Synthesis and use of new substituted 1,3,5-hexatrienes in studying thermally induced 6π-electrocyclizations

FULL PAPER

DOI: 10.1002/ejoc.200700201

Synthesis and Use of New Substituted 1,3,5-Hexatrienes in Studying

Thermally Induced 6π-Electrocyclizations

Hans Wolf Sünnemann,^[a]Martin G. Banwell,^[b]and Armin de Meijere*^[a]

Dedicated to Professor Miguel Yus on the occasion of his 60th birthday

Keywords: Pericyclic Reactions / Regioselectivity / Palladium catalysis / Cross coupling / Oligocyclic systems

An acyclic, two heterocyclic, and two bicyclic alkenylstann-

anes, 3, 4a, 4b, 8 and 11, respectively, were synthesized in

yields ranging from 43 to 97%, and each was subjected to a

cyclic cyclohexadienes 28, 30 and 34, incorporating allylic

alcohol and allyl ether termini, by 6π-electrocyclization and

subsequent [1,5]-hydrogen shift, as single products in good

sequence of Stille and Heck couplings with 2-bromocy- yields (85–93%). In contrast, the hexatrienes 19, 20, 21 and

clohexenyl triflate (13) and alkyl (tert-butyl and methyl) acryl- 39 furnished mixtures of the initial electrocyclization prod-

ate to furnish seven new 1,3,5-hexatrienes 19, 20, 21, 22-tBu,

22-Me, 23 and 43, respectively, in 58–84% yields. For the

alkenylstannanes 4a,b, 8 and 11, customized combinations of

catalysts had to be used. The Stille–Heck sequence involving

13, 3 and tert-butyl acrylate could be performed in a one-pot

mode and proceeded in 75% yield. The hexatrienes were

heated in decalin solutions so as to effect 6π-electrocycliza-

tion. Temperatures and reaction times were optimized indi-

vidually. The hexatrienes 29, 31 and 36 gave the bi- and tri-

ucts 26, 32, 37 and 40 as well as the products of a subsequent

[1,5]-hydrogen shift 27, 33, 38 and 41, respectively. The tricy-

clic hexatrienes 22-tBu, 22-Me and 23 bearing alkyl (tert-bu-

tyl, methyl) acrylate termini also selectively gave the tetra-

cyclic dienes 48-tBu, 48-Me and 50 in 71–77% yields by elec-

trocyclizations and subsequent hydrogen shifts.

Germany, 2007)

retarded or accelerated and the selectivity thus enhanced by

a proper choice of substituents, we set out to prepare vari-

ously unsymmetrically substituted 1,3,5-hexatrienes using

previously established^[6b,7]Stille–Heck cross-coupling se-

quences, then undertake various functional group transfor-

mations, and study the outcome of the thermal rearrange-

ments of the compounds so formed.

Introduction

Although the Diels–Alder reaction remains unsurpassed

in its scope and versatility as a method for accessing six-

membered carbocycles,^[1]the more recently developed ther-

mal 6π-electrocyclizations of 1,3,5-hexatrienes^[2]have come

to complement such [4+2] cycloadditions in terms of func-

tionality in and substitution patterns on the rings.^[3]Espe-

cially since modern metal-catalyzed cross-coupling method-

ology^[4]has made variously substituted 1,3,5-hexatrienes

readily accessible,^[3,5]their thermal 6π-electrocyclizations

have become a feasible stereoselective approach to oligo-

substituted cyclohexa-1,3-dienes.^[3,6]However, when ring-

annelated cyclohexadienes are formed, the initial products

were frequently found to undergo subsequent [1,5]-hydro-

gen shifts so that mixtures of products were obtained. In

order to establish whether this sigmatropic process can be

Results and Discussion

Preparation of Substrates

For the preparation of a set of diverse 1,3,5-hexatrienes

by Stille–Heck cross-coupling sequences, a variety of alken-

ylstannanes had to be synthesized. The new acyclic (trialk-

ylsilylethenyl)stannane 3 was prepared by a rhodium-cata-

lyzed hydrostannylation^[8]of (tert-butyldimethylsilyl)acetyl-

ene (2).^[9]It is noteworthy that at 22 °C this hydrostan-

nylation led to a 1:1 mixture of 3 and its (Z) isomer as well

as a trace of the 1,1-disubstituted isomer. However, when

this reaction was carried out at 60 °C, the desired alkene 3

was the main product (57%) and accompanied by only

traces of the isomers just mentioned (Scheme 1).

[a] Institut für Organische und Biomolekulare Chemie der Georg-

August-Universität Göttingen,

Tammannstrasse 2, 37077 Göttingen, Germany

Fax: +49-551-399475

E-mail: Armin.deMeijere@chemie.uni-goettingen.de

[b] Research School of Chemistry, Building 35, Australian

National University,

Canberra ACT0200, Australia

Supporting information for this article is available on the

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

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the targeted bicyclo[4.4.0]decenylstannanes 8 and 11 had to

be prepared from the α,β-unsaturated bicyclo[4.4.0]dec-1-

en-3-ones 6 and 9. Reductive enolate formation using lith-

ium dissolved in liquid ammonia, and trapping with N,N-

bis(trifluoromethylsulfonyl)aniline furnished the trans-an-

nelated bicyclo[4.4.0]dec-2-enol triflates 7 and 10 with com-

plete diastereoselectivity.^[12]The latter could be transformed

into the corresponding (bicyclodecenyl)tributylstannanes 8

and 11 in 98 and 97% yields, respectively, by treatment with

dilithium cyanobis(tributylstannyl)cuprate. It is noteworthy

that the reductive enolization of the corresponding inde-

none derivatives yielded lithium enolates with the same high

diastereoselectivities, but furnished the cis-annelated bicy-

cles (Scheme 1).^[7a]

2-Tris(n-butylstannyl)-1,4-dioxine (25) was prepared

from dioxine and tributyltin chloride according to a litera-

ture procedure.^[13]

The yield associated with the conversion of 2-bromocy-

clohexanone (12) into 2-bromocyclohexenyl triflate (13) as

described previously,^[6b]was significantly improved by em-

ploying potassium bis(trimethylsilyl)amide (KHMDS) and

trapping the regioselectively formed potassium enolate with

trifluoromethanesulfonic anhydride. By such means the tar-

get compound 13 was obtained as the sole product in 94%

yield (Scheme 2).

Scheme 1. Synthesis of various alkenylstannanes to be applied in

Stille–Heck coupling sequences.

The 4-azacyclohexenylstannanes 4a,b were synthesized

from N-benzylpiperidinone via the enol triflate 5 which was

prepared according to a standard protocol.^[10]The tributyl-

stannane 4b was obtained from 5 and dilithium cyano-

bis(tributylstannyl)cuprate in 43% yield,^[11]whereas the

The Stille coupling^[14]of compound 13 with the relevant

corresponding trimethyl(alkenyl)stannane 4a was prepared acyclic (trialkylsilylethenyl)stannane 3 was effected using

by a palladium-catalyzed transfer of a trimethyltin group [Pd(PPh₃)₄] as catalyst and occurred with a high degree of

from hexamethylditin to 5, and this conversion proceeded chemoselectivity for the triflate leaving group to give the

with a significantly higher yield of 72%. Because decalin-2- intermediate bromodiene 14 in 80% yield (Scheme 2). With

ones preferably form the undesired enolate regioisomers, [Pd₂(dba)₃] in the presence of LiCl^[15]in DMF, the twofold

Scheme 2. Stille–Heck coupling sequences used to access unsymmetrically 1,6-disubstituted 1,3,5-hexatrienes.

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Substituted 1,3,5-Hexatrienes in Thermally Induced 6π-Electrocyclizations

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coupling product 24 was obtained along with the desired % each of the precatalyst, methyl acrylate was coupled with

bromodiene 14 in a ratio of 1:1. With CuI and AsPh₃as 17 to provide 22-Me in 84% yield.^[20]

additives, the catalytic activity towards the reaction with the

bromine leaving group was further increased, and the ratio Heck reaction with tert-butyl acrylate and with addition of

of 24/14 increased to 4:3. two portions of 4 mol-% each of the precatalyst, gave the

The subsequent Heck reaction of diene 14 with tert-butyl tricyclic hexatriene 23 in 60% yield (Scheme 2).^[18]

acrylate was brought about under conventional conditions Attempts to combine the Stille and Heck coupling reac-

The functionalized tricyclic bromobutadiene 23, upon

using Pd(OAc)₂and PPh₃and so provided the unsymmetri- tions so as to prepare the hexatrienes 22-tBu and 22-Me

cally 1,5-disubstituted 1,2-dialkenylcyclohexene 19 in 78% directly could not be realized in a one pot procedure, be-

yield. This Stille–Heck sequence could also be performed cause the Heck reaction under catalysis of the palladacycle

in a one-pot procedure to give product 19 in an overall yield did not proceed at all in the presence of NMP.

of 75% from 13 which constitutes a real increase in effi-

ciency. Clearly, the rather simple catalytic system derived

from Pd(OAc)₂and PPh₃is not retarded by the presence of

[Pd(PPh₃)₄] and vice versa. As proved by an X-ray structure

Studies of the 6π-Electrocyclization Reactions

analysis, the 1,3,5-hexatriene system in 19 adopts an

The thermally induced 6π-electrocyclization reactions

were conveniently carried out in the high-boiling, chemi-

s-trans,s-trans conformation.^[16]

The dioxinylstannane 25 was also smoothly coupled with cally inert solvent decalin. After completion of the reaction,

the bromocyclohexenyl triflate 13 using [Pd(PPh₃)₄] as a the decalin could easily be removed at ambient temperature

catalyst and so gave the bicyclic bromodiene 15 in 82% under reduced pressure.

yield. An attempted Heck coupling with tert-butyl acrylate

For the cyclization of the hexatriene 19 incorporating an

employing Pd(OAc)₂and PPh₃as a precatalyst gave only electron-withdrawing tert-butoxycarbonyl substituent, dif-

low yields (Ͻ20%) of the bicyclic hexatriene 20. In bromo- ferent temperatures were investigated. For example, heating

dienes of type 15, the alkenyl bromide moiety is sterically the substrate at 150 °C for 11 h, afforded a mixture of the

more encumbered than that associated with compounds of two isomeric bicyclo[4.4.0]decadienes 26 and 27, the latter

type 14. In order to compensate for the resulting lower reac- apparently arising from 26 by a [1,5]-hydrogen shift. How-

tivity, the palladacycle prepared by heating palladium ace- ever, the major component of the reaction mixture was the

tate with tris(o-tolyl)phosphane,^[17]and a higher tempera- starting material 19. At 170 and 190 °C, the transforma-

ture were employed for the Heck reaction of 15 with tert- tions were also incomplete, but at 205 °C, the triene 19 was

butyl acrylate. Through such modifications, the 1,3,5-hexa- completely consumed within 1 h and so provided a 1:1.9

triene 20 was obtained in 65% yield although full consump- mixture of the dienes 26 and 27 in a combined yield of

tion of substrate 15 required addition of the palladacycle in 79%. Extended heating of the mixture did not change this

two portions (Scheme 2).^[18]

ratio significantly. The impossibility readily separating re-

The 4-azacyclohexenylstannane 4b was not readily cou- gioisomers 26 and 27 detracts from this approach to hexa-

pled with the cyclohexenyl triflate 13 when [Pd(PPh₃)₄] was hydronaphthalenes.

used as catalyst. A much better yield (84%) of the bromodi-

In order to be able to extend this investigation to thermal

ene 16 was achieved with [Pd₂(dba)₃] and CuI.^[19]It is note- 6π-electrocyclizations of 1,3,5-hexatrienes with significantly

worthy that the addition of AsPh₃to the catalyst cocktail different steric and electronic properties, the tert-butoxycar-

had no significant influence on the yield. The attempted bonyl moiety in compound 19 was reduced using diisobut-

coupling of the same substrate with the trimethylstannyl de- ylaluminum hydride (DIBALH) in toluene and thus yielded

rivative 4a led to low yields regardless of the catalyst. The triene 29 incorporating an allylic alcohol residue that could

Heck coupling of compound 16 with tert-butyl acrylate be protected by its transformation into the tetrahydro-

gave product 21 in 71% yield although, once again, the pal- pyranyl ether 31.^[21]

ladacycle had to be added in two portions.

Attempts to prepare the allyl ether 31 directly by Heck

Stille coupling of the bicyclodecenylstannane 8 with the cross coupling of the bromodiene 14 with the relevant part-

bromoenol triflate 13 was achieved with the precatalyst sys- ners in the presence of silver acetate or carbonate^[22]only

tem consisting of [Pd₂(dba)₃], AsPh₃and CuI in DMF and provided impure samples of the product and only in low

so furnished the tricyclic bromodiene 17 in 76% yield. Em- yield (0–30%). Under Heck conditions without an added

ploying NMP instead of DMF, provided 17 in 89% yield, silver salt, a minor amount of the non-conjugated 1,3,6-

while product 18 was obtained from substrate 13 and the hexatriene was also formed.

bicyclodecenylstannane 11 in an even higher yield of 94%.

Heating triene 31 in decalin at 205 °C for 45 min cleanly

Heck coupling of the bromodiene 17 with tert-butyl acry- furnished, in 93% yield, the bicyclic diene 30 resulting from

late required two portions of 4 mol-% each of the pallada- 6π-electrocyclization and a subsequent [1,5]-hydrogen shift

cycle to furnish the tricyclic hexatriene 22-tBu in 58% yield. (Scheme 3).

To achieve reasonable yields, a solvent mixture consisting

After 30 min at 205 °C, only a mixture of the starting

of MeCN, DMF and water as well as the additive tetrabu- material 31 and the diene 30 was observed. Since none of

tylammonium acetate serving as a base proved essential. the primary cyclization product analogous to 26 could be

Under the same conditions, but with two portions of 8 mol- detected, the [1,5]-hydrogen shift obviously proceeds more

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the heterobicyclic hexatriene 21 having a tert-butoxycar-

bonyl substituent required heating at 205 °C for 45 min to

furnish, in 73% yield, a 1:2.6 mixture of the dienes 37 and

38. Extended heating did not lead to a significant change

in favor of the [1,5]-hydrogen-shifted product 38.

In contrast, the hexatriene 39 incorporating an allylic

alcohol terminus and obtained from precursor 21 in 89%

yield by reduction with DIBALH, upon heating at 205 °C

for 30 min furnished a mixture of the two regioisomeric 40

and 41 in a ratio of 4.3:1 in a total yield of 82%. After 2.5 h

at the same temperature, the ratio of the two regioisomers

was 1:2.5, although the isomerization of compound 40 to

congener 41 could not be completed through extended heat-

ing, because both products decomposed under such condi-

tions (Scheme 5).

Scheme 3. Thermal 6π-electrocyclizations of the 1,2-dialkenylcy-

clohexene derivatives 19, 29 and 31.

rapidly than the 6π-electrocyclization, a situation that con-

trasts with the one involving substrate 19. After 12 h at

150 °C, no consumption of 31 was observed. The free allylic

alcohol 29 could also be cleanly cyclized to give the diene

28 as a single product in 88% yield. Thus, this reaction

proceeds without decomposition, even at 205 °C.

As observed for the cyclization of the hexatriene 19,

upon heating the tert-butoxycarbonyl-substituted hexatri-

ene 20 at 205 °C for 45 min, a 1:3.1 mixture of the 6π-elec-

trocyclization product 32 and isomer 33 arising from a sub-

sequent [1,5]-hydrogen shift was obtained. In contrast, tri-

ene 36 incorporating an allyl ether moiety, which was ob-

tained from compound 20 by reduction with DIBAL-H

(85% yield) and subsequent etherification with MOMCl

(77%), yielded only the tricyclic diene 34 in 86% yield upon

heating at 205 °C for 1 h. Just as observed for congeners 29

and 31, the 6π-electrocyclization of compound 36 is fol-

lowed by a rapid [1,5]-hydrogen shift (Scheme 4). Interest-

ingly, the hexatriene 36 could also be transformed into iso-

mer 34 by heating the former at the significantly lower tem-

perature of 150 °C for 12 h. Indeed, under such conditions

the yield of the reaction could even be raised to 91%. The

facility with which both the electrocyclization of compound

36 and the subsequent hydrogen migration take place, must

arise from the relative electron richness of the substrate al-

though, according to literature precedents,^[2a]hexatrienes

like 19 and 20 carrying electron-withdrawing substituents

should cyclize more readily. As with congeners 19 and 20,

Scheme 5. Thermal 6π-cyclizations of the heterobicyclic hexatrienes

21 and 39.

