.79 (m, 36 H, overlapping signals from

aliphatic CH in chain in rac-35 and rac-36, aliphatic CH₂in five-

ring in rac-35 and rac-36, aliphatic CH₂in five-ring in rac-38 and

rac-39), 2.44 (m, 24 H, overlapping signals from CH₃attached to

the aromatic ring in rac-35, rac-36, rac-38 and rac-39), 2.19 (br. s,

8 H, OH in rac-35, rac-36, rac-38 and rac-39), 1.20 (d, J = 6.72 Hz,

12 H, CH₃attached to the aliphatic chain in rac-35, rac-36, rac-38

and rac-39), 0.77 (d, J = 7.01 Hz, 12 H, CH₃attached to the ali-

phatic chain in rac-35, rac-36, rac-38 and rac-39) ppm. The ratio

between the mixtures could not been determined by ¹H NMR spec-

troscopy due to overlapping signals. ¹³C NMR (100.6 MHz,

CDCl₃): overlapping of some of the quaternary carbons with sig-

nals from other carbons δ = 145.74 (C_q), 144.53 (C_q), 141.83 (C_q),

141.42 (C_q), 139.49 (2 olefinic CH in chain in rac-35 and rac-36

and 2 olefinic CH in chain in rac-38 and rac-39), 138.92 (2 olefinic

CH in chain in rac-38 and rac-39), 138.80 (2 olefinic CH in chain

in rac-35 and rac-36), 133.51 (C_q), 133.23 (C_q), 131.14 and 131.05

(signals from aromatic carbons in rac-35, rac-36, rac-38 and rac-

39), 128.18–127.73 (signals from aromatic carbons in rac-35, rac-

36, rac-38 and rac-39), 117.57 (2 olefinic CH₂in chain in rac-35

and rac-36), 116.40 (2 olefinic CH₂in chain in rac-38 and rac-39),

115.39 (2 olefinic CH₂in chain in rac-35 and rac-36), 115.23 (2

olefinic CH₂in chain in rac-38 and rac-39), 88.39 (2 C-OH in rac-

35 and rac-36), 88.03 (2 C-OH in rac-35 and rac-36), 87.92 (2 C-

OH in rac-38 and rac-39), 46.14 (2 aliphatic CH in chain in rac-35

and rac-36), 45.45 (2 aliphatic CH in chain in rac-38 and rac-39),

45.00 (2 aliphatic CH in chain in rac-38 and rac-39), 44.46 (2 ali-

phatic CH in chain in rac-35 and rac-36), 35.67 (2 aliphatic CH₂

in five-ring in rac-35 and rac-36 and/or rac-38 and rac-39), 35.56

(2 aliphatic CH₂in five-ring in rac-35 and rac-36 and/or rac-38 and

rac-39), 29.68 (2 aliphatic CH₂in five-ring in rac-35 and rac-36

and/or rac-38 and rac-39), 29.14 (2 aliphatic CH₂in five-ring in

rac-35 and rac-36 and/or rac-38 and rac-39), 18.01 (2 CH₃attached

to the aromatic ring in rac-35 and rac-36 and/or rac-38 and rac-

39), 17.81 (2 CH₃attached to the aromatic ring in rac-35 and rac-

36 and/or rac-38 and rac-39), 17.51 (2 CH₃attached to the aromatic

ring in rac-35 and rac-36 and/or rac-38 and rac-39), 14.83 (2 CH₃

attached to the chain in rac-35 and rac-36), 14.74 (2 CH₃attached

to the chain in rac-38 and rac-39), 13.24 (2 CH₃attached to the

chain in rac-35 and rac-36), 13.17 (2 CH₃attached to the chain in

rac-38 and rac-39) ppm. EIMS (30 eV): calcd. C₁₄H₁₇OCl

236.0968; found 236.0978.

A Mixture of 3-Allyl-7-chloro-4-methyl-1H-indene (32), 4-Chloro-7-

methyl-1-prop-2-en-(E)-ylidene-indane (33), and 3-Allyl-4-chloro-7-

methyl-1H-indene (34): By applying General Procedure 3, a mixture

of 1-allyl-4-chloro-7-methyl-indan-1-ol (rac-30) and 1-allyl-7-

chloro-4-methyl-indan-1-ol (rac-31) [0.1729 g, 0.78 mmol] and Am-

berlyst 15 (0.1169 g) in pentane (10 mL) gave, after a 2-h reaction

time and column chromatography (hexane as eluent), 0.0554 g

(35%) of a mixture of the title compounds as a colorless oil. ¹H

NMR (400 MHz, CDCl₃): δ = 7.13 (dm, J = 8.09 Hz, 1 H, arom.

CH in 34), 7.06 (d, J = 8.01 Hz, 1 H, arom. CH in 32 or 33), 7.05

(d, J = 8.01 Hz, 1 H, arom. CH in 32 or 33), 6.96 (dm, J = 8.01 Hz,

1 H, arom. CH in 32 or 33), 6.91 (dm, J = 8.01 Hz, 1 H, arom.

CH in 32 or 33), 6.91 (m, 1 H, arom. CH in 34), 6.63 (m, 2 H,

olefinic CH in chain in 33), 6.25 (m, 2 H, olefinic CH in five-ring

in 32 and olefinic CH in five-ring in 34), 6.09 (m, 2 H, olefinic CH

in chain in 32 and olefinic CH in chain in 34), 5.31 (m, 1 H, olefinic

CH in chain in 33), 5.19 (m, 1 H, olefinic CH in chain in 33), 5.14

(m, 2 H, olefinic CH in chain in 32 and olefinic CH in chain in

34), 5.08 (m, 2 H, olefinic CH in chain in 32 and olefinic CH in

chain in 34), 3.61 (m, 2 H, aliphatic CH₂in chain in 34), 3.45 (m,

2 H, aliphatic CH₂in chain in 32), 3.30 (m, 2 H, aliphatic CH₂in

five-ring in 32), 3.19 (m, 2 H, aliphatic CH₂in five-ring in 34), 2.98

(m, 2 H, aliphatic CH₂in five-ring in 33), 2.90 (m, 2 H, aliphatic

CH₂in five-ring in 33), 2.52 (s, 3 H, CH₃attached to the aromatic

ring in 32), 2.47 (s, 3 H, CH₃attached to the aromatic ring in 33),

2.30 (s, 3 H, CH₃attached to the aromatic ring in 34) ppm. The

ratio between 3-allyl-7-chloro-4-methyl-1H-indene (32), 4-chloro-7-

methyl-1-prop-2-en-(E)-ylidene-indane (33), and 3-allyl-4-chloro-7-

methyl-1H-indene (34) was 47% of 32, 42% of 33and 11% of 34.

¹³C NMR (100.6 MHz, CDCl₃): δ = 146.28 (C_qin 32, 33 or 34),

145.78 (C_qin 32, 33 or 34), 145.42 (C_qin 32, 33 or 34), 144.23 (C_q

in 32, 33 or 34), 143.88 (C_qin 32, 33 or 34), 143.54 (C_qin 32, 33

or 34), 142.76 (C_qin 32, 33 or 34), 142.63 (C_qin 32, 33 or 34),

140.61 (C_qin 32, 33 or 34), 140.38 (C_qin 32, 33 or 34), 132.58 (C_q

in 32, 33 or 34), 131.40 (C_qin 32, 33 or 34), 129.52 (C_qin 32, 33

or 34), 128.66 (C_qin 32, 33 or 34), 127.47 (C_qin 32, 33 or 34),

136.42 (olefinic CH in chain in 34), 136.21 (olefinic CH in chain

in 32), 134.89 (olefinic CH in chain in 33), 130.75 (arom. CH in 32

or 33 or olefinic CH in five-ring in 32), 130.64 (arom. CH in 34

and in 32 or 33 or olefinic CH in five-ring in 32), 130.62 (arom.

CH in 32 or 33 or olefinic CH in five-ring in 32), 130.57 (olefinic

CH in five-ring in 34), 128.10 (arom. CH in 34), 127.05 (arom. CH

in 32 or 33), 124.58 (arom. CH in 32 or 33), 124.27 (olefinic CH

in chain in 33), 117.25 (olefinic CH₂in chain in 33), 116.33 (olefinic

CH₂in chain in 32), 115.92 (olefinic CH₂in chain in 34), 37.12

(aliphatic CH₂in five-ring in 32), 36.75 (aliphatic CH₂in five-ring

in 34), 34.80 (aliphatic CH₂in chain in 32), 34.66 (aliphatic CH₂

in chain in 34), 29.45 (aliphatic CH₂in five-ring in 33), 28.55 (ali-

phatic CH₂in five-ring in 33), 21.54 (CH₃attached to the aromatic

ring in 33), 19.40 (CH₃attached to the aromatic ring in 32), 18.05

(CH₃attached to the aromatic ring in 34) ppm. EIMS (70 eV):

calcd. C₁₃H₁₃Cl 204.0706; found 204.0700.

A Mixture of 4-Chloro-7-methyl-1-(1-methyl-allyl)-indan-1-ol (rac-

A Mixture of 7-Chloro-4-methyl-3-(1-methyl-allyl)-1H-indene (rac-

35 and rac-36) and 7-Chloro-4-methyl-1-(1-methyl-allyl)-indan-1-ol 37) and 4-Chloro-7-methyl-3-(1-methyl-allyl)-1H-indene (rac-40): By

Eur. J. Org. Chem. 2005, 1058–1081

Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

applying General Procedure 3, a mixture of 4-chloro-7-methyl-1-

(1-methyl-allyl)-indan-1-ol (rac-35 and rac-36) and 7-chloro-4-

methyl-1-(1-methyl-allyl)-indan-1-ol (rac-38 and rac-39) [0.1828 g,

0.77 mmol] and Amberlyst 15 (0.1189 g) in pentane (10 mL) gave,

after a 2-h reaction time and column chromatography (hexane as

eluent), 0.0560 g (33%) of a mixture of the title compounds as a

colorless, cloudy oil. H NMR (400 MHz, CDCl₃): δ = 7.13 (dm,

J = 8.09 Hz, 2 H, arom. CH in rac-40), 7.04 (dm, J = 8.09 Hz, 2

H, arom. CH in rac-37), 6.96 (dm, J = 8.09 Hz, 2 H, arom. CH in

A Mixture of 3-Allyl-4-bromo-7-methyl-1H-indene (42) and 7-

Bromo-4-methyl-1-prop-2-en-(E)-ylidene-indane (43): By applying

General Procedure 3, an enantiomeric mixture of 1-allyl-7-bromo-

4-methyl-indan-1-ol (rac-41) [0.1462 g, 0.55 mmol] and Amberlyst

15 (0.0805 g) in pentane (5 mL) gave, after a 2-h reaction time and

column chromatography (hexane as eluent), 0.0368 g (27%) of a

mixture of the title compounds as a colorless oil. ¹H NMR

(600 MHz, CDCl₃): δ = 7.51 (m, 1 H, arom. CH in 43), 7.33 (dm,

J = 8.09 Hz, 1 H, arom. CH in 42), 7.28 (m, 1 H, arom. CH in 43),

1

rac-37), 6.91 (dm, J = 8.09 Hz, 2 H, arom. CH in rac-40), 6.33 (m, 6.84 (dm, J = 8.09 Hz, 1 H, arom. CH in 42), 6.80 (m, 1 H, olefinic

