Studies on the mercury-desilylation of chiral cyclopropylmethylsilanes - A stereocontrolled access to carba-sugars

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Studies on the Mercury-Desilylation of Chiral Cyclopropylmethylsilanes –

A Stereocontrolled Access to Carba-Sugars

Yannick Landais*^[b]and Parra-Rapado^[a]

Keywords: Cyclopropanation / Allylsilanes / Mercury-desilylation / Carbva-sugars / Dihydroxylation

Mercury-desilylation of cyclopropylmethylsilanes affords a

stereospecific access to homoallylic mercury intermediates,

which can be elaborated further. This strategy is illustrated

with a short access to carba-furanoses and carba-C-

disaccharides.

Introduction

During the course of our studies on the epoxidation and

cyclopropanation of acyclic 2-silyl-3-alkenols 1, we have ex-

perienced unexpected problems with the determination of

the stereochemistry of the cyclopropyl- and epoxysilanes 2

and 4 (Scheme 1).^{[1] 1}H NMR afforded no decisive infor-

mation regarding the relative configuration between C2 and

C3 and we were also unable to produce suitable crystals of

2 and 4 (as well as derivatives) for X-ray structure determi-

nation. It was thus decided to convert 2 and 4, using a

transformation of known stereochemical course, into com-

1

pounds whose structure would be more amenable to H-

NMR structure determination. We thus showed that the

acid-catalyzed Peterson-like ring opening of epoxides 4^[2]

afforded stereospecifically the corresponding homoallylic

alcohols 5 in high yields. We then reasoned that the anal-

ogous cyclopropylmethylsilanes 2 might behave similarly in

the presence of electrophiles (E^ϩ), affording stereospecif-

ically the olefin 3. The opening of small rings such as cyclo-

propanes under electrophilic conditions is usually easy, ow-

ing to the release of the angle strain energy (ca. 30 kcal

mol^Ϫ1).^[3]While the epoxymethylsilanes opened regio- and

stereospecifically, previous studies indicated that the same

process with cyclopropylmethylsilanes was not so clear-

cut.^[4]Moreover, the presence, in our case, of a β-hydroxysi-

lyl moiety, prone to Peterson elimination,^[5]represented an

additional problem.

After many unsuccessful attempts, it was finally found

that mercury salts efficiently mediated the ring-opening

with concomitant desilylation in a stereospecific fashion

and with excellent regiocontrol.^[6]This method constitutes

an efficient stereocontrolled SEЈ₂alkylation of allylsilanes,

since the mercury derivatives 3 (E ϭ HgBr) can be func-

tionalized further using radical or organometallic pro-

cesses.^[7]We describe here a full account of these studies

and the extension of the strategy to the cyclopropanations

Scheme 1

of cyclic 2-silyl-3-alkenols and the ring-opening of their

cyclopropane. The utility of this methodology is further il-

lustrated with a short and stereocontrolled access to carba-

sugars and carba-C-disaccharides.

Results and Discussion

Cyclopropanation of Acyclic Allylsilanes

The cyclopropanation of acyclic 2-silyl-3-alkenols 1a؊d

was carried out using Furukawa^[8]conditions (CH₂I₂,

ZnEt₂in CH₂Cl₂) affording the desired cyclopropanes

2a؊d in good yields and with excellent diastereoselectivities

(Scheme 2, Table 1). 2a؊d were assigned the anti-configura-

tions as will be demonstrated below. It is noteworthy that

no Peterson elimination was observed under these acidic

conditions. The high level of stereocontrol was rationalized

invoking a chair-like transition state such as A (Figure 1),

where the sterically-demanding silicon group occupies a

pseudo-equatorial position to minimize A_1,3interactions.^[9]

Steric interactions between R and RЈ and the ligands at the

zinc centre (including iodine) probably prevent the cyclo-

propanation of (E)-olefin to proceed through conformation

B, explaining the absence of the syn-isomer in this reaction.

In the meantime, we also prepared the cyclopropanes 2e؊f

lacking the OH group at C-1.^[10]As reported in the litera-

[a]

`

University of Lausanne, Institute of Organic Chemistry, College

´

Propedeutique,

CH-1015 Lausanne-Dorigny, Switzerland

[b]

Present address: University Bordeaux-I, Laboratoire de Chimie

´

Organique et Organometallique,

´

351, Cours de la Liberation, F-33405 Talence Cedex, France

Fax: (internat.) ϩ 33-5/56844664

E-mail: y.landais@lcoo.u-bordeaux.fr

Eur. J. Org. Chem. 2000, 401Ϫ418

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401

Y. Landais, L. Parra-Rapado

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ture, the (Z)-olefin 1f afforded solely the anti diastereomer moallylsilanes 6a؊b have also been treated using Furu-

2f while the (E)-isomer 1e gave a mixture of the syn and kawa^[8]conditions and led to the expected cyclopropanes

anti diastereomers 2e in a 1:1 ratio (Scheme 2).^[10]Such a 7a؊b in good yields but, more surprisingly, with excellent

difference of diastereofacial selectivity between closely-re- diastereoselectivities (Scheme 3). It is worthy of note that

lated 1a؊b and 1e may be attributed to the directing effect 6a؊b react much slower than the corresponding allylsilanes

of the homoallylic hydroxy group in 1a؊b and the absence (36 h vs. 6 h). The directing effect of a bishomoallylic OH

of such an effect in 1e.^[11]This supports the hypothesis of group is likely to be less effective than that of a homoallylic

an internal delivery of the zinc-carbenoid in 1a؊b through group.^[11]However, the high level of diastereocontrol is in-

conformation A. This hypothesis was further supported by dicative of such an effect. Therefore, it is reasonable to as-

the cyclopropanation of the acetate and the silyl ether sume that similarly to 2a؊g, cyclopropanes 7a؊b possess a

(SiPh₂tBu) derivative of 1a which both provided the Peter- C2ϪC4 anti-configuration and have been formed through

son elimination products and no trace of cyclopropane. Fi- the chair-like transition state C (Figure 2).^[11]As above, the

nally, cyclopropanation of the dienylsilane 1g under the bulky silicon group occupies a pseudo-equatorial position

same conditions as above led to the mono-cyclopropan- and the zinc reagent linked to the alcohol group delivers

ation product 2g in moderate yield, but with complete dia- the methylene group on the Si-face of the olefin. An open

stereocontrol.

transition state similar to that proposed recently for the

hydroboration of closely-related homoallylsilanes^[12]has

been precluded owing to the much higher diastereocontrol

observed in our case. As a comparison, hydroboration of

the homoallylsilane analogue of 6a lacking the bishomoal-

lylic OH group led to the corresponding addition product

in a 75:25 syn/anti ratio.^[12]

Scheme 3

Figure 2

Scheme 2

Our first attempts to selectively open cyclopropanes

2a؊d with concomitant desilylation were carried out using

various electrophiles such as thallium salts,^[13]halogens (I₂,

Br₂, NIS)^[14]as well as Lewis acids (BF₃• Et₂O).^[15]All

these conditions were found unsuitable and produced com-

plex mixtures. Much better results were obtained using Col-

lum conditions,^[16]i.e. Hg(NO₃)₂in a 5:2 CH₃CN/DME

mixture, followed by addition of aqueous KBr. The ex-

pected olefins 8a؊b and 8d were thus isolated in good

Table 1. Cyclopropanation of allylsilanes 1a؊f (Scheme 2)

Entry Allylsilane

R

RЈ

anti/syn^[a]Yield [%]^[b]

1

2

3

4

5

6

1a

1b

1c

1d

1e

1f

Ph

H

93:7

>98:2

88

83

79

71

80

86

n-C₅H₁₁

Ph

H

Me

H

n-C₅H₁₁>98:2

1

yields. H-NMR studies unambiguously showed that they

Ph

H

Ph

50:50

>98:2

H

all possess the (E)-stereochemistry with selectivity as high

as 98:2, whatever the original configuration of the allylsil-

ane precursors 1 (Scheme 4). Interestingly, the cyclopropane

2c having a quaternary carbon centre afforded, under the

same conditions, a mixture of the (E)-olefin 8c and a tetra-

hydrofuran 9 as a unique diastereomer with the stereochem-

istry as shown (determined using difference nOe experi-

ments). We assumed that the stereochemistry at C2 and C3

centres is conserved during the 5-endo-trig like cycliza-

tion^[17]leading to 9, which supports the anti configuration

for cyclopropane 2c. The homologous cyclopropanes 7a؊b

were treated similarly but gave rise to a mixture of products,

^[a]Estimated from ¹H NMR (400 MHz) and GC of the crude reac-

tion mixture. Ϫ

lumn chromatography.

[b]

Isolated yields after purification through co-

Figure 1

402

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

whose structures were tentatively given that of tetrahydrofu-

rans, presumably a result of a 5-exo-trig cyclization.^[18]The

attempts to separate the different isomers failed owing to

the sensitivity of these mercury derivatives towards silica.

Similar results were obtained when we tried to oxidize or

reduce the CϪHgBr bond. Finally, pTsOH, BF₃• AcOH,

or BF₃• Et₂O treatment of 7b led only to the Peterson elim-

ination product 8e.

Scheme 5

ing the 5-endo-trig like process, the stereochemistry of the

precursors 11a؊c was thus well secured. Therefore, if one

assume that the oxidation of the CϪSi bond occurs with

retention of configuration,^[19]then cyclopropanation of al-

lylsilanes 10c (and 1a؊f) led to products having the anti

configuration. Cyclopropanation of the analogous allylic al-

cohols 10a؊b provided syn cyclopropanes through the well

documented hydroxy-directed effect,^[11]further supporting

our hypothesis. The complete reversal of regioselectivity ob-

served during ring opening of cyclopropylmethyl alcohols

11a؊c, relative to their silyl analogues is worthy of note

and provides a stereospecific access to polysubstituted

tetrahydrofurans.

The results above have demonstrated that our mercury-

desilylation is a much more regioselective process than the

Lewis acid mediated ring opening of silylcyclopropylme-

thylsilanes reported in the literature.^[4]Such a selectivity can

be tentatively rationalized as illustrated in Figure 3. The

mercury-desilylation of cyclopropanes 2a؊b and 2d؊f is

thought to occur through path a, which involves the stabil-

ization of a nascent positive charge developing at the β-

position relative to the silicon group during the C2ϪC3Ј

bond-breaking (β-silicon effect).^[20]Alternatively, if the

cyclopropane possesses both a quaternary carbon centre at

C3 and substituents which are able to stabilize such a native

positive charge (as in 2c), then a reversal of the regioselec-

tivity may be operative through path b. ^[17]The 5-endo-trig

cyclization process illustrated by E thus becomes predomi-

nant, leading to the tetrahydrofuran (i.e. 9). This route is

the only one observed with cyclopropylmethyl alcohols

11a؊c and it is noticable that the choice of the R group in

11a؊c is not restricted to aromatic groups (i.e. 11b). Fi-

nally, the stereospecificity of the process may be explained

assuming a conformation such as D, where both the

C2ϪC3Ј and the CϪSi bonds, which are breaking, are in

an antiperiplanar arrangement. Such a conformation thus

resembles that generally accepted for acid-catalysed Peter-

son elimination.

Scheme 4

The stereochemistry of 9 is the first evidence that cyclo-

propanes 2 possess a C2ϪC3 anti configuration. However,

as the stereochemistry of the electrophile mediated cyclo-

propane ring-opening had never been addressed before, no

definitive conclusion could be drawn. Therefore, it was de-

cided to further investigate the stereochemistry of this reac-

tion, starting from precursors of known stereochemistry, i.e.

the anti-cyclopropanes 2f and the syn-anti mixture 2e.^[10]

We thus observed that treatment of 2f, under the same con-

ditions as above, produced exclusively the (E)-olefin 8f,

whereas the 1:1 mixture of 2e led to an equimolar amount

1

of (E)- and (Z)-olefin 8f؊g (determined using H NMR)

(Scheme 5). This clearly indicates that similarly to the acid-

catalysed Peterson elimination,^[5]the mercury-desilylation

of cyclopropylmethylsilanes is anti-stereospecific. Conse-

quently, cyclopropanes 2a؊f could be assigned the anti con-

figuration.

An independent proof of the stereochemistry of 2a؊f was

provided by the series of experiments below (Scheme 6).

Treatment of the cyclopropanes 11a؊c under the same con-

ditions as above provided the corresponding tetrahydrofu-

rans 12a؊c in good overall yield and with excellent stereo-

control. The stereochemistry of 12a؊c was determined

Cyclopropanation of Cyclic Allylsilanes ؊ Access to

Carba-Sugars

Having demonstrated in acyclic series that the mercury-

through difference nOe and NOESY experiments. As the desilylation of cyclopropylmethylsilanes was regioselective

relative configuration at C2 and C3 should be retained dur- and led to the desired homoallylic derivatives in high yield,

Eur. J. Org. Chem. 2000, 401Ϫ418

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Y. Landais, L. Parra-Rapado

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utilization of such compounds for chemotherapeutic

uses.^[22]A better resistance to this enzymatic degradation

is usually observed with the carba analogues lacking the

anomeric centre.^[23]Natural aristeromycin 13a^[21a]and syn-

thetic anti-HIV agent carbovir 13b^[21a]are poor substrates

for the phosphorylases and are effectively more active than

their oxygenated counterparts (Scheme 7). Similar trends

are observed with carba-sugars and their homologues, the

carba-disaccharides.^[24]These biologically relevant targets

have thus been the subject of intense synthetic research.^[25]

Our approach would offer a new and flexible access to such

targets and analogues 14a؊b as well as carba-C-disacchar-

ides starting from readily-available cyclopentadienylsilanes

17 following the disconnection illustrated in Scheme 8. Our

route involves a mercury-desilylation of the cyclopro-

pylmethylsilane 16, itself available through cyclopropan-

ation and dihydroxylation of 17. The common intermediate

to all targets would be the homoallylic mercury substrate

15, which should be easy to functionalize further.

Scheme 7

Scheme 6

Scheme 8

Cyclopentadienylsilanes 17a؊c were easily prepared in

high yields through lithiation (nBuLi, Ϫ78°C) of cyclopen-

tadiene and silylation with the suitable chlorosilanes

(Scheme 9). It is worthy of note that using this protocol,

dienylsilanes 17a؊c were obtained almost free of the iso-

meric vinylsilanes^[26]and were used in the next step without

further purifications. Cyclopropanation of 17a؊c using Fu-

rukawa conditions proceeded in high yields, leading exclus-

ively to the anti-isomers 18a؊c. The remaining double

Figure 3

we then planned to extend such a strategy to cyclic series. bond of 18a؊c was then dihydroxylated using either Sharp-

One of our final goals was to devise a regio- and stereocon- less-AD conditions^[27](conditions A, Table 2) in which the

trolled access to carba-furanoses, carba-nucleosides as well chiral ligand was replaced by the achiral amine Et(iPr)₂N

as carba-C-disaccharides. Natural nucleosides and ana- or the usual OsO₄-NMMO protocol^[28](conditions B, Table

logues have been extensively studied owing to their antivi- 2). The reaction did proceed faster and with better yields

ral, antifungal, and anticancer activities.^[21]However, de- using biphasic conditions A. The level of diastereocontrol

activation of these substrates through phosphorylase-me- was good with PhMe₂Si and Ph₂MeSi but dropped dra-

diated cleavage of the N-glycosidic bond have hampered the matically when increasing the steric bulk at silicon, which

404

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

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contrast with the observations made during the cyclopro- Table 2. Dihydroxylation of cyclopropylsilanes 18a؊d (Scheme 9)

panation and dihydroxylation of the analogous cyclohexa-

Entry Substrate Product^[a]Conditions^[b]syn/anti^[c]Yield [%]^[d]

dienylsilanes.^[29]This can be rationalised invoking the con-

formation of the cyclopropane 18a؊c, where the cyclopro-

pane ring is nearly perpendicular to the plane of the cyclo-

pentene (Figure 4). Therefore, both diastereotopic faces are

not so well-differentiated (as compared with those of the

corresponding 6-membered ring) and the osmium reagent

experience large steric interactions with both the silicon

group and one hydrogen of the cyclopropane ring. Surpris-

ingly, the use of a bulkier silicon group led to no diastereo-

selectivity at all. The moderate overall yield observed in en-

1

2

3

4

18a

18b

18c

19a

19b

19c

19d

A

B

8:2

9:1

1:1

60

42

40

33

[a]

[b]

Major isomer. Ϫ

Conditions A: K₂OsO₄· 2 H₂O, K₂CO₃,

K₃Fe(CN)₆, Et(iPr)₂N, tBuOH/H₂O 1:1, CH₃SO₂NH₂, room

temp., 3d; Conditions B: OsO₄, NMMO, acetone/H₂O 9:1, room

[c]

temp., 7Ϫ16 h. Ϫ syn/anti refers to the relative stereochemistry

between the diol and the silicon group. Ratio estimated from ¹H

[d]

NMR (400 MHz) of the crude dihydroxylation mixture. Ϫ

Iso-

try 2 and 3 (Table 2) arise from the decomposition of the lated yield of the major isomer (2 steps) after chromatography.

minor isomer (having the OH groups syn relative to the

silicon group) through a base-catalyzed Peterson elimin-

ation^[5]during the protection of the diol using NaH-BnBr.

No trace of the syn isomer could be found when it was

present in the crude dihydroxylation mixture. The elimin-

ation product 21 was isolated instead. On the contrary, pro-

tection of the diols as acetonides was carried out in acidic

conditions and afforded a mixture of the anti (major) and

syn (minor) isomers which could be separated through col-

umn chromatography (i.e. 19a/20a, 19d/20b).

Figure 4

worth noticing that under the same conditions, the minor

cyclopropane stereoisomer 20a led to a complex mixture.

Finally, 23a was osmylated giving the desired diol 24a as a

unique diastereomer. Similarly, 23b afforded a unique diol

which was directly converted into its acetonide 24b. In both

cases, the osmylation occurred anti relative to the three sub-

stituents already on the ring. This simple route thus pro-

vides a ready access to racemic carba-sugars having 5 con-

tiguous stereogenic centres, in only 6 steps from cyclopen-

tadiene.