The tricyclic 1,3,5-hexatriene 43 bearing an allylic

alcohol group was prepared from 42,^[7a]as a potential pre-

cursor to the steroid framework. Upon heating compound

43 at 205 °C for 45 min, it reacted to give the regioisomeric

tetracyclic compounds 44 and 45 in yields of 20 and 26%,

respectively. In contrast, the oxohexatriene 46 underwent

smooth cyclization and a subsequent (formal) [1,3]-hydro-

gen shift to yield, exclusively and in 75% yield, the conju-

gated steroidal dienone 47 (Scheme 6).^[6c]

The tricyclic hexatrienes 22-tBu, 22-Me and particularly

23 may be considered as precursors to Baccharan-type tri-

terpenes.^[23]In decalin solution, 22-tBu at 205 °C smoothly

rearranged within 45 min to give 48-tBu as the sole reaction

product and as a single diastereomer in 77% yield

(Scheme 7). Apparently, the initial 6π-electrocyclization oc-

curred with a high degree of outward-directed disrotational

selectivity.^[24]Under the same conditions, the tricyclic hexa-

triene 23 also gave the tetracycle 50 as a single product in

71% yield. By employing the enantiomerically pure and

readily available form of bicyclodecenylstannane 11^[25]in

the initial Stille cross coupling, the tetracyclic compound 50

would also be accessible in enantiomerically pure form.

Interestingly, upon heating the 1-methoxycarbonyl-sub-

stituted hexatriene 22-Me at 205 °C for 30 min, a 7:1 mix-

Scheme 4. Thermal 6π-electrocylizations of the heterobicyclic hexa-

trienes 20 and 36.

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through straightforward functional-group manipulations.

All of those trienes underwent 6π-electrocyclizations and

the primary products of such processes engaged in subse-

quent [1,5]-hydrogen shift reactions, and so provided mix-

tures of products. However, when the hexatrienes incorpo-

rate an allylic alcohol or allyl ether at their terminus, the

electrocyclization/[1,5]-hydrogen shift sequences went to

completion. Such transformations may find applications in

the construction of multifunctional bi- and tricyclic skel-

etons that can participate in [4+2] cycloaddition reactions

and thus resulting in further increase in molecular complex-

ity.^[26]

Experimental Section

1

General Remarks: H NMR: Varian VXR-300 (300 MHz), Bruker

AM 250 (250 MHz). Chemical shifts in CDCl₃are reported as δ

values relative to chloroform (δ = 7.26 ppm) or benzene (δ =

7.20 ppm) as internal references. ¹³C NMR: Varian VXR-300

(75.5 MHz), Bruker AW 250 (62.9 MHz). Chemical shifts in CDCl₃

are reported as δ values relative to chloroform (δ = 77.0 ppm) or

benzene (δ = 128 ppm); the multiplicities of the signals were deter-

mined by the DEPT (APT) (62.9 MHz) technique and quoted as

(+) for CH₃and CH groups, (–) for CH₂groups and (C_quat) for

quaternary carbon atoms. IR: Bruker IFS 66. Low-resolution EI

mass spectra: Finnigan MAT 95, ionizing voltage 70 eV. High-reso-

lution mass spectra: Finnigan MAT 95; preselected ion peak

matching at R ca. 10000 to be within Ϯ2 ppm of the exact masses.

Elemental analyses: Mikroanalytisches Labor des Instituts für Or-

ganische und Biomolekulare Chemie der Universität Göttingen,

Germany. Melting points are uncorrected. Solvents for extraction

and chromatography were of technical grade and distilled before

use. Flash chromatography (FC) was performed using Merck Kie-

selgel 60 (200–400 mesh). Aluminum oxide (ICN Alumina N, Su-

per I) was obtained from ICN Biomedicals. Unless otherwise speci-

fied, aluminum oxide was deactivated with 5% water. TLC analyses

were performed using Macherey–Nagel precoated plates, 0.25 mm,

Alugram Sil G/UV₂₅₄(I) and Merck precoated silica gel 60 F₂₅₄

aluminum sheets (II). All reactions were carried out under dry ni-

trogen or argon in oven- and/or flame-dried glassware. Unless

otherwise specified, solutions of NH₄Cl, NaCl, Na₂SO₃and

NaHCO₃were saturated aqueous solutions. Benzene, decalin, tolu-

ene, THF and diethyl ether were distilled from sodium/benzophen-

one. Dichloromethane was distilled from CaH₂. 1-Benzyl-4-tri-

Scheme 6. Tricyclic 1,3,5-hexatrienes as precursors to steroidal

compounds.

Scheme 7. Thermal rearrangement of the tricyclic hexatrienes 22-

tBu, 22-Me and 23 to tetracycles 48, 49 and 50.

ture of the initial 6π-electrocyclization product 49 and the

[1,5]-hydrogen-shifted product 48-Me was obtained. In con-

trast, heating the same reaction mixture for a total of

60 min provided compound 48-Me exclusively and in a

yield of 69%.

fluoromethylsulfonyloxy-1,2,3,6-tetrahydropyridine (5),^[10]

∆

^1,9-oc-

talone-2 (6),^[27]5-tert-butoxy-4a-methyl-4,4a,5,6,7,8-hexahydro-

2(3H)-naphthalenone (9),^[25]tributyl(5,6-dihydro[1,4]dioxin-2-yl)-

stannane (25),^[13]N,N-bis(trifluoromethylsulfonyl)aniline^[28]were

prepared according to published procedures.

Conclusions

General Procedure for the Preparation of the Bicycloalkenylstann-

anes (GP 1): n-Butyllithium (2.60 equiv. of a 2.36  solution in

hexane) was added at –78 °C to a solution of diisopropylamine

(2.60 equiv.) in THF and the resulting mixture was stirred for

30 min. The resulting solution was treated with tributyltin hydride

(2.20 equiv.), and stirring was continued for 30 min before cop-

per(I) cyanide (1.10 equiv.) was added in one portion. The reaction

mixture was then warmed to –50 °C, and after a yellow solution

had formed, this was treated with the respective enol triflate

(1.00 equiv.) in THF. The resulting solution was warmed to –25 °C,

then stirred continuously at this temperature for 2 h, before being

The bicyclo[4.4.0]decadienes 28 and 30 can be prepared

in an efficient manner through a sequence of Stille–Heck

cross couplings and subsequent thermally induced cycliza-

tion of the resulting 1,3,5-hexatrienes. They represent inter-

esting intermediates for organic synthesis because they can

be employed for the construction of various complex car-

bon skeletons.^[26]

The Stille–Heck cross-coupling sequence also provides

easy access to various unsymmetrically 1,6-disubstituted

1,3,5-hexatrienes, and further examples could be prepared poured into pentane and washed with NH₃solution (10%), water

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H. W. Sünnemann, M. G. Banwell, A. de Meijere

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and brine. After drying with MgSO₄and removal of the solvents

under reduced pressure, the residue was dissolved in ethyl acetate,

and the ensuing solution treated with silver(I) acetate (3.00 equiv.)

for 2 h at ambient temperature, using an unsealed vessel. The reac-

tion mixture was then filtered through Celite, the filtrate washed

with water, brine and dried with MgSO₄. After removal of the sol-

vent under reduced pressure, the residue was purified by

chromatography on neutral aluminum oxide (deactivated with 5%

water).

temperature for the stated time. The cooled reaction mixture was

concentrated at 25 °C and 5 mbar, and the residue so obtained sub-

jected to FC.

(tert-Butyldimethylsilyl)acetylene (2):

A saturated solution of

acetylene in THF (300 mL) was treated carefully and at –78 °C

over 30 min with nBuLi (66.0 mL of a 2.38  solution in hexane,

156 mmol). After stirring the ensuing mixture for 1 h, tert-butyl-

chlorodimethylsilane (18.1 g, 120 mmol) was added over 30 min.

The reaction mixture was then warmed to ambient temperature

and stirred for a total of 24 h. After washing with water (50 mL),

drying with MgSO₄, the volatile components were removed by dis-

tillation through a 25 cm Vigreux column. Further distillation of

the residue without the column yielded the product 2 (14.6 g, 87%)

as a clear, colorless oil. The analytical data obtained on this mate-

rial are consistent with those reported previously.^[29]

General Procedure for Stille Couplings of the 2-Bromocyclohex-1-

enyl Triflate 13 (GP 2): A Pyrex bottle containing a magnetic stir-

ring bar was charged with the specified solvent, the bromoenol

triflate 13 and the specified alkenylstannane. The bottle was sealed

with a septum and the solution purged, using inlet and outlet need-

les, with argon in an ultrasonic bath for 5 min. The specified cata-

lyst mixture was then added, and the resulting suspension was

purged with argon for another 5 min. After removal of the septum,

the bottle was sealed with a screw cap and then heated with vigor-

ous stirring at the specified temperature for the specified time. The

reaction mixture was then poured into diethyl ether and aqueous

NH₃solution (5%). The organic layer was washed with water, and

the combined aqueous layers were extracted with diethyl ether. The

combined organic layers were then treated with satd. KF solution,

dried with MgSO₄, concentrated under reduced pressure, and the

residue was purified by chromatography on silica gel.

(E)-tert-Butyldimethyl(2-tributylstannylvinyl)silane (3): Tributyltin

hydride (4.17 g, 14.3 mmol) was treated with chlorido(1,5-cyclooc-

tadiene)rhodium(I) dimer (50.0 mg, 0.101 mmol) at 0 °C for 5 min.

The resulting mixture was treated with (tert-butyldimethylsilyl)-

acetylene (2) (2.69 g, 10.0 mmol), stirred at 60 °C for 1.5 h, then

cooled and subjected directly to FC (70 g of silica gel, pentane) to

yield, after concentration of the relevant fractions (R_f= 0.8), the

alkenylstannane 3 (2.43 g, 57%) as a clear, colorless oil. IR (film):

ν = 2956 cm^–1, 2927, 2872, 2856, 1524, 1463, 1418, 1376, 1361,

˜

1340, 1291, 1247, 1197, 1181, 1156, 1110, 1071, 1047, 1008, 958,

938, 873, 862, 825, 773, 748. ¹H NMR (300 MHz, CDCl₃): δ = 0.16

(s, 6 H, SiCH₃), 0.80–0.97 (m, 14 H, nBu CH₃, nBu CH₂), 0.99 [s,

9 H, C(CH₃)₃], 1.20–1.41 (m, 8 H, nBu CH₂), 1.42–1.59 (m, 5 H,

General Procedure for Heck Reactions of Bromobutadienes with Ac-

rylates (GP 3): A Pyrex bottle containing a magnetic stirring bar

was charged with the specified solvent, the bromobutadiene and

the acrylate. The bottle was sealed with a septum, and the solution

purged, using inlet and outlet needles, with argon in an ultrasonic

bath for 5 min. The specified catalyst mixture was then added, and

the resulting suspension was purged with argon for another 5 min.

After removal of the septum, the bottle was sealed with a screw

cap and then heated with vigorous stirring at the specified tempera-

ture for the stated time. The reaction mixture was then poured into

diethyl ether and water. The organic layer was repeatedly washed

with water, and the combined aqueous layers were extracted with

diethyl ether. The combined organic layers were then dried with

MgSO₄, filtered and concentrated under reduced pressure. The resi-

due thus obtained was purified by FC on silica gel.

3

nBu CH₂), 6.58 (d, J = 21.6 Hz, 1 H, 2-H), 6.99 (d, J = 21.6 Hz,

1 H, 1-H) ppm. ¹³C NMR (75.6 MHz, CDCl₃, add. APT): δ = –6.5

[+, 2 C, CH₃, Si(CH₃)₂], 8.8 [–, C_quat, C(CH₃)₃], 9.5 (–, 3 C, nBu

CH₂), 10.0 [+, 3 C, C(CH₃)₃], 13.7 (+, 3 C, nBu CH₃), 27.4 (–, 3

C, nBu CH₂), 29.3 (–, 3 C, nBu CH₂), 151.9 (+, CH), 152.5 (+,

CH) ppm.

1-Benzyl-4-trimethylstannyl-1,2,3,6-tetrahydropyridine

(4a):

A

thick-walled Pyrex bottle, containing a magnetic stirring bar, was

charged with a solution of the heterocyclic enol triflate 5 (0.840 g,

2.74 mmol) in THF (10 mL), hexamethylditin (1.00 g, 3.05 mmol)

and lithium chloride (0.777 g, 6.12 mmol). This mixture was purged

with argon in an ultrasonic bath for 5 min, before tetrakis(triphen-

ylphosphane)palladium(0) (71.0 mg, 61.2 µmol) was added. The

bottle was sealed with a screw cap and heated at 60 °C for 5 h.

After cooling to ambient temperature, the reaction mixture was

poured into diethyl ether (100 mL), the mixture washed with water

(2ϫ25 mL), then dried with MgSO₄. The volatile components were

removed under reduced pressure, and the residue subjected to FC

(65 g of neutral aluminum oxide, 5:1 v/v pentane/diethyl ether elu-

tion) to yield, after concentration of the relevant fractions (R_f=

0.4), 4a (645 mg, 72%) as a clear, colorless oil. ¹H NMR (300 MHz,

CDCl₃): δ = 0.09 (s, 9 H, SnCH₃), 2.24–2.40 (m, 2 H, 5-H), 2.56

(t, ³J = 5.4 Hz, 2 H, 6-H), 3.02 (m_C, 2 H, 2-H), 3.58 (s, 2 H,

PhCH₂N), 5.80 (m_C, 1 H, 3-H), 7.16–7.47 (m, 5 H, Ar-H) ppm.

General Procedure for the Reduction of the tert-Butoxycarbonyl-

Substituted Hexatrienes to Allylic Alcohols (GP 4): A magnetically

stirred solution of the respective α,β-unsaturated carboxylic ester

in toluene at –78 °C was treated dropwise with diisobutylaluminum

hydride (DIBALH) (4.00–8.00 equiv., 1.00  in toluene), and the

ensuing mixture was stirred at –78 °C for 1 h. After warming to

ambient temperature, it was stirred for an additional 4 h, then

poured into diethyl ether and the mixture washed with 1.00 

KHSO₄solution and water. After extraction of the combined aque-

ous phases with diethyl ether, washing of the combined organic

layers with satd. NaHCO₃solution, water and drying with MgSO₄,

the volatile components were removed under reduced pressure, and

the residue so obtained was subjected to FC.

1-Benzyl-4-tributylstannyl-1,2,3,6-tetrahydropyridine (4b): Accord-

ing to GP 1, a solution of diisopropylamine (1.71 g, 16.9 mmol)

in THF (80 mL), nBuLi (10.6 mL of a 1.60  solution in hexane,

16.9 mmol), tributyltin hydride (4.17 g, 14.3 mmol), CuCN

(641 mg, 7.16 mmol), the heterocyclic enol triflate 5 (2.00 g,

6.51 mmol) in THF (10 mL), after workup with diethyl ether

(100 mL), NH₃solution (2ϫ35 mL), water (2ϫ25 mL), brine

(30 mL), purification with AgOAc (6.50 g, 39.0 mmol) in ethyl ace-

tate (100 mL), water (2ϫ30 mL), brine (25 mL) and FC (100 g on

neutral aluminum oxide, 5:1 v/v pentane/diethyl ether elution), gave

General Procedure for the Thermally Induced 6π-Electrocyclization

of 1,3,5-Hexatrienes in Solution (GP 5): A thick-walled Pyrex test

tube, containing a magnetic stirring bar, was charged with a solu-

tion of the respective hexatriene (1.00 equiv.) in the specified sol-

vent. The test tube was sealed with a septum and, using inlet and

outlet needles, the solution was purged with argon in an ultrasonic

bath for 10 min. The septum was then replaced by a screw cap, and

the solution was heated in a prewarmed oil bath at the specified

3884

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Eur. J. Org. Chem. 2007, 3879–3893

Substituted 1,3,5-Hexatrienes in Thermally Induced 6π-Electrocyclizations

FULL PAPER

4b (1.29 g, 43%) as a clear, colorless oil. R = 0.56. IR (film): ν =

(–, CH₂), 41.2 (+, CH), 44.8 (+, CH), 139.5 (C_quat, C-2), 143.2 (+,

C-1) ppm. MS (70 eV): m/z (%) = 424 (2) [M⁺], 371/370/369/368/

˜

f

3027 cm^–1, 2957, 2842, 1604, 1462, 1369, 1336, 1283, 1250, 1142,

1

1111, 1013, 945, 900, 870. H NMR (300 MHz, CDCl₃): δ = 0.79– 367/366/365 (15/19/100/40/79/31/45) [M⁺– C₄H₉], 315/314/313/312/

1.01 (m, 14 H, nBu CH₃, nBu CH₂), 1.19–1.39 (m, 8 H, nBu CH₂),

311/310/309 (2/2/18/6/14/6/7) [M⁺– C₄H₉– C₄H₈], 292/291/290/

1.40–1.60 (m, 5 H, nBu CH₂), 2.31 (m_C, 2 H, 5-H), 2.52 (t, ³J =

289/288 (0.5/1/0.5/1/0.5) [SnBu₃⁺], 259/258/257/256/255/254/253 (4/

5.5 Hz, 2 H, 6-H), 3.00–3.09 (m, 2 H, 2-H), 3.56 (s, 2 H, PhCH₂N), 2/30/8/25/7/17) [M⁺– C₄H₉– 2ϫC₄H₈], 179/178/177/176/175 (2/1/

5.76 (m_C, 1 H, 3-H), 7.24–7.40 (m, 5 H, Ar-H) ppm. ¹³C NMR 4/1/2) [SnBu⁺], 135 (10) [M⁺– SnBu₃], 122/120/119/118/117/116 (1/

(75.6 MHz, CDCl₃, additional APT): δ = 8.9 (–, 3 C, nBu CH₂),

13.7 (+, 3 C, nBu CH₃), 27.4 (–, 3 C, nBu CH₂), 29.2 (–, 3 C, nBu

CH₂), 32.7 (–, CH₂), 50.2 (–, CH₂), 54.77 (–, CH₂), 63.1 (–, CH₂,

PhCH₂), 126.9 (+, CH, Ph), 128.1 (+, 2 C, CH, Ph), 129.3 (+, 2 C,

CH, Ph), 134.8 (+, CH, C-3), 138.3 (–, C_quat), 138.5 (–, C_quat) ppm.