4 H, olefinic CH in five-ring in rac-37 and rac-40), 6.15 (m, 2 H, CH in chain in 43), 6.64 (ddd, J = 10.07 Hz, 10.98 Hz, 16.86 Hz,

olefinic CH in chain in rac-40), 6.10 (ddd, J = 5.72 Hz, 10.38 Hz,

17.31 Hz, 2 H, olefinic CH in chain in rac-37), 5.04 (m, 4 H, ole-

finic CH₂in chain in rac-40), 5.02 (dt, J = 1.45 Hz, 10.38 Hz, 2 H,

olefinic CH in chain in rac-37), 4.93 (dt, J = 1.57 Hz, 17.31 Hz, 2

H, olefinic CH in chain in rac-37), 4.14 (m, 2 H, aliphatic CH in

chain in rac-40), 3.74 (m, 2 H, aliphatic CH in chain in rac-37),

3.32 (m, 4 H, aliphatic CH₂in five-ring in rac-37), 3.20 (m, 4 H,

aliphatic CH₂in chain in rac-40), 2.53 (s, 6 H, CH₃attached to the

aromatic ring in rac-37), 2.30 (s, 6 H, CH₃attached to the aromatic

ring in rac-40), 1.35 (d, J = 6.87 Hz, 6 H, CH₃attached to the

chain in rac-37), 1.36 (d, J = 6.87 Hz, 6 H, CH₃attached to the

chain in rac-40) ppm. The mixture contained 78% of an enantio-

1 H, olefinic CH in chain in 43), 6.31 (m, 1 H, olefinic CH in five-

ring in 42), 6.11 (mt, J = 6.48 Hz, 1 H, olefinic CH in chain in 42),

5.37 (dm, J = 16.86 Hz, 1 H, olefinic CH in chain in 43), 5.21 (dm,

J = 10.07 Hz, 1 H, olefinic CH in chain in 43), 5.12 (m, 1 H, ole-

finic CH in chain in 42), 5.11 (m, 1 H, olefinic CH in chain in 42),

3.62 (m, 2 H, aliphatic CH₂in chain in 42 or aliphatic CH₂in five-

ring in 42), 3.18 (m, 2 H, aliphatic CH₂in chain in 42 or aliphatic

CH₂in five-ring in 42), 2.89 (m, 4 H, aliphatic CH₂in five-ring in

43), 2.28 (s, 3 H, CH₃attached to the aromatic ring in 42), 2.18 (s,

3 H, CH₃attached to the aromatic ring in 43) ppm. ¹³C NMR

(150.9 MHz, CDCl₃): δ = 149.16 (C_qin 43), 146.16 (C_qin 42),

144.23 (C_qin 43), 143.97 (C_qin 42), 141.95 (C_qin 42), 137.88 (C_q

meric mixture of 7-chloro-4-methyl-3-(1-methyl-allyl)-1H-indene in 43), 136.38 (olefinic CH in chain in 42), 134.60 (olefinic CH in

and 22% of an enantiomeric mixture of 4-chloro-7-methyl-3-(1-

chain in 43), 132.32 (arom. CH in 43), 132.06 (C_qin 42), 131.59

(arom. CH in 42), 131.15 (olefinic CH in five-ring in 42), 129.50

methyl-allyl)-1H-indene. ¹³C NMR (100.6 MHz, CDCl₃): δ =

149.37 (4C, C_qin rac-37 and rac-40), 144.11 (4C, C_qin rac-37 and (olefinic CH in chain in 43), 127.39 (arom. CH in 42), 124.41

rac-40), 142.83 (4C, C_qin rac-37 and rac-40), 142.61 (2 olefinic CH

in chain in rac-37), 142.53 (2 olefinic CH in chain in rac-40), 131.00

(arom. CH in 43), 122.35 (C_qin 43), 117.88 (olefinic CH in chain

in 43), 116.05 (olefinic CH in chain in 42), 115.15 (C_qin 43), 112.07

(2 arom. CH in rac-37), 129.42 (4C, C_qin rac-37 and rac-40), (C_qin 42), 36.71 (aliphatic CH₂in chain in 42 or aliphatic CH₂in

129.15 (2 olefinic CH in five-ring in rac-40), 129.05 (2 olefinic CH

in five-ring in rac-37), 128.46 (2 arom. CH in rac-40), 127.53 (4C,

C_qin rac-37 and rac-40), 126.96 (2 arom. CH in rac-40), 124.49 (2

five-ring in 42), 34.74 (aliphatic CH₂in chain in 42 or aliphatic

CH₂in five-ring in 42), 29.13 (aliphatic CH₂in five-ring in 43),

28.81 (aliphatic CH₂in five-ring in 43), 18.46 (CH₃attached to the

arom. CH in rac-37), 113.56 (2 olefinic CH₂in chain in rac-37), aromatic ring in 43), 18.15 (CH₃attached to the aromatic ring in

112.81 (2 olefinic CH₂in chain in rac-40), 37.19 (2 aliphatic CH₂

in five-ring in rac-37), 36.80 (2 aliphatic CH₂in five-ring in rac-

40), 36.65 (2 aliphatic CH in chain in rac-37), 35.97 (2 aliphatic

CH in chain in rac-40), 20.46 (2 CH₃attached to the chain in rac-

37), 19.96 (2 CH₃attached to the chain in rac-40), 19.65 (2 CH₃

attached to the aromatic ring in rac-37), 18.11 (2 CH₃attached to

the aromatic ring in rac-40). EIMS (70 eV): calcd. C₁₄H₁₅Cl

218.0862; found 218.0864.

42) ppm. EIMS (70 eV): calcd. C₁₃H₁₃Br 248.0201; found 248.0195.

A Mixture of 7-Bromo-4-methyl-1-(1-methyl-allyl)-indan-1-ol (rac-

44 and rac-45): By applying General Procedure 1, zinc (0.5132 g,

7.8 mmol), 7-bromo-4-methyl-indan-1-one (0.8606 g, 3.8 mmol),

and crotyl bromide (930 µL, 7.6 mmol) gave, after a 3-h reaction

time, 0.8213 g (77%) of a mixture of the title compounds as a color-

less oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.23 (m, 4 H, arom. CH

in rac-44 and/or rac-45), 6.90 (m, 4 H, arom. CH in CH in rac-44

An Enantiomeric Mixture of 1-Allyl-7-bromo-4-methyl-indan-1-ol and/or rac-45), 6.14 (m, 2 H, olefinic CH in chain in CH in rac-44

(rac-41): By applying General Procedure 1, zinc (0.3655 g,

5.6 mmol), 7-bromo-4-methyl-indan-1-one (0.5577 g, 2.5 mmol),

and allyl bromide (430 µL, 5.0 mmol) gave, after a 3-h reaction

time, 0.566 g (85%) of the enantiomeric mixture of the title com-

or rac-45), 5.40 (ddd, J = 6.79 Hz, 10.45 Hz, 17.25 Hz, 2 H, olefinic

CH in chain in rac-44 or rac-45), 5.20 (m, 4 H, olefinic CH₂in

chain in rac-44 or rac-45), 4.91 (dt, J = 1.54 Hz, 17.25 Hz, 2 H,

olefinic CH in chain in rac-44 or rac-45), 4.79 (dt, J = 1.37 Hz,

10.45 Hz, 2 H, olefinic CH in chain inrac-44 or rac-45), 3.29 (m, 4

H, aliphatic CH in chain in rac-44 and rac-45), 2.95–2.35 and 2.02–

1.90 (m, 16 H, overlapping signals from aliphatic CH₂in five-ring

in rac-44 and rac-45), 2.29 (br. s, 2 H, OH in rac-44 or rac-45), 2.28

(br. s, 2 H, OH in rac-44 or rac-45), 2.17 (s, 6 H, CH₃attached to

the aromatic ring inrac-44 or rac-45), 2.15 (s, 6 H, CH₃attached

to the aromatic ring in rac-44 or rac-45), 1.23 (d, J = 6.72 Hz, 6

H, CH₃attached to the chain in rac-44 or rac-45), 0.72 (d, J =

6.94 Hz, 6 H, CH₃attached to the chain in rac-44 or rac-45) ppm.

¹³C NMR (100.6 MHz, CDCl₃): δ = 145.68 (2 C_qin rac-44 or rac-

1

pounds as a yellow oil. H NMR (600 MHz, CDCl₃): δ = 7.15 (m,

2 H, arom. CH), 6.82 (m, 2 H, arom. CH), 5.63 (ddt, J = 7.36 Hz,

10.41 Hz, 17.17 Hz, 2 H, olefinic CH in chain), 5.05 (dm, J =

17.17 Hz, 2 H, olefinic CH in chain), 4.99 (dm, J = 10.41 Hz, 2 H,

olefinic CH in chain), 2.73 (m, 2 H, aliphatic CH in five-ring), 2.69

(dd, J = 7.36 Hz, 13.75 Hz, 2 H, aliphatic CH in chain), 2.62 (dd,

J = 7.36 Hz, 13.75 Hz, 2 H, aliphatic CH in chain), 2.53 (m, 2 H,

aliphatic CH in five-ring), 2.35 (m, 2 H, aliphatic CH in five-ring),

2.21 (br. s, 2 H, OH), 2.11 (s, 6 H, CH₃), 2.02 (m, 2 H, aliphatic

CH in five-ring) ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 144.70

(2 C_q), 143.24 (2 C_q), 133.47 (2 C_q), 133.22 (2 olefinic CH in chain), 45), 145.50 (2 C_qin rac-44 or rac-45), 143.17 (2 C_qin rac-44 or

131.10 (2 arom. CH), 130.28 (2 arom. CH), 118.18 (2 olefinic CH₂rac-45), 142.49 (2 C_qin rac-44 or rac-45), 139.38 (2 olefinic CH in

in chain), 115.13 (2 C_q), 84.99 (2 C–OH), 43.85 (2 aliphatic CH₂

in chain), 38.01 (2 aliphatic CH₂in five-ring), 27.86 (2 aliphatic

CH₂in five-ring), 18.20 (2 CH₃) ppm. EIMS (30 eV): calcd.

C₁₃H₁₅OBr 266.0306; found 266.0313.

chain in rac-44 or rac-45), 138.73 (2 olefinic CH in chain inrac-44

or rac-45), 133.65 (2 C_qin rac-44 or rac-45), 133.61 (2 C_qin rac-

44 or rac-45), 131.61 (2 arom. CH in rac-44 or rac-45), 131.30 (2

arom. CH in rac-44 or rac-45), 130.57 (2 arom. CH in rac-44 or

Eur. J. Org. Chem. 2005, 1058–1081

www.eurjoc.org

1073

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

FULL PAPER

rac-45), 130.49 (2 arom. CH in rac-44 or rac-45), 116.39 (2 olefinic

CH₂in chain in rac-44 or rac-45), 115.45 (2 C_qin rac-44 or rac-

45), 115.20 (2 olefinic CH₂in chain in rac-44 or rac-45), 115.16 (2

C_qin rac-44 or rac-45), 88.21 (4 C-OH in rac-44 or rac-45), 45.27

(2 aliphatic CH in chain in rac-44 or rac-45), 44.72 (2 aliphatic CH

in chain rac-44 or rac-45), 34.33 (2 aliphatic CH₂in five-ring in

rac-44 or rac-45), 33.62 (2 aliphatic CH₂in five-ring in rac-44 or

rac-45), 29.23 (2 aliphatic CH₂in five-ring in rac-44 or rac-45),

28.94 (2 aliphatic CH₂in five-ring in rac-44 or rac-45), 18.38 (4

CH₃attached to the aromatic ring in rac-44 and rac-45), 14.54 (2

CH₃attached to the chain in rac-44 or rac-45), 13.05 (2 CH₃at-

tached to the chain in rac-44 or rac-45) ppm. EIMS (30 eV): calcd.