Scheme 9

The cyclopropanes were then subjected to mercury-desi-

lylation as described in the acyclic series. Treatment of

19a؊c with Hg(NO₃)₂yielded the mercury derivatives

Scheme 10

This approach is also flexible and should allow for the

22a؊b in good yields, which were then converted into the introduction of various heteroatoms on the 5-membered

corresponding alcohols 23a؊b using NaBH₄in DMF un- ring. This was demonstrated as illustrated in Scheme 11.

der a saturated oxygen atmosphere (Scheme 10).^[30]It is The homoallylic alcohol 23b was epoxidized using m-CPBA

Eur. J. Org. Chem. 2000, 401Ϫ418

405

Y. Landais, L. Parra-Rapado

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(90% after recrystallization from CH₂Cl₂) affording the moiety and a 5-membered ring carba-sugar. Our strategy

epoxide 25a as a unique diastereomer. nOe experiments un- was based on the utilization of the Sinay¨ϪBeau^[32]method-

ambiguously showed that the epoxidation took place anti ology which involves the condensation of a glycosyllithium

relative to the three substituents and that the directing effect such as 28 with aldehydes 29, this process occurring with

of the homoallylic OH group was not operative (Figure 5). retention of configuration at the anomeric centre. Aldehydes

25a was then acetylated and the epoxide opened using 29 having various chain lengths (n ϭ 1, 2) could be pre-

NaN₃in DMF. The resulting azide 26 was obtained in a pared using the strategy described above. As the aldehydes

moderate yield but as a single regio- and diastereomer, thus are racemic, their condensation with enantiopure sugars

opening a route to the synthesis of the corresponding should thus lead, after oxidation or radical deoxygenation

carba-nucleoside analogues of aristeromycin 13a. nOe of the resulting alcohol, to a resolved 1:1 mixture of two

experiments were used to establish unambiguously the carba-C-disaccharides which could be separated by chro-

Ϫ

structure of 26, which showed that the N₃group prefers matography.

to approach away from the benzyloxy groups (Figure 5).

Another route to carba-nucleoside precursors involving the

conversion of the triol 24a into the corresponding sulfate

and subsequent nucleophilic displacement with adenine was

attempted but led essentially to the recovery of the sulfate.

Scheme 12

Our first attempt to prepare carba-C-disaccharides

started from aldehyde 30 (chain length n ϭ 1), which was

easily prepared in high yield through the Swern oxi-

dation^[33]of the corresponding alcohol 24b (Scheme 13). 2-

Deoxyglucosyllithium 31 (prepared from the corresponding

stannyl intermediate following literature protocol)^[32a]was

then condensed with racemic 30 at low temperature, lead-

ing, after purification by column chromatography to only

one stereoisomer 32. The low yield may be attributed to the

Scheme 11

high sensitivity of 30 towards bases. Deprotonation α to the

aldehyde may initiate the decomposition of 30 through β-

elimination (of a BnO group)^[34]or condensation of the al-

dehyde with itself, thus leading to a complex mixture where

the desired carba-C-disaccharide 32 is present only in small

1

amounts. Nevertheless, H-NMR studies on 32 (NOESY,

COSY, ROESY) unambiguously showed that the coupling

had occurred with retention of configuration at the anom-

eric centre. The configuration of the CαϪOH stereogenic

centre could not be assigned with certainty and therefore,

it has not been possible to determine which enantiomer of

30 reacted with 31. Recent reports suggest that SmI₂-me-

diated coupling between a sugar-sulfone and the carba-al-

dehyde 30 might constitute a more suitable route and an

Figure 5

Preparation of Carba-C-Disaccharides

Carba-C-disaccharides have received a great deal of at- attractive alternative to the use of strongly basic lithio-sug-

tention recently, owing to their potent glycosidases and gly- ars.^[35]

cosyltransferases inhibitory activity.^[31]Recent reports sug-

An alternative pathway was developed in parallel using,

gest that better level of inhibition of the glycosidase activity instead of the fragile aldehyde 30, the iodide 33 prepared in

should be attained using inhibitors mimicking both the gly- one step from the corresponding mercury-intermediate 22b

con and the aglycon moieties.^[31]Numerous approaches to (Scheme 14).^[36]Condensation of the glycosyllithium 31

carba-disaccharides and carba-C-glycosides have thus been with 33 unfortunately did not produce the expected carba-

devised,^[25]leading to various types of disaccharides, but C-disaccharide, but led to the recovery of the starting mate-

as far as we know, none of them contain a carba-furanose rials, under all conditions.

skeleton. We therefore initiated a study on the preparation

Much more satisfying results were obtained in the hom-

of carba-C-disaccharides 27 possessing a sugar-pyranose ologous series starting from an aldehyde 29 having a two-

406

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

racemic aldehyde 39, eventually obtained in 8 steps and

30% overall yield from 17a.

Scheme 13

Scheme 14

carbon chain (n ϭ 2, Scheme 12). This aldehyde was pre-

pared in racemic form in 8 steps from cyclopentadienylsil-

ane 17a (Scheme 15). Cyclopropanation of 17a was carried

out through Cu^IOTf decomposition of ethyldiazoacetate

(EDA)^[37]in the presence of a Schiff base.^[38]As above, the

cyclopropanation occurred predominantly anti relative to

the silicon group, a small amount (5%) of a stereoisomer of

34 (probably with the CO₂Et group up) also being ob-

served. The osmylation of 34 then led to the expected diol

as a 7:3 mixture of the anti and syn (relative to the silicon

group) stereoisomers respectively, which were purified as

their acetonides 35a؊b. As the cyclopropane is activated by

an ester group, we anticipated that a nucleophilic attack at

the silicon centre would assist the cyclopropane ring open-

ing.^[39]Treatment of 35a؊b with CsF in DMF effectively

gave, concomitantly with the desilylation, a clean cyclopro-

pane ring opening. The reaction was performed separately

on stereoisomers anti-35a and syn-35b which afforded the

corresponding esters 36 (syn and anti respectively) using 2

equivalents of CsF (50°C) for the anti isomer and 8 equiva-

lents (100°C) for the syn isomer. 36 was then dihydroxylated

and the diol protected as an acetonide, thus leading to a

carba-sugar 37 having a pseudo C₂symmetry. It is thus pos-

sible to carry out the 3 steps from 35a؊b to 37 without

prior separation of the diastereomers. The ester 37 was then

Scheme 15

The condensation of racemic 39 with 2-deoxyglucosyl-

lithium 31 afforded a mixture of only 3 stereoisomers whose

alcohol functions were directly oxidized to the ketones

using PDC,^[32]producing a 1:1 mixture of the desired

carba-C-disaccharides 40a and 40b. As before, ¹H-NMR

studies confirmed that the condensation step occurred with

a complete retention of configuration at the anomeric cen-

tre. We have thus devised a short route to carba-C-disac-

charides possessing a carba-furanose skeleton in 20% over-

all yield from cyclopentadiene. Our approach is flexible

since we may envisaged the extension of the strategy to the

synthesis of other carba-C-disaccharides varying the nature

of the sugar unit as well as the substituents on the carba-

sugar moiety.

Conclusion

As a summary, we have shown that the stereoselective

reduced to the alcohol 38 which was oxidized to the desired cyclopropanation of allylsilanes followed by the regio- and

Eur. J. Org. Chem. 2000, 401Ϫ418

407

Y. Landais, L. Parra-Rapado

FULL PAPER

General Procedure for the Preparation of 3,4-cyclopropylsilanes

2a؊d: To a solution of allylsilane 1a؊d (0.33 mmol), in dry CH₂Cl₂

(1 mL) was added CH₂I₂(0.442 g, 1.65 mmol) in CH₂Cl₂(1 mL).

The mixture was cooled to 0°C and a 1  solution of Et₂Zn in

hexane (1.65 mL, 1.65 mmol) was added carefully. The mixture be-

came heterogeneous (white solid) and was stirred for 6 hours at

room temp. Then, the mixture was treated with a solution of

NH₄Cl, the organic layer was decanted and the aqueous layer ex-

tracted with ether (3 ϫ 20 mL), the combined organic layers

washed with brine, dried with MgSO₄, and the solvents were evapo-

rated under vacuum. The yellow oil was purified by chromatogra-

phy through silica gel (Petroleum ether/EtOAc/Et₃N, 95:4.5:0.5) af-

fording the cyclopropane 2a؊d as a pale yellow oil.

Cyclopropane (2a): Following the general procedure, 2a was ob-

tained in 88% yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3000,

1600, 1500, 1440, 1250, 1110, 840, 780, 700. Ϫ H NMR (CDCl₃):

Scheme 16

1

δ ϭ 7.64Ϫ6.88 (m, 10 H, aromatic H), 3.87 (dd, J ϭ 4.6, 10.8 Hz,

1 H, CH_aH_bOH), 3.80 (dd, J ϭ 7.5, 10.8 Hz, 1 H, CH_aH_bOH),

1.55 (dt, J ϭ 4.9, 8.6 Hz, 1 H, CHPh), 1.1Ϫ0.88 (m, 3 H, CH₂,

CH), 0.69 (ddd, J ϭ 4.6, 7.5, 15.2 Hz, 1 H, CHSi), 0.57 (dd, J ϭ

4.1, 5.8 Hz, 1 H, CH_aH_b), 0.35 (s, 3 H, SiCH₃), 0.34 (s, 3 H,

SiCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 143.2 (s, aromatic C), 137.8 (s,

aromatic C), 133.9 (d, aromatic CH), 129.0 (d, aromatic CH), 128.2

(d, aromatic CH), 127.8 (d, aromatic CH), 125.3 (d, aromatic CH),

125.3 (d, aromatic CH), 65.0 (t, J ϭ 143 Hz, CH₂OH), 35.9 (d, J ϭ

117 Hz, CHPh), 22.7 (d, J ϭ 158 Hz, CHSi, CH), 17.3 (t, J ϭ

161 Hz, CH₂), Ϫ3.5 (q, J ϭ 120 Hz, SiCH₃), Ϫ3.8 (q, J ϭ 120 Hz,

SiCH₃). Ϫ MS (CI, NH₃): m/z (%): 279 (0.3) [M^ϩϪ 17], 180 (3),

144 (21), 135 (62), 129 (100), 116 (5), 91 (22), 75 (10). Ϫ C₁₉H₂₄OSi

(296.48): calcd. C 76.99, H 8.17, Si 9.45; found C 75.54; H 7.93,

Si 9.23.

stereospecific mercury-desilylation of the cyclopropylmeth-

ylsilanes offers an entry to homoallylic derivatives which

can be versatile synthons for organic synthesis. This was

demonstrated through a short and stereoselective access to

carba-sugars, to precursors of carba-nucleosides and to

carba-C-disaccharides. The silicon group plays a central

role in this context, controlling the diastereofacial selec-

tivity of the cyclopropanation, the regio- and also the

stereoselectivity of the cyclopropane ring opening. It is also

worth noting the remarkable dichotomy between the silicon

and the hydroxy groups, as indicated by the reversal of re-

gioselectivity observed during the mercury-mediated cyclo-

propane ring opening. This was used to devise a stereocon-

trolled route to diastereomeric trisubstituted tetrahydrofu-

rans.

Cyclopropane (2b): Following the general procedure, 2b was ob-

tained in 83% yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3050,

1

2980, 2850, 1250, 1110, 850. Ϫ H NMR (CDCl₃): δ ϭ 7.55Ϫ7.33

(m, 5 H, aromatic H), 3.73Ϫ3.66 (m, 2 H, CH₂OH), 1.57Ϫ1.47 (m,

1 H, CHSi), 1.34Ϫ1.17 (m, 8 H, 4 ϫ CH₂), 1.29 (t, J ϭ 7.1 Hz, 3

H, CH₃), 0.52Ϫ0.38 (m, 2 H, 2 ϫ CH), 0.38 [s, 6 H, Si(CH₃)₂],

0.35Ϫ0.23 (m, 2 H, CH₂). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.3 (s,

aromatic C), 133.9 (d, J ϭ 158 Hz, aromatic CH), 129.0 (d, J ϭ

161 Hz, aromatic CH), 127.8 (d, J ϭ 158 Hz, aromatic CH), 65.3

(t, J ϭ 141.2 Hz, CH₂OH), 35.4 (d, J ϭ 118.9 Hz, CHSi), 34.1 (t,

J ϭ 122.6 Hz, CH₂), 31.8 (t, J ϭ 124.7 Hz, CH₂), 28.8 (d, J ϭ

125 Hz, CH₂), 22.6 (t, J ϭ 126 Hz, CH₂), 18.1 (d, J ϭ 157 Hz,

CH), 17.3 (d, J ϭ 157 Hz, CH₂), 14.1 (d, J ϭ 125 Hz, CH₃), 12.4

(t, J ϭ 159 Hz, CH₂), Ϫ3.4 (q, J ϭ 120 Hz, SiCH₃), Ϫ3.8 (q, J ϭ

120 Hz, SiCH₃). Ϫ MS (CI, NH₃): m/z (%): 290 (5) [M^ϩ], 273 (51),

245 (1), 175 (2), 152 (44), 135 (100), 110 (28), 96 (45), 81 (45). Ϫ

C₁₈H₃₀OSi (290.52): calcd. C 74.43, H 10.42, Si 9.64; found C

74.55, H 10.48, Si 9.69.

Experimental Section

1

General Remarks: H- and ¹³C-NMR spectra were recorded on a

Bruker AC-250 FT (¹H: 250 MHz, ¹³C: 62.9 MHz), Bruker WH-

360 FT and (¹H: 360 MHz, ¹³C: 90.55 MHz), Bruker ARX-400 FT

(¹H: 400 MHz, ¹³C: 100.6 MHz) using CDCl₃as internal reference

unless otherwise indicated. The chemical shifts (δ) and coupling

constants (J) are expressed in ppm and Hz, respectively. Ϫ Gas

chromatography was run on a Fisons Intruments, GC 8000 series.

Ϫ IR spectra were recorded on a PerkinϪElmer 1710 spectropho-

tometer, on a PerkinϪElmer Paragon 500 FT-IR spectrophoto-

meter or on a PerkinϪElmer Mattson Unicam 500 16PC FT-IR.

Ϫ Mass spectra were recorded on a Nermag R10Ϫ10C, chemical

ionization (CI) with NH₃or Vacuum Generators micromass VG

70/70E and DS 11Ϫ250 and EI (70 eV); m/z (%). High resolution

mass spectra were recorded on a FTICR mass spectrometer Bruker

Cyclopropane (2c): Following the general procedure, 2c was ob-

4.7T BioApex II. Ϫ Specific rotations were recorded on a PerkinϪ tained in 79% yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3000,

1

Elmer 241 polarimeter. Ϫ Elemental analyses were performed

by the I. Beetz laboratory, W-8640 Kronach (D). Ϫ Melting points

were not corrected and were determined by using a Büchi Totolli

apparatus. Kugelrohr distillations were carried out using a Büchi

GKR-50 apparatus. Ϫ Merk silica gel 60 (70Ϫ230 mesh), (230Ϫ400

1630, 1510, 1475, 1275, 1110, 855, 770, 710. Ϫ H NMR (CDCl₃):

δ ϭ 7.52Ϫ7.09 (m, 10 H, aromatic H), 3.85 (d, J ϭ 5.6 Hz, 2 H,

CH₂OH), 1.25 (s, 3 H, CH₃), 1.19 (dd, J ϭ 4.1, 8.6 Hz, 1 H,

CH_aH_b), 1.11 (ddd, J ϭ 5.8, 8.6, 11.1 Hz, 1 H, CH), 0.99 (dt, J ϭ

5.6, 11.1 Hz, 1 H, CHSi), 0.57 (dd, J ϭ 4.1, 5.8 Hz, 1 H, CH_aH_b),

mesh ASTM) and Baker silica gel (0.063Ϫ0.200 mm) were used 0.39 (s, 6 H, Si(CH₃)₂). Ϫ ¹³C NMR (CDCl₃): δ ϭ 147.8 (s, aro-

for flash chromatography. Slow additions were conducted using a

Precidor apparatus. Ϫ CH₂Cl₂, Et₃N, (iPr)₂NH were distilled from

CaH₂. THF was distilled from potassium. Et₂O, hexane and DME

were distilled from sodium. Chlorosilanes were distilled from mag-

nesium.

matic C), 138.0 (s, aromatic C), 134.0 (d, aromatic CH), 133.9 (d,

aromatic CH), 129.1 (d, aromatic CH), 128.1 (d, aromatic CH),

127.8 (d, aromatic CH), 126.0 (d, aromatic CH), 125.3 (d, aromatic

CH), 65.6 (t, CH₂OH), 29.8 (d, CHSi), 26.8 (d, J ϭ 143.2 Hz, CH),

23.4 (s, CPhCH₃), 21.3 (t, J ϭ 155 Hz, CH₂), 20.5 (q, J ϭ 128 Hz,

408

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

CH₃), Ϫ3.3 (q, J ϭ 120 Hz, SiCH₃), Ϫ3.8 (q, J ϭ 120 Hz, SiCH₃). 1604, 1496, 1250, 1111, 1067, 1031, 959. Ϫ ¹H NMR (CDCl₃): δ ϭ

Ϫ MS (CI, NH₃): m/z (%): 310 (0.11) [M^ϩ], 293 (6), 194 (4), 158 7.58Ϫ7.22 (m, 10 H, aromatic H), 6.28 (d, J ϭ 15.8 Hz, 1 H, olef-

(19), 143 (88), 135 (100), 128 (19), 91 (26), 75 (11). Ϫ C₂₀H₂₆OSi inic H), 5.71 (dd, J ϭ 5.8, 15.8 Hz, 1 H, olefinic H), 3.85Ϫ3.72 (m,

(310.51): calcd. C 77.38, H 8.45, Si 9.02; found C 77.42, H 8.43,

Si 8.97.

2 H, CH₂OH), 1.60Ϫ1.52 (m, 1 H, CH), 126Ϫ1.15 (m, 1 H, CHSi),

0.85Ϫ0.74 (m, 2 H, CH₂), 0.65Ϫ0.51 (m, 1 H, CH), 0.42 (s, 6 H,

Si(CH₃)₂). Ϫ MS (CI, NH₃): m/z (%): 231 (0.4) [M^ϩϪ 17], 215 (3),

153 (6), 137 (100), 135 (94), 119 (6), 105 (11), 81 (62). Ϫ HRMS

[M ϩ Na] C₂₁H₂₆ONaSi: calcd. 345.1645; found 345.1644.

Cyclopropane (2d): Following the general procedure, 2d was ob-

tained in 71% yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3050,

1

2980, 2850, 1250, 1110, 840. Ϫ H NMR (CDCl₃): δ ϭ 7.57Ϫ7.55

(m, 2 H, aromatic H), 7.37Ϫ7.34 (m, 3 H, aromatic H), 3.76 (d,

J ϭ 4.3 Hz, 2 H, CH₂OH), 1.60 (m, 1 H, OH), 1.33Ϫ1.22 (m, 8 H,

4 ϫ CH₂), 0.88 (t, J ϭ 6.8 Hz, 3 H, CH₃), 0.75Ϫ0.69 (m, 5 H, 2

ϫ CH, ϪCH₂Ϫ, CHSi), 0.39 (s, 3 H, SiCH₃), 0.38 (s, 3 H, SiCH₃).