MS (70 eV): m/z (%) = 465/464/463/462/461 (1/1/5/1/4), 460/459/

458/457/456/455/454 (2/2/9/2/8/2/4), 408/407/406/405/404/403/402

(6/8/32/12/26/11/15), 343 (52), 271/270/269/268/267/266/265 (6/3/20/

5/12/4/6), 251 (6), 224 (28), 174 (9), 172 (84), 134 (6), 91 (100) 65

(6). HRMS: calcd. for C₂₄H₄₁NSn 456.1839 (correct HRMS).

5/2/4/2/3) [Sn⁺], 91 (9), 67 (4), 41 (3). C₂₂H₄₂Sn (424.9): calcd. C

62.13, H 9.96; found C 62.05, H 10.07.

2-(trans-5-tert-Butoxy-4a-methyl-3,4,4a,5,6,7,8,8a-octahydronaph-

thyl) Trifluoromethanesulfonate (10): Under argon, a mixture of li-

quid ammonia (200 mL) and THF (150 mL) at Ϫ78 °C was treated

with lithium metal (233 mg, 31.2 mmol). To the resulting blue solu-

tion was added dropwise the α,β-unsaturated ketone 9 (3.20 g,

13.6 mmol) and aniline (100 µL, 1.10 mmol) in THF (75 mL). The

reaction mixture was warmed to Ϫ33 °C and stirred for 2 h. Excess

lithium was oxidized with isoprene, then the mixture was warmed

to 22 °C, and the remaining volatile components were removed en

vacuo. The residue was dissolved in THF (150 mL), the solution

cooled to Ϫ78 °C, and N,N-bis(trifluoromethanesulfonyl)aniline

(12.1 g, 32.5 mmol) in THF (100 mL) was added dropwise. The re-

action mixture was warmed to 22 °C overnight and stirred for a

total of 24 h, it was then directly absorbed on silica gel and sub-

jected to FC (80 g of silica, 20:1 v/v pentane/diethylether elution)

to yield, after concentration of the relevant fractions (R_f= 0.43),

2-(trans-3,4,4a,5,6,7,8,8a-Octahydronaphthyl) Trifluoromethanesul-

fonate (7): Under argon, a mixture of liquid ammonia (400 mL)

and diethyl ether (200 mL) at Ϫ78 °C was treated with lithium

metal (322 mg, 46.4 mmol). To the resulting blue solution was

added dropwise ∆^1,9-octalone-2 (6) (3.00 g, 20.0 mmol) and aniline

(133 µL, 1.46 mmol) in diethyl ether (50 mL). The reaction mixture

was warmed to Ϫ33 °C and stirred for 2 h. Excess lithium was oxid-

ized with isoprene, then the mixture was warmed to 22 °C, and the

remaining volatile components were removed in vacuo. The residue

was dissolved in THF (250 mL), the solution cooled to Ϫ78 °C,

the product 10 (4.54 g, 90%) as a clear colorless oil. IR (film): ν =

˜

2976, 2933, 2867, 1685, 1489, 1417, 1363, 1319, 1247, 1208, 1143,

and N,N-bis(trifluoromethanesulfonyl)aniline (19.1 g, 53.4 mmol) 1091, 1078, 1042, 1008, 991, 958, 929, 871, 816, 764 cm^Ϫ^{1 1}H

.

in THF (100 mL) was added dropwise. The reaction mixture was

warmed to 22 °C overnight and stirred for a total of 24 h, it was

then directly absorbed on silica gel and subjected to FC (400 g of

silica, pentane) to yield, after concentration of the relevant frac-

tions (R_f= 0.56), the product 7 (4.87 g, 86%) as a clear colorless

NMR (250 MHz, CDCl₃): δ = 0.73 (s, 3 H, CH₃), 0.80Ϫ0.95 (m, 3

H), 1.02 [s, 9 H, C(CH₃)₃], 1.33Ϫ1.63 (m, 5 H), 1.77 (dd, ³J =

3

5.0 Hz, J = 11.3 Hz, 1 H, 8a-H) 1.91Ϫ2.23 (m, 2 H), 2.69 (dd, J

= 5.9 Hz, ³J = 8.8 Hz, 1 H, 5-H), 5.18 (s, 1 H, 1 H). ¹³C NMR

(62.9 MHz, C₆D₆, add. DEPT): δ = 10.2 (+, CH₃), 24.6 (–, CH₂),

25.2 (–, CH₂), 26.4 (–, CH₂), 28.9 [+, 3 C, (C(CH₃)₃], 30.3 (–, CH₂),

34.1 (–, CH₂), 37.5 (C_quat, C-4a), 43.2 (+, C-8a), 73.0 (+, C-5), 77.2

oil. IR (film): ν = 2926, 2857, 1684, 1448, 1418, 1369, 1248, 1208,

˜

1145, 1081, 1060, 1048, 1024, 998, 963, 886, 854, 615 cm^Ϫ1

.

¹H

1

NMR (250 MHz, CDCl₃): δ = 0.95Ϫ1.60 (m, 6 H), 1.79 (m_c, 6 H),

[C_quat, C(CH₃)₃], 121.3 (+, CH, C-1), 122.9 (q, C_quat, J = 315 Hz,

3

2.20Ϫ2.36 (dd, J = 6.2 Hz, J = 12.0 Hz, 1 H), 2.37Ϫ2.53 (m, 1

CF₃), 148.4 (C_quat, C-2). MS (70 eV): m/z (%) = 370 (2) [M⁺], 313

H), 5.51 (s, 1 H, 1-H) ppm. ¹³C NMR (62.9 MHz, CDCl₃, add. (40) [M⁺– C₄H₉], 295 (21), 269 (4), 229 (3), 181 (100), 163 (22),

DEPT): δ = 26.3 (–, CH₂), 26.9 (Ϫ, CH₂), 28.0 (–, CH₂), 29.7 (–,

121 (8), 111 (3), 57 (67) [C₄H₉⁺]. C₁₆H₂₅F₃O₄S (370.4): calcd. C

CH₂), 32.3 (–, CH₂), 32.5 (Ϫ, CH₂), 39.7 (+, CH), 40.9 (+, CH), 51.88, H 6.80; found C 51.61, H 6.57.

117.0 (q, C_quat, ¹J = 340 Hz, CF₃), 123.1 (+, C-1), 149.0 (C_quat, C-

(5-tert-Butoxy-4a-methyl-3,4,5,6,7,8,8a-heptahydronaphthyl)tri-

2) ppm. MS (70 eV): m/z (%) = 284 (33) [M⁺], 283 (17) [M⁺Ϫ H],

151 (100), 133 (47), 119 (5), 95 (18), 91 (31), 69 (44) [CF₃⁺], 55

(37), 41 (40). C₁₁H₁₅F₃O₃S (284.3): calcd. C 46.47, H 5.32; found

C 46.27, H 5.38.

butylstannane (11): According to GP 1, a solution of diisopropyl-

amine (3.66 mL, 26.0 mmol) in THF (150 mL), nBuLi (11.0 mL,

26.0 mmol, 2.36 ), tributyltin hydride (5.93 mL, 22.1 mmol),

CuCN (986 mg, 11.0 mmol) and the triflate 10 (3.70 g, 10.0 mmol),

Tributyl(trans-3,4,4a,5,6,7,8,8a-octahydronaphth-2-yl)stannane (8): after workup with pentane (150 mL), aqueous NH₃solution

According to GP 1, a solution of diisopropylamine (2.92 mL,

20.8 mmol) in THF (140 mL), nBuLi (8.80 mL of a 2.36  solution

in hexane, 20.8 mmol), tributyltin hydride (4.75 mL, 17.6 mmol),

CuCN (789 mg, 8.80 mmol) and the bicyclic enol triflate 7 (2.27 g,

7.95 mmol), after workup with pentane (100 mL) aqueous NH₃

solution purification with AgOAc (4.00 g, 24.0 mmol) in ethyl ace-

tate (140 mL), water (2ϫ45 mL) and FC (93 g on silica gel deacti-

vated with 10% NEt₃, petroleum ether), gave compound 8 (3.31 g,

(3ϫ40 mL), purification with AgOAc (4.99 g, 30.0 mmol) in ethyl

acetate (150 mL), water (2ϫ50 mL) and FC (134 g on silica gel

deactivated with 10% NEt₃, light petroleum), gave compound 11

(4.96 g, 97%) as a clear, colorless oil. (R_f= 0.5, 20:1 v/v light petro-

leum/diethyl ether). IR (film): ν = 2956 cm^–1, 2926, 1685, 1464,

˜

1427, 1418, 1376, 1361, 1272, 1248, 1192, 1048, 1020, 1002, 880,

877, 844, 768. ¹H NMR (250 MHz, C₆D₆): δ = 0.78–1.05 (m, 15

H, nBu CH₃, nBu CH₂), 1.08 (s, 3 H, CH₃), 1.11 [s, 9 H, C-

(CH₃)₃], 1.20–1.79 (m, 19 H), 1.83–1.97 (m, 1 H), 2.00–2.12 (m, 1

98%) as a clear, colorless oil. R = 0.7. IR (film): ν = 2957 cm^–1,

˜

f

3

2919, 2842, 1604, 1464, 1418, 1376, 1357, 1340, 1286, 1250, 1228,

1193, 1148, 1110, 1071, 1023, 960, 910, 875, 869, 846, 688, 663,

H) 2.30–2.42 (m, 2 H, 3-H), 2.95 (dd, J = 7.0, J = 8.4 Hz, 1 H,

5-H), 5.87 (d, J = 0.7 Hz, 1 H, 1-H) ppm. ¹³C NMR (62.9 MHz,

3

595. ¹H NMR (250 MHz, CDCl₃): δ = 0.91–1.02 (m, 15 H, nBu C₆D₆, add. DEPT): δ = 9.2 (-, nBu CH₂), 10.8 (+, CH₃), 14.0 (+,

H), 1.03–1.37 (m, 4 H), 1.38–1.51 (m, 6 H, nBu H), 1.52–1.83 (m,

12 H), 2.30–2.42 (m, 2 H, 3-H), 5.77 (m_c, 1 H, 1-H.) ppm. ¹³C [+, 3 C, C(CH₃)₃], 29.7 (–, nBu CH₂), 30.7 (–, CH₂), 31.0 (–, CH₂),

NMR (62.9 MHz, CDCl₃, add. DEPT): δ = 9.2 (–, CH₂), 13.9 (+, 35.5 (–, CH₂), 37.8 (C_quat, C-4a), 46.1 (+, C-8a), 72.5 [C_quat

nBu CH₃), 25.1 (–, CH₂), 27.3 (–, CH₂), 27.8 (–, nBu CH₂), 29.2

,

CH₃), 26.9 (–, CH₂), 27.1 (–, CH₂) 27.3 (–, CH₂), 27.8 (–, CH₂), C(CH₃)], 77.6 (+, C-5), 139.3 (C_quat, C-2), 141.2 (+, C-1) ppm. MS

29.7 (–, CH₂), 31.4 (–, CH₂), 33.4 (–, CH₂), 33.6 (–, CH₂), 34.1 (70 eV): m/z (%) = 512 (1) [M⁺], 457/456/455/454/453/452/451 (16/

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3885

H. W. Sünnemann, M. G. Banwell, A. de Meijere

FULL PAPER

24/100/44/83/33/46) [M⁺– C₄H₉], 401/400/399/398/397/396/395 (1/

1/10/4/8/4/5) [M⁺– C₄H₉– C₄H₈], 345/344/343/342/341/340/339 (1/

2/13/3/10/3/4) [M⁺– C₄H₉– 2ϫC₄H₈], 293/292/291/290/289/288/

287 (1/1/6/3/5/2/3) [SnBu₃⁺], 237/236/235/234/233/232/231 (1/1/4/2/

776, 729. ¹H NMR (300 MHz, CDCl₃): δ = 1.62–1.79 [m_c, 4 H,

4Ј(5Ј)-H], 2.10–2.30 (m, 3 H), 2.48–2.59 (m, 3 H), 2.64 (t, ³J =

5.5 Hz, 2 H), 3.08 (m_c, 2 H), 3.64 (s, 2 H, PhCH₂), 5.46 (m_c, 1 H,

3-H), 7.24–7.42 (m, 5 H, Ph-H) ppm. ¹³C NMR (75.6 MHz, CDCl₃

3/2/1) [SnBu₂H⁺], 179/178/177/176/175 (2/1/4/1/2) [SnBu⁺], 147 (6), add. APT): δ = 22.9 (–, CH₂), 24.6 (–, CH₂), 27.9 (–, CH₂), 31.3

105 (5), 57 (18) [Bu⁺], 41 (2). C₂₇H₅₂OSn (511.4): calcd. C 63.41,

H 10.25; found C 63.44, H 9.98.

(–, CH₂), 36.7 (–, CH₂), 49.8 (–, CH₂), 52.5 (–, CH₂), 62.7 (–, CH₂,

PhCH₂), 118.4 (–, C_quat), 122.7 (+, CH, C-3), 127.3 (+, CH, Ar),

128.5 (+, 2 C, CH, Ar), 129.5 (+, 3 C), 138.5 (–, C_quat), 138.9 (–,

C_quat) ppm. MS (70 eV): m/z (%) = 333/331 (33/33) [M⁺], 252 (88)

[M⁺– Br], 234 (13), 233 (10), 172 (33), 158 (17), 133 (20), 117

(11), 105 (17), 91 (100) [Bn⁺], 77 (18), 65 (21). HRMS: calcd. for

C₁₈H₂₂BrN 331.0937 (correct HRMS).

[(E)-2-(2-Bromocyclohex-1-enyl)vinyl]tert-butyldimethylsilane (14):

According to GP 2, a solution of bromoenol triflate 13 (309 mg,

1.00 mmol) in DMF (10 mL) with the alkenylstannane 3 (431 mg,

1.00 mmol), after treatment with tetrakis(triphenylphosphane)pal-

ladium (57.8 mg, 50.0 µmol), LiCl (127 mg, 3.00 mmol) at 90 °C

for 12 h, workup with diethyl ether (50 mL), water (2ϫ20 mL),

extraction with diethyl ether (2ϫ20 mL), and FC (55 g of silica

gel, pentane), gave compound 14 (240 mg, 80%) as a colorless oil.

trans-2-(2Ј-Bromocyclohex-1Ј-enyl)-3,4,4a,5,6,7,8,8a-octahydro-

naphthalene (17): According to GP 2, the bromoenol triflate 13

(403 mg, 1.30 mmol) with the bicycloalkenylstannane 8 (424 mg,

R = 0.6. IR (film): ν = 2951 cm^–1, 2929, 2857, 2882, 1614, 1575, 1.00 mmol) in DMF (8 mL), after treatment with [Pd₂(dba)₃]·

˜

f

1470, 1462, 1448, 1435, 1409, 1389, 1361, 1334, 1247, 1193, 1137,

CHCl₃(104 mg, 100 µmol), AsPh₃(24 mg, 78.0 µmol), LiCl

(128 mg, 3 mmol), CuI (10 mg, 52 µmol), at 65 °C for 5 h, workup

1089, 1007, 987, 973, 938, 874, 832, 811, 791. ¹H NMR (300 MHz,

CDCl₃): δ = 0.09 [s, 6 H, Si(CH₃)₂], 0.89 [s, 9 H, C(CH₃)₃], 1.72 with diethyl ether (50 mL), water (2ϫ20 mL), extraction with di-

[m_c, 4 H, 4Ј(5Ј)-H], 2.29 (m_C, 2 H, 6Ј-H), 2.64 (m, 2 H, 3Ј-H), 5.92 ethyl ether (2ϫ35 mL) and FC (40 g of silica gel, light petroleum),

3

(d, J = 19.2 Hz, 1 H, 1-H), 7.10 (d, J = 19.2 Hz, 1 H, 2-H) ppm.

gave compound 17 (261 mg, 89%) as a colorless wax. R_f= 0.7. IR

¹³C NMR (75.6 MHz, CDCl₃additional APT): δ = –5.8 [+, 2 C, (film): ν = 2918 cm^–1, 2851, 2824, 1640, 1446, 1326, 978. ¹H NMR

˜

Si(CH₃)₂], 16.9 [–, C_quat, C(CH₃)₃], 22.4 (–, CH₂), 24.9 (–, CH₂), (250 MHz, CDCl₃): δ = 0.80–1.19 (m, 3 H), 1.20–1.53 (m, 3 H),

26.8 [+, 3 C, C(CH₃)₃] 27.4 (–, CH₂), 38.1 (–, CH₂), 126.0 (–, C_quat),

1.55–1.86 (m, 10 H), 1.96–2.35 [m_coalesced, 4 H, 3(3Ј)-H], 2.47–2.59

127.8 (+, CH, C-1), 133.2 (–, C_quat), 145.2 (+, CH, C-2) ppm. MS (m, 2 H, 6Ј-H), 5.20 (s, 1 H, 1-H) ppm. ¹³C NMR (62.9 MHz,

(70 eV): m/z (%) = 302/300 (18/18) [M⁺], 246/244 (38/38), 245/243

(100/97), 223 (21), 221 (10), 201 (4), 189 (7), 175 (10), 167 (13), 165

(17), 163 (30), 149 (12), 147 (27), 139/137 (74/76), 135 (8), 123 (13),

121 (17), 105 (54), 95 (13), 93 (19), 91 (24), 83 (14), 79 (27), 73

(45), 67 (12), 59 (49), 57 (46). HRMS: calcd. for C₁₄H₂₅BrSi

300.0909 (correct HRMS).