C₁₄H₁₇OBr 280.0463; found 280.0451.

CH₂in chain), 2.25 (s, 1 H, OH) ppm. ¹³C NMR (100.6 MHz,

CDCl₃): δ = 141.11 (2 C_q), 133.93 (olefinic CH in chain), 126.51

(2 arom. CH), 124.88 (2 arom. CH), 118.85 (olefinic CH₂in chain),

81.41 (C–OH), 46.34 (2 aliphatic CH₂in five-ring), 44.92 (aliphatic

CH₂in chain) ppm. EIMS (70 eV): calcd. C₁₂H₁₄O 174.1045; found

174.1044.

2-Allyl-1H-indene (48): By applying General Procedure 4, 2-allyl-

indan-2-ol (47) [14.67 g, 84.2 mmol] and p-TSA (1.4 g, 7.4 mmol)

in toluene (200 mL) gave, after a 2-h reaction time and column

chromatography (hexane as eluent), 5.031 g (38%) of the title com-

pound as a colorless oil. ¹H NMR (600 MHz, CDCl₃): δ = 7.55

(ddd, J = 0.84 Hz, 1.83 Hz, 7.32 Hz, 1 H, arom. CH), 7.44 (m, 2

H, arom. CH), 7.31 (td, J = 1.30 Hz, 7.32 Hz, 1 H, arom. CH),

6.72 (m, 1 H, olefinic CH in five-ring), 6.16 (ddt, J = 6.79 Hz,

10.0 Hz, 16.86 Hz, 1 H, olefinic CH in chain), 5.35 (dm, J =

16.86 Hz, 1 H, olefinic CH in chain), 5.31 (dm, J = 10.0 Hz, 1 H,

olefinic CH in chain), 3.46 (m, 2 H, aliphatic CH₂in five-ring),

3.40 (m, 2 H, aliphatic CH₂in chain) ppm. ¹³C NMR (150.9 MHz,

CDCl₃): δ = 148.11 (C_q), 145.38 (C_q), 143.15 (C_q), 136.04 (olefinic

CH in chain), 126.99 (olefinic CH in five-ring), 126.16 (arom. CH),

123.70 (arom. CH), 123.33 (arom. CH), 120.01 (arom. CH), 115.98

(olefinic CH₂in chain), 40.88 (aliphatic CH₂in five-ring), 35.65

(aliphatic CH₂in chain) ppm. EIMS (70 eV): calcd. C₁₂H₁₂

156.0939; found 156.0939.

An Enantiomeric Mixture of 4-Bromo-7-methyl-3-(1-methyl-allyl)-

1H-indene (rac-46): By applying General Procedure 3, a mixture of

7-bromo-4-methyl-1-(1-methyl-allyl)-indan-1-ol (rac-44 and rac-45)

[0.2042 g, 0.73 mmol] and Amberlyst 15 (0.1159 g) in pentane

(10 mL) gave, after a 1-h reaction time and column chromatog-

raphy (hexane as eluent), 0.0701 g (36%) of an enantiomeric mix-

1

ture of the title compounds as a colorless oil. H NMR (400 MHz,

CDCl₃): δ = 7.35 (d, J = 8.01 Hz, 2 H, arom. CH), 6.85 (dm, J =

8.01 Hz, 2 H, arom. CH), 6.37 (m, 2 H, olefinic CH in five-ring),

6.19 (ddd, J = 5.64 Hz, 9.84 Hz, 17.85 Hz, 2 H, olefinic CH in

chain), 5.05 (dt, J = 1.57 Hz, 9.84 Hz, 2 H, olefinic CH in chain),

5.04 (dt, J = 1.68 Hz, 17.85 Hz, 2 H, olefinic CH in chain), 4.27

(m, 2 H, aliphatic CH in chain), 3.19 (m, 4 H, aliphatic CH₂in

five-ring), 2.30 (s, 6 H, CH₃attached to the aromatic ring), 1.38

(d, J = 6.87 Hz, 6 H, CH₃attached to the chain) ppm. ¹³C NMR

(100.6 MHz, CDCl₃): δ = 149.38 (2 C_q), 146.35 (2 C_q), 142.49 (2

olefinic CH in chain), 141.43 (2 C_q), 132.02 (2 C_q), 131.95 (2 arom.

CH), 129.74 (2 olefinic CH in five-ring), 127.27 (2 arom. CH),

112.79 (2 olefinic CH₂in chain), 111.96 (2 C_q), 36.71 (2 aliphatic

CH₂in five-ring), 35.42 (2 aliphatic CH in chain), 20.03 (2 CH₃

attached to the chain), 18.14 (2 CH₃attached to the aromatic ring)

ppm. EIMS (70 eV): calcd. C₁₄H₁₅Br 262.0357; found 262.0360.

An Enantiomeric Mixture of 2-(1-Methyl-allyl)-indan-2-ol (rac-49):

By applying General Procedure 1, zinc (13.08 g, 200 mmol), 2-in-

danone (13.22 g, 100 mmol), and crotyl bromide (27.0 g,

200 mmol) gave, after a 4-h reaction time, 16.5 g (88%) of an enan-

1

tiomeric mixture of the title compounds as a green oil. H NMR

(400 MHz, CDCl₃): δ = 7.26 (m, 8 H, arom. CH), 6.02 (ddd, J=

8.01 Hz, 10.38 Hz, 17.17 Hz, 2 H, olefinic CH in chain), 5.23 (dm,

J = 17.17 Hz, 2 H, olefinic CH in chain), 5.21 (dm, J = 10.38 Hz,

2 H, olefinic CH in chain), 3.18 (m, 4 H, aliphatic CH₂in five-ring),

2.93 (m, 4 H, aliphatic CH₂in five-ring), 2.55 (m, 2 H, aliphatic CH

in chain), 2.00 (br. s, 2 H, OH), 1.22 (d, J = 6,9 Hz, 3 H, CH₃)

ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ = 141.25 (2 C_q), 141.23 (2

C_q), 140.14 (2 olefinic CH in chain), 126.46 (4 C, arom. CH),

124.91 (4 C, arom. CH), 115.92 (2 olefinic CH₂in chain), 83.81 (2

C–OH), 46.86 (2 aliphatic CH in chain), 45.73 (2 aliphatic CH₂in

five-ring), 45.18 (2 aliphatic CH₂in five-ring), 14.87 (2 CH₃) ppm.

EIMS (70 eV): calcd. C₁₃H₁₆O 188.1201; found 188.1200.

An Enantiomeric Mixture of 1-Allyl-indan-1-ol (rac-1) from Al-

lylation of 2-Bromo-indan-1-one: By applying General Procedure 1,

zinc (0.4719 g, 7.2 mmol), 2-bromo-indan-1-one (0.6706 g,

3.2 mmol), and allyl bromide (550 µL, 6.4 mmol) gave, after a 2-h

reaction time, 0.3855 g (48%) of an enantiomeric mixture of the

1

title compounds as a brown oil. H NMR (600 MHz, CDCl₃): δ =

An Enantiomeric Mixture of 2-(1-Methyl-allyl)-1H-indene (rac-50):

By applying General Procedure 4, an enantiomeric mixture of 2-

(1-methyl-allyl)-indan-2-ol (rac-49) (16.5 g, 88 mmol) and concen-

trated sulfuric acid (22 drops) in toluene (30 mL) gave, after a 9.5-

h reaction time and column chromatography (hexane as eluent),

7.93 g (53%) of an enantiomeric mixture of the title compounds as

7.25 (m, 2 H, arom. CH), 7.16 (m, 2 H, arom. CH), 5.77 (m, 2 H,

olefinic CH in chain), 5.08 (m, 2 H, olefinic CH in chain), 5.06 (m,

2 H, olefinic CH in chain), 2.93 (m, 2 H, aliphatic CH in five-ring),

2.73 (m, 2 H, aliphatic CH in five-ring), 2.56 (m, 2 H, aliphatic CH

in chain), 2.43 (m, 2 H, aliphatic CH in chain), 2.25 (m, 4 H, OH

and aliphatic CH in five-ring), 1.99 (m, 2 H, aliphatic CH in five-

ring) ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 146.99 (2 C_q),

142.95 (2 C_q), 133.73 (2 olefinic CH in chain), 128.22 (2 arom.

CH), 126.62 (2 arom. CH), 124.89 (2 arom. CH), 122.85 (2 arom.

CH), 118.78 (2 olefinic CH₂in chain), 82.70 (2 C-OH), 44.94 (2

aliphatic CH₂in chain), 39.62 (2 aliphatic CH₂in five-ring), 29.37

(2 aliphatic CH₂in five-ring) ppm. EIMS (30 eV): calcd. C₁₂H₁₄O

174.1045; found 174.1032.

1

a yellow oil. H NMR (400 MHz, CDCl₃): δ = 7.25 (dm, J = 7.40,

2 H, arom. CH), 7.16 (dm, J = 7.40, 2 H, arom. CH), 7.10 (tm, J

= 7.40 Hz, 2 H, arom. CH), 6.99 (tm, J = 7.40 Hz, 2 H, arom.

CH), 6.43 (m, 2 H, olefinic CH in five-ring), 5.78 (ddd, J = 7.33 Hz,

10.15 Hz, 17.24 Hz, 2 H, olefinic CH in chain), 4.98 (dt, J =

1.30 Hz, 17.24 Hz, 2 H, olefinic CH in chain), 4.91 (ddd, J =

0.99 Hz, 1.60 Hz, 10.15 Hz, 2 H, olefinic CH in chain) 3.19 (m, 6

H, aliphatic CH₂in five-ring and aliphatic CH in chain), 1.22 (d,

J = 6,9 Hz, 6 H, CH₃) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ =

2-Allyl-indan-2-ol (47): By applying General Procedure 1, zinc

(13.08 g, 200 mmol), 2-indanone (13.215 g, 100 mmol), and allyl 153.57 (2 C_q), 145.31 (2 C_q), 143.14 (2 C_q), 142.52 (2 olefinic CH

bromide (24.194 g, 200 mmol) gave, after a 19-h reaction time,

14.674 g (84%) of the title compound as a green oil. ¹H NMR

(400 MHz, CDCl₃): δ = 7.25 (m, 4 H, arom. CH), 6.03 (m, 1 H,

olefinic CH in chain), 5.27 (m, 2 H, olefinic CH₂in chain), 3.14 (d,

J = 16,2 Hz, 2 H, aliphatic CH in five-ring), 2.99 (d, J = 16,2 Hz, 2

H, aliphatic CH in five-ring), 2.56 (d, J = 7.25 Hz, 2 H, aliphatic

in chain), 126.24 (2 arom. CH), 125.57 (2 olefinic CH in five-ring),

123.78 (2 arom. CH), 123.47 (2 arom. CH), 120.19 (2 arom. CH),

113.47 (2 olefinic CH₂in chain), 39.69 (2 aliphatic CH₂in five-ring

or aliphatic CH in chain), 39.49 (2 aliphatic CH₂in five-ring or

aliphatic CH in chain), 19.53 (2 CH₃) ppm. EIMS (70 eV): calcd.