Cyclopropane (7a): Following the general procedure, 7a was ob-

tained in 80% yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3050,

2980, 2850, 1250, 1110, 850, 700. Ϫ ¹H NMR (CDCl₃): δ ϭ

7.55Ϫ7.51 (m, 2 H, aromatic H), 7.39Ϫ7.34 (m, 3 H, aromatic H),

3.88 (dd, J ϭ 4.1, 10.4 Hz, 1 H, CH_aH_bOH), 3.77 (dd, J ϭ 6.5,

10.8 Hz, 1 H, CH_aH_bOH), 1.49Ϫ1.2 (m, 4 H, OH, CHSi, CH₂),

0.98 (d, J ϭ 5.6 Hz, 3 H, CH₃), 0.5Ϫ0.4 (m, 2 H, 2 ϫ CH), 0.33

[s, 6 H, Si(CH₃)₂], 0.15Ϫ0.098 (m, 2 H, CH₂). Ϫ ¹³C NMR

(CDCl₃): δ ϭ 138.4 (s, aromatic C), 133.9 (d, J ϭ 154 Hz, aromatic

CH), 129.0 (d, J ϭ 160 Hz, aromatic CH), 127.8 (d, J ϭ 158 Hz,

aromatic CH), 64.0 (t, J ϭ 101 Hz, CH₂OH), 32.2 (t, J ϭ 125 Hz,

CH₂), 30.9 (d, J ϭ 115 Hz, CHSi), 20.1 (d, J ϭ 138 Hz, CH), 18.8

(q, J ϭ 127 Hz, CH₃), 14.0 (d, J ϭ 152 Hz, CH), 12.9 (t, J ϭ

158 Hz, CH₂), Ϫ3.7 (q, J ϭ 120 Hz, SiCH₃), Ϫ3.8 (q, J ϭ 120 Hz,

SiCH₃). Ϫ MS (CI, NH₃): m/z (%): 231 (0.4), [M^ϩϪ 17], 215 (3),

153 (6), 137 (100), 135 (94), 119 (6), 105 (11), 81 (62). Ϫ C₁₅H₂₄OSi

(248.44): calcd. C 72.52, H 9.74, Si 11.30; found C 72.52, H 9.64,

Si 11.46.

Ϫ

¹³C NMR (CDCl₃): δ ϭ 138.4 (s, aromatic C), 134.0 (d, J ϭ

157 Hz, aromatic CH), 129.0 (d, J ϭ 159 Hz, aromatic CH), 127.7

(d, J ϭ 159 Hz, aromatic CH), 65.8 (t, J ϭ 142 Hz, CH₂OH), 31.8

(t, J ϭ 125 Hz, CH₂), 29.5 (t, J ϭ 125 Hz, CH₂), 29.1 (t, J ϭ

126 Hz, CH₂), 28.4 (d, J ϭ 121 Hz, CHSi), 22.6 (t, J ϭ 125 Hz,

CH₂), 15.7 (d, J ϭ 163 Hz, CH), 15.3 (q, J ϭ 124 Hz, CH₃), 14.1

(d, J ϭ 126 Hz, CH), 10.8 (t, J ϭ 160 Hz, CH₂), Ϫ3.3 (q, J ϭ

120 Hz, SiCH₃), Ϫ4.0 (q, J ϭ 120 Hz, SiCH₃). Ϫ MS (CI, NH₃):

m/z (%): 290 [M^ϩ] (11), 273 (81), 152 (73), 135 (100), 110 (31), 96

(52), 81 (53). Ϫ C₁₈H₃₀OSi (290.52): calcd. C 74.43, H 10.42, Si

9.64; found C 74.51, H 10.31, Si 9.67.

General Procedure for the Yamamoto Cyclopropanation. ؊ Cyclo-

propane (2e): To a solution of (E)-3-dimethylphenylsilyl-1-phe-

nylbut-1-ene 1e (92 mg, 0.35 mmol), in dry CH₂Cl₂(4 mL) was ad-

ded CH₂I₂(188 mg, 0.7 mmol) in CH₂Cl₂(1 mL). The mixture was

cooled down to 0°C and a 2  solution of Me₃Al in heptane

(0.7 mmol, 0.35 mL) was carefully added. The heterogeneous reac-

tion mixture was then stirred for 24 hours at room temp. The mix-

ture was treated with a solution of NH₄Cl, the organic layer was

decanted and the aqueous layer extracted with ether (3 ϫ 20 mL).

The combined extracts were washed with brine, dried with MgSO₄,

and the solvents were evaporated under vacuum. The yellow oil

was purified by chromatography through silica gel (Petroleum

ether/EtOAc/Et₃N, 95:4.5:0.5) affording 78 mg of a 1:1 mixture of

anti- and syn-cyclopropanes 2e (80%). Spectroscopic data were in

Cyclopropane (7b): Following the general procedure, 7b was ob-

tained in 90% yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3050,

2950, 2850, 1600, 1500, 1420, 1250, 1030, 840, 820, 780, 720, 700.

Ϫ

¹H NMR (CDCl₃): δ ϭ 7.55Ϫ7.52 (m, 2 H, aromatic H),

7.38Ϫ7.33 (m, 3 H, aromatic H), 7.24 (t, J ϭ 7.5 Hz, 2 H, aromatic

H), 7.13 (t, J ϭ 7.4 Hz, 1 H, aromatic H), 6.99 (d, J ϭ 7.5 Hz, 2

H, aromatic H), 3.91Ϫ3.75 (m, 2 H, CH₂OH), 1.66Ϫ1.50 (m, 2 H,

CH₂), 1.35Ϫ1.20 (m, 1 H, CH), 1.13Ϫ1.04 (m, 1 H, CH),

0.94Ϫ0.83 (m, 1 H, CH), 0.81Ϫ0.76 (m, 1 H, CH), 0.73Ϫ0.67 (m,

1 H, CH), 0.34 [s, 6 H, Si(CH₃)₂]. Ϫ ¹³C NMR (CDCl₃): δ ϭ 143.5

(s, aromatic C), 138.2 (s, aromatic C), 133.8 (d, J ϭ 158 Hz, aro-

matic CH), 128.9 (d, J ϭ 160 Hz, aromatic CH), 128.2 (d, J ϭ

166 Hz, aromatic CH), 127.8 (d, J ϭ 165 Hz, aromatic CH), 125.4

(d, J ϭ 149 Hz, aromatic CH), 125.2 (d, J ϭ 161 Hz, aromatic

CH), 63.7 (t, J ϭ 142 Hz, CH₂OH), 32.2 (t, J ϭ 126 Hz, CH₂),

30.7 (d, J ϭ 117 Hz, CHSi), 24.3 (d, J ϭ 157 Hz, CH), 23.8 (d,

J ϭ 156 Hz, CH), 16.2 (t, J ϭ 161 Hz, CH₂), Ϫ3.7 (q, J ϭ 120 Hz,

SiCH₃), Ϫ3.8 (q, J ϭ 120 Hz, SiCH₃). Ϫ MS (CI, NH₃): m/z (%):

328 [M^ϩϩ 17], 311 [M^ϩ], 293 (14), 277 (4), 232 (23), 214 (36), 189

(9), 175 (2), 152 (46), 135 (100), 117 (100), 91 (76). Ϫ C₂₀H₂₆OSi

(310.51): calcd. C 77.36, H 8.44, Si 9.04; found C 77.48, H 8.53,

Si 9.04.

good agreement with those reported in the literature.^[10a]

Ϫ

¹H

NMR (CDCl₃): δ ϭ 7.57Ϫ7.11 (m, 20 H, aromatic H), 1.62Ϫ1.52

(m, 2 H, 2 ϫ CHSi), 1.08 (d, J ϭ 6.1 Hz, 3 H, CH₃), 1.06 (d, J ϭ

6.1 Hz, 3 H, CH₃), 1.01Ϫ0.72 (m, 6 H, 6 ϫ CH), 0.48Ϫ0.42 (m, 2

H, 2 ϫ CH), 0.36 (s, 6 H, 2 ϫ SiCH₃), 0.31 (s, 6 H, 2 ϫ SiCH₃).

Cyclopropane (2f): Following the general protocol reported for 2e,

the cyclopropane 2f was obtained from 1f in 86% yield. Spectro-

scopic data were in good agreement with those reported ref.^[10a]

Ϫ

¹H NMR (CDCl₃): δ ϭ 7.38Ϫ7.01 (m, 10 H, aromatic H),

2.18Ϫ2.11 (m, 1 H, CHSi), 1.19Ϫ1.08 (m, 1 H, CH), 0.98 (d, J ϭ

6.1 Hz, 3 H, CH₃), 0.76Ϫ0.74 (m, 1 H, CH), 0.52Ϫ0.43 (m, 1 H,

CH), 0.11 (s, 3 H, SiCH₃), 0.04 (s, 3 H, SiCH₃).

Monocyclopropane (2g): To

a

solution of dienol 1g

General Procedure for the Mercury-Desilylation of 2a؊f: To a solu-

(0.41 g,1.33 mmol), in dry CH₂Cl₂(4 mL) was added CH₂I₂(1.42 g, tion of cyclopropane 2a؊f (0.16 mmol) in DME (4 mL) were added

5.32 mmol) in CH₂Cl₂(1 mL). The mixture was cooled to 0°C and

a 1  solution of Et₂Zn in hexane (5.32 mL, 5.32 mmol) was added

carefully. The heterogeneous mixture was then stirred for 8 hours

at room temp. Then, the mixture was treated with a solution of

successively at room temp. CH₃CN (10 mL), then mercury nitrate

monohydrate (59 mg, 0.17 mmol). The resulting mixture was stirred

at room temp. for 6 hours, then quenched with aqueous KBr and

diluted with ether. The mixture was stirred for 2 hours at room

NH₄Cl, the organic layer was decanted, and the aqueous layer ex- temp. and the organic layer was decanted. The aqueous layer was

tracted with ether (3 ϫ 20 mL). The combined organic extracts

were washed with brine, dried with MgSO₄, and the solvents were

evaporated under vacuum. The yellow oil was purified by chroma-

tography through silica gel (Petroleum ether/EtOAc/Et₃N,

95:4.5:0.5) affording 0.55 g (98%) of 2g as a pale yellow oil. Ϫ IR

extracted with ether (2 ϫ 20 mL) and the combined extracts were

washed with a solution of saturated KHCO₃(twice) and water,

dried with MgSO₄and the solvents were evaporated under vacuum

to give the crude homoallylic mercury bromides 8 in 80Ϫ90 yield.

The relative instability of these organometallic compounds did not

(film, KBr): ν˜ ϭ 3404 cm^Ϫ1(OH), 3067, 3024, 2997, 2955, 2868, allow us to obtain satisfactory elemental analysis.

Eur. J. Org. Chem. 2000, 401Ϫ418

409

Y. Landais, L. Parra-Rapado

FULL PAPER

(8a): Following the general procedure, 8a was obtained in 85%

acids [pTsOH (cat.) or 36% BF₃·2 AcOH (1 equiv.) or 48% BF₃·

OEt₂(1 equiv.)]. The reaction mixture was stirred at room temp.

1660, 1600, 1500, 1460, 1180, 980, 770, 700. Ϫ H NMR (CDCl₃): for 3 hours and the solvent was evaporated in vacuo affording the

yield. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 3050, 2960, 2850,

1

δ ϭ 7.42Ϫ7.29 (m, 5 H, aromatic H), 5.99 (ddd, J ϭ 1.4, 7.15,

15.4 Hz, 1 H, CHϭCHCH₂OH), 5.79 (dtd, J ϭ 1.1, 5.4, 15.4 Hz,

elimination product 8e [pTsOH (64%), BF₃-2 AcOH (33%), BF₃·

OEt₂(55%)]. Ϫ IR (film, KBr): ν˜ ϭ 2920 cm^Ϫ1, 1734, 1684, 1559,

1 H, CHϭCHCH₂OH), 4.17 (d, J ϭ 5.4 Hz, 2 H, CH₂OH), 3.88 1457, 1243, 697. Ϫ ¹H NMR (CDCl₃): δ ϭ 7.36Ϫ7.04 (m, 5 H,

(dd, J ϭ 7.2, 7.3 Hz, 1 H, CHCH₂HgBr), 2.42 (d, J ϭ 7.3 Hz, 2

H, CH₂HgBr). Ϫ ¹³C NMR (CDCl₃): δ ϭ 145.9 (s, aromatic C),

136.8 (d, J ϭ 148 Hz, aromatic CH), 129.2 (d, J ϭ 160 Hz, aro-

matic CH), 127.0 (d, J ϭ 161 Hz, aromatic CH), 126.7 (d, J ϭ

aromatic H), 5.96Ϫ5.87 (m, 1 H, CHϭCH₂), 5.13Ϫ5.98 (m, 2 H,

CHϭCH₂), 2.19Ϫ2.15 (m, 1 H, CH), 1.71Ϫ1.60 (m, 2 H, CH₂),

1.30Ϫ1.24 (m, 1 H, CH), 0.97Ϫ0.89 (m, 2 H, CH₂). Ϫ MS (CI,

NH₃): m/z (%): 159 [M^ϩ], 145 (8), 131 (19), 117 (48), 105 (13), 91

156 Hz, aromatic CH), 63.2 (t, J ϭ 142 Hz, CH₂OH), 46.8 (d, J ϭ (30), 81 (24), 75 (2), 55 (5).

131 Hz, CHCH₂HgBr), 41.02 (t, J ϭ 139 Hz, CH₂HgBr). Ϫ MS

(8f): Following the general procedure, 8f was obtained from cyclo-

(CI, NH₃): m/z (%): 459 [M^ϩϩ 17], 442 [M^ϩ], 416 (58), 378 (13),

345 (6), 304 (17), 210 (13), 143 (100), 91 (74).

propane 2f in 85% yield. Ϫ IR (film, KBr): ν˜ ϭ 2950 cm^Ϫ1, 2850,

1650, 1080, 980. Ϫ ¹H NMR (CDCl₃): δ ϭ 7.39Ϫ7.23 (m, 5 H,

aromatic H), 5.74 (qdd, J ϭ 1.4, 7.1, 15.1 Hz, 1 H, CHϭCHCH₃),

5.62 (dqd, J ϭ 0.7, 6.1, 15.1 Hz, 1 H, CHϭCHCH₃), 3.82 (q, J ϭ

(8b): Following the general procedure, 8b was obtained in 90% yield

from cyclopropanes 2b and 2d. Ϫ IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1

(OH), 3050, 2960, 2850, 1660, 1380, 1090, 980. Ϫ ¹H NMR 7.1 Hz, 1 H, CHPh), 2.40 (dd, J ϭ 1.4, 7.1 Hz, 2 H, CH₂HgBr),

(CDCl₃): δ ϭ 5.71 (td, J ϭ 5.5, 15.4 Hz, 1 H, CHϭCHCH₂OH), 1.72 (dd, J ϭ 0.8, 6.1 Hz, 3 H, CH₃). Ϫ MS (EI): m/z (%): 360

5.59 (dd, J ϭ 7.8, 15.4 Hz, 1 H, CHϭCHCH₂OH), 4.13 (d, J ϭ

5.4 Hz, 2 H, CH₂OH), 2.17 (d, J ϭ 5.5 Hz, 2 H, CH₂HgBr),

1.39Ϫ1.27 (m, 8 H, 4 ϫ CH₂), 0.89 (t, J ϭ 6.4 Hz, 3 H, CH₃). Ϫ

¹³C NMR (CDCl₃): δ ϭ 138.7 (d, J ϭ 157 Hz, C vinyl), 128.8 (d,

J ϭ 153 Hz, C vinyl), 63.3 (t, J ϭ 141 Hz, CH₂OH), 41.4 (d, J ϭ

127 Hz, CHCH₂HgBr), 40.8 (t, J ϭ 127 Hz, CH₂), 39.5 (t, J ϭ

137 Hz, CH₂), 31.7 (t, J ϭ 122 Hz, CH₂), 27.1 (t, J ϭ 126 Hz,

CH₂), 22.5 (t, J ϭ 126 Hz, CH₂), 14.0 (q, J ϭ 124 Hz, CH₃). Ϫ

MS (CI, NH₃): m/z (%): 452 (M^ϩϩ 17], 410 (100), 378 (26), 304

(15), 210 (7), 137 (67), 95 (66).

(12), 202 (25, 145 (100), 105 (66), 91 (51), 77 (65).

(8f and 8g): Following the general procedure, mercury-desilylation

of cyclopropylmethylsilane 2e afforded a 1:1 mixture of 8f and 8g

in 86% yield. Ϫ IR (film, KBr): ν˜ ϭ 2950 cm^Ϫ1, 2850, 1650, 1080,

1

980. Ϫ H NMR (CDCl₃): δ ϭ 7.56Ϫ7.23 (m, 10 H, aromatic H),

5.77Ϫ5.51 (dd, 4 H, 4 ϫ E/Z-vinyl CH), 4.16 (q, J ϭ 7.1 Hz, 1 H,

Z-CHPh), 3.82 (q, J ϭ 7.1 Hz, 1 H, E-CHPh), 2.40 (dd, J ϭ 1.4,

7.1 Hz, 4 H, 2 ϫ CH₂HgBr), 1.71 (d, J ϭ 6.1 Hz, 6 H, 2 ϫ CH₃).

Ϫ MS (EI): m/z (%): 357 (6), 283 (10), 221 (7), 202 (9), 159 (16),

105 (100), 91 (40), 77 (46).