CDCl₃, add. DEPT): δ = 22.6 (–, CH₂), 24.7 (–, CH₂), 26.8 (–,

CH₂), 26.9 (–, CH₂), 27.3 (–, CH₂), 30.1 (–, CH₂), 31.9 (–, CH₂),

33.0 (–, CH₂), 33.4 (–, CH₂), 36.3 (–, CH₂), 40.4 (+, CH), 42.1 (+,

CH), 117.7 (C_quat, C-2), 129.4 (+, C-H, C-1), 139.5 (C_quat, C-1Ј),

139.6 (C_quat, C-2Ј) ppm. MS (70 eV): m/z (%) = 296/294 (13/13)

[M⁺], 215 (100) [M⁺– Br], 187 (7), 133 (10), 95 (6), 91 (6), 67 (4),

41 (3). HRMS: calcd. for C₁₆H₂₃Br 294.0984 (correct HRMS).

5-(2-Bromocyclohex-1-en-1-yl)-2,3-dihydro-1,4-dioxine (15): Ac-

cording to GP 2, the bromoenol triflate 13 (309 mg, 1.00 mmol) in

DMF (10 mL) and the alkenylstannane 25 (450 mg, 1.20 mmol),

after treatment with tetrakis(triphenylphosphane)palladium

(116 mg, 100 µmol), LiCl (127 mg, 3.00 mmol) at 90 °C for 14 h

and workup with diethyl ether (50 mL), water (2ϫ20 mL), extrac-

tion with diethyl ether (2ϫ25 mL) and FC (45 g of silica gel, 10:1

v/v pentane/diethyl ether elution), gave compound 15 (201 mg,

2-(2Ј-Bromocyclohex-1Ј-enyl)-5-tert-butoxy-4a-methyl-

1,2,3,3,4,4a,5,6,8a-octahydronaphthalene (18): According to GP 2,

the bromoenol triflate 13 (0.713 g, 2.30 mmol) with the bicycloalk-

enylstannane 11 (1.02 g, 2.00 mmol) in NMP (20 mL), after treat-

ment with [Pd₂(dba)₃]·CHCl₃(104 mg, 100 µmol), AsPh₃(24.0 mg,

78.0 µmol), LiCl (384 mg, 9.05 mmol), CuI (10.0 mg, 52.0 µmol) at

65 °C for 5 h and after workup with diethyl ether (75 mL), water

(2ϫ25 mL), extraction with diethyl ether (2ϫ20 mL) and FC (90 g

of silica gel, 20:1 v/v light petroleum/diethyl ether elution), gave

compound 18 (716 mg, 94%) as a colorless wax. R_f= 0.5. IR (film):

82%) as a clear, colorless oil. R = 0.5. IR (film): ν = 2931 cm^–1,

˜

f

2870, 1666, 1642, 1554, 1435, 1368, 1333, 1308, 1283, 1257, 1229,

1155, 1114, 1091, 1027, 982, 944, 920, 878, 829, 795, 750. ¹H NMR

(300 MHz, CDCl₃): δ = 1.56–1.85 [mc, 4 H, 4Ј(5Ј)-H], 2.23 (m_c, 2 ν = 2927 cm^–1, 2858, 1643, 1456, 1446, 1387, 1378, 1362, 1265,

˜

1

H, 6Ј-H), 2.54 (m, 2 H, 3Ј-H), 4.09 [m_c, 4 H, 2(3)-H], 6.16 (s, 1 H, 1248, 1137, 1124, 1075, 1050, 1019, 1000, 959, 848, 740. H NMR

6-H) ppm. ¹³C NMR (75.6 MHz, CDCl₃, add. APT): δ = 22.1 (–,

(250 MHz, CDCl₃): δ = 0.84 (s, 3 H, CH₃), 1.18 [s, 9 H, C(CH₃)₃],

CH₂), 24.42 (–, CH₂), 30.7 (–, CH₂), 37.1 (–, CH₂), 64.2 (–, CH₂, 1.21–1.40 (m, 4 H), 1.43–1.81 (m, 7 H), 1.85–2.09 (m, 2 H), 2.10–

3

-OCH₂-), 64.4 (–, CH₂, -OCH₂-), 122.3 (–, C_quat), 126.6 (+, CH, 2.28 (m, 4 H), 2.41–2.55 (m, 2 H), 3.08 (dd, ³J = 6.8, J = 11.0 Hz,

C-6), 139.5 (–, C_quat), 136.7 (–, C_quat) ppm. MS (70 eV): m/z (%) = 1 H, 5-H), 5.28–5.31 (d, ³J = 1.3 Hz, 1 H, 1-H) ppm. ¹³C NMR

246/244 (95/95) [M⁺], 235 (8), 189/187 (99/100), 179/177 (8/8), 165

(62.9 MHz, CDCl₃, add. DEPT): δ = 10.5 (+, CH₃), 22.5 (–, CH₂),

(40), 137 (10), 121 (10), 108 (10), 105 (7), 93 (14), 91 (26), 81 (12), 24.4 (–, CH₂), 24.7 (–, CH₂), 24.8 (–, CH₂), 26.7 (–, CH₂), 29.1 [+,

79 (85), 77 (55), 65 (20), 57 (7). HRMS: calcd. for C₁₀H₁₃BrO₂3 C, C(CH₃)₃], 30.7 (–, CH₂), 32.0 (–, CH₂), 34.1 (–, CH₂), 36.3

244.0100 (correct HRMS).

(–, CH₂), 37.4 (C_quat, C-4a), 43.7 (+, CH, C-8a), 72.7 [C_quat,

C(CH₃)₃], 77.4 (+, CH, C-5), 117.8 (C_quat, C-2), 127.5 (+, C-1),

139.0 (C_quat, C-2Ј), 139.4 (C_quat, C-1Ј) ppm. MS (70 eV): m/z (%)

= 382/380 (59/58) [M⁺], 326/324 (44/52) [M⁺– C₄H₈], 307/305 (62/

52), 279 (8), 251 (10), 245 (52) [M⁺– Br – C₄H₈], 243 (79), 227 (98)

[M⁺– C₄H₈– H₂O – Br], 225 (52), 199 (13), 159 (9), 152 (10), 145

(27), 93 (38), 81/79 (21/20), 57 (100) [C₄H₉⁺], 41 (25). HRMS:

calcd. for C₂₁H₃₃BrO 380.1717 (correct HRMS).

1-Benzyl-4-(2-bromocyclohex-1-enyl)-1,2,3,6-tetrahydropyridine

(16): According to GP 2, the bromoenol triflate 13 (309 mg,

1.00 mmol) in NMP (5.00 mL) and the alkenylstannane 4b

(505 mg, 1.09 mmol), after treatment with [Pd₂(dba)₃] (46.0 mg,

50.2 µmol), LiCl (127 mg, 3.00 mmol) at 65 °C for 5 h, workup with

diethyl ether (50 mL), water (2ϫ20 mL), extraction with diethyl

ether (2ϫ20 mL) and FC (30 g on silica gel, 1:1 v/v pentane/diethyl

ether elution), gave compound 16 (279 mg, 84%) as a clear, yellow

tert-Butyl (E)-3-{2Ј-[(E)-2ЈЈ-(tert-Butyldimethylsilyl)vinyl]cyclohex-

1Ј-enyl}acrylate (19): According to GP 3, the bromobutadiene 14

(230 mg, 0.764 mmol) in DMF (10.0 mL) after treatment with

oil. R = 0.4. IR (film): ν = 3027 cm^–1, 2927, 2858, 2798, 1622,

˜

f

1595, 1494, 1453, 1367, 1327, 1158, 1126, 1074, 1028, 977, 877,

3886

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Eur. J. Org. Chem. 2007, 3879–3893

Substituted 1,3,5-Hexatrienes in Thermally Induced 6π-Electrocyclizations

FULL PAPER

Pd(OAc)₂(17.1 mg, 0.0760 mmol), PPh₃(60.1 mg, 0.229 mmol),

NEt₃(232 mg, 2.29 mmol), tert-butyl acrylate (490 mg, 3.82 mmol)

at 90 °C for 14 h, workup with diethyl ether (50 mL), water

(20 mL), extraction with diethyl ether (25 mL) and FC (30 g on

silica gel, 20:1 v/v pentane/diethyl ether elution), gave the 1,3,5-

hexatriene 19 as a colorless solid (208 mg, 78%), m.p. 155–157 °C.

Good-quality crystals for X-ray diffraction were grown from pen-

tane/diethyl ether (20:1) at 23 °C by slow evaporation of the sol-

tert-Butyl (E)-3-[2Ј-(1ЈЈ-Benzyl-1ЈЈ,2ЈЈ,3ЈЈ,6ЈЈ-tetrahydropyridin-4ЈЈ-

yl)cyclohex-1Ј-enyl]acrylate (21): According to GP 3, the bromobu-

tadiene 16 (110 mg, 0.331 mmol) in DMF/water (10:1) (2.2 mL)

was treated with the palladacycle (16.0 mg, 16.6 µmol), NaOAc

(82.0 mg, 0.993 mmol), nBu₄NBr (70.0 mg, 0.331 mmol), tert-butyl

acrylate (1.00 mL) at 105 °C for 4 h. For complete consumption of

the bromobutadiene 16, a second portion of the palladacycle

(16.0 mg, 16.6 µmol) was added and the mixture again heated at

105 °C for 4 h. Workup with diethyl ether (45 mL), water (15 mL),

extraction with diethyl ether (15 mL) and FC (22 g of silica gel,

10:1 v/v diethyl ether/methanol elution) gave compound 21

vents. R = 0.3. IR (film): ν = 2951 cm^–1, 2930, 2883, 2857, 1708,

˜

f

1621, 1470, 1462, 1391, 1366, 1340, 1305, 1278, 1248, 1202, 1147,

1070, 1038, 1007, 981, 938, 828, 813, 792, 751, 728. ¹H NMR

(300 MHz, CDCl₃): δ = 0.09 [s, 6 H, Si(CH₃)₂], 0.89 [s, 9 H,

(89.2 mg, 71 %) as a colorless wax. R = 0.5. IR (film): ν =

˜

f

SiC(CH₃)₃], 1.15 [s, 9 H, CO₂C(CH₃)₃], 1.59–1.76 [m, 4 H, 4Ј(5Ј)- 3024 cm^–1, 2974, 2930, 2862, 1761, 1703, 1614, 1476, 1452, 1390,

H], 2.28 (m_c, 2 H, 3Ј-H), 2.36 (m, 2 H, 6Ј-H), 5.81 (d, ³J = 15.4 Hz,

1366, 1310, 1275, 1257, 1149, 1049, 985, 884, 855, 733. H NMR

1

1 H, 3-H), 6.05 (d, ³J = 18.7 Hz, 1 H, 1ЈЈ-H), 7.33 (d, ³J = 18.9 Hz, (300 MHz, CDCl₃): δ = 1.25–1.38 [m, 4 H, 4Ј(5Ј)-H], 1.47 [s, 9 H,

1 H, 2ЈЈ-H), 8.06 (d, ³J = 15.7 Hz, 1 H, 2-H) ppm. ¹³C NMR CO₂C(CH₃)₃], 1.91–2.01 (m, 4 H), 2.02–2.11 (m, 2 H), 2.44 (t, ³J =

(75.6 MHz, CDCl₃, add. APT): δ = –5.8 [+, 2 C, CH₃, Si(CH₃)₂],

5.5 Hz, 2 H), 2.87 (m_c, 2 H), 3.38 (s, 2 H, PhCH₂), 5.33 (m_c, 1 H,

16.9 [–, C_quat, C(CH₃)₃], 22.4 (–, CH₂), 22.5 (–, CH₂), 26.5 (–, CH₂), 3ЈЈ-H), 6.01 (d, ³J = 15.7 Hz, 1 H, 3-H), 7.09–7.22 (m, 3 H, Ph-H),

3

26.8 [+, 3 C, CH₃, C(CH₃)₃], 26.9 (–, CH₂), 28.4 [+, 3 C, 7.35–7.45 (m, 2 H, Ph-H), 8.19 (d, J = 15.8 Hz, 1 H, 2-H) ppm.

CO₂C(CH₃)₃], 80.2 [–, C_quat, CH₃, C(CH₃)₃], 118.6 (–, C_quat), 129.0 ¹³C NMR (75.6 MHz, CDCl₃, add. APT): δ = 22.5 (–, CH₂), 22.6

(+, CH, C-1ЈЈ), 131.6 (–, C_quat), 140.5 (+, CH, C-2ЈЈ), 141.2 (+,

(–, CH₂), 24.9 (–, CH₂), 25.4 (–, CH₂), 28.5 [+, 3 C, CO₂C(CH₃)₃],

CH, C-3), 141.3 (+, CH, C-2), 175.6 (–, C_quat, C=O) ppm. MS 30.5 (–, CH₂), 49.7 (–, CH₂), 52.9 (–, CH₂), 62.9 (–, CH₂, PhCH₂),

(70 eV): m/z (%) = 348 (7) [M⁺], 292 (9) [M⁺– C₄H₈], 247 (11), 235 79.9 [C_quat, CO₂C(CH₃)₃], 116.7 (+, CH, C-3ЈЈ), 124.7 (+, CH),

(100), 207 (9), 191 (7), 189 (20), 161 (14), 159 (6), 132 (6), 131 (18), 127.3 (+, CH, Ph), 128.0 (–, C_quat), 128.5 (+, 2 C, CH, Ph), 129.4

116 (6), 115 (32) 103 (7), 91 (10), 75 (68), 57 (21) [C₄H₉⁺]. HRMS:

calcd. for C₂₁H₃₆O₂Si 348.2477 (correct HRMS).