C₁₃H₁₄170.1096; found 170.1093.

1074

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Eur. J. Org. Chem. 2005, 1058–1081

Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

An Enantiomeric Mixture of 2-(1-Phenyl-allyl)-indan-2-ol (rac-51):

By applying General Procedure 1, zinc (13.08 g, 200 mmol), 2-in-

danone (13.215 g, 100 mmol), and cinnamyl chloride (30.522 g,

200 mmol) gave, after a 19-h reaction time, 34.9 g (100%, contains

some solvent) of an enantiomeric mixture of the title compounds

CH), 7.29 (d, J = 7.25 Hz, 1 H, arom. CH), 7.22 (t, J = 7.25 Hz,

1 H, arom. CH), 7.11 (t, J = 7.25 Hz, 1 H, arom. CH), 6.57 (s, 1

H, olefinic CH in five-ring), 5.97 (dd, J = 11.32 Hz, 17.89 Hz, 1 H,

olefinic CH in chain), 5.03 (dm, J = 17.89 Hz, 1 H, olefinic CH in

chain), 4.97 (dm, J = 11.32 Hz, 1 H, olefinic CH in chain), 3.35 (s,

2 H, aliphatic CH₂in the five-ring), 1.35 (s, 6 H, CH₃attached to

the chain) ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 157.46 (C_q),

147.43 (olefinic CH in chain), 145.30 (C_q), 143.43 (C_q), 126.39

(arom. CH), 125.19 (olefinic CH in the five-ring), 123.99 (arom.

CH), 123.65 (arom. CH), 120.45 (arom. CH), 110.96 (olefinic CH₂

in chain), 38.28 (aliphatic CH₂in the five-ring), 27.46 (CH₃at-

1

as a dark oil. H NMR (400 MHz, CDCl₃): δ = 7.39–7.10 (m, 18

H, arom. CH), 6.40 (ddd, J = 9.08 Hz, 10.22 Hz, 17.01 Hz, 2 H,

olefinic CH in chain), 5.22 (dm, J = 10.22 Hz, 2 H, olefinic CH in

chain), 5.18 (dm, J = 17.01 Hz, 2 H, olefinic CH in chain), 3.54 (d,

J = 9.08 Hz, 2 H, aliphatic CH in chain), 3.20 (m, 4 H, aliphatic

CH in five-ring), 2.95 (m, 2 H, aliphatic CH in five-ring), 2.57 (m,

2 H, aliphatic CH in five-ring), 1.75 (br. s, 2 H, OH) ppm. ¹³C tached to the chain) ppm. EIMS (70 eV): calcd. C₁₄H₁₆184.1252;

NMR (100.6 MHz, CDCl₃): δ = 141.03 (6C_q), 137.81 (2 olefinic

CH in chain), 129.00 (2 arom. CH), 128.49 (2 arom. CH), 126.88

(2 arom. CH), 126.60 (2 arom. CH), 125.01 (2 arom. CH), 124.93

(2 arom. CH), 117.56 (2 olefinic CH₂in chain), 84.14 (2 C–OH),

59.24 (2 aliphatic CH in chain), 46.15 (2 aliphatic CH₂in five-ring),

45.94 (2 aliphatic CH₂in five-ring) ppm. EIMS (30 eV): calcd.

C₁₈H₁₈O 250.1358; found 250.1353.

found 184.1253.

An Enantiomeric Mixture of 4,7-Dimethyl-2-(1-methyl-allyl)-indan-

2-ol (rac-55): By applying General Procedure 1, zinc (0.1930 g,

2.95 mmol), 4,7-dimethyl-indan-2-one (0.2323 g, 1.45 mmol), and

crotyl bromide (350 µL, 2.90 mmol) gave, after a 2-h reaction time,

0.2345 g (75%) of an enantiomeric mixture of the title compounds

as a very pale brown oil. ¹H NMR (600 MHz, CDCl₃): δ = 6.91

An Enantiomeric Mixture of 2-(1-Phenyl-allyl)-1H-indene (rac-52): (m, 4 H, arom. CH), 5.98 (ddd, J = 8.12 Hz, 10.61 Hz, 17.48 Hz,

By applying General Procedure 4, an enantiomeric mixture of 2-

(1-phenyl-allyl)-indan-2-ol (rac-51) [34.9 g, 139 mmol] and p-TSA

(1.7 g, 8.9 mmol) in toluene (200 mL) gave, after a 6.5-h reaction

time and column chromatography (hexane as eluent), 3.18 g (15%)

of an enantiomeric mixture of the title compounds as a colorless

oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.31 (m, 8 H, arom. CH),

2 H, olefinic CH in chain), 5.18 (dm, J = 17.48 Hz, 2 H, olefinic

CH in chain), 5.15 (dm, J = 10.61 Hz, 2 H, olefinic CH in chain),

3.02 (d, J = 16.70 Hz, 2 H, aliphatic CH in five-ring), 3.01 (d, J =

16.70 Hz, 2 H, aliphatic CH in five-ring), 2.86 (d, J = 16.23 Hz, 2

H, aliphatic CH in five-ring), 2.82 (d, J = 16.23 Hz, 2 H, aliphatic

CH in five-ring), 2.50 (m, 2 H, aliphatic CH in chain), 2.21 (s, 6

7.22 (m, 8 H, arom. CH), 7.10 (m, 2 H, arom. CH), 6.59 (m, 2 H, H, CH₃attached to the aromatic ring), 2.20 (s, 6 H, CH₃attached

olefinic CH in five-ring), 6.27 (ddd, J = 7.47 Hz, 10.07 Hz,

17.09 Hz, 2 H, olefinic CH in chain), 5.19 (ddd, J = 1.07 Hz,

1.60 Hz, 10.07 Hz, 2 H, olefinic CH in chain), 5.08 (ddd, J =

1.30 Hz, 1.60 Hz, 17.09 Hz, 2 H, olefinic CH in chain), 4.50 (dm,

J = 7.47 Hz, 2 H, aliphatic CH in chain), 3.26 (m, 4 H, aliphatic

CH₂in five-ring) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ = 151.35

(2 C_q), 144.95 (2 C_q), 143.34 (2 C_q), 142.49 (2 C_q), 139.78 (2 olefinic

CH in chain), 128.49, 128.23, 128.03, 126.52, 126.28, 124.05,

123.48, 120.45 (18 C, overlapping arom. CH), 115.88 (2 olefinic

CH₂in chain), 51.78 (2 aliphatic CH in chain), 40.20 (2 aliphatic

CH₂in five-ring) ppm. EIMS (70 eV): calcd. C₁₈H₁₆232.1252;

found 232.1251.

to the aromatic ring), 1.71 (br. s, 2 H, OH), 1.17 (d, J = 6.87 Hz,

6 H, CH₃attached to the aliphatic chain) ppm. ¹³C NMR

(150.9 MHz, CDCl₃): δ = 140.40 (2 olefinic CH in chain), 139.80

(2 C_q), 131.69 (2 C_q), 127.76 (4C, arom. CH), 116.22 (2 olefinic

CH₂in chain), 83.30 (2 C–OH), 47.25 (2 aliphatic CH in chain),

45.01 (2 aliphatic CH₂in five-ring), 44.41 (2 aliphatic CH₂in five-

ring), 18.95 (4 CH₃attached to the aromatic ring), 15.23 (2 CH₃

attached to the aliphatic chain) ppm. EIMS (70 eV): calcd.

C₁₅H₂₀O 216.1514; found 216.1514.

An Enantiomeric Mixture of 4,7-Dimethyl-2-(1-methyl-allyl)-1H-in-

dene (rac-56): By applying General Procedure 3, an enantiomeric

mixture of 4,7-dimethyl-2-(1-methyl-allyl)-indan-2-ol (rac-55)

2-(1,1-Dimethyl-allyl)-indan-2-ol (53): By applying General Pro- (0.0796 g, 0.37 mmol) and Amberlyst 15 (0.0598 g) in pentane

cedure 1, zinc (1.134 g, 17,34 mmol), 2-indanone (1.119 g,

8.47 mmol), and prenyl bromide (2.0 mL, 16.96 mmol) gave, after

a 3-h reaction time, 1.5617 g (91%) of the title compound as a

(5 mL) gave, after a 24-h reaction time and column chromatog-

raphy (hexane as eluent), 0.0094 g (13%) of an enantiomeric mix-

ture of the title compounds as a colorless oil. H NMR (600 MHz,

1

brown oil. H NMR (600 MHz, CDCl₃): δ = 7.20 (m, 2 H, arom.

CDCl₃): δ = 6.97 (d, J = 7.69 Hz, 2 H, arom. CH), 6.85 (d, J =

CH), 7.15 (m, 2 H, arom. CH), 6.04 (dd, J = 10.46 Hz, 17.0 Hz, 1 7.69 Hz, 2 H, arom. CH), 6.65 (m, 2 H, olefinic CH in five-ring),

H, olefinic CH in chain), 5.17 (dm, J = 17.0 Hz, 1 H, olefinic CH

in chain), 5.11 (dm, J = 10.46 Hz, 1 H, olefinic CH in chain), 3.32

(s, 1 H, aliphatic CH in five-ring), 3.30 (s, 1 H, aliphatic CH in

five-ring), 2.76 (s, 1 H, aliphatic CH in five-ring), 2.73 (s, 1 H,

aliphatic CH in five-ring), 1.16 (s, 6 H, CH₃attached to the chain)

ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 141.39 (olefinic CH in

chain), 137.90 (C_q), 126.73 (arom. CH), 126.52 (arom. CH), 125.29

(arom. CH), 125.11 (arom. CH), 114.06 (olefinic CH₂in chain),

86.49 (C–OH), 42.96 (2 aliphatic CH₂in five-ring), 22.86 (CH₃at-

tached to the chain), 22.81 (CH₃attached to the chain) ppm. EIMS

(30 eV): calcd. C₁₄H₁₈O 202.1358; found 202.1363.

5.93 (ddd, J = 7.02 Hz, 10.23 Hz, 17.66 Hz, 2 H, olefinic CH in

chain), 5.10 (dm, J = 17.66 Hz, 2 H, olefinic CH in chain), 5.04

(dm, J = 10.23 Hz, 2 H, olefinic CH in chain), 3.37 (m, 2 H, ali-

phatic CH in chain), 3.25 (d, J = 22.36 Hz, 2 H, aliphatic CH in

five-ring), 3.20 (d, J = 22.36 Hz, 2 H, aliphatic CH in five-ring),

2.39 (s, 6 H, CH₃attached to the aromatic ring), 2.30 (s, 6 H, CH₃

attached to the aromatic ring), 1.35 (d, J = 6.96 Hz, 6 H, CH₃

attached to the aliphatic chain) ppm. ¹³C NMR (150.9 MHz,

CDCl₃): δ = 152.74 (2 C_q), 143.10 (2 olefinic CH in chain), 141.69

(2 C_q), 130.20 (2 C_q), 127.81 (2 arom. CH), 125.41 (2 arom. CH),

124.19 (2 olefinic CH in five-ring), 113.56 (2 olefinic CH₂in chain),

39.98 (2 aliphatic CH in chain), 38.82 (2 aliphatic CH₂in five-ring),

19.84 (2 CH₃attached to the aliphatic chain), 18.61 (2 CH₃at-

tached to the aromatic ring), 18.30 (2 CH₃attached to the aromatic

ring) ppm. EIMS (70 eV): calcd. C₁₅H₁₈198.1409; found 198.1409.