(8c) and Tetrahydrofuran (9): Following the general procedure, mer-

cury-desilylation of 2c produced a 34:66 mixture of 8c and 9,

respectively which were purified by column chromatography (Petro-

leum ether/EtOAc/Et₃N, 95:4.5:0.5), affording 8c in 30% yield: Ϫ

IR (film, KBr): ν˜ ϭ 3400 cm^Ϫ1(OH), 2960, 2850, 1690, 1600, 1500,

1420, 1380, 1080, 980, 760, 700. Ϫ ¹H NMR (CDCl₃): δ ϭ

7.41Ϫ7.24 (m, 5 H, aromatic H), 6.06 (dd, J ϭ 1.3, 15.7 Hz, 1 H,

Tetrahydrofuran (12a): To a solution of 10a (0.385 g, 1.86 mmol)

in dry CH₂Cl₂(4 mL) was added dropwise at 0°C, CH₂I₂(2.49 g,

9.32 mmol,) then a 1  solution of Et₂Zn in hexane (9.32 mL,

9.32 mmol). The mixture was stirred overnight at room temp. and

then quenched with a saturated solution of NH₄Cl. The organic

layer was decanted and the aqueous layer was extracted with ether

(3 ϫ 20 mL). The combined extracts were washed with brine, dried

with MgSO₄, filtered and the solvents were evaporated under vac-

uum to give 0.371 g of the desired cyclopropane as a yellow oil

(91%). This product was used in the next step without further puri-

fication. An analytical sample afforded the following structural

CHϭCHCH₂OH), 5.76 (td,

J ϭ 5.5, 15.7 Hz, 1 H, CHϭ

CHCH₂OH), 4.22 (dd, J ϭ 1.3, 5.5 Hz, 2 H, CH₂OH), 2.53 (d, J ϭ

0.52 Hz, 2 H, CH₂HgBr), 1.60 (s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃):

δ ϭ 148.7 (s, aromatic C), 142.2 (d, aromatic CH), 128.8 (d, aro-

matic CH), 126.7 (d, aromatic CH), 126.4 (d, aromatic CH), 125.5

(d, aromatic CH), 63.4 (t, CH₂OH), 49.6 (t, CH₂HgBr), 44.6 (s,

CCH₃Ph). Ϫ MS (CI, NH₃): m/z (%): 430 (4), 378 (2), 157 (100),

129 (59), 105 (80), 91 (85) and 9 in 60% yield: Ϫ IR (film, KBr):

ν˜ ϭ 2960 cm^Ϫ1, 2850, 1650, 1550, 1400, 1380, 1260, 1120, 820, 800,

1

data: Ϫ H NMR (CDCl₃): δ ϭ 7.31Ϫ7.29 (m, 2 H, aromatic H),

7.21Ϫ7.17 (m, 1 H, aromatic H), 7.13Ϫ7.10 (m, 2 H, aromatic H),

4.30 (q, 1 H, J ϭ 7.2 Hz, CO₂CH_aH_bCH₃), 4.39 (q, J ϭ 7.2 Hz, 1

H, CO₂CH_aH_bCH₃), 4.08 (d, J ϭ 6.4 Hz, 1 H, CHOH), 3.16 (m,

1 H, OH), 2.19Ϫ2.15 (m, 1 H, CHPh), 1.49Ϫ1.43 (m, 1 H,

CHCHOH), 1.32 (t, J ϭ 7.2 Hz, 3 H, CO₂CH₂CH₃), 1.18Ϫ1.13

(m, 1 H, CH_aH_b), 1.02Ϫ0.98 (m, 1 H, CH_aH_b). Ϫ ¹³C NMR

(CDCl₃): δ ϭ 171.5 (s, CO), 141.8 (s, aromatic C), 128.2 (d, J ϭ

168 Hz, aromatic CH), 125.9 (d, J ϭ 158 Hz, aromatic CH), 125.6

(d, J ϭ 161 Hz, aromatic CH), 70.9 (d, J ϭ 148 Hz, CHOH), 61.7

(t, J ϭ 148 Hz, CO₂CH₂), 25.7 (d, J ϭ 162 Hz, CHPh), 19.6 (d,

J ϭ 161 Hz, CH), 14.1 (q, J ϭ 127 Hz, CO₂CH₂CH₃), 11.3 (t, J ϭ

83 Hz, CH₂). Ϫ C₁₃H₁₆O₃(220.27): calcd. C 70.89, H 7.32; found

C 70.80, H 7.38. To a solution of the preceding cyclopropane in

dry ether (10 mL) was added at 0°C a 1  solution of LiAlH₄in

ether (1.7 mL, 1.69 mmol). The mixture was stirred at 0°C for 2

hours then quenched with a saturated solution of NH₄Cl. The or-

ganic layer was decanted and the aqueous layer extracted with ether

(3 ϫ 20 mL). The combined extracts were washed successively with

a 1  solution of HCl, sat. NaHCO₃and brine, dried with MgSO₄,

filtered, and the solvents were evaporated under vacuum, affording

1

720. Ϫ H NMR (CDCl₃): δ ϭ 7.60Ϫ7.28 (m, 10 H, aromatic H),

4.23 (dd, J ϭ 7.5, 10.5 Hz, 1 H, CH_aH_bO), 4.21 (dd, J ϭ 7.5,

10.5 Hz,

1 H, CH_aH_bO), 3.16 (dt, J ϭ 4, 5.7 Hz, 1 H,

CHCH₂HgBr), 1.88 (dd, J ϭ 3, 12.3 Hz, 1 H, CH_aH_bHgBr), 1.76

(dd, J ϭ 4, 12.3 Hz, 1 H, CH_aH_bHgBr), 1.62 (dt, J ϭ 5.7, 10.5 Hz,

1 H, CHSi), 1.46 (s, 3 H, CH₃), 0.41 (s, 3 H, SiCH₃), 0.29 (s, 3 H,

SiCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 147.8 (s, aromatic C), 137.5 (s,

aromatic C), 134.2 (d, aromatic CH), 133.0 (d, aromatic CH), 130.1

(d, aromatic CH), 129.2 (d, aromatic CH), 128.9 (d, aromatic CH),

128.4 (d, aromatic CH), 127.7 (d, aromatic CH), 126.6 (d, aromatic

CH), 124.2 (d, aromatic CH), 87.4 (s, CCH₃Ph), 67.5 (t, J ϭ

150 Hz, CH₂O), 49.4 (d, J ϭ 131 Hz, CHCH₂HgBr), 31.2 (d, J ϭ

108 Hz, CHSi), 25.7 (q, J ϭ 127 Hz, CH₃), Ϫ2.1 (q, J ϭ 103 Hz,

SiCH₃), Ϫ3.1 (q, J ϭ 103 Hz, SiCH₃). Ϫ MS (CI, NH₃): m/z (%):

608 [M^ϩϩ 18], 607 [M^ϩϩ 17], 590 [M^ϩ], 564 (43), 526 (4), 452

(3), 378 (7), 304 (16), 255 (55), 210 (8), 152 (100), 135 (75), 105 (26).

1

4,5-Cyclopropan-5-phenylpentene (8e): To a solution of 7b (53 mg,

0.24 g of the diol 11a (80%): Ϫ H NMR (CDCl₃): δ ϭ 7.34Ϫ7.04

0.17 mmol), in dry CHCl₃(3 mL) was added one of the following

(m, 5 H, aromatic H), 3.81 (dd, J ϭ 2.8, 11.5 Hz, 1 H, CH_aH_bOH),

Eur. J. Org. Chem. 2000, 401Ϫ418

410

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

3.64 (dd, J ϭ 7.8, 11.5 Hz, 1 H, CH_aH_bOH), 3.38Ϫ3.33 (m, 1 H,

ether, dried with MgSO₄, filtered and the solvent was evaporated

CHOH), 1.91Ϫ1.84 (m, 1 H, CHPh), 1.28Ϫ1.21 (m, 2 H, CH), in vacuo to give a yellow oil, which was purified by chromatogra-

1.14Ϫ1.09 (m, 1 H, CH), 1.03Ϫ0.95 (m, 1 H, CH). Ϫ ¹³C NMR phy through florisil (100Ϫ200 mesh, Petroleum ether/EtOAc, 1:1)

(CDCl₃): δ ϭ 141.9 (s, aromatic C), 128.3 (d, J ϭ 159 Hz, aromatic affording the expected diol 11c as a colourless oil (0.210 g, 82%),

CH), 125.8 (d, J ϭ 148 Hz, aromatic CH), 75.5 (d, J ϭ 142 Hz,

CHOH), 66.3 (t, J ϭ 142 Hz, CH₂OH), 24.93 (d, J ϭ 158 Hz,

CHPh), 20.2 (d, J ϭ 158 Hz, CH), 13.2 (t, J ϭ 161 Hz, CH₂). To

a solution of 11a (81 mg, 0.46 mmol) in DME (4 mL) were added

successively at room temp. CH₃CN (10 mL), then mercury nitrate

monohydrate (0.165 g, 0.48 mmol). The resulting mixture was

stirred at room temp. overnight, then quenched with aqueous KBr

and diluted with ether. The mixture was stirred for 2 hours at room

temp. and the organic layer was decanted. The aqueous layer was

extracted with ether (2 ϫ 20 mL) and the combined extracts were

which was directly used in the next step: Ϫ ¹H NMR (CDCl₃): δ ϭ

7.40Ϫ7.06 (m, 5 H, aromatic H), 3.77 (dd, J ϭ 3.0, 11.3 Hz, 1 H,

CH_aH_bOH), 3.62 (dd, J ϭ 7.3, 11.3 Hz, 1 H, CH_aH_bOH),

3.29Ϫ3.28 (m, 1 H, CHOH), 1.96Ϫ1.91 (m, 1 H, CHPh),

1.29Ϫ1.23 (m, 2 H, CH₂), 0.96Ϫ0.89 (m, 1 H, CHCHOH). Ϫ ¹³C

NMR (CDCl₃): δ ϭ 142.3 (s, aromatic C), 128.2 (d, aromatic CH),

125.8 (d, aromatic CH), 75.6 (d, CHOH), 65.9 (t, J ϭ 145 Hz,

CH₂OH), 25.0 (d, J ϭ 159 Hz, CHPh), 20.6 (d, J ϭ 162 Hz, CH),

12.8 (t, J ϭ 125 Hz, CH₂). To a solution of 11c (30 mg, 0.17 mmol,)

in DME (1 mL) were added successively at room temp. CH₃CN

washed with a saturated solution of KHCO₃(2 ϫ), water, dried (2.5 mL) then mercury nitrate monohydrate (61 mg, 0.18 mmol).

with MgSO₄, and the solvents were evaporated under vacuum. The

residue was purified by chromatography through silica gel,

The resulting mixture was stirred at room temp. overnight, then

quenched with aqueous KBr and diluted with ether. The mixture

was stirred for 2 hours at room temp. and the organic layer was

(CH₂Cl₂/Ether, 9:1) affording 84 mg of tetrahydrofuran 12a (40%):

1

Ϫ H NMR (CDCl₃): δ ϭ 7.39Ϫ7.26 (m, 5 H, aromatic H), 4.27 decanted. The aqueous layer was extracted with ether (2 ϫ 20 mL)

(d, J ϭ 10 Hz, 1 H, PhCHO), 4.09 (dd, J ϭ 6.8, 8.7 Hz, 1 H,

CH_aH_bO), 3.91 (m, 1 H, CHOH), 3.79 (dd, J ϭ 6.5, 8.7 Hz, 1 H,

and the combined extracts were washed with a saturated solution

of KHCO₃(2 ϫ) and water, dried with MgSO₄, and the solvents

CH_aH_bO), 2.16Ϫ2.14 (m, 1 H, CHCH₂HgBr), 1.71 (d, J ϭ 7.9 Hz, were evaporated under vacuum. The residue was purified by chro-

2 H, CH₂HgBr). Ϫ ¹³C NMR (CDCl₃): δ ϭ 139.7 (s, aromatic C), matography through silica gel, (CH₂Cl₂/Ether, 9:1) affording 38 mg

128.9 (d, J ϭ 161 Hz, aromatic CH), 128.6 (d, J ϭ 161 Hz, aro-

of the tetrahydrofuran 12c (50%): Ϫ ¹H NMR (CDCl₃): δ ϭ

matic CH), 126.7 (d, J ϭ 158 Hz, aromatic CH), 87.5 (d, J ϭ 7.42Ϫ7.27 (m, 5 H, aromatic H), 4.51 (d, J ϭ 10.1 Hz, 1 H,

148 Hz, CHPh), 78.0 (d, CHOH), 73.0 (t, J ϭ 148 Hz, CH₂O), 55.1 PhCHO), 4.37 (dd, J ϭ 3.9, 10.1 Hz, 1 H, CH_aH_bO), 4.32 (t, J ϭ

(d, J ϭ 132 Hz, CHCH₂HgBr), 29.2 (t, J ϭ 137 Hz, CH₂HgBr). Ϫ

MS (CI, NH₃): m/z (%): 476 [M^ϩϩ 18], 475 [M^ϩϩ 17], 457 [M^ϩ,

0.2], 432 (15), 396 (1.3), 328 (0.9), 274 (3), 196 (45), 177 (100), 117

(66), 105 (64), 91 (63).

3.83 Hz, 1 H, CHOH), 3.95 (d, J ϭ 10 Hz, 1 H, CH_aH_bO),

2.50Ϫ2.44 (m, 1 H, CHCH₂HgBr), 1.81Ϫ1.82 (m, 2 H, CH₂HgBr).

Ϫ

¹³C NMR (CDCl₃): δ ϭ 140.0 (s, aromatic C), 129.0 (d, J ϭ

161 Hz, aromatic CH), 128.7 (d, J ϭ 161 Hz, aromatic CH), 126.6

(d, J ϭ 164 Hz, aromatic CH), 86.3 (d, CHPh), 76.2 (t, J ϭ 126 Hz,

CH₂O), 74.2 (d, CHOH), 52.4 (d, J ϭ 131 Hz, CHCH₂HgBr),

25.31 (t, CH₂HgBr). Ϫ MS (CI, NH₃): 476 (M^ϩϩ 18, 25), 457 (1),

396 (2), 275 (5), 196 (49), 177 (100), 118 (25), 105 (50), 91 (62).

Tetrahydrofuran (12b): Following the procedure described for 12a,

12b was obtained in 30% overall yield (3 steps) from 10b: Ϫ ¹H

NMR (CDCl₃): δ ϭ 4.01 (dd, J ϭ 6.5, 8.9 Hz, 1 H, CH_aH_bO),

3.93Ϫ3.89 (m, 1 H, CHOH), 3.64 (dd, J ϭ 5.8, 8.9 Hz, 1 H,

CH_aH_bO), 3.45Ϫ3.39 (m, 1 H, CHO), 2.46 (d, J ϭ 6 Hz, 1 H, OH),

2.12 (dd, J ϭ 4.8, 11.2 Hz, 1 H, CH_aH_bHgBr), 2.08Ϫ1.99 (m, 2 H,

CHCH₂HgBr), 1.76 (dd, J ϭ 10.5, 11.2 Hz, 1 H, CH_aH_bHgBr),

1.68Ϫ1.32 (m, 8 H, 4 ϫ CH₂), 0.90 (t, J ϭ 6.4 Hz, 3 H, CH₃). Ϫ

¹³C NMR (CDCl₃): δ ϭ 86.1 (d, J ϭ 140 Hz, CHOH), 79.2 (d, J ϭ

149 Hz, CHO), 72.5 (t, J ϭ 146 Hz, CH₂O), 52.3 (d, J ϭ 131 Hz,

CHCH₂HgBr), 33.8 (t, CH₂), 31.9 (t, CH₂), 25.7 (t, J ϭ 123 Hz,

CH₂), 22.6 (t, J ϭ 128 Hz, CH₂), 14.0 (q, J ϭ 124 Hz, CH₃). Ϫ

MS (CI, NH₃): m/z (%): 451 [M^ϩ], 381 (3), 298 (6), 202 (2), 171

(9), 135 (44), 83 (100).

General Procedure for the Silylation-Cyclopropanation of Cyclopen-

tadiene. ؊ Cyclopropane (18a): To a solution of freshly distilled

cyclopentadiene (2 g, 30 mmol) in dry THF (90 mL) was added at

Ϫ80°C a 1.6  solution of nBuLi in hexane (23 mL, 33.3 mmol).

The mixture was stirred at Ϫ80°C for 45 minutes then a solution

of dimethylphenylchlorosilane (5 mL, 30 mmol) in dry THF

(10 mL) was added dropwise. The reaction mixture was stirred at

Ϫ80°C for 1.5 hour, then quenched with a saturated solution of

NH₄Cl and allowed to warm to room temp. The organic layer was

decanted and the aqueous layer was extracted with ether (3 ϫ

20 mL). The combined extracts were washed with brine and dried

Tetrahydrofuran (12c): To a solution of silyl alcohol 10c^[40](447 mg,

1.7 mmol) in dry CH₂Cl₂(5 mL) was added CH₂I₂(8.5 mmol, with MgSO₄. The solvents were evaporated in vacuo affording 5.9 g

2.3 g). The mixture was cooled down to 0°C, then a 1  solution

of Et₂Zn in hexane (8.5 mmol, 8.5 mL) was added dropwise. The

mixture was stirred at room temp. overnight, then treated with a

saturated solution of NH₄Cl. The organic layer was decanted and

the aqueous layer was extracted with ether (3 ϫ 20 mL). The com-

bined extracts were washed with brine, dried with MgSO₄, and the

solvent was evaporated under vacuum to afford the crude cyclopro-

pane (0.424 g, 90%) which was directly submitted to TamaoϪKum-

ada oxidation without further purification. To a solution of the

preceding cyclopropane (0.401 g, 1.45 mmol) in a 1:1 mixture of

of dienylsilane 17a (98%) which was used in the next step without

further purification. Ϫ ¹H NMR (CDCl₃): δ ϭ 7.58Ϫ7.51 (m, 2 H,

aromatic H), 7.42Ϫ7.35 (m, 3 H, aromatic H), 6.62Ϫ6.52 (m, 4 H,

vinylic H), 3.61 (t, J ϭ 6.5 Hz, 1 H, CHSi), 0.20 (s, 6 H, Si(CH₃)₂).

To a solution of 17a (2 g, 10 mmol) in dry CH₂Cl₂(20 mL) was

added at room temp. CH₂I₂(0.8 mL, 10 mmol,). The mixture was

stirred for 5 minutes and cooled down to 0°C. A 1  solution of

Et₂Zn in hexane (10 mL, 10 mmol) was then added dropwise. The

reaction mixture was stirred at room temp. for 24 hours, then

quenched with a saturated solution of NH₄Cl. The organic layer

MeOH/THF (25 mL) was added at room temperature KHCO₃was decanted and the aqueous layer was extracted with ether (3 ϫ

(0.388 g, 4.41 mmol,), KF (0.227 g, 4.41 mmol), then a 30% wt. 20 mL). The combined extracts were washed with brine, dried with

solution of H₂O₂(2.7 mL, 30 mmol). The mixture was stirred for MgSO₄, filtered, and the solvents were evaporated under vacuum.

16 hours at 60°C, then treated cautiously at 0°C with solid The yellow oil was purified by chromatography through silica gel,

Na₂S₂O₃. The reaction mixture was stirred at room temp. for (Petroleum ether) affording 1.98 g of 18a as a pale yellow oil (93%).