(+, 2 C, CH, Ph), 136.9 (–, C_quat), 138.5 (–, C_quat, Ph), 144.2 (+,

CH, C-2), 149.2 (–, C_quat), 167.7 (–, C_quat, C=O) ppm. MS (70 eV):

m/z (%) = 379 (6) [M⁺], 333 (7), 323 (7) [M⁺– C₄H₈], 322 (22)

[M⁺– C₄H₉], 278 (6), 252 (33), 220 (5), 205 (17), 172 (7), 149 (7),

135 (9), 122 (24), 105 (37), 91 (100) [Bn⁺], 77 (32), 65 (11), 57 (22)

[C₄H₉⁺]. HRMS: calcd. for C₂₅H₃₃NO₂379.2513 (correct HRMS).

tert-Butyl (E)-3-{2Ј-[(E)-2ЈЈ-(Trimethylsilyl)vinyl]cyclohex-1Ј-

enyl}acrylate (19-SiMe₃): According to GP 3, the bromobutadiene

14-SiMe₃(200 mg, 0.775 mmol) in DMF (5.00 mL), after treatment

with Pd(OAc)₂(17.4 mg, 0.0780 mmol), PPh₃(61.0 mg,

0.233 mmol), NEt₃(235 mg, 2.33 mmol), tert-butyl acrylate

(497 mg, 3.88 mmol) at 90 °C for 14 h, workup with diethyl ether

(50 mL), water (20 mL) extraction with diethyl ether (25 mL) and

FC (24 g of silica gel, 20:1 v/v pentane/diethyl ether elution), gave

19-SiMe₃(211 mg, 89%) as a colorless wax. The analytical data

obtained on this material are identical with those reported pre-

viously.^[7b]

tert-Butyl (E)-3-[2Ј-(trans-3ЈЈ,4ЈЈ,4aЈЈ,5ЈЈ,6ЈЈ,7ЈЈ,8ЈЈ,8aЈЈ-Octahy-

dronaphth-2ЈЈ-enyl)cyclohex-1Ј-enyl]acrylate (22-tBu): According to

GP 3, the bromobutadiene 17 (340 mg, 1.15 mmol) in DMF/

MeCN/H₂O (10:5:1) (6 mL) was treated with the palladacycle

(41.0 mg, 46.0 µmol), nBu₄NOAc (722 mg, 2.39 mmol), tert-butyl

acrylate (2.5 mL) at 105 °C for 4 h. For complete consumption of

the bromobutadiene 17, a second portion of the palladacycle

(41.0 mg, 46.0 µmol) was added and the mixture again heated at

105 °C for 4 h. Workup with diethyl ether (50 mL), water

(2ϫ30 mL), extraction with diethyl ether (50 mL) and FC (31 g

of silica gel, 20:1 v/v light petroleum/diethyl ether elution) gave

compound 22-tBu (228 mg, 58%) as a colorless wax. R_f= 0.2. IR

tert-Butyl (E)-3-[2Ј-(5ЈЈ,6ЈЈ-Dihydro-1ЈЈ,4ЈЈ-dioxin-2ЈЈ-yl)cyclohex-

1Ј-enyl]acrylate (20): According to GP 3, the bromobutadiene 15

(230 mg, 0.764 mmol) in DMF/water (10:1) (1.10 mL), after treat-

ment with the palladacycle (7.6 mg, 8.2 µmol), NaOAc (40.2 mg,

0.490 mmol), nBu₄NBr (52.5 mg, 0.163 mmol), tert-butyl acrylate

(105 mg, 0.816 mmol) at 105 °C for 12 h, workup with diethyl ether

(30 mL), water (2ϫ10 mL) extraction with diethyl ether (10 mL)

and FC (18 g of silica gel, 5:1 v/v pentane/diethyl ether elution),

gave compound 20 (31.1 mg, 65%) as a colorless wax. R_f= 0.4. IR

(film): ν = 2976 cm^–1, 2922, 2852, 1704, 1613, 1449, 1391, 1367,

˜

1311, 1296, 1273, 1255, 1207, 1149, 1068, 1036, 986, 911, 885, 854,

825, 734, 648. ¹H NMR (250 MHz, C₆D₆): δ = 0.83–1.13 (m, 4 H),

1.14–1.23 (m, 7 H), 1.28 [s, 9 H, C(CH₃)₃], 1.29–1.76 (m, 5 H),

1.95–2.13 (m, 6 H), 5.14 (s, 1 H, 1ЈЈ-H), 5.98 (d, ³J = 15.8 Hz, 1 H,

3

2-H), 8.12 (d, J = 15.8 Hz, 1 H, 3-H) ppm. ¹³C NMR (62.9 MHz,

(film): ν = 2974 cm^–1, 2930, 2871, 1703, 1640, 1608, 1458, 1391,

˜

C₆D₆, add. DEPT): δ = 22.6 (–, CH₂), 22.7 (–, CH₂), 25.3 (–, CH₂),

27.0 (–, CH₂), 27.2 (–, CH₂), 28.3 [+, 3 C, C(CH₃)₃], 29.2 (–, CH₂),

30.4 (–, CH₂), 30.8 (–, CH₂), 33.5 (–, CH₂), 33.6 (–, CH₂), 40.8 (+,

CH), 42.5 (+, CH), 79.2 [C_quat, CO₂C(CH₃)₃], 117.0 (+, C-2), 128.0

(C_quat), 132.0 (+, C-1ЈЈ), 138.2 (C_quat), 144.4 (+, C-3), 149.7 (C_quat),

167.8 (C_quat, C=O) ppm. MS (70 eV): m/z (%) = 342 (1) [M⁺], 286

(21) [M⁺– C₄H₈], 241 (12), 226 (10), 218 (2), 192 (11), 190 (10),

162 (4), 146 (14), 145 (100), 105 (14), 91 (22), 84 (48), 69 (17), 57

(66) [C₄H₉⁺], 56 (65) [C₄H₈⁺], 41 (56). HRMS: calcd. for C₂₃H₃₄O₂

342.2561 (correct HRMS).

1366, 1311, 1278, 1258, 1150, 1091, 1028, 985, 922, 882, 855, 796.

¹H NMR (300 MHz, C₆D₆): δ = 1.49 [s, 9 H, CO₂C(CH₃)₃], 1.57–

1.71 [m, 4 H, 4Ј(5Ј)-H], 2.16–2.24 (m, 2 H, 6Ј-H), 2.26–2.35 (m, 2

3

H, 3Ј-H), 4.11 [m_c, 4 H, 5ЈЈ(6ЈЈ)-H], 5.74 (d, J = 15.9 Hz, 1 H, 3-

3

H), 5.96 (m_c, 1 H, 3ЈЈ-H), 7.88 (d, J = 15.9 Hz, 1 H, 2-H) ppm.

¹³C NMR (75.6 MHz, CDCl₃, add. APT): δ = 22.09 (–, CH₂), 22.14

(–, CH₂), 25.87 (–, CH₂), 28.20 [+, 3 C, CO₂C(CH₃)₃], 28.88 (–,

CH₂), 64.20 (–, CH₂, -OCH₂-), 64.34 (–, CH₂, -OCH₂-), 79.74 [–,

C_quat, CO₂C(CH₃)₃], 117.16 (+, CH, C-3), 128.06 (+, CH, C-3ЈЈ),

131.18 (–, C_quat), 135.71 (–, C_quat), 138.34 (–, C_quat), 143.42 (+, CH,

C-2), 167.25 (–, C_quat, C=O) ppm. MS (70 eV): m/z (%) = 292 (7)

[M⁺], 236 (31) [M⁺– C₄H₈], 235 (34) [M⁺– C₄H₉], 219 (12), 217

Methyl (E)-3-[2Ј-trans-(3ЈЈ,4ЈЈ,4aЈЈ,5ЈЈ,6ЈЈ,7ЈЈ,8ЈЈ,8aЈЈ-Octahydro-

naphth-2ЈЈ-enyl)cyclohex-1Ј-enyl]acrylate (22-Me): According to GP

(7), 191 (100), 162 (6), 149 (67), 134 (6), 105 (7), 91 (15), 77 (8), 57 3, bromobutadiene 17 (205 mg, 0.695 mmol) in DMF/MeCN/H₂O

(26) [C₄H₉⁺]. HRMS: calcd. for C₁₇H₂₄O₄292.1676 (correct

HRMS).

(10:5:1) (6 mL) was treated with the palladacycle (49.0 mg,

55.0 µmol), nBu₄NOAc (418 mg, 1.39 mmol) and methyl acrylate

Eur. J. Org. Chem. 2007, 3879–3893

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3887

H. W. Sünnemann, M. G. Banwell, A. de Meijere

FULL PAPER

(298 mg, 3.48 mmol) at 105 °C for 4 h. For complete consumption

of 17, a second portion of the palladacycle (49.0 mg, 55.0 µmol)

was added, and the mixture again heated at 105 °C for 4 h. Workup

with diethyl ether (50 mL), water (2ϫ30 mL), extraction with di-

ethyl ether (50 mL) and FC (27 g of silica gel, 20:1 v/v light petro-

leum/diethyl ether elution) gave compound 22-Me (176 mg, 84%)

1,2,5,6,7,8-hexahydronaphthalene-2-carboxylate (27): According to

GP 5, the hexatriene 19 (70.0 mg, 0.201 mmol) in decalin (2.00 mL)

was heated at 205 °C for 45 min. FC (25 g of silica gel, 20:1 v/v

pentane/diethyl ether elution) yielded a mixture of diene 26 and

diene 27 in a ratio of 1:1.9 (according to¹H NMR) as a colorless

wax (55.3 mg, 79%). R_f= 0.3. ¹H NMR (300 MHz, CDCl₃, signals

which can be assigned to the minor product 26 are marked with

^#): δ = 0.05 [s, 6 H, Si(CH₃)₂], 0.08 [s, 6 H, Si(CH₃)₂]^#, 0.85 [s, 9

H, SiC(CH₃)₃], 0.90 [s, 9 H, SiC(CH₃)₃]^#, 1.18 [s, 9 H, CO₂C-

as a colorless wax. R = 0.3. IR (film): ν = 2921 cm^–1, 2851, 1721,

˜

f

1615, 1433, 1296, 1273, 1164, 1134, 1068, 1037, 1018, 923, 880,

852, 752, 665. ¹H NMR (250 MHz, CDCl₃): δ = 0.90–1.11 (m,

3 H), 1.13–1.47 (m, 3 H), 1.52–1.80 (m, 10 H), 1.94–2.28 (m, 6 H), (CH₃)₃], 1.38 [s, 9 H, CO₂C(CH₃)₃]^#, 1.77–1.89 (m, 4 H), 1.92–2.17

3.72 (s, 3 H, CH₃), 5.14 (s, 1 H, 1ЈЈ-H), 5.71 (d, ³J = 15.1 Hz, 1 H,

(m, 4 H), 2.22–2.37 (m, 2 H), 2.48 (m_c, 1 H), 2.72–2.83 (m, 3 H),

3

2-H), 7.78 (d, J = 15.1 Hz, 1 H, 3-H) ppm. ¹³C NMR (62.9 MHz,

2.98 (m_c, 1 H), 6.08 (s, 1 H), 6.62 (s, 1 H)^#ppm.

CDCl₃, add. DEPT): δ = 22.2 (–, CH₂), 22.4 (–, CH₂), 25.1 (–,

CH₂), 26.7 (–, CH₂), 26.8 (–, CH₂), 28.8 (–, CH₂), 30.0 (–, CH₂),

30.5 (–, CH₂), 33.1 (–, CH₂), 33.3 (–, CH₂), 40.5 (+, CH), 42.3 (+,

CH), 51.2 (+, CH₃), 113.4 (+, C-2), 127.4 (C_quat), 132.1 (+, C-1ЈЈ),

137.6 (C_quat), 145.6 (+, C-3), 151.6 (C_quat), 168.5 (C_quat, C=O) ppm.

MS (70 eV): m/z (%) = 300 (39) [M⁺], 294 (2), 269 (2) [M⁺– OCH₃],

257 (1), 241 (32) [M⁺– CO₂CH₃], 226 (8), 192 (2), 159 (3), 145

(100), 131 (7), 117 (7), 91 (10), 67 (5), 55 (4), 41 (6). HRMS: calcd.

for C₂₀H₂₈O₂300.2091 (correct HRMS).

[3-(tert-Butyldimethylsilyl)-1,2,5,6,7,8-hexahydronaphthalen-2-yl]-

methanol (28): According to GP 5, the hexatriene 29 (60.0 mg,

0.215 mmol) in decalin (0.60 mL) was heated at 205 °C for 1.75 h.

FC (15 g of silica gel, 2:1 v/v pentane/diethyl ether elution) yielded

compound 28 (52.7 mg, 88 %) as a colorless wax. R_f= 0.4. IR

(film): ν = 3306 cm^–1, 2951, 2927, 2856, 1655, 1566, 1470, 1462,

˜

1437, 1360, 1315, 1247, 1187, 1147, 1050, 1024, 937, 864, 825, 809,

767. ¹H NMR (300 MHz, CDCl₃): δ = 0.05 [s, 3 H, Si(CH₃)₂], 0.07

[s, 3 H, Si(CH₃)₂], 0.89 [s, 9 H, C(CH₃)₃], 1.24–1.40 (m, 1 H), 1.49–

1.74 [m, 4 H, 4Ј(5Ј)-H], 1.88–2.20 (m, 6 H), 2.22–2.48 (m, 1 H, 2-

tert-Butyl (E)-3-[2Ј-(5ЈЈ-tert-Butoxy-4aЈЈ-methyl-1ЈЈ,2ЈЈ,3ЈЈ,4ЈЈ,

5ЈЈ,6ЈЈ,8aЈЈ-heptahydronaphth-2ЈЈ-enyl)cyclohex-1Ј-enyl]acrylate

(23): According to GP 3, the bromobutadiene 18 (270 mg,

700 µmol) in DMF/MeCN/H₂O (10:5:1) (5 mL) was treated with

the palladacycle (52.5 mg, 56 µmol), nBu₄NOAc (527 mg,

3

H), 3.37 (d, J = 6.3 Hz, 2 H, CH₂O), 6.02 (s, 1 H, 4-H) ppm. ¹³C

NMR (75.6 MHz, CDCl₃, add. APT): δ = –6.5 [+, CH₃, Si-

(CH₃)₂], –6.2 [+, CH₃, Si(CH₃)₂], 17.2 [–, C_quat, C(CH₃)₃], 22.7 (–,

CH₂), 23.2 (–, CH₂), 26.9 [+, 3 C, CH₃, C(CH₃)₃], 27.8 (–, CH₂),

1.75 mmol) tert-butyl acrylate (2.00 mL) at 105 °C for 4 h. For 30.0 (–, CH₂), 30.6 (–, CH₂), 38.0 (+, CH, C-2), 62.4 (–, CH₂,

complete consumption of the bromobutadiene 18, a second portion

of the palladacycle (52.5 mg, 56 µmol) was added and the mixture

again heated at 105 °C for 4 h. Workup with diethyl ether (40 mL),

water (2ϫ30 mL), extraction with diethyl ether (40 mL) and FC

(34 g on silica gel, 20:1 v/v light petroleum/diethyl ether elution)

gave compound 23 (180 mg, 60%) as a colorless wax. R_f= 0.2. IR

CH₂OH), 126.7 (–, C_quat), 130.3 (–, C_quat), 132.1 (–, C_quat), 140.2

(+, CH) ppm. MS (70 eV): m/z (%) = 278 (3) [M⁺], 221 (27) [M⁺

–

C₄H₉], 203 (20), 189 (6), 161 (4), 145 (68), 131 (17), 118 (11), 104

(8), 91 (17), 75 (100), 73 (43), 61 (8), 59 (19). HRMS: calcd. for

C₁₇H₃₀OSi 278.2068 (correct HRMS).

[3-(Trimethylsilyl)-1,2,5,6,7,8-hexahydronaphthalene-2-yl]methanol

(28-SiMe₃): According to GP 5, the hexatriene 29-SiMe₃(15 mg,

0.063 mmol) in decalin (1.0 mL) was heated at 205 °C for 1.75 h.

FC (10 g of silica, 2:1 v/v pentane/diethyl ether elution) yielded 28-

(film): ν = 2975 cm^–1, 2928, 2857, 1704, 1614, 1450, 1389, 1365,

˜

1309, 1293, 1274, 1247, 1192, 1148, 1076, 1050, 1019, 999, 984,

899, 881, 851. ¹H NMR (250 MHz, C₆D₆): δ = 0.72–0.93 (m, 2 H),

1.07 (s, 3 H, CH₃), 1.17 [s, 9 H, C(CH₃)₃], 1.18–1.31 (m, 4 H), 1.43

[s, 9 H, CO₂C(CH₃)₃], 1.51–1.88 (m, 7 H), 1.90–2.19 (m, 6 H), 2.93

SiMe₃(5.0 mg, 33%) as a colorless wax. R = 0.4. IR (film): ν =

˜

f

3356 cm^–1, 2929, 2858, 1673, 1570, 1447, 1438, 1309, 1247, 1150,

1024, 998, 929, 866, 836, 752. ¹H NMR (300 MHz, CDCl₃): δ =

0.19 [s, 9 H, Si(CH₃)₃], 1.28–1.72 (m, 1 H), 1.89–2.15 (m, 3 H),

2.23–2.39 (m, 6 H), 2.40–2.50 (m, 1 H, 2-H), 3.36–3.53 (m, 2 H,

CH₂O), 6.19 (s, 1 H, 4-H) ppm. MS (70 eV): m/z (%) = 236 (26)

3

(t, ³J = 5.8, J = 6.0 Hz, 1 H, 5ЈЈ-H), 5.14 (d, ³J = 0.6 Hz 1 H, 1ЈЈ-

3

H), 5.98 (d, J = 16.7 Hz, 1 H, 2-H) 8.11 (d, J = 16.7 Hz, 1 H, 3-

H) ppm. ¹³C NMR (62.9 MHz, C₆D₆, add. DEPT): δ = 11.0 (+,

CH₃), 22.6 (–, CH₂), 22.8 (–, CH₂), 24.9 (–, CH₂), 25.4 (–, CH₂),

26.4 (–, CH₂), 27.1 (–, CH₂), 28.2 [+, 3 C, C(CH₃)₃], 29.2 [+, 3 C,

CO₂C(CH₃)], 30.8 (–, CH₂), 31.0 (–, CH₂), 34.5 (–, CH₂), 37.7

(C_quat, C-4aЈЈ), 44.1 (+, C-8aЈЈ), 72.6 [C_quat, C(CH₃)₃], 77.5 (+, C-

5ЈЈ), 79.2 [C_quat, CO₂C(CH₃)₃], 117.1 (+, C-2), 128.2 (C_quat), 130.2

[M⁺], 219 (8) [M⁺– OH], 205 (8) [M⁺– CH₂OH], 204 (6) [M⁺

–

CH₃OH], 189 (14), 146 (17), 145 (22), 132 (15), 131 (36), 129 (11),

118 (24), 117 (13), 105 (16), 104 (18), 103 (7), 91 (31), 75 (42),

73 (100) [Si(CH₃)⁺], 61 (6), 59 (12). HRMS: calcd. for C₁₄H₂₄OSi

236.1598 (correct HRMS).