2-(1,1-Dimethyl-allyl)-1H-indene (54): By applying General Pro-

cedure 3, 2-(1,1-dimethyl-allyl)-indan-2-ol (53) [0.0865 g,

0.43 mmol] and Amberlyst 15 (0.0751 g) in pentane (3 mL) gave,

after a 19-h reaction time and column chromatography (hexane as

eluent), 0.0088 g (11%) of the title compound as a colorless oil. ¹H

NMR (600 MHz, CDCl₃): δ = 7.37 (d, J = 7.25 Hz, 1 H, arom.

An Enantiomeric Mixture of 1-Allyl-3,4-diphenyl-cyclopent-2-enol

(rac-57): By applying General Procedure 1, zinc (0.5332 g,

Eur. J. Org. Chem. 2005, 1058–1081

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1075

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

FULL PAPER

8.2 mmol), 3,4-diphenyl-cyclopent-2-enone (0.9379 g, 4.0 mmol),

and allyl bromide (700 µL, 8.0 mmol) gave, after a 19-h reaction

time and column chromatography (dichloromethane as eluent),

0.1035 g (9%) of the title compound as a yellow oil. ¹H NMR

(400 MHz, CDCl₃): δ = 7.17 (m, 20 H, arom. CH), 6.25 (m, 2 H,

olefinic CH in five-ring), 5.85 (m, 2 H, olefinic CH in chain), 5.12

(m, 4 H, olefinic CH₂in chain), 4.22 (m, 2 H, aliphatic CH in five-

ring), 2.71 (m, 2 H, aliphatic CH in five-ring), 2.44 (m, 4 H, ali-

phatic CH₂in chain), 1.86 (m, 2 H, aliphatic CH in five-ring), 1.82

(s, 2 H, OH) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ = 146.25 (2

C_q), 144.84 (2 C_q), 134.92 (2 C_q), 133.68 (2 olefinic CH in chain),

133.03 (2 olefinic CH in five-ring), 128.64, 128.21, 127.63, 126.93,

126.20 (20 overlapping arom. CH), 118.98 (2 olefinic CH₂in chain),

83.32 (2 C-OH), 50.30 (2 aliphatic CH in five-ring), 48.91 (2 ali-

phatic CH₂five-ring), 45.67 (2 aliphatic CH₂five-ring) ppm.

in five-ring in rac-60 and rac-61), 2.53 (m, 4 H, aliphatic CH in

chain in rac-60 and rac-61), 1.88 (m, 4 H, aliphatic CH in five-ring

in rac-60 and rac-61), 1.82 (m, 4 H, OH in rac-60 and rac-61), 1.15

(d, J = 6.8 Hz, 6 H, CH₃in rac-60 or rac-61), 1.11 (d, J = 6.9 Hz,

6 H, CH₃in rac-60 or rac-61) ppm.¹³C NMR (100.6 MHz, CDCl₃):

δ = 146.84 (2 C_qin rac-60 or rac-61), 146.71 (2 C_qin rac-60 or rac-

61), 145.07 (4 C_qin rac-60 and rac-61), 139.95 (2 olefinic CH in

chain in rac-60 or rac-61), 139.85 (2 olefinic CH in chain in rac-60

or rac-61), 135.00 (2 C_qrac-60 or rac-61), 134.96 (2 C_qin rac-60 or

rac-61), 131.99 (2 olefinic CH in five-ring in rac-60 or rac-61),

131.81 (2 olefinic CH in five-ring in rac-60 or rac-61), 128.63,

128.21, 127.62, 126.95, 126.16 (40 C, overlapping arom. CH in rac-

60 and rac-61), 116.54 (2 olefinic CH₂in chain in rac-60 or rac-

61), 116.36 (2 olefinic CH₂in chain in rac-60 or rac-61), 85.99 (2

C-OH in rac-60 or rac-61), 85.91 (2 C–OH in rac-60 or rac-61),

50.44 (2 aliphatic CH in five-ring in rac-60 or rac-61), 50.12 (2

aliphatic CH in five-ring in rac-60 or rac-61), 47.55 (2 aliphatic CH

in chain in rac-60 or rac-61), 47.23 (2 aliphatic CH in chain in rac-

60 or rac-61), 45.76 (4 C, aliphatic CH₂in five-ring in rac-60 and

rac-61), 15.16 (2 CH₃in rac-60 or rac-61), 14.36 (2 CH₃in rac-60

or rac-61).

A

Mixture of 1,5-Diphenyl-3-prop-2-en-(Z)-ylidene-cyclopentene

(58) and 1,5-Diphenyl-3-prop-2-en-(E)-ylidene-cyclopentene (59): By

applying General Procedure 3, an enantiomeric mixture of 1-allyl-

3,4-diphenyl-cyclopent-2-enol (rac-57) [103.5 mg, 0.37 mmol] and

Amberlyst 15 (0.0430 g) in pentane (5 mL) gave, after a 23-h reac-

tion time and purification by preparative TLC (10% dichlorometh-

ane/90% hexane as eluent), 0.0207 g (22%) of a 2:1 mixture of the

An Enantiomeric Mixture of 1,2-Diphenyl-4-(1-methyl-allyl)-cy-

clopenta-1,3-diene (rac-62): By applying General Procedure 5, a

1

title compounds as a yellow oil. H NMR (400 MHz, CDCl₃): δ =

7.20 (m, 20 H, arom. CH from 58 and 59), 6.80 (m, 2 H, five-ring mixture of 1-(1-methyl-allyl)-3,4-diphenyl-cyclopent-2-enol(rac-60

olefinic CH in 58 and 59), 6.77 (ddd, J = 16,9 Hz, 11,1 Hz, 10,1 Hz,

1 H, chain olefinic CH in 59), 6.42 (ddd, J = 16,9 Hz, 11,3 Hz,

10,1 Hz, 1 H, chain olefinic CH in 58), 6.18 (dm, J = 11,1 Hz, 1

H, chain olefinic CH in 58), 5.91 (dm, J = 11,2 Hz, 1 H, chain

olefinic CH in 59), 5.17 (dm, J = 16,7 Hz, 1 H, chain olefinic CH

in 58), 5.11 (dm, J = 16,7 Hz, 1 H, chain olefinic CH in 59), 5.03

(dm, J = 10,2 Hz, 1 H, chain olefinic CH in 58), 5.02 (dm, J =

10,4 Hz, 1 H, chain olefinic CH in 59), 4.48 (dm, J = 8,7 Hz, 1 H,

five-ring aliphatic CH in 58), 4.41 (dm, J = 8,5 Hz, 1 H, five-ring

aliphatic CH in 59), 3.30 (ddd, J = 17,1 Hz, 8,6 Hz, 2,6 Hz, 1 H,

andrac-61) [0.6969 g, 2.4 mmol] and MgSO₄(0.3652 g, 3.0 mmol)

in toluene (20 mL) gave, after a 1-h reaction time and column

chromatography (a mixture of 30% of dichloromethane and 70%

of hexane as eluent), 0.2210 g of a yellow oil. ¹H NMR (400 MHz,

CDCl₃): δ = 7.31 (m, 20 H, arom. CH), 6.42 (m, 2 H, olefinic CH

in five-ring), 5.98 (m, 2 H, olefinic CH in chain), 5.16 (dm, J =

17.17 Hz, 2 H, olefinic CH in chain), 5.07 (dm, J = 10.07 Hz, 2 H,

olefinic CH in chain), 3.55 (dm, J = 23.23 Hz, 2 H, aliphatic CH

in five-ring), 3.50 (dm, J = 23.23 Hz, 2 H, aliphatic CH in five-

ring), 3.38 (m, 2 H, aliphatic CH in chain), 1.38 (d, J = 6.94 Hz, 6

five-ring aliphatic CH in 58), 3.29 (ddm, J = 17 Hz, 8 Hz, 1 H, H, CH₃attached to the chain) ppm. The yield of the desired com-

five-ring aliphatic CH in 59), 2.66 (dt, J = 17,2 Hz, 2,4 Hz, 1 H, pound could not be determined due to the high-molecular-weight

five-ring aliphatic CH in 58), 2.57 (dm, J = 16.9 Hz, 1 H, five-ring

side-products present in the reaction product. ¹³C NMR

(100.6 MHz, CDCl₃): the signals for the quaternary carbon atoms

aliphatic CH in 59) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ =

151.92, 150.98, 148.23, 147.12, 145.32, 145.06 (8 C, overlapping of the desired reaction product could not be separated from the

signals from C_qfrom both stereoisomers), 134.52 (1 C, olefinic CH

signals which originate from the high-molecular-weight side-prod-

in chain in 58), 134.00 (1 C, olefinic CH in chain in 59), 131.53 (2

ucts, δ = 142.94 (2 olefinic CH in chain), 130.45 (2 olefinic CH in

C, five-ring olefinic CH in 58 and 59), 128.70 (4 C, overlapping five-ring), 128.77–126.11 (overlapping signals from arom. CH both

arom. CH in 58 and 59), 128.29 (4 C, overlapping arom. CH in 58

and 59), 127.12 (4 C, overlapping arom. CH in 58 and 59), 126.54

(4 C, overlapping arom. CH in 58 and 59), 126.28 (4 C, overlapping

arom. CH in 58 and 59), 121.22 (1 C, olefinic CH in chain in 58),

120.50 (1 C, olefinic CH in chain in 59), 115.35 (1 C, olefinic chain

CH₂in 58), 114.09 (1 C, olefinic chain CH₂in 59), 50.44 (1 C, five-

ring aliphatic CH in 58), 49.70 (1 C, five-ring aliphatic CH in 59),

42.18 (1 C, five-ring aliphatic CH₂in 59), 39.00 (1 C, five-ring ali-

phatic CH₂in 58) ppm.

in the desired compound and in the side products), 113.20 (2 ole-

finic CH₂in chain), 45.78 (2 aliphatic CH₂in five-ring), 39.43 (2

aliphatic CH in chain), 19.79 (2 CH₃attached to the chain) ppm.

EIMS (70 eV): calcd. C₂₁H₂₀272.1565; found 272.1567.