30 min, then diluted with ether, filtered through celite, and the sol-

vents were evaporated under vacuum. The residue was diluted with

Ϫ IR (film, KBr): ν˜ ϭ 3067 cm^Ϫ1, 3023, 2987, 2852, 1587, 1428,

1248, 1114, 998, 874, 824, 758, 699. Ϫ ¹H NMR (CDCl₃): δ ϭ

Eur. J. Org. Chem. 2000, 401Ϫ418

411

Y. Landais, L. Parra-Rapado

FULL PAPER

7.66Ϫ7.63 (m, 2 H, aromatic H), 7.46Ϫ7.43 (m, 3 H, aromatic H),

5.95Ϫ5.92 (m, 1 H, vinylic H), 5.39 (d, J ϭ 3.9 Hz, 1 H, vinylic

Major Diastereoisomer 19a: Ϫ IR (film, KBr): ν

˜ ϭ 3069 cm^Ϫ1

2987, 2881, 1379, 1250, 1208, 1043, 958, 864, 815, 732, 700. Ϫ H

,

1

H), 2.26 (s, 1 H, CHSi), 1.86Ϫ1.82 (1 H, m, allylic H), 1.54Ϫ1.49 NMR (CDCl₃): δ ϭ 7.56Ϫ7.54 (m, 2 H, aromatic H), 7.41Ϫ7.37

(m, 1 H, CHCHSi), 0.83Ϫ0.78 (m, 1 H, CH_aH_b), 0.37 (s, 3 H, (m, 3 H, aromatic H), 4.63 (dd, J ϭ 5.4, 6.2 Hz, 1 H, OCH), 4.55

SiCH₃), 0.36 (s, 3 H, SiCH₃), Ϫ0.09-(-0.12) (m, 1 H, CH_aH_b). Ϫ (d, J ϭ 6.2 Hz, 1 H, OCHCHSi), 1.56Ϫ1.52 (m, 1 H, CH), 1.49 (s,

¹³C NMR (CDCl₃): δ ϭ 138.1 (s, aromatic C), 134.0 (d, J ϭ 3 H, CH₃), 1.43Ϫ1.38 (m, 1 H, CH), 1.24 (s, 3 H, CH₃), 0.88Ϫ0.84

156.6 Hz, CH:CH), 132.4 (d, J ϭ 162 Hz, aromatic CH), 128.9 (d,

J ϭ 159 Hz, aromatic CH), 128.2 (d, J ϭ 163 Hz, aromatic CH),

127.7 (d, J ϭ 158 Hz, CH:CH), 38.3 (d, J ϭ 124 Hz, SiCH), 23.7

(m, 1 H, CH), 0.36 (s, 3 H, SiCH₃), 0.35 (s, 3 H, SiCH₃). Ϫ ¹³C

NMR (CDCl₃): δ ϭ 136.9 (s, aromatic C), 133.8 (d, J ϭ 158 Hz,

aromatic CH), 129.2 (d, J ϭ 158 Hz, aromatic CH), 127.8 (d, aro-

(d, J ϭ 170 Hz, CH), 15.6 (d, J ϭ 166 Hz, CH), 15.1 (t, J ϭ 161 Hz, matic CH), 83.9 (d, J ϭ 157 Hz, OCH), 82.9 (d, J ϭ 151 Hz, OCH),

CH₂), Ϫ5.0 (q, J ϭ 120 Hz, SiCH₃), Ϫ5.5 (q, J ϭ 120 Hz, SiCH₃). 32.7 (d, J ϭ 123 Hz, CHSi), 26.5 (q, J ϭ 127 Hz, CH₃), 24.4 (q,

Ϫ MS (CI, NH₃): m/z (%): 214 [M^ϩ], 197 (14), 185 (1), 159 (3), J ϭ 126 Hz, CH₃), 23.44 (d, J ϭ 172 Hz, CH), 22.57 (d, J ϭ

135 (100), 121 (8), 105 (18), 91 (25), 78 (16). Ϫ C₁₄H₁₈Si (214.38): 202 Hz, CH), 12.56 (t, J ϭ 159 Hz, CH₂), Ϫ4.34 (q, J ϭ 120 Hz,

calcd. C 78.44, H 8.46, Si 13.10; found C 78.44, H 8.53, Si 13.15.

SiCH₃), Ϫ4.73 (q, J ϭ 120 Hz, SiCH₃). Ϫ MS (CI, NH₃): m/z (%):

288 [M^ϩϪ 1], 273 (4), 230 (7), 193 (5), 168 (1), 152 (20), 135 (100),

117 (64), 105 (26), 91 (20). Ϫ C₁₇H₂₄O₂Si (288.46): calcd. C 70.78,

H 8.39, Si 9.74; found C 70.68, H 8.22, Si 9.75. Ϫ Minor Dia-

stereomer 20a: Ϫ IR (film, KBr): ν˜ ϭ 3069 cm^Ϫ1, 2987, 2881, 1379,

1250, 1208, 1043, 958, 864, 815, 732, 700. Ϫ ¹H NMR (CDCl₃):

δ ϭ 7.65Ϫ7.63 (m, 2 H, aromatic H), 7.38Ϫ7.36 (m, 3 H, aromatic

H), 4.68 (dd, J ϭ 5.3, 5.2 Hz, 1 H, OCHCHSi), 4.46 (d, J ϭ 5 Hz,

1 H, OCH), 1.56Ϫ1.51 (m, 1 H, CH), 1.48 (s, 3 H, CH₃), 1.47Ϫ1.43

(m, 1 H, CH), 1.33 (d, J ϭ 5.5 Hz, 1 H, CHSi), 1.27 (s, 3 H, CH₃),

0.84Ϫ0.80 (m, 1 H, CH_aH_b), 0.45 (s, 3 H, SiCH₃), 0.41 (3 H, s,

SiCH₃), Ϫ .015-(-0.19) (m, 1 H, CH_aH_b). Ϫ ¹³C NMR (CDCl₃):

δ ϭ 136.8 (s, aromatic C), 133.9 (d, J ϭ 157 Hz, aromatic CH),

128.6 (d, J ϭ 159 Hz, aromatic CH), 127.5 (d, J ϭ 156 Hz, aro-

matic CH), 88.5 (d, J ϭ 151 Hz, OCH), 84.6 (d, J ϭ 152 Hz, OCH),

36.0 (d, J ϭ 119 Hz, CHSi), 26.8 (q, J ϭ 127 Hz, CH₃), 25.2 (q,

J ϭ 171 Hz, CH), 24.6 (q, J ϭ 127 Hz, CH₃), 21.1 (d, J ϭ 168 Hz,

CH), 15.9 (t, J ϭ 153 Hz, CH₂), Ϫ2.2 (q, J ϭ 119 Hz, SiCH₃),

Ϫ2.9 (q, J ϭ 119 Hz, SiCH₃). Ϫ MS (CI, NH₃): m/z (%): 273 [M^ϩ

Ϫ 17], 230 (6), 193 (9), 152 (11), 135 (100), 119 (5), 105 (12), 91

(6). C₁₇H₂₄O₂Si (288.46): calcd. C 70.78, H 8.39, Si 9.74; found C

70.72, H 8.21, Si 9.88.

Cyclopropane (18b): Following the general procedure, 18b was ob-

tained from cyclopentadiene in 74% yield (2 steps). Ϫ IR (film,

KBr): ν˜ ϭ 3067 cm^Ϫ1, 3023, 2986, 2855, 1587, 1486, 1428, 1250,

948, 792, 726. Ϫ ¹H NMR (CDCl₃): δ ϭ 7.70Ϫ7.40 (m, 10 H,

aromatic H), 5.97Ϫ5.94 (m, 1 H, CHϭCHCHSi), 5.41 (d, J ϭ

5.5 Hz, 1 H, CHϭCHSi), 2.66 (d, J ϭ 2.4 Hz, 1 H, CHSi),

1.87Ϫ1.83 (m, 1 H, CH), 1.63Ϫ1.59 (m, 1 H, CH), 0.86Ϫ0.82 (m,

1 H, CH_aH_b), 0.62 (s, 3 H, SiCH₃), Ϫ0.02-(-0.04) (m, 1 H, CH_aH_b).

Ϫ

¹³C NMR (CDCl₃): δ ϭ 136.3 (s, aromatic C), 136.0 (s, aromatic

C), 134.9 (d, CH), 134.8 (d, CH), 134.7 (d, CH), 132.9 (d, CH),

129.2 (d, CH), 128.1 (d, CH), 127.8 (d, CH), 127.7 (d, CH), 37.1

(d, J ϭ 126 Hz, SiCH), 24.1 (d, J ϭ 169 Hz, CH), 16.0 (d, J ϭ

183 Hz, CH), 15.4 (t, J ϭ 162 Hz, CH₂), Ϫ6.9 (q, J ϭ 120 Hz,

SiCH₃). Ϫ MS (CI, NH₃): m/z (%): 276 [M^ϩ], 261 (5), 214 (4), 197

(100), 181 (17), 165 (8), 137 (8), 120 (49), 105 (50), 93 (17). C₁₉H₂₀Si

(276.45): calcd. C 82.55, H 7.29, Si 10.16; found C 82.46, H 7.34,

Si 10.24.

Cyclopropane (18c): Following the general procedure, 18c was ob-

tained from cyclopentadiene in 59% yield (2 steps). Ϫ IR (film,

KBr): ν˜ ϭ 3067 cm^Ϫ1, 3022, 2987, 2853, 1585, 1428, 1249, 1114.

Ϫ

¹H NMR (CDCl₃): δ ϭ 7.38Ϫ6.92 (m, 15 H, aromatic H),

Dibenzyl Ether 19b (Conditions A): Following the dihydroxylation

procedure A, cyclopropane 18a afforded the diol, which was di-

rectly protected as a dibenzyl ether. The crude diol was then added

at 0°C to a suspension of NaH (1.17 g, 48.9 mmol,) in dry THF

(50 mL), then benzylbromide (4.3 mL, 34.2 mmol) and KI (cat.)

were successively added. The reaction mixture was stirred overnight

at room temp., then quenched with a saturated solution of NH₄Cl

5.88Ϫ5.82 (m, 1 H, CHϭCHCHSi), 5.05Ϫ4.98 (m, 1 H, CHϭ

CHSi), 2.25Ϫ2.12 (m, 6 H, 3 ϫ CH₂Ph), 2.09Ϫ2.06 (m, 1 H,

CHSi), 1.82Ϫ1.70 (m, 1 H, CH), 1.38Ϫ1.25 (m, 1 H, CH),

0.79Ϫ0.71 (m, 1 H, CH_aH_b), Ϫ0.15 to Ϫ0.21 (m, 1 H, CH_aH_b). Ϫ

HRMS [M ϩ Na] C₂₁H₂₆ONaSi: calcd. 345.1645; found 345.1644.

General Procedure for the Sequence Dihydroxylation-Diol Protection

of Cyclopropane 18a؊c (Conditions A): In a 250 mL flask were and extracted with Et₂O. The combined extracts were dried with

placed 7.2 g of AD-mix [K₃FeCN₆(5 g, 15.3 mmol), K₂CO₃MgSO₄and the solvents evaporated under vacuum. The resulting

(2.1 g, 15.3 mmol), (DHQ)₂PYR (0.05 mmol) or Et(iPr)₂N oil was purified by chromatography through silica gel (Petroleum

(0.25 mmol), K₂OsO₄• 2 H₂O (19 mg, 0.05 mmol)], H₂O (26 mL);

and tBuOH (26 mL). The solution was stirred for 5 minutes and

methanesulfonamide (0.485 g, 5.1 mmol) was added. The reaction

ether/EtOAc, 9:1) affording 3 g of a 9:1 mixture of diastereomer

19b and Peterson elimination product 21 (42%, 2 steps). Major Dia-

stereomer 19b: Ϫ IR (film, KBr): ν˜ ϭ 3067 cm^Ϫ1, 3028, 2956, 2815,

mixture was stirred for 10 minutes, then 18a (1.1 g, 5.1 mmol) was 1606, 1587, 1496, 1453, 1249 (SiϪC), 1113 (CϪO), 829, 779, 764.

introduced under vigorous stirring. After 3 days at room tempera-

¹H NMR (CDCl₃): δ ϭ 7.53Ϫ7.51 (m, 2 H, aromatic H),

ture, Na₂SO₃(7.7 g) was added and the mixture was stirred at room 7.42Ϫ7.22 (m, 13 H, aromatic H), 4.56 (d, J ϭ 11.9 Hz, 1 H, OCH-

Ϫ

temp. for 45 minutes. After extractions with EtOAc (5 ϫ), the com-

bined extracts were washed with a 10% NaOH solution, the organic

layer dried with MgSO₄, and the solvents were evaporated under

vacuum to give a yellow oil which was directly dissolved in dimeth-

_aH_bPh), 4.48 (d, J ϭ 11.9 Hz, 1 H, OCH_aH_bPh), 4.38 (s, 1 H, OCH-

_aH_bPh), 4.37 (s, 1 H, OCH_aH_bPh), 3.98 (t, J ϭ 5.3 Hz, 1 H,

CHOBn), 3.72 (dd, J ϭ 3.6, 5.8 Hz, 1 H, CHOBn), 1.64 (dd, J ϭ

0.9, 3.6 Hz, 1 H, CH), 1.46Ϫ1.40 (m, 1 H, CH), 1.24Ϫ1.14 (m, 2

oxypropane (8 mL). A catalytic amount of pTsOH was added and H, 2 ϫ CH), 0.66Ϫ0.61 (m, 1 H, CH), 0.32 (s, 3 H, SiCH₃), 0.31

the solution was stirred for 2 hours at room temp. The solvents

were then evaporated under vacuum and a saturated Na₂CO₃solu-

tion was added. The aqueous layer was extracted with Et₂O, dried

(s, 3 H, SiCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.6 (s, aromatic C),

137.6 (s, aromatic C), 133.8 (d, J ϭ 158 Hz, aromatic CH), 129.1

(d, aromatic CH), 128.2 (d, aromatic CH), 128.1 (d, aromatic CH),

with MgSO₄, and the solvent was evaporated in vacuo. The residue 127.9 (d, aromatic CH), 127.8 (d, aromatic CH), 127.7 (d, aromatic

was purified by chromatography through silica gel (Petroleum

ether/EtOAc, 98:2) affording 0.885 g of the protected diol (60%, 2

steps) as a 8:2 mixture of diastereomers 19a and 20a respectively.

CH), 127.4 (d, aromatic CH), 127.2 (d, aromatic CH), 80.4 (d, J ϭ

141 Hz, CHOBn), 80.3 (d, J ϭ 141 Hz, CHOBn), 71.3 (t, J ϭ

141 Hz, OCH₂Ph), 70.9 (t, J ϭ 142 Hz, OCH₂Ph), 33.8 (d, J ϭ

412

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

121 Hz, CHSi), 19.9 (d, J ϭ 168 Hz, CH), 15.7 (d, J ϭ 166 Hz, tion of 18c afforded 0.225 g (33%) of a 1:1 mixture of diastereomers

CH), 11.6 (t, J ϭ 158 Hz, CH₂), Ϫ4.1 (q, J ϭ 119 Hz, SiCH₃),

19d and 20b. Diastereomer 19d: Ϫ IR (film, KBr): ν˜ ϭ 3024 cm^Ϫ1

Ϫ4.4 (q, J ϭ 120 Hz, SiCH₃). Ϫ MS (CI, NH₃): m/z (%): 446 [M^ϩ2985, 2928, 1709, 1599, 1492, 1452, 1207, 1161, 1039, 912, 866,

ϩ 17], 321 (4), 241 (7), 135 (47), 91 (100), 75 (15). Ϫ C₂₈H₃₂O₂Si

808, 779. Ϫ ¹H NMR (CDCl₃): δ ϭ 7.27Ϫ6.95 (m, 15 H, aromatic

(428.65): calcd. C 78.46, H 7.52, Si 6.55; found C 78.34, H 7.44, Si H), 4.46 (t, J ϭ 6.1 Hz, 1 H, OCH), 4.25 (d, J ϭ 6.7 Hz, 1 H,

,

6.63. Ϫ Elimination product (21). Ϫ IR (film, KBr): ν˜ ϭ 3062 cm^Ϫ1

,

OCHCHSi), 2.23 (d, J ϭ 17.7 Hz, 1 H, CH_aH_bPh), 2.19 (d, J ϭ

17.7 Hz, 1 H, CH_aH_bPh) 1.59Ϫ1.57 (m, 2 H, 2 ϫ CH), 1.44 (s, 3

2988, 2859, 1592, 1496, 1454, 1362, 1066, 767, 735, 698. Ϫ ¹H

NMR (CDCl₃): δ ϭ 7.43Ϫ7.28 (m, 5 H, aromatic H), 6.35Ϫ6.33 H, CH₃), 1.23Ϫ1.18 (m, 1 H, CH), 1.08 (s, 3 H, CH₃), 0.75Ϫ0.64

(m, 1 H, vinylic H), 5.60Ϫ5.53 (m, 1 H, vinylic H), 4.67 (d, J ϭ

(m, 2 H, CH₂). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.4 (s, aromatic C),

11.8 Hz, 1 H, OCH_aH_bPh), 4.62 (d, J ϭ 11.8 Hz, 1 H, OCH_aH_bPh), 128.8 (d, aromatic CH), 128.6 (d, aromatic CH), 128.6 (d, aromatic

4.41 (s, 1 H, CHOBn), 2.01Ϫ1.89 (t, 1 H, J ϭ 5.3 Hz, CHOBn), CH), 128.4 (d, aromatic CH), 128.3 (d, aromatic CH), 128.2 (d,

3.72 (dd, J ϭ 3.6, 5.8 Hz, 1 H, CHOBn), 1.64 (dd, J ϭ 0.9, 3.6 Hz,

1 H, CH), 1.46Ϫ1.40 (m, 2 H, 2 ϫ CH), 1.06Ϫ1.01 (m, 1 H, CH),

aromatic CH), 128.1 (d, aromatic CH), 124.6 (d, aromatic CH),

124.5 (d, aromatic CH), 110.7 (s), 84.4 (d, OCH), 82.8 (d, OCH),

Ϫ0.03-(-0.06) (m, 1 H, CH). Ϫ ¹³C NMR (CDCl₃): δ ϭ 140.6 (d, 31.9 (d, CHSi), 26.5 (q, CH₃), 24.4 (q, CH₃), 23.0 (d, CH), 22.57

J ϭ 164 Hz, vinylic H), 138.8 (s, aromatic C), 128.2 (d, J ϭ 167 Hz,

aromatic CH), 127.7 (d, J ϭ 158 Hz, aromatic CH), 127.3 (d, J ϭ 454 [M^ϩ], 395 (78), 377 (86), 363 (17), 301 (100), 287 (16), 227 (18),

160 Hz, vinylic CH), 83.7 (d, J ϭ 144 Hz, CHOBn), 69.1 (t, J ϭ 167 (3), 123 (7), 91 (21), 79 (61). Ϫ HRMS [M ϩ Na] C₃₀H₃₄O₂Si:

(d, CH), 21.2 (t, CH₂Ph), 13.6 (t, CH₂). MS (CI, CH₄); m/z (%):

141 Hz, OCH₂Ph), 22.6 (d, J ϭ 172 Hz, CH), 22.5 (d, J ϭ 172 Hz, calcd. 477.2220; found: 477.2232. Ϫ Diastereomer 20b. Ϫ IR (film,

CH), 20.8 (t, J ϭ 158 Hz, CH₂). MS (CI, NH₃): m/z (%): 185 [M^ϩKBr): ν˜ ϭ 3024 cm^Ϫ1, 2985, 2928, 1709, 1599, 1492, 1452, 1207,

Ϫ 1], 155 (6), 135 (100), 121 (5), 105 (12), 91 (78).