(+, C-7ЈЈ), 137.7 (C_quat), 144.3 (+, C-3), 149.6 (C_quat), 167.0 (C_quat

,

C=O) ppm. MS (70 eV): m/z (%) = 428 (10) [M⁺], 372 (51) [M⁺

–

C₄H₈], 355 (6), 316 (18) [M⁺– 2ϫC₄H₈], 315 (32) [M⁺– C₄H₉–

C₄H₈], 297 (36) [M⁺– C₄H₉– C₄H₈– H₂O], 269 (12), 253 (28),

231 (3), 205 (8), 185 (13), 171 (9), 145 (28), 105 (4), 95 (6), 84 (15),

57 (100) [C₄H₉⁺], 41 (20). HRMS: calcd. for C₂₈H₄₄O₃428.3293

(correct HRMS).

(E)-3-{2Ј-[(E)-2ЈЈ-(tert-Butyldimethylsilyl)vinyl]cyclohex-1Ј-

enyl}prop-2-en-1-ol (29): According to GP 4, the hexatriene 19

(100 mg, 0.287 mmol) in toluene (5.00 mL), DIBALH (2.30 mL,

2.30 mmol), workup with diethyl ether (50 mL), KHSO₄solution

(20 mL), extraction with diethyl ether (20 mL), NaHCO₃solution

(20 mL), water (20 mL) and FC (20 g of silica gel, 2:1 v/v pentane/

diethyl ether elution) gave compound 29 (64.7 mg, 81%) as a color-

(E)-1,2-Bis[2-(tert-butyldimethylsilyl)vinyl]cyclohexene (24): ¹H

NMR (300 MHz, CDCl₃): δ = –0.03 [s, 12 H, Si(CH₃)₂], 0.83 [s, 18

H, C(CH₃)₃], 1.60 [m_C, 4 H, 4Ј(5Ј)-H], 2.27 [m_c, 4 H, 6Ј(3Ј)-H],

less oil. R = 0.4. IR (film): ν = 3398 cm^–1, 2928, 2883, 2856, 1665,

˜

f

1499, 1463, 1445, 1409, 1389, 1361, 1252, 1154, 1048, 1007, 987,

3

5.83 (d, J = 18.9 Hz, 2 H, 1-H), 7.29 (d, J = 18.9 Hz, 2 H, 2-H)

ppm. MS (ESI, MeOH): m/z (%) = 599 (10), 569 (12), 455 (10),

363 (40) [M + H⁺], 2291 (22), 289 (15), 235 (23), 231 (10), 179 (16),

146 (9), 115 (20), 102 (100), 74 (14).

1

938, 834, 832, 810, 777. H NMR (300 MHz, CDCl₃): δ = 0.07 [s,

6 H, Si(CH₃)₂], 0.88 [s, 9 H, C(CH₃)₃], 1.61–1.70 [m, 4 H, 4Ј(5Ј)-

3

H], 2.22–2.37 [m, 4 H, 3Ј(6Ј)-H], 4.26 (dd, J₁= 6.0, J₂= 0.8 Hz,

3

2 H, 1-H), 4.87 (dt, J₁= 15.5, J₂= 6.0 Hz, 1 H, 2-H), 5.91 (d, J

3

tert-Butyl 3-(tert-Butyldimethylsilyl)-2,3,5,6,7,8-hexahydronaphthal- = 19.0 Hz, 1 H, 1ЈЈ-H), 7.00 (d, J = 15.4 Hz, 1 H, 3-H), 7.24 (d,

ene-2-carboxylate (26), tert-Butyl 3-(tert-Butyldimethylsilyl)-

³J = 19.0 Hz, 1 H, 2ЈЈ-H) ppm. ¹³C NMR (75.6 MHz, CDCl₃, add.

3888

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Eur. J. Org. Chem. 2007, 3879–3893

Substituted 1,3,5-Hexatrienes in Thermally Induced 6π-Electrocyclizations

FULL PAPER

APT): δ = –6.01 [+, 2 C, CH₃, Si(CH₃)₂], 16.63 [–, C_quat, C-

(CH₃)₃], 22.44 (–, CH₂), 22.47 (–, CH₂), 26.14 (–, CH₂), 26.50 [+,

3 C, CH₃, C(CH₃)₃], 26.67 (–, CH₂), 64.40 (–, CH₂, C-1), 125.59

(+, CH), 127.20 (+, CH), 129.02 (+, CH), 132.25 (–, C_quat), 134.43

(–, C_quat), 141.64 (+, CH) ppm. MS (70 eV): m/z (%) = 278 (3)

[M⁺], 203 (6), 145 (17), 131 (7), 115 (13), 105 (3), 91 (8), 75 (100),

59 (13), 43 (7). HRMS: calcd. for C₁₇H₃₀OSi 278.2068 (correct

HRMS).

159 (69), 141 (27), 117 (17), 101 (12), 91 (15), 85 (91), 75 (100),

59 (41), 55 (16). HRMS: calcd. for C₂₂H₃₈O₂Si 362.2643 (correct

HRMS).

tert-Butyl 2,3,4a,5,7,8,9,10-Octahydronaphtho[1,2-b][1,4]dioxine-5-

carboxylate (32) and tert-Butyl 2,3,5,6,7,8,9,10-Octahydronaph-

tho[1,2-b][1,4]dioxine-5-carboxylate (33): According to GP 5, the

hexatriene 20 (32.0 mg, 0.109 mmol) in decalin (0.50 mL) was

heated at 205 °C for 45 min. After FC (20 g of silica gel, 5:1 v/v

pentane/diethyl ether elution), a mixture of compounds 32 and 33

in a ratio of 1:3.1 (according to ¹H NMR) was obtained as a color-

tert-Butyldimethyl[3-(tetrahydropyran-2-yloxymethyl)-3,4,5,6,7,8-

hexahydronaphthalen-2-yl]silane (30): According to GP 5, the hexa-

triene 31 (81.0 mg, 0.223 mmol) in decalin (3.00 mL) was heated at

205 °C for 2 h. FC (13 g of silica gel, 10:1 v/v pentane/diethyl ether

elution) yielded compound 30 (75.2 mg, 93%) as a colorless wax.

The diastereomeric ratio was found to be 1:1. R_f= 0.5. IR (film):

less wax (23.0 mg, 72%). R = 0.4. IR (film): ν = 2976 cm^–1, 2933,

˜

f

2877, 1723, 1638, 1612, 1578, 1481, 1457, 1437, 1392, 1368, 1327,

1308, 1245, 1156, 1091, 1067, 988, 966, 919, 848. ¹H NMR

(300 MHz, CDCl₃, signals which can be assigned to the minor

product 32 are marked with ^#): δ = 1.42 [s, 9 H, CO₂C(CH₃)₃], 1.44

[s, 9 H, CO₂C(CH₃)₃]^#, 1.51–1.73 (m, 4 H), 1.75–1.78 (m, 4 H)^#,

ν = 2926 cm^–1, 2856, 2737, 1655, 1566, 1463, 1440, 1410, 1387,

˜

1360, 1351, 1322, 1257, 1200, 1189, 1120, 1077, 1056, 1030, 975,

936, 907, 868, 825. ¹H NMR (300 MHz, CDCl₃distinguishable

signals of the diastereomers are marked with ^#): δ = 0.07 [s, 3 H,

Si(CH₃)₂], 0.09 [s, 3 H, Si(CH₃)₂], 0.89 [s, 9 H, C(CH₃)₃], 1.21–1.40

(m, 1 H), 1.41–1.91 (m, 11 H), 1.92–2.34 (m, 4 H), 2.48–2.61 (m, 1

H, 3-H), 3.03–3.19 (m, 1 H), 3.36–3.58 (m, 1 H), 3.70–3.95 (m, 1

H, OCHO), 4.45 (m_c, 1 H, 3-CH₂O), 4.59 (m_c, 1 H, 3-CH₂O), 5.99

(d, ³J = 2.5 Hz, 1 H, 1-H) ppm. ¹³C NMR (75.6 MHz, CDCl₃,

add. APT): δ = –6.5 [+, CH₃, Si(CH₃)₂], –6.4 [+, CH₃, Si(CH₃)₂],

17.3 [–, C_quat, C(CH₃)₃], 19.5 (–, CH₂), 20.0 (–, CH₂), 23.1 (–, CH₂),

23.4 (–, CH₂)^#, 25.7 (–, CH₂), 25.8 (–, CH₂)^#, 27.1 [+, 3 C, CH₃,

C(CH₃)₃], 28.1 (–, CH₂), 28.1 (–, CH₂)^#, 30.1 (–, CH₂), 30.2 (–,

CH₂)^#, 30.8 (–, CH₂), 30.9 (–, CH₂), 35.4 (+, CH, C-3), 36.2 (+,

CH, C-3)^#, 61.7 (–, CH₂), 62.6 (–, CH₂)^#, 65.4 (–, CH₂), 66.9 (–,

CH₂)^#, 97.8 (+, CH), 100.3 (+, CH)^#, 126.9 (–, C_quat), 130.1 (–,

C_quat), 130.3 (–, C_quat)^#, 132.5 (–, C_quat), 132.8 (–, C_quat)^#, 140.2

(+, CH), 140.3 (+, CH)^#ppm. MS (70 eV): m/z (%) = 362 (3) [M⁺],

305 (12) [M⁺– C₄H₉], 262 (10), 221 (31), 219 (7), 205 (20), 203

(27), 189 (23), 159 (6), 146 (18), 145 (37), 131 (15), 118 (7), 115

(18), 103 (9), 89 (5), 85 (100), 73 (60), 67 (17), 57 (22) [C₄H₉⁺].

HRMS: calcd. for C₂₂H₃₈O₂Si 362.2643 (correct HRMS).

3

1.91–2.23 (m, 6 H), 2.25–2.55 (m, 2 H), 3.04 (dd, J₁= 8.5, J₂=

5.8 Hz, 1 H), 3.31 (dd, ³J₁= 11.3, J₂= 5.2 Hz, 1 H)^#, 3.93–4.24

3

(m_c, 4 H), 5.74 (m_c, 1 H) ppm. ¹³C NMR (75.6 MHz, CDCl₃, add.

APT): δ = 22.0 (–, CH₂), 22.1 (–, CH₂), 22.3 (–, CH₂), 22.6 (–,

CH₂), 22.6 (–, CH₂), 22.8 (–, CH₂), 25.4 (–, CH₂), 28.2 [+, 3 C,

CO₂C(CH₃)₃], 28.3 [+, 3 C, CO₂C(CH₃)₃]^#, 64.4 (–, CH₂), 64.8

(–, CH₂), 65.0 (–, CH₂), 66.1 (–, CH₂), 67.4 (–, CH₂), 80.7 [C_quat

,

CO₂C(CH₃)₃], 80.9 [C_quat, CO₂C(CH₃)₃], 116.6 (+, CH), 123.8 (–,

C_quat), 124.3 (–, C_quat), 128.1 (–, C_quat), 128.1 (–, C_quat), 131.3 (–,

C_quat), 131.3 (–, C_quat), 131.9 (–, C_quat), 132.6 (–, C_quat), 172.7 (–,

C

_quat, C=O), 173.1 (–, C_quat, C=O)^#ppm. MS (70 eV): m/z (%) =

292 (50) [M⁺], 290 (22), 236 (65) [M⁺– C₄H₈], 234 (58), 217 (18),

206 (10), 191 (100), 190 (53), 162 (23), 149 (49), 134 (11), 122 (47),

107 (11), 94 (14), 91 (25), 86 (69), 84 (87), 79 (28), 77 (19), 73

(17), 65 (7), 57 (52) [C₄H₉⁺], 55 (17). HRMS: calcd. for C₁₇H₂₄O₄

292.1676 (correct HRMS).

5-Methoxymethoxymethyl-2,3,5,6,7,8,9,10-octahydronaphtho[1,2-b]-

[1,4]dioxine (34): According to GP 5, the hexatriene 36 (36.3 mg,

0.136 mmol) in decalin (1.0 mL) was heated at 150 °C for 12 h. FC

(10 g of silica gel, 2:1 v/v pentane/diethyl ether elution) yielded

compound 34 (33.1 mg, 91 %) as a colorless wax. R_f= 0.6. IR

(E)-tert-Butyldimethyl(2-{(E)-2Ј-[3ЈЈ-(tetrahydropyran-2-yloxy)prop-

enyl]cyclohex-1Ј-enyl}vinyl)silane (31): To a solution of the hexatri-

ene 29 (140 mg, 0.485 mmol) and 3,4-dihydro-2H-pyran (81.6 mg,

0.970 mmol) in ethyl acetate (3.00 mL) was added at ambient tem-

perature scandium(III) trifluoromethanesulfonate (3.0 mg,

0.0060 mmol), and the mixture was stirred for 1 h. It was poured

into diethyl ether (50 mL), and the mixture washed with satd.

NaHCO₃solution (20 mL). After extraction of the combined aque-

ous phases with diethyl ether (2ϫ20 mL), the combined organic

layers were dried with MgSO₄and concentrated in vacuo. FC (24 g

of silica gel, 10:1 v/v pentane/diethyl ether elution) yielded com-

(film): ν = 2928 cm^–1, 2882 (C-H), 1681, 1632, 1491, 1441, 1381,

˜

1333, 1292, 1277, 1242, 1201, 1175, 1150, 1109, 1075, 1041, 944,

1

918, 799 cm^–1. H NMR (300 MHz, CDCl₃): δ = 1.47–1.68 [m, 4

H, 8(9)-H], 1.92–2.00 (m, 2 H, 7-H), 2.01–2.07 (m, 2 H, 10-H),

2.08–2.17 (m, 1 H, 6-H), 2.28–2.41 (m, 1 H, 6-H), 2.53 (h, ³J =

3

4.4 Hz, 1 H, 5-H), 3.35 (s, 3 H, OCH₃), 3.40 (dd, J₁= 18.4, J₂=

9.1 Hz, 1 H, CH₂O), 3.52 (dd, ³J₁= 9.2, ³J₂= 4.7 Hz, 1 H, CH₂O),

3.95–4.12 [m, 4 H, 2(3)-H], 4.60 (d, ³J = 6.6 Hz, 1 H, OCH₂O),

4.63 (d, ³J = 6.6 Hz, 1 H, OCH₂O) ppm. ¹³C NMR (75.6 MHz,

CDCl₃, add. APT): δ = 22.6 (–, CH₂), 22.7 (–, CH₂), 22.9 (–, CH₂),

30.2 (–, CH₂), 32.0 (–, CH₂), 36.7 (+, CH, C-5), 55.3 (+, CH₃,

OCH₃), 64.7 (–, CH₂, OCH₂CH₂O), 65.0 (–, CH₂, OCH₂CH₂O),

67.2 (–, CH₂, CH₂O), 96.8 (–, CH₂, OCH₂O), 123.6 (–, C_quat), 123.9

(–, C_quat), 129.9 (–, C_quat), 131.9 (–, C_quat) ppm. MS (70 eV): m/z

(%) = 266 (48) [M⁺], 264 (5), 235 (5) [M⁺– CH₂OH], 205 (14), 204

(24), 191 (100), 179 (6), 176 (7), 163 (10), 162 (8), 149 (68), 133 (5),

120 (8), 117 (6), 105 (10), 91 (28), 77 (18), 67 (5), 65 (9), 55 (12).