A Mixture of 3,4-Diphenyl-1-(1-phenyl-allyl)-cyclopent-2-enol (rac-

63 and rac-64): By applying General Procedure 1, zinc (0.7079 g,

10.8 mmol), 3,4-diphenyl-cyclopent-2-enone (1.2405 g, 5.3 mmol),

and cinnamyl chloride (1.6218 g, 10.6 mmol) gave, after a 5-h reac-

tion time and column chromatography (dichloromethane as elu-

ent), 0.9521 g (51%) of a mixture of the title compounds as a yellow

A Mixture of 1-(1-Methyl-allyl)-3,4-diphenyl-cyclopent-2-enol (rac-

60 and rac-61): By applying General Procedure 1, zinc (0.5797 g,

1

oil. H NMR (400 MHz, CDCl₃): δ = 7.32 (m, 60 H, arom. CH in

8.9 mmol), 3,4-diphenyl-cyclopen-2-enone (1.2405 g, 5.3 mmol), rac-63 and rac-64), 6.48 (m, 2 H, olefinic CH in five-ring in rac-63

and crotyl bromide (1.05 mL, 8.7 mmol) gave, after a 5.5-h reaction

time and column chromatography (dichloromethane as eluent),

0.5012 g (40%) of a mixture of the title compounds as a yellow oil.

¹H NMR (400 MHz, CDCl₃): δ = 7.35 (m, 8 H, arom. CH in rac-

60 and rac-61), 7.17 (m, 32 H, arom. CH in rac-60 and rac-61),

6.34 (m, 4 H, olefinic CH in five-ring in rac-60 and rac-61), 5.92

(m, 4 H, olefinic CH in chain in rac-60 and rac-61), 5.17 (m, 8 H,

olefinic CH₂in chain in rac-60 and rac-61), 4.27 (m, 4 H, aliphatic

CH in five-ring in rac-60 and rac-61), 2.84 (m, 4 H, aliphatic CH

or rac-64), 6.40 (m, 4 H, olefinic CH in chain in rac-63 and rac-

64), 6.25 (m, 2 H, olefinic CH in five-ring in rac-63 or rac-64), 5.29

(m, 8 H, olefinic CH₂in chain in rac-63 and rac-64), 4.21 (m, 2 H,

aliphatic CH in five-ring in rac-63 or rac-64), 3.95 (m, 2 H, ali-

phatic CH in five-ring in rac-63 or rac-64), 3.61 (m, 4 H, aliphatic

CH in chain in rac-63 and rac-64), 2.93 (m, 4 H, aliphatic CH in

five-ring in rac-63 and rac-64), 2.10 (s, 2 H, OH in rac-63 or rac-

64), 1.94 (m, 6 H, aliphatic CH in five-ring in rac-63 and rac-64

and OH in rac-63 or rac-64) ppm. ¹³C NMR (100.6 MHz, CDCl₃):

1076

www.eurjoc.org

Eur. J. Org. Chem. 2005, 1058–1081

Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

δ = 147.41 (2 C_qin rac-63 or rac-64), 147.05 (2 C_qin rac-63 or rac-

64), 144.77 (2 C_qin rac-63 or rac-64), 144.62 (2 C_qin rac-63 or

rac-64), 140.57 (2 C_qin rac-63 or rac-64), 140.38 (2 C_qin rac-63 or

zinc (0.5501 g; 8.4 mmol), 1,3-dihydro-cyclopenta[l]phenanthren-2-

one (0.9793 g, 4.2 mmol), and allyl bromide (740 µL, 8.4 mmol)

gave, after a 24-h reaction time and column chromatography

rac-64), 137.52 (2 olefinic CH in chain in rac-63 or rac-64), 137.46 (dichloromethane as eluent), 0.0747 g (7%) of the title compound

1

(2 olefinic CH in chain in rac-63 or rac-64), 135.00 (2 C_qin rac-63

or rac-64), 134.96 (2 C_qin rac-63 or rac-64), 131.59 (2 olefinic CH

in five-ring in rac-63 or rac-64), 131.57 (2 olefinic CH in five-ring

as a pale yellow oil. H NMR (400 MHz, CDCl₃): δ = 8.69 (m, 2

H, arom. CH), 7.79 (m, 2 H, arom. CH), 7.61 (m, 4 H, arom. CH),

6.06 (ddt, J = 7.25 Hz, 10.22 Hz, 17.47 Hz, 1 H, olefinic CH in

in rac-63 or rac-64), 129.25, 129.10, 128.54, 128.49, 128.31, 128.25, chain), 5.26 (dm, J = 17.47 Hz, 1 H, olefinic CH in chain), 5.25

128.18, 128.15, 127.64, 126.95, 126.89, 126.80, 126.78, 126.13,

126.11 (60C, overlapping signals from arom. CH in rac-63 and rac-

64), 117.94 (2 olefinic CH₂in chain in rac-63 or rac-64), 117.89 (2

olefinic CH₂in chain in rac-63 or rac-64), 85.82 (2 C–OH in rac-

63 or rac-64), 85.73 (2 C–OH in rac-63 or rac-64), 60.28 (2 aliphatic

CH in chain in rac-63 or rac-64), 60.09 (2 aliphatic CH in chain in

rac-63 or rac-64), 50.41 (2 aliphatic CH in five-ring in rac-63 or

rac-64), 50.29 (2 aliphatic CH in five-ring in rac-63 or rac-64), 48.12

(2 aliphatic CH in five-ring in rac-63 or rac-64), 47.94 (2 aliphatic

CH in five-ring in rac-63 or rac-64) ppm.

(dm, J = 10.22 Hz, 1 H, olefinic CH in chain) 3.43 (m, 4 H, ali-

phatic CH₂in five-ring), 2.66 (m, 2 H, aliphatic CH₂in chain), 2.13

(m, 1 H, OH) ppm. ¹³C NMR (100.6 MHz, CDCl₃): δ = 134.67 (2

C, C_q), 133.93 (olefinic CH in chain), 130.30 (2 C, C_q), 129.78 (2

C, C_q), 126.70 (2C, arom. CH), 125.83 (2 C, C_q), 124.73 (2 C, C_q),

123.15 (2 C, C_q), 119.26 (olefinic CH₂in chain), 80.66 (C–OH),

46.22 (2 C, aliphatic CH₂in five-ring), 45.91 (aliphatic CH₂in

chain) ppm. EIMS (70 eV): calcd. C₂₀H₁₈O 274.1358; found

274.1355.

2-Allyl-2,3-dihydro-1H-cyclopenta[l]phenanthren-2-ol (68)

– Al-

A Mixture of [1-(3,4-Diphenyl-cyclopenta-1,3-dienyl)-allyl]benzene

(rac-65), 1-[3,4-Diphenyl-cyclopent-2-en-(Z)-ylidene]-allyl}-benzene

(66), and 1-[3,4-Dimethyl-cyclopent-2-en-(E)-ylidene]-allyl}-benzene

(67): By applying General Procedure 5, a mixture of 3,4-diphenyl-

1-(1-phenyl-allyl)-cyclopent-2-enol (rac-63 and rac-64) [0.3172 g,

0.90 mmol] and MgSO₄(0.3404 g, 2.83 mmol) in toluene (20 mL)

gave, after a 1-h reaction time and column chromatography (a mix-

ture of 30% of dichloromethane and 70% of hexane as eluent),

0.0944 g of a yellow oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.16 (m,

45 H, arom. CH), 6.60 (m, 3 H, olefinic CH in five-ring in 66,

olefinic CH in five-ring in 67 and olefinic CH in chain in 66 or 67),

6.30 (m, 2 H, olefinic CH in five-ring in rac-65), 6.19 (m, 3 H,

olefinic CH in chain in rac-65 and olefinic CH in chain in 66 or

67), 5.08 (ddd, J = 0.61 Hz, 0.99 Hz, 10.07 Hz, 2 H, olefinic CH in

chain in rac-65, 66 or 67), 5.00 (ddd, J = 0.3 Hz, 1.3 Hz, 17.01 Hz,

2 H, olefinic CH in chain in rac-65, 66 or 67), 4.98 (m, 3 H, olefinic

CH₂in chain in rac-65, 66 or 67), 4.75 (dm, J = 17.24, 2 H, olefinic

CH in chain in rac-65, 66 or 67), 4.65 (dm, J = 17.17 Hz, 2 H,

olefinic CH in chain in rac-65, 66 or 67), 4.44 (m, 1 H, aliphatic

CH in five-ring in 66 or olefinic CH in five-ring in 67), 4.40 (m, 2

H, aliphatic CH in chain in rac-65), 4.27 (m, 1 H, aliphatic CH in

five-ring in 66 or olefinic CH in five-ring in 67), 3.38 (m, 1 H,

aliphatic CH in five-ring in 67), 3.32 (m, 4 H, aliphatic CH₂in five-

ring in rac-65), 2.98 (m, 1 H, aliphatic CH in five-ring in 67), 2.73

(dd, J = 2.52 Hz, 17.47 Hz, 1 H, aliphatic CH in five-ring in 67),

2.28 (dd, J = 2.48 Hz, 17.47 Hz, 1 H, aliphatic CH in five-ring in

66) ppm. The ratio between rac-65, 66 and 67 was 1.3:1:1. The yield

of the reaction could not be determined due to the high-molecular-

weight side-products present in the reaction product. ¹³C NMR

(100.6 MHz, CDCl₃): quaternary carbons could not be determined

from the carbon spectrum due to excessive number of signals from

the side products, δ = 140.16 (2C, olefinic CH in chain in rac-65,

66 or 67), 136.22 (olefinic CH in five-ring in 66 and 67), 134.09

(2C, olefinic CH in chain in rac-65, 66 or 67), 132.84 (2 olefinic

CH in five-ring in rac-65), 124.87 (2C, olefinic CH in chain in rac-

65, 66 or 67), 115.61 (2 olefinic CH₂in chain in rac-65), 115.20

(olefinic CH₂in chain in 66 or 67), 114.10 (olefinic CH₂in chain

in 66 or 67), 51.58 (2 aliphatic CH in chain in rac-65), 50.29 (ali-

phatic CH in five-ring in 66 or olefinic CH in five-ring in 67), 49.81

(aliphatic CH in five-ring in 66 or olefinic CH in five-ring in 67),

46.37 (2 aliphatic CH₂in five-ring in rac-65), 41.91 (aliphatic CH₂

in five-ring in 66 or 67) ppm. EIMS (70 eV): calcd. C₂₆H₂₂

334.1722; found 334.1722.

lylation in the Presence of Indium. By applying General Procedure

2, indium powder (0.1812 g, 1.6 mmol), 1,3-dihydro-cyclopenta[l]

phenanthren-2-one (0.067 g, 0.3 mmol), and allyl bromide (40 µL,

0.4 mmol) gave, after column chromatography (dichloromethane as

eluent), 0.0319 g (40%) of the title compound as a pale yellow oil.

2-(3-Triethoxysilylpropyl)indene (69): By applying General Pro-

cedure 6, 2-allyl-1H-indene (48) [0.8171 g, 5.2 mmol] and triethoxy-

silane (990 µL, 5.2 mmol) gave, after column chromatography

(dichloromethane as eluent), 0.797 g (48%) of the title compound

1

as a pale yellow oil. H NMR (600 MHz, CDCl₃): δ = 7.41 (m, 1

H, arom. CH), 7.29 (m, 1 H, arom. CH), 7.25 (m, 1 H, arom. CH),

7.13 (m, 1 H, arom. CH), 6.54 (m, 1 H, olefinic CH in five-ring),

3.86 (m, 6 H, CH₂in EtO groups), 3.33 (m, 2 H, aliphatic CH₂in

five-ring), 2.56 (m, 2 H, aliphatic CH₂in chain), 1.77 (m, 2 H,

aliphatic CH₂in chain), 1.27 (m, 9 H, CH₃in EtO groups), 0.74

(m, 2 H, aliphatic CH₂in chain) ppm. ¹³C NMR (150.9 MHz,

CDCl₃): δ = 150.57 (C_q), 145.80 (C_q), 143.27 (C_q), 126.64 (olefinic

CH in five-ring), 126.31 (arom. CH), 123.65 (arom. CH), 123.48

(arom. CH), 119.99 (arom. CH), 58.48 (3C, CH₂in EtO groups),

41.07 (aliphatic CH₂in five-ring), 34.64 (aliphatic CH₂in chain),

22.60 (aliphatic CH₂in chain), 18.44 (3C, CH₃in EtO groups),

10.42 (aliphatic CH₂in chain) ppm. EIMS (70 eV): calcd.