1161, 1039, 912, 866, 808, 779. Ϫ ¹H NMR (CDCl₃): δ ϭ

7.27Ϫ6.99 (m, 15 H, aromatic H), 4.40 (t, J ϭ 5.2 Hz, 1 H, OCH),

4.36 (d, J ϭ 4.9 Hz, 1 H, OCHCHSi), 2.30 (d, J ϭ 18.4 Hz, 1 H,

CH_aH_bPh), 2.19 (d, J ϭ 18.4 Hz, 1 H, CH_aH_bPh), 1.61 (s, 3 H,

CH₃), 1.53Ϫ1.46 (m, 1 H, CH), 1.26 (s, 3 H, CH₃), 1.12Ϫ1.06 (m,

1 H, CH), 1.02Ϫ1.00 (m, 1 H, CH), 0.74Ϫ0.69 (m, 1 H, CH),

Ϫ0.25-(-0.35) (m, 1 H, CH). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.7 (s,

aromatic C), 128.8 (d, aromatic CH), 128.7 (d, aromatic CH), 128.6

(d, aromatic CH), 128.5 (d, aromatic CH), 128.3 (d, aromatic CH),

128.2 (d, aromatic CH), 128.1 (d, aromatic CH), 128.0 (d, aromatic

CH), 126.2 (d, aromatic CH), 124.5 (d, aromatic CH), 124.1 (d,

aromatic CH), 110.9 (s), 88.5 (d, OCH), 84.5 (d, OCH), 32.9 (d,

CHSi), 26.8 (q, CH₃), 25.7 (q, CH₃), 24.3 (d, CH), 22.4 (t, CH₂Ph),

21.4 (d, CH), 16.1 (t, CH₂). MS (CI, NH₃); m/z (%): 379 (10), 363

(100), 301 (19), 287 (4), 255 (2), 227 (33), 149 (3), 91 (9), 79 (86).

Ϫ HRMS [M ϩ Na] C₃₀H₃₄O₂Si: calcd. 477.2220; found: 477.2242.

General Procedure for the Sequence Dihydroxylation-Diol Protection

(Conditions B). ؊ Dibenzyl Eether 19c: To a solution of 18b (3.18 g,

11.5 mmol) and N-methylmorpholine oxide (NMMO) (1.71 g,

12.7 mmol,) in a 9:1 mixture of acetone/water (100 mL), was added

at room temp. a solution of OsO₄(49 mmol/l in THF) (11.7 mL,

0.57 mmol). The reaction mixture was stirred at room temp. for 16

hours and the solvent was evaporated in vacuo. The residue was

treated with aqueous Na₂S₂O₃and extracted with EtOAc (5 ϫ

20 mL). The combined extracts were washed with saturated

NaHCO₃(2 ϫ) and brine, dried with MgSO₄and the solvent was

evaporated in vacuo. The crude diol was then added to a suspen-

sion of KH (1.09 g, 27.3 mmol) in 100 mL of THF at 0°C, then

benzyl bromide (20.1 mmol, 2.4 mL) and KI (cat.) were success-

ively added. After stirring overnight at room temperature, the solu-

tion was quenched with a saturated solution of NH₄Cl and ex-

tracted with Et₂O, dried with MgSO₄, and the solvents were evapo-

rated under vacuum. The residue was purified by chromatography

through silica gel (Petroleum ether/EtOAc, 95:5) affording 1.85 g

of 19c (40%). Ϫ IR (film, KBr): ν˜ ϭ 2958 cm^Ϫ1, 2900, 2956, 1606,

1587, 1496, 1428, 1350, 1317, 1256 (SiϪC), 1193 (CϪO), 1059, 844,

General Procedure for the Sequence Mercury-Desilylation-Oxi-

dation of Cyclopropanes 19a؊c. Following the general mercury-de-

silylation procedure, 22a was obtained in 80% yield from cyclopro-

pane 19a and was used in the next step without further purification.

22a: Ϫ IR (film, KBr): ν˜ ϭ 3016 cm^Ϫ1, 2930, 1634 (CϭC), 1374

(CH₃), 1205 (CϪO), 1043, 969. Ϫ ¹H NMR (CDCl₃): δ ϭ

5.81Ϫ5.79 (1 H, m, vinylic H), 5.63Ϫ5.61 (m, 1 H, vinylic H),

5.11Ϫ5.09 (m, 1 H, OCH), 4.65Ϫ4.63 (m, 1 H, OCH), 3.38Ϫ3.36

(m, 1 H, CHCH₂HgBr), 2.16 (dd, J ϭ 5.4, 12.1 Hz, 1 H,

CH_aH_bHgBr), 2.03 (dd, J ϭ 4.3, 12.1 Hz, 1 H, CH_aH_bHgBr), 1.55

(s, 3 H, CH₃), 1.38 (s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 136.8

(d, J ϭ 162 Hz, vinylic C), 130.9 (d, J ϭ 170 Hz, vinylic C), 110.9

(s, C), 85.6 (d, J ϭ 141 Hz, OCH), 78.4 (d, J ϭ 159 Hz, COH),

45.7 (d, J ϭ 133 Hz, CHCH₂HgBr), 28.4 (t, J ϭ 104 Hz,

CH₂HgBr), 27.6 (q, J ϭ 124 Hz, CH₃), 25.8 (q, J ϭ 126 Hz, CH₃).

In a 25 mL three necked round-bottomed flask were placed DMF

(6 mL) and sodium borohydride (61 mg, 1.6 mmol,). Oxygen was

then bubbled through the solution for 1 hour. A solution of 22a in

DMF (10 mL) was then added dropwise over a 1 hour period using

a syringe pump. The mixture was stirred under an O₂atmosphere

for an additional 2 hours. Then, the mixture was centrifuged,

quenched with a 1  HCl solution (6 mL) and extracted with

EtOAc (5 ϫ 20 mL). The combined extracts were washed with a

saturated NaHCO₃solution (2 ϫ), brine, dried with MgSO₄, and

the solvents were evaporated under vacuum. The residue was puri-

fied by chromatography through silica gel (Petroleum ether/EtOAc,

8:2) affording 64 mg of 23a as a yellow oil (32%, 2 steps). Ϫ IR

(CHCl₃): ν˜ ϭ 3391 (OH), 3065, 2934, 1633, 1372, 1047, 952, 732

1

802, 732, 700. Ϫ H NMR (CDCl₃): δ ϭ 7.65Ϫ7.60 (m, 4 H, aro-

matic H), 7.48Ϫ7.29 (m, 14 H, aromatic H), 7.26Ϫ7.52 (m, 2 H,

aromatic H), 4.61 (d, J ϭ 12 Hz, 1 H, OCH_aH_bPh), 4.50 (d, J ϭ

12 Hz, 1 H, OCH_aH_bPh), 4.47 (d, J ϭ 12 Hz, 1 H, OCH_aH_bPh),

4.42 (d, J ϭ 12 Hz, 1 H, OCH_aH_bPh), 3.97 (t, J ϭ 5.5 Hz, 1 H,

CHOBn), 3.87 (dd, J ϭ 3.8, 5.8 Hz, 1 H, CHOBn), 2.13 (dd, J ϭ

0.9, 2.8 Hz, 1 H, CH), 1.50Ϫ1.43 (m, 1 H, CH), 1.38Ϫ1.34 (m, 1

H, CH), 1.32Ϫ1.28 (m, 1 H, CH_aH_b), 0.76Ϫ0.71 (m, 1 H, CH_aH_b),

0.62 (s, 3 H, SiCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.5 (s, aromatic

C), 134.8 (d, J ϭ 157 Hz, aromatic CH), 134.7 (d, J ϭ 157 Hz,

aromatic CH), 129.3 (d, J ϭ 158 Hz, aromatic CH), 129.2 (d, J ϭ

158 Hz, aromatic CH), 128.1 (d, J ϭ 157 Hz, aromatic CH), 128.0

(d, J ϭ 157 Hz, aromatic CH), 127.8 (d, J ϭ 157 Hz, aromatic

CH), 127.3 (d, J ϭ 157 Hz, aromatic CH), 127.2 (d, J ϭ 157 Hz,

aromatic CH), 80.7 (d, J ϭ 145 Hz, CHOBn), 80.1 (d, J ϭ 141 Hz,

CHOBn), 71.6 (t, J ϭ 141 Hz, OCH₂Ph), 70.8 (t, J ϭ 142 Hz,

OCH₂Ph), 32.7 (d, J ϭ 122 Hz, CHSi), 20.1 (d, J ϭ 169 Hz, CH),

16.0 (d, J ϭ 169 Hz, CH), 11.8 (t, J ϭ 165 Hz, CH₂), Ϫ5.2 (q, J ϭ

119 Hz, SiCH₃). MS (CI, NH₃); m/z (%): 508 [M^ϩϩ 17], 383 (1),

303 (1), 197 (18), 165 (10), 91 (100). Ϫ C₃₃H₃₄O₂Si (490.72): calcd.

C 80.77, H 6.98, Si 5.72; found C 80.84, H 7.10, Si 5.80.

Dibenzyl Ether 19d and 20b: Following the general procedure (Con-

ditions B) described for 19c, the dihydroxylation-acetonide protec-

Eur. J. Org. Chem. 2000, 401Ϫ418

413

Y. Landais, L. Parra-Rapado

FULL PAPER

cm^Ϫ1. Ϫ ¹H NMR (CDCl₃): δ ϭ 5.88Ϫ5.86 (m, 1 H, CHϭ

(s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 110.4 (s, C(CH₃)₂), 82.4

CHCHO), 5.76Ϫ5.74 (m, 1 H, CHϭCHCHO), 5.14Ϫ5.12 (m, 1 H, (d, J ϭ 156 Hz, OCH), 79.2 (d, J ϭ 171 Hz, OCH), 74.9 (d, J ϭ

CHϭCHCHO), 4.86 (dd, J ϭ 5.9, 6 Hz, 1 H, OCH), 3.91 (dd, J ϭ 153 Hz, OCH), 72.7 (d, J ϭ 147 Hz, OCH), 60.9 (t, J ϭ 143 Hz,

3.8, 11.4 Hz, 1 H, CH_aH_bOH), 3.79 (dd, J ϭ 7.1, 11.4 Hz, 1 H, CH₂OH), 46.3 (d, J ϭ 125 Hz, CH), 25.9 (q, J ϭ 127 Hz, CH₃),

CH_aH_bOH), 2.91Ϫ2.88 (m, 1 H, CHCH₂OH), 1.44 (s, 3 H, CH₃), 23.3 (q, J ϭ 124 Hz, CH₃). MS (CI, NH₃); m/z (%): 155 [M^ϩ

Ϫ

1.36 (s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 133.9 (d, J ϭ 167 Hz, 15], 141 (7), 125 (9), 113 (18), 95 (100), 82 (87), 81 (55). Ϫ C₉H₁₆O₅

vinylic C), 131.3 (d, J ϭ 168 Hz, vinylic C), 85.4 (d, J ϭ 149 Hz,

OCH), 79.5 (d, J ϭ 155 Hz, OCH), 61.8 (t, J ϭ 139 Hz, CH₂OH),

49.6 (d, J ϭ 131 Hz, CH), 27.1 (q, J ϭ 127 Hz, CH₃), 25.4 (q, J ϭ

124 Hz, CH₃). MS (CI, NH₃); m/z (%): 155 [M^ϩϪ 15], 141 (7),

125 (9), 113 (18), 95 (100), 82 (87), 81 (55).

(204.22): calcd C 52.93, H 7.90; found C 52.93, H 7.82.

Carba-Sugar (24b): To a solution of 23b (0.387 g, 1.24 mmol) in

acetone (9 mL) and water (1 mL) at room temp. was added

NMMO (185 mg, 1.4 mmol) followed by a solution of OsO₄

(49 mmol/l in THF) (1.3 mL, 0.06 mmol). The reaction mixture

(3R*,4S*,5R*)-3,4-Dibenzyloxy-5-hydroxymethycyclopentene (23b): was stirred at room temp. for 1 hour and the solvent was evapo-

Following the general mercury-desilylation procedure, 22b was ob-

tained in 85% yield from cyclopropanes 19b and 19c. Ϫ IR (solu-

rated in vacuo. The residue was quenched with saturated Na₂S₂O₃

and extracted with EtOAc (5 ϫ 20 mL). The combined extracts

tion, CHCl₃): ν˜ ϭ 3061 cm^Ϫ1, 3030, 1605, 1500, 1453, 1118 (CϪO), were washed with saturated NaHCO₃(2 ϫ) and brine then dried

1060, 830, 780, 735, 698. Ϫ ¹H NMR (CDCl₃): δ ϭ 7.44Ϫ7.30 (m,

10 H, aromatic H), 6.14 (dd, J ϭ 3, 6.2 Hz, 1 H, vinylic H), 5.9 (d, low oil, which was directly dissolved in dimethoxypropane (6 mL).

J ϭ 6.2 Hz, 1 H, vinylic H), 4.78 (d, J ϭ 12.8 Hz, 1 H, OCH_a- A catalytic amount of pTsOH was added and the solution was

H_bPh), 4.75 (d, J ϭ 12.8 Hz, 1 H, OCH_aH_bPh), 4.69 (d, J ϭ stirred at room temp. for 2 hours. The solvents were then evapo-

with MgSO₄. The solvent was evaporated in vacuo affording a yel-

11.6 Hz, 1 H, OCH_aH_bPh), 4.54 (d, J ϭ 11.6 Hz, 1 H, OCH_a-

H_bPh), 4.21 (dd, J ϭ 3, 5.6 Hz, 1 H, CHOBn), 3.90 (dd, J ϭ 6.1,

7.1 Hz, 1 H, CHOBn), 3.29Ϫ3.26 (m, 1 H, CHCH₂HgBr), 2.15 (dd,

J ϭ 5.4, 11.9 Hz, 1 H, CH_aH_bHgBr), 2.01 (dd, J ϭ 4.4, 11.9 Hz, 1

rated and a saturated Na₂CO₃solution was added. The aqueous

layer was extracted with Et₂O, the combined extracts dried with

MgSO₄, and the solvent evaporated in vacuo. The residue was puri-

fied by chromatography through silica gel (Petroleum ether/EtOAc,

H, CH_aH_bHgBr). MS (CI, NH₃); m/z (%): 592 [M^ϩϩ 18], 576 [M^ϩ8:2) affording 0.286 g of 24b as a pale yellow oil (60%). Ϫ IR (film,

ϩ 2], 548 (33), 495 (4), 312 (1), 186 (8), 91 (100). Following the KBr): ν˜ ϭ 3452 cm^Ϫ1(OH), 3031, 2987, 2934, 1607, 1497, 1455,

general oxidation procedure, 22b afforded the alcohol 23b as a yel-

1373, 1275, 1209, 1138, 1063, 911, 867, 734, 698. Ϫ ¹H NMR

(CDCl₃): δ ϭ 7.31Ϫ7.18 (m, 10 H, aromatic H), 4.70 (d, J ϭ

11.7 Hz, 1 H, OCH_aH_bPh), 4.67 (d, J ϭ 2.1 Hz, 1 H, CHOBn),

low oil (45%, 2 steps). Ϫ IR (film, KBr): ν˜ ϭ 3389 cm^Ϫ1(OH),

1

3063, 3030, 1600, 1496, 1135, 963, 736, 698. Ϫ H NMR (CDCl₃):

δ ϭ 7.39Ϫ7.27 (m, 10 H, aromatic H), 6.09Ϫ6.07 (m, 1 H, vinylic 4.59 (d, J J ϭ 11.7 Hz, 1 H, OCH_aH_bPh), 4.58 (d, J ϭ 11.7 Hz, 1

H), 6.04 (dd, J ϭ 2.9, 6.3 Hz, 1 H, vinylic H), 4.76 (d, J ϭ 11.8 Hz, H, OCH_aH_bPh), 4.55 (dd, J ϭ 1.6, 6.7 Hz, 1 H, CHOBn), 4.46 (d,

1 H, OCH_aH_bPh), 4.70 (s, 2 H, OCH₂Ph), 4.60 (1 H, d, J ϭ J ϭ 11.7 Hz, 1 H, OCH_aH_bPh), 4.22 (dd, J ϭ 4.8, 6.8 Hz, 1 H,

11.8 Hz, OCH_aH_bPh), 4.33 (1 H, dd, J ϭ 2.4, 5.7 Hz, CHOBn), CHO), 3.89 (dd, J ϭ 1.6, 4.8 Hz, 1 H, CHO), 3.84 (dd, J ϭ 3.3,

4.11 (1 H, dd, J ϭ 5.6, 7.3 Hz, CHOBn), 3.87 (1 H, dt, J ϭ 3,

11.2 Hz, CH_aH_bOH), 3.68 (1 H, ddd, J ϭ 4.8, 8.8 Hz, 11.2, CH_aH_b-

11.4 Hz, 1 H, CH_aH_bOH), 3.69Ϫ3.67 (m, 1 H, CH_aH_bOH),

2.41Ϫ2.38 (m, 1 H, CHCH₂OH), 1.38 (s, 3 H, CH₃), 1.25 (s, 3 H,

OH), 3.28 (1 H, dd, J ϭ 3.4, 8.8 Hz, OH), 2.94Ϫ2.90 (1 H, m, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 137.9 (s, aromatic C), 137.3 (s,

CHCH₂OH). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.1 (s, aromatic C), aromatic C), 128.3 (d, J ϭ 162 Hz, aromatic CH), 127.7 (d, J ϭ

136.6 (d, J ϭ 168 Hz, vinylic C), 130.3 (d, J ϭ 162 Hz, vinylic C),

161 Hz, aromatic CH), 127.4 (d, J ϭ 158 Hz, aromatic CH), 110

128.4 (d, aromatic CH), 128.3 (d, aromatic CH), 127.8 (d, aromatic (s, C), 82.5 (d, J ϭ 147 Hz, CHOBn), 82.2 (d, J ϭ 156 Hz,

CH), 127.6 (d, aromatic CH), 127.5 (d, aromatic CH), 79.1 (d, J ϭ CHOBn), 79.9 (d, J ϭ 158 Hz, OCH), 79.8 (d, J ϭ 141 Hz, OCH),

148 Hz, CHOBn), 77.8 (d, J ϭ 148 Hz, CHOBn), 71.9 (t, J ϭ 72.5 (t, J ϭ 142 Hz, OCH₂Ph), 72.1 (t, J ϭ 142 Hz, OCH₂Ph), 59.5

142 Hz, OCH₂Ph), 71.3 (t, J ϭ 142 Hz, OCH₂Ph), 60.1 (t, J ϭ (t, J ϭ 140 Hz, CH₂OH), 48.4 (d, J ϭ 130 Hz, CH), 26.4 (q, J ϭ

145 Hz, CH₂OH), 48.3 (d, J ϭ 131 Hz, CH). MS (CI, NH₃); m/z

(%): 328 [M^ϩϩ 17], 311 [M^ϩ], 281 (8), 236 (2), 220 (28), 203 (34),

142 (11), 108 (50), 91 (75). Ϫ C₂₀H₂₂O₃(316.39): calcd C 77.39, H

7.14; found C 77.19, H 7.04.