HRMS: calcd. for C₁₅H₂₂O₄266.1519 (correct HRMS).

pound 31 (171 mg, 97%) as a colorless oil. R = 0.3. IR (film): ν =

˜

f

2926 cm^–1, 2854, 1591, 1557, 1462, 1445, 1360, 1247, 1200, 1182,

1130, 1077, 1023, 980, 905, 867, 827. ¹H NMR (300 MHz, CDCl₃):

δ = 0.06 [s, 6 H, Si(CH₃)₂], 0.89 [s, 9 H, C(CH₃)₃], 1.20–1.39 (m,

4 H), 1.47–1.92 (m, 6 H), 2.21–2.36 (m, 4 H), 3.45–3.62 (m, 1 H),

3.82–3.98 (m, 1 H), 4.00–4.18 (m, 1 H), 4.23–4.43 (m, 1 H), 4.63–

3

4.76 (m, 1 H), 5.82 (dt, J₁= 15.1, J₂= 5.5 Hz, 1 H, 2ЈЈ-H), 5.89

(dt, ³J = 18.7 Hz, 1 H, 1-H), 7.05 (d, ³J = 16.5 Hz, 1 H, 3ЈЈ-H),

7.27 (d, ³J = 18.9 Hz, 1 H, 2-H) ppm. ¹³C NMR (75.6 MHz, C₆D₆,

add. APT): δ = –5.9 [+, 2 C, CH₃, Si(CH₃)₂], 16.9 [–, C_quat, C-

(E)-3-[2Ј-(5ЈЈ,6ЈЈ-Dihydro[1ЈЈ,4ЈЈ]dioxin-2ЈЈ-yl)cyclohex-1Ј-enyl]prop-

(CH₃)₃], 19.4 (–, CH₂), 22.7 (–, CH₂), 22.7 (–, CH₂), 25.8 (–, CH₂), 2-en-1-ol (35): According to GP 4, the hexatriene 20 (274 mg,

26.3 (–, CH₂), 26.6 [+, 3 C, CH₃, C(CH₃)₃], 26.8 (–, CH₂), 30.9 0.937 mmol) in toluene (10.0 mL), DIBALH (4.69 mL, 4.69 mmol),

(–, CH₂), 61.3 (–, CH₂, C-1ЈЈ), 67.8 (–, CH₂), 97.5 (+, CH, OCHO), workup with diethyl ether (75 mL), KHSO₄solution (20 mL), ex-

124.6 (+, CH), 126.0 (+, CH), 128.8 (+, CH), 133.2 (–, C_quat), 133.7

traction with diethyl ether (25 mL), NaHCO₃solution (20 mL),

(–, C_quat), 142.8 (+, CH) ppm. MS (70 eV): m/z (%) = 362 (10) water (20 mL) and FC (24 g of silica gel, 1:1 v/v pentane/diethyl

[M⁺], 278 (2), 261 (14), 247 (6), 221 (3), 205 (14), 203 (17), 177 (7), ether elution) yielded compound 35 (177 mg, 85%) as a colorless

Eur. J. Org. Chem. 2007, 3879–3893

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3889

H. W. Sünnemann, M. G. Banwell, A. de Meijere

FULL PAPER

oil. R = 0.3. IR (Film): ν = 3405 cm^–1, 2928, 2870, 2837, 1651,

23.4 (–, CH₂), 23.5 (–, CH₂), 24.8 (–, CH₂), 25.8 (–, CH₂), 25.9

(–, CH₂), 28.1 [+, 3 C, CO₂C(CH₃)₃], 28.3 [+, 3 C, CO₂C(CH₃)₃]^#,

˜

f

1499, 1450, 1434, 1366, 1306, 1284, 1258, 1235, 1209, 1149, 1091,

1

1026, 1010, 970, 921, 902, 879. H NMR (300 MHz, CDCl₃): δ = 29.9 (–, CH₂), 30.3 (–, CH₂), 30.5 (+, CH), 30.7 (–, CH₂), 40.0 (+,

1.49–1.74 [m, 4 H, 4Ј(5Ј)-H], 2.14–2.35 [m, 4 H, 3Ј(6Ј)-H], 4.05– CH), 43.1 (+, CH), 55.9 (–, CH₂), 56.4 (–, CH₂), 63.2 (–, CH₂),

3

4.15 [m, 4 H, 5ЈЈ(6ЈЈ)-H], 4.20 (dt, J₁= 6.3, J₂= 1.1 Hz, 2 H, 1- 80.4 [C_quat, CO₂C(CH₃)₃], 123.2 (+, CH)^#, 126.1 (–, C_quat), 127.2

3

H), 5.78 (dt, J₁= 15.9, J₂= 6.0 Hz, 1 H, 1-H), 5.92 (s, 1 H, 3ЈЈ-

(+, CH), 127.7 (+, CH), 128.1 (–, C_quat), 128.5 (+, CH), 129.3 (+,

H), 6.86 (d, J = 15.9 Hz, 1 H, 3-H) ppm. ¹³C NMR (75.6 MHz, CH), 129.4 (+, CH), 129.5 (+, CH), 132.3 (–, C_quat), 133.6 (–,

CDCl₃, add. APT): δ = 22.3 (–, CH₂), 22.5 (–, CH₂), 25.9 (–, CH₂), _quat), 137.0 (–, C_quat), 138.8 (–, C_quat), 173.7 (–, C_quat, C=O) ppm.

29.0 (–, CH₂), 64.2 [–, CH₂, 2 C, C-5ЈЈ(6ЈЈ)], 64.3 (–, CH₂, C-1), MS (70 eV): m/z (%) = 379 (77) [M⁺], 324 (22), 323 (55) [M⁺

125.7 (+, CH), 126.5 (+, CH), 131.3 (–, C_quat), 131.8 (+, CH), 132.3

C₄H₈], 322 (65) [M⁺– C₄H₉], 306 (34), 278 (52), 276 (22), 232 (31),

3

C

–

(–, C_quat), 136.0 (–, C_quat) ppm. MS (70 eV): m/z (%) = 222 (46) 204 (39), 186 (13), 159 (30), 146 (20), 134 (66), 120 (89), 117 (23),

[M⁺], 204 (7) [M⁺– H₂O], 191 (98), 189 (7), 176 (8), 164 (6), 161 115 (15), 105 (13), 91 (100), 77 (8), 65 (15), 57 (42) [C₄H₉⁺]. HRMS:

(11) 149 (100), 147 (100), 136 (6), 135 (8), 131 (9), 121 (8), 119 (17),

107 (20), 105 (15), 93 (13), 91 (50), 81 (9), 79 (29), 77 (32), 73

(12), 65 (16), 57 (6), 55 (23). HRMS: calcd. for C₁₃H₁₈O₃222.1257

(correct HRMS).

calcd. for C₂₅H₃₃NO₂379.2513 (correct HRMS).

(E)-3-[2Ј-(1ЈЈ-Benzyl-1ЈЈ,2ЈЈ,3ЈЈ,6ЈЈ-tetrahydropyridin-4ЈЈ-yl)cyclo-

hex-1Ј-enyl]prop-2-en-1-ol (39): According to GP 4, the hexatriene

21 (90.0 mg, 0.237 mmol) in toluene (3.00 mL) was treated with

DIBALH (1.90 mL, 1.90 mmol). The reaction mixture was poured

into diethyl ether (75 mL), the solution washed with satd. NH₄Cl

5-{2Ј-[(E)-3ЈЈ-Methoxymethylenoxyprop-1-enyl]cyclohex-1Ј-enyl}-

2,3-dihydro[1,4]dioxine (36): A solution of the allylic alcohol 35

(180 mg, 0.810 mmol), ethyldiisopropylamine (523 mg, 4.05 mmol) solution (2.0 mL) and treated with 1  NaOH solution (20.0 mL).

and 4-(dimethylamino)pyridine (39.9 mg, 0.323 mmol) in dichloro-

methane (2.00 mL) was treated with methoxymethyl chloride

(130 mg, 1.62 mmol) at 0 °C and stirred for 1 h. After warming to

ambient temperature, stirring was continued for 1 h. The reaction

mixture was then poured into diethyl ether (75 mL) and washed

with 1  KHSO₄solution (2ϫ15 mL). After extraction of the com-

bined aqueous phases with diethyl ether (2ϫ25 mL), the combined

organic layers were washed with satd. NaHCO₃(15 mL), water

(15 mL) and dried with MgSO₄. Concentration under reduced pres-

sure and FC (20 g of silica, 2:1 v/v pentane/diethyl ether elution)

yielded compound 36 (166 mg, 77%) as a colorless oil. R_f= 0.5.

The resulting precipitate was filtered through Celite. After extrac-

tion of the combined aqueous phases with diethyl ether

(2ϫ30 mL), the combined organic layers were dried with MgSO₄.

Concentration in vacuo and FC of the residue (20 g of silica gel,

10:1 v/v diethyl ether/methanol elution) yielded compound 39

(65.1 mg, 89%) as a yellow oil. R = 0.7. IR (film): ν = 3395 cm^–1,

˜

f

3028, 2929, 2798, 1613, 1494, 1452, 1391, 1366, 1310, 1148, 1029,

983, 856, 807, 753. ¹H NMR (300 MHz, CDCl₃): δ = 1.50–1.71 (m,

3 H), 2.05–2.20 (m, 4 H), 2.51–2.75 (m, 5 H), 3.00–3.07 (m, 2 H,

2ЈЈ-H), 3.60 (s, 2 H, PhCH₂), 4.15 (d, ³J = 5.2 Hz, 2 H, 1-H), 5.28–

3

5.34 (m, 1 H, 3ЈЈ-H), 5.68 (dt, J₁= 15.9, J₂= 5.8 Hz, 1 H, 2-H),

(d, ³J = 15.9 Hz, 1 H, 3-H), 7.23–7.39 (m, 5 H, Ph-H) ppm. ¹³C

NMR (75.6 MHz, CDCl₃, add. APT): δ = 22.5 (–, CH₂), 25.1 (–,

IR (film): ν = 2928 cm^–1, 2877, 1651, 1458, 1450, 1367, 1305, 1285,

˜

1212, 1149, 1093, 1042, 1027, 970, 953, 921, 880, 839, 787, 734,

1

694. H NMR (300 MHz, CDCl₃): δ = 1.53–1.75 [m, 4 H, 4Ј(5Ј)- CH₂), 28.5 (–, CH₂), 29.9 (–, CH₂), 49.7 (–, CH₂), 50.4 (–, CH₂),

H], 2.13–2.34 [m, 4 H, 3Ј(6Ј)-H], 3.38 (s, 3 H, OCH₃), 4.01–4.22 52.5 (–, CH₂), 62.7 (–, CH₂, PhCH₂), 63.6 (–, CH₂, C-1), 121.7 (+,

[m, 6 H, 5(6)-H, 1ЈЈ-H], 4.65 (s, 2 H, O-CH₂-O), 5.70 (dt, ³J₁

=

CH, C-3ЈЈ), 124.8 (+, CH), 127.2 (+, CH, Ph), 128.0 (–, C_quat),

128.2 (+, 2 C, CH, Ph), 129.5 (+, 2 C, CH, Ph), 131.0 (+, CH),

15.7, ³J₂= 6.6 Hz, 1 H, 2ЈЈ-H), 5.92 (s, 1 H, 6-H), 6.87 (d, ³J =

15.7 Hz, 1 H, 3ЈЈ-H) ppm. ¹³C NMR (75.6 MHz, CDCl₃, add. 137.0 (–, C_quat), 137.7 (–, C_quat, Ph), 140.0 (–, C_quat) ppm. MS

APT): δ = 22.3 (–, CH₂), 22.5 (–, CH₂), 25.9 (–, CH₂), 28.9 (–, (70 eV): m/z (%) = 309 (42) [M⁺], 308 (44), 305 (43), 292 (23), 278

CH₂), 55.2 (+, CH₃, OCH₃), 64.2 (–, CH₂, O-CH₂CH₂O), 64.3 (–, (39), 264 (80), 252 (30), 218 (7) 200 (4), 172 (15), 159 (22), 146 (25),

CH₂, O-CH₂CH₂O), 68.6 (–, CH₂, C-1ЈЈ), 95.6 (–, CH₂, O-CH₂- 134 (14), 105 (14), 91 (100) [Bn⁺], 77 (11), 65 (16), 63 (3). HRMS:

O), 122.7 (+, CH), 126.6 (+, CH), 131.3 (–, C_quat), 132.3 (–, C_quat), calcd. for C₂₁H₂₇NO 309.2094 (correct HRMS).

133.2 (+, CH), 135.9 (–, C_quat) ppm. MS (70 eV): m/z (%) = 266

(3-Benzyl-1,2,3,4,5,6,7,8,9,10-decahydrobenzo[f]isoquinolin-5-yl)-

methanol (40) and (3-Benzyl-1,2,3,4,4a,5,7,8,9,10-decahydrobenzo-

[f]isoquinolin-5-yl)methanol (41): According to GP 5, the hexatriene

39 (20.0 mg, 0.0650 mmol) in decalin (0.50 mL) was heated at

(29) [M⁺], 234 (14) [M⁺– CH₃OH], 221 (13) [M⁺– CH₃OCH₂O],

205 (34), 204 (22), 191 (100), 176 (10), 163 (14), 149 (82), 133 (12),

120 (14), 107 (13), 105 (15), 91 (45), 81 (6), 79 (21), 65 (10), 55

(12). HRMS: calcd. for C₁₅H₂₂O₄266.1519 (correct HRMS).

205 °C for 0.5 h. FC (10 g of silica gel, 20:1 v/v diethyl ether/meth-

tert-Butyl 3-Benzyl-1,2,3,4,4a,5,7,8,9,10-decahydrobenzo[f]isoquinol-

anol elution) gave a mixture of compounds 40 and 41 with a ratio

ine-5-carboxylate (37) and tert-Butyl 3-Benzyl-1,2,3,4,5,6,7,8,9,10- of 4.3:1 (according to ¹H NMR) as a colorless wax (16.4 mg, 82%).

decahydrobenzo[f]isoquinoline-5-carboxylate (38): According to GP

5, the hexatriene 21 (40.0 mg, 0.105 mmol) in decalin (1.00 mL)

was heated at 205 °C for 1.5 h. After FC (20 g of silica gel, 1:1 v/v

pentane/diethyl ether elution), a mixture of compounds 37 and 38

in a ratio of 1:2.6 (according to ¹H NMR) was obtained as a color-

R_f= 0.6. ¹H NMR (300 MHz, CDCl₃, signals which can be as-

signed to the minor component 41 are marked with ^#): δ = 1.05–

1.29 (m, 6 H), 1.31–1.72 (m, 6 H), 1.98–2.40 (m, 3 H), 2.58–2.68

(m, 2 H, PhCH₂)^#, 2.60 (m_c, 2 H, PhCH₂), 2.90 (m_c, 1 H)^#, 3.12

(m_c, 1 H)^#, 3.26–3.74 (m, 2 H), 3.09–3.21 (m, 2 H), 3.30–3.54 (m,

4 H), 5.34–5.38 (m, 1 H), 6.99–7.31 (m, 3 H, Ar), 7.32–7.56 (m, 2

H, Ar) ppm. ¹³C NMR (75.6 MHz, CDCl₃, add. APT): δ = 23.0

(–, CH₂)^#, 23.5 (–, CH₂)^#, 24.4 (–, CH₂), 24.5 (–, CH₂), 24.8 (–,

CH₂)^#, 25.1 (–, CH₂)^#, 26.0 (–, CH₂), 27.0 (–, CH₂), 30.9 (–,

CH₂)^#, 31.0 (–, CH₂)^#, 32.0 (–, CH₂), 39.1 (+, CH)^#, 39.3 (+, CH),

40.0 (+, CH), 50.4 (–, CH₂)^#, 52.2 (–, CH₂), 55.8 (–, CH₂), 56.4

less wax (29.1 mg, 73%). R = 0.4. IR (film): ν = 3086 cm^–1, 3028,

˜

f

2927, 2858, 2833, 1726, 1703, 1684, 1494, 1453, 1391, 1366, 1350,

1283, 1253, 1211, 1149, 1085, 1076, 1064, 1000, 970, 934, 910, 849.

¹H NMR (300 MHz, CDCl₃signals which can be assigned to the

minor product 37 are marked with ^#): δ = 1.29 [s, 9 H, CO₂C-

(CH₃)₃], 1.43–1.64 (m, 6 H), 1.81–2.00 (m, 3 H), 2.01–2.20 (m,

5 H), 2.22–2.48 (m, 2 H), 2.46–2.60 (m, 3 H), 2.63–2.74 (m, 2 H), (–, CH₂)^#, 61.2 (–, CH₂), 62.3 (–, CH₂)^#, 62.8 (–, CH₂)^#, 63.3 (–,

2.89–3.08 (m, 3 H), 3.31–3.63 (m, 4 H), 5.39–5.53 (m, 1 H)^#, 7.05–

CH₂), 120.9 (+, CH), 125.6 (–, C_quat)^#, 125.4 (–, C_quat), 126.9 (–,

7.31 (m, 3 H, Ph), 7.33–7.52 (m, 2 H, Ph) ppm. ¹³C NMR C_quat)^#, 127.2 (–, C_quat)^#, 127.3 (+, CH, Ar), 127.3 (+, CH, Ar)^#,

(75.6 MHz, CDCl₃, add. APT): δ = 22.8 (–, CH₂), 23.2 (–, CH₂), 128.4 (+, 2 C, CH, Ar)^#, 128.5 (+, 2 C, CH, Ar), 129.1 (+, 2 C,

3890

www.eurjoc.org

Eur. J. Org. Chem. 2007, 3879–3893

Substituted 1,3,5-Hexatrienes in Thermally Induced 6π-Electrocyclizations

FULL PAPER

CH, Ar)^#, 129.1 (–, C_quat), 129.4 (+, 2 C, CH, Ar), 136.3 (–, C_quat), (C_quat), 173.6 (C_quat, C=O) ppm. ¹³C NMR (62.9 MHz, CDCl₃,

#

138.6 (–, C_quat)^#, 138.8 (–, C_quat, Ar), 139.4 (–, C_quat

)

ppm. MS add. DEPT): δ = 22.5 (–, CH₂), 23.2 (–, CH₂), 25.3 (–, CH₂), 25.9

(70 eV): m/z (%) = 309 (63) [M⁺], 278 (52), 276 (6), 252 (43), 250 (–, CH₂), 26.9 (–, CH₂), 27.1 (–, CH₂), 28.0 [+, C(CH₃)₃], 29.7 (–,

(6), 218 (15), 172 (14), 159 (17), 146 (15), 134 (28), 120 (16), 117 CH₂), 30.3 (–, CH₂), 30.8 (–, CH₂), 32.4 (–, CH₂), 34.1 (–, CH₂),

(14), 91 (100), 77 (10), 65 (14). HRMS: calcd. for C₂₁H₂₇NO 40.2 (+, CH), 41.1 (+, CH), 44.2 (+, C-7), 79.2 [C_quat, CO₂C-

309.2094 (correct HRMS).