C₁₈H₂₈O₃Si 320.1808; found 320.1812.

2-(3-Triethylsilylpropyl)indene (70): By applying General Procedure

6, 2-allyl-1H-indene (48) [0.6880 g; 4.4 mmol] and triethylsilane

(700 µL, 4.4 mmol) gave, after column chromatography (hexane as

eluent), 0.3434 g (29%) of the title compound as a colorless oil. ¹H

NMR (600 MHz, CDCl₃): δ = 7.53 (m, 1 H, arom. CH), 7.43 (m,

1 H, arom. CH), 7.38 (m, 1 H, arom. CH), 7.26 (m, 1 H, arom.

CH), 6.67 (m, 1 H, olefinic CH in five-ring), 3.44 (m, 2 H, aliphatic

CH₂in five-ring), 2.66 (m, 2 H, aliphatic CH₂in chain), 1.79 (m,

2 H, aliphatic CH₂in chain), 1.13 (m, 9 H, CH₃in Et groups), 0.77

(m, 2 H, aliphatic CH₂in chain), 0.71 (m, 6 H, CH₂in Et groups)

ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 150.79 (C_q), 145.86 (C_q),

143.24 (C_q), 126.50 (olefinic CH in five-ring), 126.33 (arom. CH),

123.64 (arom. CH), 123.48 (arom. CH), 119.94 (arom. CH), 41.08

(aliphatic CH₂in five-ring), 35.56 (aliphatic CH₂in chain), 23.74

(aliphatic CH₂in chain), 11.61 (aliphatic CH₂in chain), 7.63 (3C,

CH₃in Et- groups), 3.47 (3C, CH₂in Et groups) ppm. EIMS

(70 eV): calcd. C₁₈H₂₈Si 272.1960; found 272.1960.

2-(3-Triphenylsilylpropyl)indene (71): By applying General Pro-

cedure 6, 2-allyl-1H-indene (48) [0.6119 g, 3.9 mmol] and tri-

phenylsilane (1.0459, 4.2 mmol) gave, after column chromatog-

raphy (a mixture of 10% dichloromethane and 90% hexane as elu-

2-Allyl-2,3-dihydro-1H-cyclopenta[l]phenanthren-2-ol (68)

– Al-

lylation in the Presence of Zinc: By applying General Procedure 1,

Eur. J. Org. Chem. 2005, 1058–1081

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1077

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

FULL PAPER

ent), 0.2467 g (15%) of the title compound as white crystals.

Recrystallization from pentane at –20 °C yielded 0.1118 g (7%) of

white crystals. ¹H NMR (600 MHz, CDCl₃): δ = 7.43 (m, 6 H,

arom. CH), 7.30 (m, 10 H, arom. CH), 7.14 (m, 2 H, arom. CH),

7.00 (m, 1 H, arom. CH), 6.36 (m, 1 H, olefinic CH in five-ring),

3.11 (m, 2 H, aliphatic CH₂in five-ring), 2.45 (m, 2 H, aliphatic

in 73), 135.74 (olefinic CH in five-ring in 73), 134.99 (olefinic CH

in five-ring in 74), 129.07 (olefinic CH in five-ring in 73), 126.60

(olefinic CH in five-ring in 73), 126.36 (arom. CH in 73), 126.20

(arom. CH in 74), 125.10 (arom. CH in 74), 124.93 (arom. CH in

73), 124.38 (arom. CH in 74), 123.89 (arom. CH in 74), 123.85

(arom. CH in 74), 123.74 (arom. CH in 73), 123.69 (arom. CH in

CH₂in chain), 1.71 (m, 2 H, aliphatic CH₂in chain), 1.35 (m, 2 73), 123.62 (arom. CH in 74), 123.53 (arom. CH in 73), 122.83

H, aliphatic CH₂in chain) ppm. ¹³C NMR (150.9 MHz, CDCl₃): (arom. CH in 73), 122.10 (arom. CH in 74), 121.16 (arom. CH in

δ = 150.29 (C_q), 145.67 (C_q), 143.24 (C_q), 135.81 (6C, arom. CH), 73), 120.01 (arom. CH in 73), 119.97 (arom. CH in 74), 45.71 (ali-

135.25 (C_q), 129.56 (3C, arom. CH), 128.01 (6C, arom. CH), 126.87

(olefinic CH in five-ring), 126.37 (arom. CH), 123.73 (arom. CH),

123.51 (arom. CH), 119.98 (arom. CH), 41.06 (aliphatic CH₂in

five-ring), 35.14 (aliphatic CH₂in chain), 23.66 (aliphatic CH₂in

chain), 13.16 (aliphatic CH₂in chain) ppm. M.p. 127–128 °C.

EIMS (70 eV): calcd. C₃₀H₂₈Si 416.1960; found 416.1953.

phatic CH in five-ring in 73), 41.06 (3C, aliphatic CH₂in five-ring

in 73 and 74), 35.06 (2 C, aliphatic CH₂in chain in 73 and 74),

23.60 (2 C, aliphatic CH₂in chain in 73 and 74), 14.50 (2 C, ali-

phatic CH₂in chain in 73 and 74), –2.73 (2C, CH₃attached to Si

in 74), –3.77 (CH₃attached to Si in 73), –4.17 (CH₃attached to Si

in 73) ppm. EIMS (70 eV): calcd. C₂₃H₂₆Si 330.1804; found

330.1807.

1-{[2-(Dimethyl-indenyl-silanyl)-ethyl]-dimethyl-silanyl}-indene (72):

By applying General Procedure 6, 2-allyl-1H-indene (48) [0.3717 g,

2-(3-Naphthylphenylmethylsilylpropyl)indene (75): By applying Ge-

2.4 mmol] and 1,2-bis-dimethyl-silyl-ethane (0.1782 g, 1.2 mmol) neral Procedure 6, 2-allyl-1H-indene (48) [0.1812 g; 1.2 mmol] and

gave, after column chromatography (a mixture of 10% dichloro-

methane and 90% hexane as eluent), 0.3255 g (30%) of the title

compound as a colorless oil. ¹H NMR (600 MHz, CDCl₃): δ =

(+)-(R)-methyl-1-naphthalenylphenylsilane (0.3112, 1.3 mmol)

gave, after column chromatography (a mixture of 10% dichloro-

methane and 90% hexane as eluent), 0.0627 g (13%) of the title

7.45 (m, 2 H, arom. CH), 7.35 (m, 2 H, arom. CH), 7.30 (m, 2 H, compound as a colorless oil. ¹H NMR (600 MHz, CDCl₃): δ =

arom. CH), 7.18 (m, 2 H, arom. CH), 6.59 (m, 2 H, olefinic CH in 7.91 (m, 2 H, arom. CH), 7.86 (m, 1 H, arom. CH), 7.75 (m, 1 H,

five-ring), 3.37 (m, 4 H, aliphatic CH₂in five-ring), 2.59 (m, 4 H, arom. CH), 7.53 (m, 2 H, arom. CH), 7.46 (m, 1 H, arom. CH),

aliphatic CH₂in chain), 1.69 (m, 4 H, aliphatic CH₂in chain), 0.66 7.42 (m, 1 H, arom. CH), 7.31 (m, 5 H, arom. CH), 7.21 (m, 2 H,

(m, 4 H, aliphatic CH₂in chain), 0.48 (m, 4 H, aliphatic CH₂in

arom. CH), 7.10 (m, 1 H, arom. CH), 6.43 (m, 1 H, olefinic CH in

chain between Si atoms), 0.07 (m, 12 H, CH₃attached to Si) ppm. five-ring), 3.17 (m, 2 H, aliphatic CH₂in five-ring), 2.52 (m, 2 H,

¹³C NMR (150.9 MHz, CDCl₃): δ = 150.88 (2C, C_q), 145.88 (2C, aliphatic CH₂in chain), 1.70 (m, 2 H, aliphatic CH₂in chain), 1.34

C_q), 143.30 (2C, C_q), 126.52 (2C, olefinic CH in five-ring), 126.34

(m, 2 H, aliphatic CH₂in chain), 0.73 (s, 3 H, CH₃attached to Si)

(2C, arom. CH), 123.63 (2C, arom. CH), 123.49 (2C, arom. CH), ppm. ¹³C NMR (150.9 MHz, CDCl₃): δ = 150.39 (C_q), 145.75 (C_q),

119.97 (2C, arom. CH), 41.08 (2C, aliphatic CH₂in chain), 35.28

(2C, aliphatic CH₂in chain), 23.76 (2C, aliphatic CH₂in chain),

14.79 (2C, aliphatic CH₂in chain), 7.30 (2C, aliphatic CH₂in chain

between Si atoms), 3.76 (4C, CH₃attached to Si) ppm. EIMS

(70 eV): calcd. C₃₀H₄₂Si₂458.2825; found 458.2829.

143.25 (C_q), 138.14 (C_q), 137.19 (C_q), 135.06 (arom. CH), 134.81

(C_q), 134.53 (2C, arom. CH), 133.56 (C_q), 130.40 (arom. CH),

129.23 (arom. CH), 129.09 (arom. CH), 128.64 (arom. CH), 128.02

(2C, arom. CH), 126.79 (arom. CH), 126.34 (olefinic CH in five-

ring), 125.80 (arom. CH), 125.54 (arom. CH), 125.21 (arom. CH),

123.63 (arom. CH), 213.48 (arom. CH), 119.93 (arom. CH), 41.00

(aliphatic CH₂in five-ring), 34.93 (aliphatic CH₂in chain), 23.62

(aliphatic CH₂in chain), 14.92 (aliphatic CH₂in chain), –2.67 (CH₃

attached to Si) ppm. [α]²_D⁵–0.9° (c, 0.0264 g/ml CHCl₃). EIMS

(70 eV): calcd. C₂₉H₂₈Si 404.1960; found 404.1957.