127 Hz, CH₃), 23.7 (q, J ϭ 126 Hz, CH₃). MS (CI, NH₃); m/z (%):

385 [M^ϩ], 293 (18), 275 (2), 235 (2), 187 (12), 155 (5), 129 (11), 91

(100). Ϫ C₂₃H₂₈O₅(384.47): calcd C 71.85, H 7.34; found C 71.85,

H 7.28.

Carba-Sugar (24a): To a solution of 23a (42 mg, 0.25 mmol) in dry

Epoxide (25a): To a solution of 23b (0.318 g, 1.03 mmol) in dry

THF (5 mL) at room temp. was added NMMO (34 mg, 0.25 mmol) CH₂Cl₂(10 mL) at room temp. was added m-CPBA (90%, 0.533 g,

then solution of OsO₄(49 mmol/L in THF) (0.25 mL, 3.09 mmol). The heterogeneous mixture was stirred at room temp.

a

0.013 mmol). The reaction mixture was stirred at room temp. for 6

hours then quenched with aqueous Na₂S₂O₃. The organic layer was

decanted and the aqueous layer extracted with EtOAc (5 ϫ 10 mL).

The combined extracts were washed with saturated NaHCO₃(2 ϫ)

and brine, dried with MgSO₄, and the solvents were evaporated in

vacuo. The residue was purified by chromatography through silica

gel (Petroleum ether/EtOAc, 9:1) affording 35 mg of 24a as a white

solid (60%), which was recrystallized from petroleum ether/CH₂Cl₂;

m.p. 102Ϫ103°C. Ϫ IR (film, KBr): ν˜ ϭ 3391 cm^Ϫ1(OH), 3065,

for 48 hours and saturated Na₂CO₃was added. The aqueous layer

was extracted with CH₂Cl₂. The combined extracts were washed

with saturated Na₂CO₃, brine, dried with MgSO₄, and the solvent

was evaporated in vacuo. The yellow oil was purified by chromatog-

raphy through florisil (Petroleum ether/EtOAc, 9:1) affording

0.22 g of 25a as a pale yellow oil (60%). Ϫ IR (film, KBr): ν˜ ϭ

3455 cm^Ϫ1(OH), 3031, 2924, 1606, 1497, 1454, 1402, 1345, 1266,

1207, 1130, 1046, 838, 737, 698. Ϫ ¹H NMR (CDCl₃): δ ϭ

7.39Ϫ7.28 (m, 10 H, aromatic H), 4.82 (d, J ϭ 11.6 Hz, 1 H, OCH_a-

H_bPh), 4.71 (d, J ϭ 11.6 Hz, 1 H, OCH_aH_bPh), 4.56 (d, J ϭ

1

2934, 1633, 1372, 1047, 952, 732. Ϫ H NMR (CDCl₃): δ ϭ 4.73

(dd, J ϭ 5.8, 6.1 Hz, 1 H, OCHCHCH₂OH), 4.5 (d, J ϭ 6.1 Hz, 1 11.8 Hz, 1 H, OCH_aH_bPh), 4.51 (d, J ϭ 11.8 Hz, 1 H, OCH_a-

H, OCHCHOH), 4.30 (dd, J ϭ 4.2, 10.6 Hz, 1 H, OHCHCH- H_bPh), 4.09 (d, J ϭ 5.3 Hz, 1 H, CHOBn), 3.97 (dd, J ϭ 5.2,

CH₂OH), 4.05 (dd, J ϭ 5.2, 11 Hz, 1 H, CH_aH_bOH), 4.03 (d, J ϭ 7.5 Hz, 1 H, CHOBn), 3.93 (dd, J ϭ 2.6, 11.7 Hz, 1 H, CHO),

4.2 Hz, 1 H, OCHCHOH), 3.99 (dd, J ϭ 5.3, 11 Hz, 1 H, CH_aH_b-

OH), 2.22Ϫ2.15 (m, 1 H, CHCH₂OH), 1.42 (s, 3 H, CH₃), 1.28

3.78Ϫ3.75 (m, 1 H, CHO), 3.58 (d, J ϭ 2.7 Hz, 1 H, CH_aH_bOH),

3.53 (d, J ϭ 2.7 Hz, 1 H, CH_aH_bOH), 3.20 (s, 1 H, OH), 2.66Ϫ2.62

414

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

(m, 1 H, CHCH₂OH). Ϫ ¹³C NMR (CDCl₃): δ ϭ 137.7 (s, aromatic Carba-Aldehyde (30): To

a

solution of (COCl)₂(0.07 mL,

C), 137.3 (s, aromatic C), 128.5 (d, J ϭ 159 Hz, aromatic CH),

128.4 (d, J ϭ 159 Hz, aromatic CH), 128.1 (d, J ϭ 160 Hz, aro-

matic CH), 127.9 (d, J ϭ 160 Hz, aromatic CH), 127.8 (d, J ϭ

153 Hz, aromatic CH), 127.4 (d, J ϭ 201 Hz, aromatic CH), 79.1

0.8 mmol) in dry CH₂Cl₂(5 mL) at Ϫ40°C was added DMSO

(0.11 mL, 1.6 mmol) then alcohol 24b (145 mg, 0.4 mmol). The

solution was allowed to warm to Ϫ10°C over a period of 20 mi-

nutes and Et₃N (0.6 mL, 4 mmol) was added. Water (5 mL) was

(d, J ϭ 158 Hz, CHOBn), 74.5 (d, J ϭ 149 Hz, CHOBn), 73.7 (t, then added at room temperature and the organic layer was de-

J ϭ 142 Hz, OCH₂Ph), 72.7 (t, J ϭ 142 Hz, OCH₂Ph), 58.9 (t, J ϭ canted. The aqueous layer was extracted with CH₂Cl₂, the com-

142 Hz, CH₂OH), 58.4 (d, J ϭ 190 Hz, OCH), 55.5 (d, J ϭ 189 Hz, bined extracts were washed with brine, dried with MgSO₄and the

CHO), 42.4 (d, J ϭ 133 Hz, CH). MS (CI, NH₃); m/z (%): 327

solvent was evaporated under vacuum affording 0.131 g of the alde-

[M^ϩ], 235 (5), 181 (1), 108 (5), 91 (100).

hyde 30 (90%). This sensitive product was used in the next step

1

without further purification. Ϫ H NMR (CDCl₃): δ ϭ 9.89 (s, 1

Epoxide (25b): To a solution of 25a (35 mg, 0.11 mmol) in pyridine

(2 mL) was added dropwise at room temp. acetic anhydride (1 mL)

and the mixture was stirred for 2 hours. The solvents were evapo-

rated under vacuum and the residue was purified by chromatogra-

phy through silica gel, (Petroleum ether/EtOAc, 9:1) affording

45 mg of the acetate 25b as a colourless oil (100%). Ϫ IR (film,

KBr): ν˜ ϭ 3089 cm^Ϫ1, 3032, 2923, 1738 (CϭO), 1497, 1454, 1365,

1247, 1127, 1045, 913, 840, 737, 698. Ϫ ¹H NMR (CDCl₃): δ ϭ

7.37Ϫ7.28 (m, 10 H, aromatic H), 4.85 (d, J ϭ 11.8 Hz, 1 H, OCH_a-

H_bPh), 4.62 (d, J ϭ 11.9 Hz, 1 H, OCH_aH_bPh), 4.64Ϫ4.49 (m, 3

H, 2 ϫ OCH_aH_bPh, CHOBn), 4.19 (dd, J ϭ 10.5, 11.5 Hz, 1 H,

CHO), 4.05 (d, J ϭ 4.9 Hz, 1 H, CHO), 3.86 (dd, J ϭ 4.9, 7.1 Hz,

1 H, CHOBn), 3.61 (d, J ϭ 2.8 Hz, 1 H, CH_aH_bOAc), 3.47 (d, J ϭ

2.6 Hz, 1 H, CH_aH_bOAc), 2.84Ϫ2.77 (m, 1 H, CHCH₂OAc), 2.07

(s, 3 H, COCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 170.8 (s, CϭO), 138.2

(s, aromatic C), 137.8 (s, aromatic C), 128.3 (d, J ϭ 160 Hz, aro-

matic CH), 127.7 (d, J ϭ 161 Hz, aromatic CH), 127.3 (d, J ϭ

159 Hz, aromatic CH), 78.8 (d, J ϭ 144 Hz, CHO), 75.1 (d, J ϭ

150 Hz, CHO), 73.5 (t, J ϭ 143 Hz, OCH₂Ph), 72.4 (t, J ϭ 140 Hz,

OCH₂Ph), 61.9 (t, J ϭ 150 Hz, CH₂OAc), 57.9 (d, J ϭ 185 Hz,

OCH), 55.3 (d, J ϭ 189 Hz, CHO), 39.3 (d, J ϭ 137 Hz, CH), 20.8

H, CHO), 7.37Ϫ7.27 (m, 10 H, aromatic H), 5.11 (dd, J ϭ 1.5,

6.5 Hz, 1 H, OCH), 4.69 (d, J ϭ 12.1 Hz, 1 H, OCH_aH_bPh), 4.68

(d, J ϭ 11.7 Hz, 1 H, OCH_aH_bPh), 4.54 (dd, J ϭ 1.3, 6.5 Hz, 1 H,

OCH), 4.43 (dd, J ϭ 3.5, 7.1 Hz, 1 H, CHOBn), 3.95 (dd, J ϭ 1.4,

3.5 Hz, 1 H, CHOBn), 2.91 (dd, J ϭ 1.4, 7.1 Hz, 1 H, CHCHO),

1.41 (s, 3 H, CH₃), 1.29 (s, 3 H, CH₃).

Carba-Disaccharide (32): Into a dry 25 mL three-necked flask

equipped with a thermometer, an inlet for argon and a septum, was

introduced the 3-deoxyglucosyltributylstannane^[32a](0.361 g,

0.51 mmol) in anhydrous THF (10 mL). A 1.5  solution of nBuLi

in hexane (0.4 mL, 0.56 mmol) was then added slowly at Ϫ80°C.

The aldehyde 30 (0.190 mg, 0.51 mmol) in dry THF (2 mL) was

then added to the reaction mixture. After 30 minutes at Ϫ80°C,

the mixture was quenched with a saturated solution of NH₄Cl. The

organic layer was decanted and the aqueous layer extracted with

ether (3 ϫ 20 mL). The combined extracts were washed with brine,

dried with MgSO₄and the solvents were evaporated under vacuum.

The crude oil was purified by chromatography through silica gel

(Petroleum ether/EtOAc, 85:15) affording 82 mg of the carba-disac-

charide 32 as a pale yellow oil (20%). [α]_D²⁵ϭ ϩ8.73, c ϭ 0.33,

CHCl₃. Ϫ IR (film, KBr): ν˜ ϭ 3460 cm^Ϫ1(OH), 3064, 3031, 2986,

2931, 1605, 1496, 1496, 1454, 1372, 1265, 1208, 1028, 866, 737,

(q, J ϭ 129 Hz, COCH₃). Ϫ MS (CI, NH₃); m/z (%): 369 [M^ϩ

ϩ

1], 277 (13), 217 (1), 171 (5), 108 (14), 91 (100). Ϫ C₂₂H₂₄O₅

(368.43): calcd C 71.72, H 7.57; found C 71.56, H 6.61.

1

698. Ϫ H NMR (CDCl₃): δ ϭ 7.39Ϫ7.25 (m, 25 H, aromatic H),

4.97 (dd, J ϭ 3.6, 6.1 Hz, 1 H, CHO), 4.77 (d, J ϭ 11.9 Hz, 1 H,

OCH_aH_bPh), 4.75 (d, J ϭ 11.6 Hz, 1 H, OCH_aH_bPh), 4.70 (d, J ϭ

11.9 Hz, 1 H, OCH_aH_bPh), 4.65 (dd, J ϭ 3.1, 7.1 Hz, 1 H, CHO),

4.60 (d, J ϭ 11.8 Hz, 1 H, OCH_aH_bPh), 4.58 (d, J ϭ 11.9 Hz, 2 H,

2 ϫ OCH_aH_bPh), 4.56 (d, J ϭ 11.8 Hz, 1 H, OCH_aH_bPh), 4.51 (d,

J ϭ 11.9 Hz, 1 H, OCH_aH_bPh), 4.50 (d, J ϭ 11.8 Hz, 1 H, OCH_a-

H_bPh), 4.44 (d, J ϭ 11.6 Hz, 1 H, OCH_aH_bPh), 4.21 (dd, J ϭ 4.2,

5.8 Hz, 1 H, CHO), 4.16Ϫ4.12 (m, 1 H, CHO), 4.01Ϫ3.89 (dd, m,

4 H, 4 ϫ CHO), 3.85 (dd, J ϭ 5.9, 10.3 Hz, 1 H, CHO), 3.69 (dd,

J ϭ 4.1, 10.3 Hz, 1 H, CHO), 3.56 (t, J ϭ 5.8 Hz, 1 H, CHO),

2.41Ϫ2.38 (m, 1 H, CH), 2.21 (ddd, J ϭ 4.1, 7.1, 13.8 Hz, 1 H, H₂

equiv.), 1.78 (ddd, J ϭ 4.3, 6.8, 13.8 Hz, 1 H, H₂ax.), 1.45 (s, 3 H,

CH₃), 1.30 (s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 138.4 (s,

aromatic C), 138.3 (s, aromatic C), 138.1 (s, aromatic C), 137.6 (s,

aromatic C), 128.4 (d, aromatic CH), 128.3 (d, aromatic CH), 127.9

(d, aromatic CH), 127.8 (d, aromatic CH), 127.7 (d, aromatic CH),

127.6 (d, aromatic CH), 127.5 (d, aromatic CH), 127.4 (d, aromatic

CH), 111.4 (s, C), 84.6 (d, CHO), 82.8 (d, CHO), 80.9 (d, CHO),

79.6 (d, CHO), 75.5 (d, CHO), 75.0 (d, CHO), 74.3 (d, CHO), 73.1

(t, 2 ϫ CH₂O), 72.9 (t, CH₂O), 72.0 (t, CH₂O), 71.1 (t, CH₂O),

70.4 (d, CHO), 69.2 (d, CHO), 68.8 (t, CH₂O), 49.3 (d, CH), 29.5

(t, CH₂), 26.7 (q, CH₃), 24.1 (q, CH₃). MS (CI, NH₃); m/z (%): 801

[M^ϩ], 181 (3), 91 (100). HRMS [M ϩ Na] C₅₀H₅₆O₉Na: calcd.

823.3816; found: 823.3813.

Azido-Carba Sugar (26): To a solution of 25a (30 mg., 0.08 mmol)

in DMF (5 mL) was added at room temp. NaN₃(35 mg,

0.54 mmol). The mixture was stirred under reflux for 3 days. An

aqueous solution of NH₄Cl was then added. The organic layer was

extracted with EtOAc. The combined organic extracts were washed

with brine, dried with MgSO₄, and the solvents were evaporated

under vacuum. The yellow oil was purified by chromatography

through silica gel (Petroleum ether/EtOAc, 8:2) affording 20 mg of

the azide 26 as a colourless oil (40%). Ϫ IR (film, KBr): ν˜ ϭ 3338

cm^Ϫ1(OH), 3030, 2929, 2101 (N₃), 1737 (CϭO), 1496, 1454, 1367,

1

1262, 1251, 1056, 735, 696. Ϫ H NMR (CDCl₃): δ ϭ 7.42Ϫ7.27

(m, 10 H, aromatic H), 4.84 (d, J ϭ 11.9 Hz, 1 H, OCH_aH_bPh),

4.73 (d, J ϭ 11.9 Hz, 1 H, OCH_aH_bPh), 4.60 (d, J ϭ 11.9 Hz, 2 H,

2 ϫ OCH_aH_bPh), 4.46 (dd, J ϭ 5.3, 8.6 Hz, 1 H, CHOH), 4.33

(dd, J ϭ 7.8, 11.2 Hz, 1 H, CH_aH_bOAc), 4.26 (dd, J ϭ 7.2, 11.2 Hz,

1 H, CH_aH_bOAc), 3.97 (t, J ϭ 3.7 Hz, 1 H, CHOBn), 3.77 (dd,

J ϭ 5.3, 9.3 Hz, 1 H, CHN₃), 3.63 (dd, J ϭ 3.3, 8.6 Hz, 1 H,

CHOBn), 2.56Ϫ2.49 (m, 1 H, CH), 2.02 (s, 3 H, CO₂CH₃). Ϫ ¹³C

NMR (CDCl₃): δ ϭ 170.8 (s, CϭO), 138.1 (s, aromatic C), 137.7

(s, aromatic C), 128.6 (d, aromatic CH), 128.3 (d, aromatic CH),

127.9 (d, aromatic CH), 127.8 (d, aromatic CH), 127.7 (d, aromatic

CH), 127.6 (d, aromatic CH), 85.5 (d, J ϭ 137 Hz, CH), 80.8 (d,

J ϭ 148 Hz, CHOBn), 75.9 (d, CH), 73.5 (t, J ϭ 142 Hz, OCH₂Ph),

72.7 (t, J ϭ 142 Hz, OCH₂Ph), 65.4 (d, J ϭ 148 Hz, CH), 60.8 (t, (3R*,4S*,5S*)-3,4-Dibenzyloxy-5-iodomethylcyclopentene (33): To

J ϭ 143 Hz, CH₂OAc), 41.0 (d, J ϭ 129 Hz, CH), 20.9 (q, J ϭ a solution of 22b (0.21 g, 0.37 mmol) in dry DME (6 mL) at room

129 Hz, CH₃). MS (CI, NH₃); m/z (%): 429 [M^ϩϩ 18], 385 (12), temp. was added I₂(94 mg, 0.37 mmol). The reaction mixture was

325 (7), 293 (2), 91 (100). Ϫ HRMS [M ϩ Na] C₂₂H₂₅N₃O₅Na:

calcd 434.16863; found 434.16692.

stirred at room temp. for 3 hours then an aqueous solution of

Na₂S₂O₃was added and the mixture was stirred for 10 minutes.