(CH₃)₃], 127.8 (C_quat), 127.9 (C_quat), 128.9 (C_quat), 130.8 (C_quat),

174.3 (C_quat, C=O) ppm. MS (70 eV): m/z (%) = 342 (12) [M⁺], 286

(82) [M⁺– C₄H₈], 267 (2), 241 (26), 208 (3), 189 (7), 165 (4), 151

(7), 145 (100), 105 (6), 91 (11),67 (6), 57 (16) [C₄H₉⁺], 41 (10).

HRMS: calcd. for C₂₃H₃₄O₂342.2561 (correct HRMS).

(E)-(1ЈЈS,3aЈЈS,7aЈЈS)-3-[8Ј-(1ЈЈ-tert-Butoxy-7aЈЈ-methyl-

2ЈЈ,3ЈЈ,3aЈЈ,6ЈЈ,7ЈЈ,7aЈЈ-hexahydro-1ЈЈH-inden-5ЈЈ-yl)-1Ј,4Ј-dioxaspi-

ro[4Ј.5Ј]dec-7Ј-en-7Ј-yl]prop-2-en-1-ol (43): According to GP 4, the

hexatriene 42 (180 mg, 0.381 mmol) in toluene (3.00 mL), DI-

BALH (3.05 mL, 3.05 mmol), workup with diethyl ether (35 mL), Methyl trans-1,2,3,4,4a,4b,5,6,7,8,9,10,11,12,12a-Tetradecahydro-

KHSO₄solution (10 mL), extraction with diethyl ether chrysene-5-carboxylate (49): According to GP 5, the hexatriene 22-

(2ϫ25 mL), NaHCO₃solution (20 mL), water (20 mL) and FC Me (40.2 mg, 0.134 mmol) in decalin (0.50 mL) was heated at

(24 g of silica gel, 3:2 v/v diethyl ether/pentane elution) yielded 205 °C for 30 min. FC (30 g of neutral aluminum oxide, 20:1 v/v

1

compound 43 (100 mg, 65%) as a colorless oil. R_f= 0.4. H NMR light petroleum/diethyl ether elution) gave compound 49 (30.8 mg,

(250 MHz, C₆D₆): δ = 1.05 (s, 3 H, CH₃), 1.15 [s, 9 H, C(CH₃)₃], 77%) and tetracycle 48-Me (4.4 mg, 11%), as a colorless oil. R_f=

1.23–1.40 (m, 2 H), 1.42–1.78 (m, 4 H), 1.80–2.40 (m, 8 H), 2.56– 0.3. IR (film): ν = 2922 cm^–1, 2853, 1739, 1616, 1446, 1433, 1330,

˜

3

2.75 (m, 1 H), 2.98 (br. s, 1 H, OH), 3.36 (t, J = 8.3 Hz, 1 H, 1ЈЈ- 1272, 1259, 1232, 1190, 1165, 1112, 1095, 1070, 1023, 990, 942,

H), 3.43 (m_c, 4 H, 2Ј-H, 3Ј-H), 3.71 (m_c, 2 H, 1-H), 5.44 (s, 1 H, 892, 863, 851, 843, 812, 765. ¹H NMR (250 MHz, C₆D₆): δ = 0.69–

3

4ЈЈ-H), 5.83 (m_c, 1 H, 2-H), 6.90 (d, J = 16.7 Hz, 1 H, 3-H) ppm. 1.49 (m, 7 H), 1.50–1.84 (m, 7 H), 1.90–2.26 (m, 9 H), 3.02 (dd, J

¹³C NMR (62.9 MHz, CDCl₃, add. DEPT): δ = 11.6 (+, CH₃), = 4.5, J = 6.1 Hz, 1 H, 5-H), 3.31 (s, 3 H, CH₃), 5.73 (m_c, 1 H,

3

25.0 (–, CH₂), 27.3 (–, CH₂), 28.9 [+, 3 C, C(CH₃)₃], 29.1 (–, CH₂), 6-H) ppm. ¹³C NMR (62.9 MHz, C₆D₆, add. DEPT): δ = 23.0 (–,

32.1 (–, CH₂), 32.3 (–, CH₂), 34.4 (–, CH₂), 42.2 (C_quat, C-7aЈЈ), CH₂), 23.5 (–, CH₂), 25.2 (–, CH₂), 26.7 (–, CH₂), 26.8 (–, CH₂),

43.8 (+, CH, C-3aЈЈ), 62.1 (–, OCH₂CH₂O), 64.1 (–, OCH₂CH₂O), 31.2 (–, CH₂), 31.6 (–, CH₂), 34.0 (–, CH₂), 34.3 (–, CH₂), 35.3

69.9 (–, CH₂, C-1), 72.2 [C_quat, C(CH₃)₃], 75.2 (+, CH, C-1ЈЈ), 79.6 (–, CH₂), 38.5 (+, CH), 39.3 (+, CH), 41.3 (+, CH), 45.1 (+, C-5),

[C_quat, CO₂C(CH₃)₃], 110.7 (C_quat, C-5Ј), 126.0 (+, CH), 126.43 (+, 51.2 (+, CH₃), 118.5 (+, C-6), 127.8 (C_quat), 128.8 (C_quat), 135.3

CH), 126.6 (+, CH), 130.9 (C_quat), 139.0 (C_quat), 140.5 (C_quat) ppm. (C_quat), 173.9 (C_quat, C=O) ppm. MS (70 eV): m/z (%) = 300 (100)

[M⁺], 296 (7), 266 (21) [M⁺– CO₂CH₃], 240 (69), 238 (18), 212

(13S,14S,17S)-(17-tert-Butoxy-13-methyl-1Ј,3Ј-spiro[2Ј,3]dioxolan-

2,3,4,7,8,11,12,13,14,15,16,17-dodecahydro-1H-cyclopenta[a]phen-

anthren-7-yl)methanol (44) and (13S,14S,17S)-(17-tert-Butoxy-13-

methyl-1Ј,3Ј-spiro[2Ј,3]dioxolan-2,3,4,6,7,11,12,13,14,15,16,17-do-

(10), 197 (12), 183 (7), 171 (9), 145 (73), 141 (12), 91 (6), 79 (4), 44

(76), 41 (3). HRMS: calcd. for C₂₀H₂₈O₂300.2091 (correct

HRMS).

decahydro-1H-cyclopenta[a]phenanthren-7-yl)methanol (45): Ac- Methyl trans-1,2,3,4,4a,5,6,7,8,9,10,11,12,12a-Tetradecahydrochrys-

cording to GP 5, the hexatriene 43 (80 mg, 0.20 mmol) in decalin ene-5-carboxylate (48-Me): According to GP 5, the hexatriene 22-

(1.0 mL) was heated at 205 °C for 0.75 h. FC (15 g of silica gel, 3:2 Me (280 mg, 0.933 mmol) in decalin (5.00 mL) was heated at

v/v diethyl ether/pentane) gave a mixture of compounds 44 and 45 205 °C for 45 min. FC (28 g of silica gel, 20:1 v/v light petroleum/

with a ratio of 1:1.3 (according to ¹H NMR) as a colorless wax diethyl ether elution) gave compound 48-Me (193 mg, 69%) as a

(37 mg, 46%). R = 0.4. IR (film): ν = 3396 cm^–1, 2973, 2933, 2872, colorless wax. R = 0.3. IR (film): ν = 2925 cm^–1, 2853, 1728, 1595,

˜

f

1669, 1653, 1617, 1559, 1540, 1490, 1472, 1457, 1437, 1419, 1388, 1447, 1331, 1275, 1195, 1072, 1021, 1001, 969, 911, 859, 735. ¹H

1362, 1253, 1193, 1108, 1062, 948, 895, 812, 736, 703, 668. ¹H NMR (250 MHz, CDCl₃): δ = 0.82–1.89 (m, 16 H), 1.91–2.18 (m,

3

NMR (300 MHz, CDCl₃, signals which can be assigned to the 6 H), 2.20–2.43 (m, 2 H), 3.21 (dd, J = 7.6, J = 9.1 Hz, 1 H, 5-

minor component 44 are marked with ^#): δ = 0.83 (s, 3 H, CH₃)^#, H), 3.62 (s, 3 H, CH₃) ppm. ¹³C NMR (62.9 MHz, CDCl₃, add.

0.93 (s, 3 H, CH₃), 1.17 [s, 9 H, C(CH₃)₃]^#, 1.18 [s, 9 H, C(CH₃)₃], DEPT): δ = 22.4 (–, CH₂), 22.6 (–, CH₂), 23.1 (–, CH₂), 25.3 (–,

1.21–1.50 (m, 7 H), 1.54–2.00 (m, 8 H), 2.03–2.52 (m, 12 H), 3.20– CH₂), 25.9 (–, CH₂), 26.4 (–, CH₂), 30.2 (–, CH₂), 30.4 (–, CH₂),

3.38 (m, 4 H, CH₂OH), 3.41–3.74 (m, 9 H), 5.59–5.67 (m, 1 H, 6- 31.2 (–, CH₂), 32.0 (–, CH₂), 33.3 (–, CH₂), 38.7 (+, CH), 40.9 (+,

H)^#ppm. MS (70 eV): m/z (%) = 402 (5) [M⁺], 358 (4), 342 (24), CH), 43.8 (+, CH, C-5), 53.0 (+, CH₃), 127.8 (C_quat), 127.8 (C_quat),

311 (100), 285 (31), 255 (35), 237 (18), 209 (9), 197 (18), 181 (10), 128.0 (C_quat), 131.3 (C_quat), 175.3 (C_quat, C=O) ppm. MS (70 eV):

155 (11), 143 (29), 105 (5), 91 (8), 81 (5), 57 (64) [C₄H₉⁺], 41 (16).

m/z (%) = 300 (52) [M⁺], 266 (2) [M⁺– CO₂CH₃], 241 (12), 226

(10), 218 (2), 192 (11), 190 (10), 162 (4), 146 (14), 145 (100), 105

(14), 239 (5), 197 (9), 171 (8), 145 (100), 129 (8), 117 (5), 91 (6), 79

(3), 67 (4), 41 (4). HRMS: calcd. for C₂₀H₂₈O₂300.2091 (correct

HRMS).

tert-Butyl trans-1,2,3,4,4a,5,6,7,8,9,10,11,12,12a-Tetradecahydro-

chrysene-5-carboxylate (48-tBu): According to GP 5, the hexatriene

22-tBu (33.2 mg, 0.110 mmol) in decalin (0.50 mL) was heated at

205 °C for 45 min. FC (32 g of silica gel, 20:1 v/v light petroleum/

diethyl ether elution) yielded compound 48-tBu (23.1 mg, 77%) as tert-Butyl 13-tert-Butoxy-12a-methyl-1,2,3,4,4a,4b,5,6,

a colorless oil. R = 0.3. IR (film): ν = 2924 cm^–1, 2853, 1711, 1448, 7,8,9,10,11,12, 12a-tetradecahydrochrysene-5-carboxylate (50): Ac-

˜

f

1392, 1368, 1347, 1303, 1257, 1214, 1152, 1086, 1029, 846, 736. ¹H cording to GP 5, the hexatriene 23 (100 mg, 0.234 mmol) in decalin

NMR (250 MHz, C₆D₆): δ = 1.01–1.85 (m, 18 H), 1.18 [s, 9 H, (3.00 mL) was heated at 205 °C for 45 min. FC (33 g of silica gel,

C(CH₃)₃], 1.87–2.08 (m, 2 H), 2.08–2.38 (m, 2 H), 2.42–2.56 (m, 2 20:1 v/v light petroleum/diethyl ether elution) gave compound 50

H, 6-H), 3.20 (dd, ³J = 6.1, ³J = 6.3 Hz, 1 H, 7-H) ppm. ¹³C NMR (71.4 mg, 71%) as a colorless wax. R_f= 0.3. IR (film): ν =

˜

(62.9 MHz, C₆D₆, add. DEPT): δ = 22.9 (–, CH₂), 23.8 (–, CH₂), 2974 cm^–1, 2927, 2854, 1725, 1595, 1450, 1388, 1378, 1368, 1332,

25.7 (–, CH₂), 26.4 (–, CH₂), 26.9 (–, CH₂), 27.6 (–, CH₂), 28.1 [+, 1284, 1270, 1249, 1227, 1192, 1154, 1067, 1023, 1000, 970, 957,

1

3 C, C(CH₃)₃], 30.8 (–, CH₂), 30.9 (–, CH₂), 31.5 (–, CH₂), 32.8 945, 903, 884, 852, 820, 759, 703. H NMR (250 MHz, CDCl₃): δ

(–, CH₂), 34.5 (–, CH₂), 40.7 (+, CH), 41.4 (+, CH), 44.6 (+, CH, = 0.78 (s, 3 H, CH₃), 1.18 [s, 9 H, C(CH₃)₃], 1.39 [s, 9 H,

C-5), 79.2 [C_quat, CO₂C(CH₃)₃], 128.2 (C_quat), 129.1 (C_quat), 131.1 CO₂C(CH₃)₃], 1.43–1.62 (m, 6 H), 1.64–1.85 (m, 7 H), 1.86–2.10

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(m, 5 H), 2.13–2.36 (m, 3 H), 2.91–3.00 (m, 1 H, 5-H), 3.09 (dd, ³J

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3

= 5.6, J = 11.4 Hz, 1 H, 1-H) ppm. ¹³C NMR (62.9 MHz, C₆D₆,

add. DEPT): δ = 11.3 (+, CH₃), 22.9 (–, CH₂), 23.0 (–, CH₂), 23.8

(–, CH₂), 24.9 (–, CH₂), 25.1 (–, CH₂), 28.1 [+, 3 C, C(CH₃)₃], 29.3

[+, 3 C, CO₂C(CH₃)₃], 30.5 (–, CH₂), 31.0 (–, CH₂), 32.2 (–, CH₂),

34.8 (–, CH₂), 38.0 (+, CH, C-4a), 40.0 (C_quat, C-12a), 46.1 (+, C-

5), 72.6 [C_quat, C(CH₃)₃], 78.3 (+, C-1), 79.1 [C_quat, CO₂C(CH₃)₃],

127.2 (C_quat), 127.8 (C_quat), 128.1 (C_quat), 130.1 (C_quat), 172.7

(C_quat, C=O) ppm. ¹³C NMR (62.9 MHz, CDCl₃, add. DEPT): δ

= 11.3 (+, CH₃), 22.8 (–, CH₂), 23.9 (–, CH₂), 24.8 (–, CH₂), 25.1

(–, CH₂), 28.2 [+, 3 C, C(CH₃)₃], 29.4 [+, 3 C, CO₂C(CH₃)₃], 30.5

(–, CH₂), 31.1 (–, CH₂), 32.3 (–, CH₂), 34.6 (–, CH₂), 37.8 (+, C-

4a), 39.9 (C_quat, C-12a), 46.0 (+, C-5), 72.7 [C_quat, C(CH₃)₃], 78.5

(+, C-1), 126.2 (C_quat), 128.1 (C_quat), 128.2 (C_quat), 130.0 (C_quat),

173.9 (C_quat, C=O) ppm. MS (70 eV): m/z (%) = 428 (9) [M⁺], 402

(11), 386 (19), 346 (18), 329 (34), 313 (52), 295 (100), 267 (29), 229

(43), 215 (14), 197 (9), 145 (7), 95 (4), 84 (10), 57 (84) [C₄H₉⁺], 41

(18). HRMS: calcd. for C₂₈H₄₄O₃428.3293 (correct HRMS).

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Supporting Information (see also the footnote on the first page of

1

this article): Copies of H and ¹³C NMR spectra of the described

compounds.

Acknowledgments

This work was supported by the State of Niedersachsen as well

as the companies BASF AG, Schering AG and Chemetall GmbH

(Chemicals). H. W. S. is indebted to the German Merit Foundation

(Studienstiftung des deutschen Volkes) for a graduate student fel-

lowship. The authors are grateful to Stefan Beußhausen

(Göttingen) for his technical support.

[15]

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[17]

We thank Dr. A. Edwards for carrying out the single-crystal

X-ray analysis of compound 19. Details will be reported else-

where.

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Substituted 1,3,5-Hexatrienes in Thermally Induced 6π-Electrocyclizations

FULL PAPER

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Received: March 6, 2007

Published Online: June 18, 2007

[26] Diels–Alder reactions exploiting similar bicyclo[4.4.0]decadi-

enes yielded interesting complex carbon skeletons: R.

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Article Doi

Synthesis and use of new substituted 1,3,5-hexatrienes in studying thermally induced 6π-electrocyclizations

DOI: 10.1002/ejoc.200700201

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