A Mixture of (1H-Inden-1-yl)-[3-(1H-inden-2-yl)propyl]-dimethyl-si-

lane (73) and (3H-Inden-1-yl)-[3-(1H-inden-2-yl)propyl]-dimethyl-si-

lane (74): By applying General Procedure 6, 2-allyl-1H-indene (48)

[0.4618 g, 3.0 mmol] and (1H-Inden-1-yl)-dimethyl-silane (contain-

ing ca 10% of (3H-inden-1-yl)-dimethyl-silane as impurity, 0.5221,

1.3 mmol) gave, after column chromatography (a mixture of 10% A Diastereomeric Mixture of 2-(1-Methyl-3-naphthylphenylmeth-

dichloromethane and 90% hexane as eluent), 0.0310 g (3%) of the

ylsilylpropyl)indene (76 and 77): By applying General Procedure 6,

an enantiomeric mixture of 2-(1-methyl-allyl)-1H-indene (rac-50)

mixture of the title compounds as a pale yellow oil. ¹H NMR

(600 MHz, CDCl₃): δ = 7.54 (m, 2 H, arom. CH in 74), 7.50 (m, 2 [0.4039 g, 2.4 mmol] and (+)-(R)-methyl-1-naphthalenylphenylsil-

H, arom. CH in 73 and 74), 7.46 (m, 1 H, arom. CH in 73), 7.41 ane (0.6014, 2.4 mmol) gave, after column chromatography (a mix-

(m, 1 H, arom. CH in 73), 7.28 (m, 6 H, arom. CH in 73 and 74), ture of 10% dichloromethane and 90% hexane as eluent), 0.2057 g

7.19 (m, 2 H, arom. CH in 73 and 74), 7.14 (m, 2 H, arom. CH in

73 and 74), 6.95 (m, 1 H, olefinic CH in five-ring in 74), 6.94 (m,

1 H, olefinic CH in five-ring in 73), 6.81 (m, 1 H, olefinic CH in

five-ring in 74), 6.67 (m, 1 H, olefinic CH in five-ring in 73), 6.49

(m, 1 H, olefinic CH in five-ring in 73), 3.59 (m, 1 H, aliphatic CH

in five-ring in 73), 3.46 (m, 2 H, aliphatic CH₂in five-ring in 74),

3.27 (m, 4 H, aliphatic CH₂in five-ring in 73 and 74), 2.53 (m, 2

H, aliphatic CH₂in chain in 74), 2.47 (m, 2 H, aliphatic CH₂in

chain in 73), 1.69 (m, 2 H, aliphatic CH₂in chain in 74), 1.55 (m,

2 H, aliphatic CH₂in chain in 73), 0.92 (m, 2 H, aliphatic CH₂in

chain in 74), 0.58 (m, 2 H, aliphatic CH₂in chain in 73), 0.35 (s, 6

H, CH₃attached to Si in 74), 0.01 (s, 3 H, CH₃attached to Si in

(21%) of a 1:1 diastereomeric mixture of the title compounds as a

colorless oil. ¹H NMR (600 MHz, CDCl₃): δ = 7.78 (m, 6 H, arom.

CH in 76 and/or 77), 7.61 (m, 2 H, arom. CH in 76 and/or 77),

7.39 (m, 4 H, arom. CH in 76 and/or 77), 7.35 (m, 4 H, arom. CH

in 76 and/or 77), 7.22 (m, 8 H, arom. CH in 76 and/or 77), 7.14

(m, 6 H, arom. CH in 76 and/or 77), 7.00 (m, 2 H, arom. CH in

76 and/or 77), 6.35 (m, 2 H, olefinic CH in five-ring in 76 and 77),

3.03 (m, 4 H, aliphatic CH₂in five-ring in 76 and 77), 2.53 (m, 2

H, aliphatic CH in chain in 76 and 77), 1.48 (m, 4 H, aliphatic

CH₂in chain in 76 and/or 77), 1.15 (m, 4 H, aliphatic CH₂in chain

in 76 and/or 77), 1.06 (m, 6 H, CH₃attached to the aliphatic chain

in 76 and 77), 0.60 (s, 6 H, CH₃attached to Si in 76 and 77) ppm.

73), –0.03 (s, 3 H, CH₃attached to Si in 73) ppm. ¹³C NMR ¹³C NMR (150.9 MHz, CDCl₃): δ = 153.31 (C_qin 76 and/or 77),

(150.9 MHz, CDCl₃): δ = 150.74 (C_qin 74), 150.51 (C_qin 73),

148.26 (C_qin 74), 145.81 (C_qin 74), 145.77 (C_qin 73), 145.40 (C_q

in 73), 144.87 (olefinic CH in five-ring in 74), 144.72 (C_qin 74),

144.52 (C_qin 74), 144.28 (C_qin 73), 143.27 (C_qin 74), 143.23 (C_q

145.63 (C_qin 76 and/or 77), 143.22 (C_qin 76 and/or 77), 137.16

(C_qin 76 and/or 77), 133.52 (C_qin 76 and/or 77), 135.08 (arom.

CH in 76 and/or 77), 134.48 (arom. CH in 76 and/or 77), 130.35

(arom. CH in 76 and/or 77), 129.19 (arom. CH in 76 and/or 77),

1078

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Eur. J. Org. Chem. 2005, 1058–1081

Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

129.08 (arom. CH in 76 and/or 77), 128.58 (arom. CH in 76 and/

or 77), 127.99 (arom. CH in 76 and/or 77), 126.31 (arom. CH in

76 and/or 77), 126.03 (olefinic CH in five-ring in 76 and 77), 125.75

(arom. CH in 76 and/or 77), 125.50 (arom. CH in 76 and/or 77),

125.19 (arom. CH in 76 and/or 77), 123.66 (arom. CH in 76 and/

or 77), 123.62 (arom. CH in 76 and/or 77), 120.08 (arom. CH in

76 and/or 77), 38.63 (aliphatic CH in chain in 76 or 77), 38.57

(aliphatic CH in chain in 76 or 77), 38.51 (aliphatic CH₂in five-

ring in 76 or 77), 38.48 (aliphatic CH₂in five-ring in 76 or 77),

30.93 (aliphatic CH₂in 76 and 77), 20.54 (CH₃attached to the

aliphatic chain in 76 or 77), 20.40 (CH₃attached to the aliphatic

chain in 76 or 77), 12.56 (aliphatic CH₂in chain in 76 or 77), 12.38

(aliphatic CH₂in chain in 76 or 77), –2.72 (CH₃attached to Si in

76 or 77), –2.76 (CH₃attached to Si in 76 or 77) ppm. EIMS

(70 eV): calcd. C₃₀H₃₀Si 418.2117; found 418.2115.

Acknowledgments

Financial support from the Neste Research Foundation is grate-

fully acknowledged. We also thank Doc. Leif Kronberg, Mr.

Markku Reunanen and Mrs. Päivi Pennanen for their assistance

with the ESIMS, EIMS and NMR analyses, and Ms. Elise Johans-

son for preparing the chiral (+)-(R)-methyl-1-naphthalenylphenyl-

silane.

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A Diastereomeric Mixture of 2-(1-Phenyl-3-naphthylphenylmethylsi-

lylpropyl)indene (78 and 79): By applying General Procedure 6, an

enantiomeric mixture of 2-(1-phenyl-allyl)-1H-indene (rac-52)

[0.2590 g, 1.1 mmol] and (+)-(R)-methyl-1-naphthalenylphenylsil-

ane (0.2716, 1.1 mmol) gave, after column chromatography (a mix-

ture of 10% dichloromethane and 90% hexane as eluent), 0.1318 g

(25%) of a 1:1 diastereomeric mixture of the title compounds as a

colorless oil. ¹H NMR (600 MHz, CDCl₃): δ = 7.95 (m, 6 H, arom.

CH in 78 and/or 79), 7.76 (m, 2 H, arom. CH in 78 and/or 79),

7.57 (m, 4 H, arom. CH in 78 and/or 79), 7.54 (m, 4 H, arom. CH

in 78 and/or 79), 7.42 (m, 2 H, arom. CH in 78 and/or 79), 7.35

(m, 6 H, arom. CH in 78 and/or 79), 7.31 (m, 12 H, arom. CH in

78 and/or 79), 7.19 (m, 4 H, arom. CH in 78 and/or 79), 7.14 (m,

2 H, arom. CH in 78 and/or 79), 6.55 (m, 1 H, olefinic CH in five-

ring in 78 or 79), 6.53 (m, 1 H, olefinic CH in five-ring in 78 or

79), 3.73 (m, 2 H, aliphatic CH in chain in 78 and 79), 3.16 (m, 4

H, aliphatic CH₂in five-ring in 78 and 79), 2.13 (m, 4 H, aliphatic

CH₂in chain in 78 and 79), 1.37 (m, 4 H, aliphatic CH₂in chain

in 78 and 79), 0.80 (s, 3 H, CH₃attached to Si in 78 or 79), 0.79

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(150.9 MHz, CDCl₃): δ = 153.12 (C_qin 78 and/or 79), 152.98 (C_q

in 78 and/or 79), 145.25 (C_qin 78 and/or 79), 144.22 (C_qin 78 and/

or 79), 144.10 (C_qin 78 and/or 79), 143.31 (C_qin 78 and/or 79),

138.01 (C_qin 78 and/or 79), 137.92 (C_qin 78 and/or 79), 137.19

(C_qin 78 and/or 79), 135.16 (arom. CH in 78 and/or 79), 135.12

(arom. CH in 78 and/or 79), 134.59 (C_qin 78 and/or 79), 134.56

(C_qin 78 and/or 79), 134.52 (arom. CH in 78 and/or 79), 133.58

(C_qin 78 and/or 79), 133.56 (C_qin 78 and/or 79), 130.46 (arom.

CH in 78 and/or 79), 129.26 (arom. CH in 78 and/or 79), 129.12

(arom. CH in 78 and/or 79), 129.09 (arom. CH in 78 and/or 79),

128.60 (arom. CH in 78 and/or 79), 128.52 (arom. CH in 78 and/

or 79), 128.09 (arom. CH in 78 and/or 79), 128.05 (arom. CH in

78 and/or 79), 126.44 (arom. CH in 78 and/or 79), 126.41 (arom.

CH in 78 and/or 79), 126.34 (olefinic CH in five-ring in 78 and 79),

125.81 (arom. CH in 78 and/or 79), 125.54 (arom. CH in 78 and/

or 79), 125.51 (arom. CH in 78 and/or 79), 125.21 (arom. CH in

78 and/or 79), 123.95 (arom. CH in 78 and/or 79), 123.54 (arom.

CH in 78 and/or 79), 120.39 (arom. CH in 78 and/or 79), 51.10

(aliphatic CH in chain in 78 or 79), 51.04 (aliphatic CH in chain

in 78 or 79), 40.04 (aliphatic CH₂in five-ring in 78 and 79), 29.26

(aliphatic CH₂in chain in 78 or 79), 29.20 (aliphatic CH₂in chain

in 78 or 79), 13.48 (aliphatic CH₂in chain in 78 or 79), 13.44 (ali-

phatic CH₂in chain in 78 or 79), –2.67 (CH₃attached to Si in 78

or 79), –2.70 (CH₃attached to Si in 78 or 79) ppm. EIMS (70 eV):

calcd. C₃₅H₃₂Si 480.2273; found 480.2267.

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Supporting Information: Copies of ¹³C NMR spectra of the com-

pounds reported are provided.

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1079

S. Silver, A.-S. Leppänen, R. Sjöholm, A. Penninkangas, R. Leino

FULL PAPER

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Preliminary metallation attempts of the indenyl anions gener-

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1

port this hypothesis. H NMR analyses of the crude products

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1080

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Towards Benign Synthesis of Indenes from Indanones

FULL PAPER

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Towards benign synthesis of indenes from indanones: Zinc-mediated allylation of ketones in aqueous media as a source of substituted indenyl ligand precursors

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