Eur. J. Org. Chem. 2000, 401Ϫ418

415

Y. Landais, L. Parra-Rapado

FULL PAPER

The organic layer was decanted and the aqueous layer extracted

with ether. The combined extracts were washed with saturated

Na₂S₂O₃, brine, dried with MgSO₄, and the solvents were evapo-

rated in vacuo. The resulting oil was purified by chromatography

CO₂CH₂CH₃), 1.22 (s, 3 H, CH₃), 0.38 (s, 3 H, SiCH₃), 0.37 (s, 3

H, SiCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 172.8 (s, CϭO), 135.9 (s,

aromatic C), 133.7 (d, J ϭ 158 Hz, aromatic CH), 129.5 (d, J ϭ

158 Hz, aromatic CH), 127.9 (d, J ϭ 158 Hz, aromatic CH), 110.8

through silica gel (Petroleum ether/EtOAc, 95:5) affording 87 mg (s, C), 109.9 (s, C), 82.9 (d, J ϭ 152 Hz, CHO), 82.1 (d, J ϭ 152 Hz,

of the iodide 33 (82%). Ϫ IR (film, KBr): ν˜ ϭ 3062 cm^Ϫ1, 1500,

1453, 1357, 1106, 734, 696. Ϫ H NMR (CDCl₃): δ ϭ 7.42Ϫ7.29 CH), 32.8 (d, J ϭ 122 Hz, CHSi), 32.5 (d, J ϭ 178 Hz, CH), 26.5

CHO), 60.3 (t, J ϭ 151 Hz, CO₂CH₂CH₃), 33.6 (d, J ϭ 175 Hz,

1

(m, 10 H, aromatic H), 6.23 (dd, J ϭ 2.7, 6.3 Hz, 1 H, CHϭ

CHCHO), 6.09Ϫ6.07 (m, 1 H, CHϭCHCHO), 4.77 (d, J ϭ 129 Hz, CH₃), 14.2 (q, J ϭ 127 Hz, CO₂CH₂CH₃), Ϫ4.5 (q, J ϭ

11.8 Hz, 1 H, OCH_aH_bPh), 4.73 (d, J ϭ 12.1 Hz, 1 H, OCH_a- 120 Hz, SiCH₃), Ϫ4.7 (q, J ϭ 120 Hz, SiCH₃). MS (CI, NH₃); m/z

H_bPh), 4.68 (d, J ϭ 12.1 Hz, 1 H, OCH_aH_bPh), 4.66 (d, J ϭ (%): 378 [M^ϩϩ 18], 360 [M^ϩ], 303 (72), 273 (4), 229 (7), 193 (40),

11.8 Hz, 1 H, OCH_aH_bPh), 4.34 (dd, J ϭ 2.4, 5.2 Hz, 1 H, 152 (100), 135 (57), 94 (22). Ϫ C₂₀H₂₈O₄Si (360.52): calcd C 66.63,

CHOBn), 4.00 (dd, J ϭ 5.3, 6.5 Hz, 1 H, CHOBn), 3.59 (dd, J ϭ H 7.83, Si 7.79; found C 66.49, H 7.66, Si 7.68. Ϫ Minor Dia-

5.2, 9.4 Hz, 1 H, CH_aH_bI), 3.23 (dd, J ϭ 9.4, 10.7 Hz, 1 H,

stereomer (35b). Ϫ IR (film, KBr): ν˜ ϭ 2985 cm^Ϫ1, 2935, 1742 (Cϭ

CH_aH_bI), 3.07Ϫ3.02 (m, 1 H, CHCH₂I). Ϫ ¹³C NMR (CDCl₃): O), 1437, 1369, 1232 (SiϪC), 1038, 871, 741, 695. Ϫ ¹H NMR

δ ϭ 138.9 (d, J ϭ 165 Hz, vinylic C), 138.6 (s, aromatic C), 130.9 (CDCl₃): δ ϭ 7.62Ϫ7.60 (m, 2 H, aromatic H), 7.37Ϫ7.34 (m, 3 H,

(d, J ϭ 168 Hz, vinylic C), 128.3 (d, aromatic CH), 128.2 (d, aro- aromatic H), 4.64 (t, J ϭ 5.2 Hz, 1 H, OCH), 4.52 (d, J ϭ 5 Hz, 1

matic CH), 127.6 (d, aromatic CH), 127.5 (d, aromatic CH), 80.3 H, OCH), 4.09 (q, J ϭ 7.1 Hz, 2 H, CO₂CH₂CH₃), 2.14 (dd, J ϭ

(d, J ϭ 155 Hz, CH), 26.4 (q, J ϭ 129 Hz, CH₃), 24.3 (q, J ϭ

(d, J ϭ 144 Hz, CHOBn), 79.7 (d, J ϭ 147 Hz, CHOBn), 72.3 (t, 3.5, 6.7 Hz, 1 H, CH), 2.03Ϫ2.00 (m, 1 H, CH), 1.47 (s, 3 H, CH₃),

J ϭ 146 Hz, OCH₂Ph), 71.6 (t, J ϭ 142 Hz, OCH₂Ph), 49.3 (d, J ϭ 1.26 (s, 3 H, CH₃), 1.24 (t, J ϭ 7.1 Hz, 3 H, CO₂CH₂CH₃), 1.09

133 Hz, CHCH₂I), 8.1 (t, J ϭ 160 Hz, CH₂I). MS (CI, NH₃); m/z (t, J ϭ 3.2 Hz, 1 H, CHCO₂CH₂CH₃), 0.46 (s, 3 H, SiCH₃), 0.43

(%): 438 [M^ϩϩ 18], 420 [M^ϩ], 313 (36), 275 (1), 187 (5), 91 (100).

(s, 3 H, SiCH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 172.1 (s, CϭO), 138.9

Ϫ C₂₀H₂₁IO₂(420.29): calcd C 57.16, H 5.04, I 30.19; found C (s, aromatic C), 133.9 (d, J ϭ 157 Hz, aromatic CH), 128.8 (d, J ϭ

57.16, H 5.08, I 30.10.

159 Hz, aromatic CH), 127.6 (d, J ϭ 156 Hz, aromatic CH), 110.8

(s, C), 111.2 (s, C), 87.5 (d, J ϭ 153 Hz, CHO), 83.9 (d, J ϭ 154 Hz,

CHO), 60.4 (t, J ϭ 143 Hz, CO₂CH₂CH₃), 35.7 (d, J ϭ 120 Hz,

CH), 35.3 (d, J ϭ 175 Hz, CH), 31.4 (d, J ϭ 174 Hz, CH), 30.3 (d,

J ϭ 171 Hz, CH), 26.7 (q, J ϭ 124 Hz, CH₃), 24.6 (q, J ϭ 124 Hz,

CH₃), 14.1 (q, J ϭ 127 Hz, CO₂CH₂CH₃), Ϫ2.3 (q, J ϭ 120 Hz,

SiCH₃), Ϫ2.9 (q, J ϭ 120 Hz, SiCH₃). MS (CI, NH₃); m/z (%): 378

[M^ϩϩ 18], 361 [M^ϩϩ 1], 345 (7), 302 (76), 283 (41), 242 (16), 209

(5), 193 (18), 168 (70), 151 (100), 135 (97), 91 (27). Ϫ C₂₀H₂₈O₄Si

(360.52): calcd C 66.63, H 7.83, Si 7.79; found C 66.72, H 7.80,

Si 7.87.

Cyclopropane (34):

A

solution of Cu^IOTfϪbenzene complex

(38 mg, 0.15 mmol) and a Schiff Base (56 mg, 0.15 mmol) in dry

CH₂Cl₂(15 mL) was stirred for 1 hour at room temp. under a nitro-

gen atmosphere. Then, the dienylsilane 17a (1 g, 5 mmol) in dry

CH₂Cl₂(1 mL) was added to the green mixture and stirred for 10

minutes. Ethyl diazoacetate (0.62 mL, 6 mmol) was then added

slowly over a period of 2 hours and the solvent was removed under

vacuum. The resulting oil was purified by chromatography through

silica gel (Petroleum Ether/EtOAc, 95:5) affording 0.587 g of 34 as

a colourless oil (65%). Ϫ IR (film, KBr): ν˜ ϭ 3050 cm^Ϫ1, 2957,

2902, 1719 (CϭO), 1380 (CϪH), 1250 (SiϪC), 1161, 831. Ϫ ¹H

Ester (36): To a solution of 35a؊b (2.4 g, 6.4 mmol) in DMF

NMR (CDCl₃): δ ϭ 7.56Ϫ7.53 (m, 2 H, aromatic H), 7.39Ϫ7.28 (50 mL) at room temp. was added CsF (1.9 g, 12.8 mmol). The het-

(m, 3 H, aromatic H), 5.88Ϫ5.86 (m, 1 H, vinylic H), 5.50Ϫ5.48 erogeneous mixture was heated at 50°C overnight and water

(m, 1 H, vinylic H), 4.11 (q, J ϭ 7.1 Hz, 2 H, CO₂CH₂CH₃), (40 mL) was added. The mixture was extracted with Et₂O (3 ϫ

2.46Ϫ2.43 (m, 1 H, CHSi), 2.36Ϫ2.35 (m, 1 H, allylic H), 1.25 (t, 20 mL) and the combined extracts were washed with brine then

J ϭ 7.1 Hz, 3 H, CO₂CH₂CH₃), 0.91 (t, J ϭ 2.6 Hz, 1 H,

dried with MgSO₄. The solvents were evaporated under vacuum to

give a yellow oil, which was purified by chromatography through

CHCO₂Et), 0.32 (s, 3 H, SiCH₃), 0.29 (s, 3 H, SiCH₃). Ϫ ¹³C NMR

(CDCl₃): δ ϭ 174.4 (s, CϭO), 137.1 (s, aromatic C), 133.9 (d, J silica gel (Petroleum ether/EtOAc, 95:5) affording 1.3 g of 36 as a

157 Hz, CHϭCH), 131.6 (d, J ϭ 165 Hz, aromatic CH), 128.6 (d,

J ϭ 177 Hz, aromatic CH), 129.2 (d, J ϭ 160 Hz, aromatic CH), 1736 (CϭO), 1414, 1372, 1232, 1208, 1160, 1058, 876, 733. Ϫ H

colourless oil (90%). Ϫ IR (film, KBr): ν˜ ϭ 3065 cm^Ϫ1, 2985, 2935,

1

127.9 (d, J ϭ 159 Hz, CHϭCH), 60.3 (t, J ϭ 143 Hz, CO₂CH₂),

39.7 (d, J ϭ 123 Hz, SiCH), 35.1 (d, J ϭ 176 Hz, CH), 29.1 (d, (dt, J ϭ 0.8, 5.8 Hz, 1 H, vinylic H), 5.09 (dd, J ϭ 0.8, 5.8 Hz, 1

J ϭ 172 Hz, CH), 27.5 (q, J ϭ 127 Hz, CO₂CH₂CH₃), Ϫ5.2 (q, H, OCH), 4.77 (t, J ϭ 5.8 Hz, 1 H, OCH), 4.15 (q, J ϭ 7.1 Hz, 2

J ϭ 120 Hz, SiCH₃), Ϫ5.5 (q, J ϭ 120 Hz, SiCH₃). Ϫ MS (CI, H, CO₂CH₂CH₃), 3.14Ϫ3.09 (m, 1 H, CH), 2.63 (dd, J ϭ 8.2,

NH₃): m/z (%): 304 [M^ϩ], 287 [M^ϩ], 241 (2), 208 (18), 180 (6), 152

16.7 Hz, 1 H, CH_aH_bCO₂CH₂CH₃), 2.42 (dd, J ϭ 7.1, 16.7 Hz, 1

(29), 135 (61), 119 (3), 106 (39), 91 (4). Ϫ C₁₇H₂₂O₂Si (286.45): H, CH_aH_bCO₂CH₂CH₃), 1.37 (s, 3 H, CH₃), 1.32 (s, 3 H, CH₃),

NMR (CDCl₃): δ ϭ 5.78 (dt, J ϭ 2, 5.8 Hz, 1 H, vinylic H), 5.71

calcd. C 71.28, H 7.74; found C 71.11, H 7.76.

1.26 (t, J ϭ 7.1 Hz, 3 H, CO₂CH₂CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ

172.7 (s, CϭO), 135.6 (d, J ϭ 163 Hz, vinylic C), 130.6 (d, J ϭ

168 Hz, vinylic C), 110.4 (s, C), 85.2 (d, J ϭ 153 Hz, CHO), 78.6

(d, J ϭ 156 Hz, CHO), 60.3 (t, J ϭ 152 Hz, CO₂CH₂), 43.8 (d, J ϭ

133 Hz, CH), 33.6 (t, J ϭ 130 Hz, CH₂CO₂), 27.2 (q, J ϭ 126 Hz,

Protected Diols (35a؊b): Following the general procedure (con-

ditions B), the dihydroxylation-acetonide protection of 34 afforded

35 as a 7:3 mixture of diastereomers (72%). Ϫ Major Diastereomer

(35a). Ϫ IR (film, KBr): ν˜ ϭ 3071 cm^Ϫ1, 3049, 2986, 1722 (CϭO),

1428, 1410, 1381, 1273 (SiϪC), 1208, 1179 (CϪO), 1072, 1040, 814,

CH₃), 25.8 (q,

J ϭ 123 Hz, CH₃), 14.2 (q, J ϭ 127 Hz,

CO₂CH₂CH₃). MS (CI, NH₃); m/z (%): 244 [M^ϩϩ 17], 227 [M^ϩ,

77], 211 (41), 186 (3), 169 (100), 152 (3), 140 (10), 123 (36), 109 (2),

81 (11). Ϫ C₁₂H₁₈O₄(226.27): calcd C 63.70, H 8.02; found C

63.80, H 8.08.

1

779, 734, 702, 649. Ϫ H NMR (CDCl₃): δ ϭ 7.55Ϫ7.52 (m, 2 H,

aromatic H), 7.40Ϫ7.35 (m, 3 H, aromatic H), 4.55 (dd, J ϭ 4.8,

6.5 Hz, 1 H, OCH), 4.50 (d, J ϭ 6.5 Hz, 1 H, OCH), 4.10 (q, J ϭ

7.1 Hz, 1 H, CO₂CH_aH_bCH₃), 4.07 (q, J ϭ 7.1 Hz, 1 H, CO_2-

CH_aH_bCH₃), 2.12Ϫ2.07 (m, 2 H, 2 ϫ CH), 1.92 (dd, J ϭ 3.2, Bis-Acetonide (37): Following the general dihydroxylation-protec-

6.6 Hz, 1 H, CH), 1.52 (s, 3 H, CH₃), 1.24 (t, J ϭ 7.1 Hz, 3 H, tion procedure, 37 was obtained from olefin 36 in 82% yield. Ϫ IR

416

Eur. J. Org. Chem. 2000, 401Ϫ418

Mercury-Desilylation of Chiral Cyclopropylmethylsilanes

FULL PAPER

(film, KBr): ν˜ ϭ 2987 cm^Ϫ1, 2938, 1736 (CϭO), 1381, 1247, 1212,

in hexane (0.4 mL, 0.54 mmol) was then added slowly at Ϫ80°C

1160, 1078, 984, 865, 806, 735. Ϫ H NMR (CDCl₃): δ ϭ 4.78 (t, and the mixture was stirred for 0.5 hour. The aldehyde 39 (0.126 g,

1

J ϭ 5.1 Hz, 1 H, OCH), 4.56 (d, J ϭ 5.3 Hz, 1 H, OCH), 4.40Ϫ4.36

0.5 mmol) in dry THF (2 mL) was then added dropwise to the re-

(m, 2 H, 2 ϫ CHO), 4.16 (q, J ϭ 7.1 Hz, 1 H, CO₂CH_aH_b), 4.15 sulting solution at Ϫ80°C. After 30 minutes at Ϫ80°C, the solution

(q, J ϭ 7.1 Hz, 1 H, CO₂CH_aH_b), 2.65 (dd, J ϭ 9.8, 16.2 Hz, 1 H, was quenched with a saturated solution of NH₄Cl. The organic

CH_aH_bCO₂), 2.57 (dd, J ϭ 5.5, 16.2 Hz, 1 H, CH_aH_bCO₂),

layer was decanted and the aqueous layer extracted with ether (3

2.48Ϫ2.41 (m, 1 H, CH), 1.47 (s, 3 H, CH₃), 1.39 (s, 3 H, CH₃), ϫ 20 mL). The combined extracts were washed with brine, dried

1.27 (t, J ϭ 7.1 Hz, 3 H, CO₂CH₂CH₃). MS (CI, NH₃); m/z (%): with MgSO₄and the solvents were evaporated under vacuum. The

318 [M^ϩϩ 17], 301 [M^ϩ], 285 (52), 255 (12), 243 (19), 227 (14),

211 (3), 197 (8), 184 (15), 155 (2), 139 (9), 125 (3), 110 (14), 85 (16).

crude oil was purified by chromatography through silica gel (Petro-

leum ether/EtOAc, 7:3) affording 0.260 g of a mixture of three dia-

stereomeric alcohols, which were not separated further (78%). To

Alcohol (38): To a solution of ester 37 (0.115 g, 0.38 mmol) in dry

ether (5 mL) was added at 0°C a 1  solution of LiAlH₄in ether

(0.4 mL, 0.38 mmol). The reaction mixture was stirred for 2 hours

at 0°C then quenched with NH₄Cl. The organic layer was decanted

and the aqueous layer extracted with ether. The combined extracts

were washed with a 1  HCl solution, saturated NaHCO₃, brine,

dried with MgSO₄, and the solvent was evaporated under vacuum.

The yellow oil was purified by chromatography through silica gel

(Petroleum ether/EtOAc, 8:2) affording 0.1 g of the alcohol 38 as a

white solid (100%), recrystallized from Petroleum ether/CH₂Cl₂;

m.p. 48Ϫ50°C. Ϫ IR (solution, CH₂Cl₂): ν˜ ϭ 3514 cm^Ϫ1(OH),

2988, 2939, 1383, 1254, 1213, 1160, 1059, 859. Ϫ ¹H NMR

(CDCl₃): δ ϭ 4.63 (t, J ϭ 5 Hz, 1 H, OCH), 4.55 (d, J ϭ 5.2 Hz,

1 H, OCH), 4.45 (dd, J ϭ 5.6, 7.8 Hz, 1 H, CHO), 4.40 (d, J ϭ

5.6 Hz, 1 H, OCH), 3.78Ϫ3.75 (m, 2 H, CH₂OH), 2.49 (s, 1 H,

OH), 2.16Ϫ2.09 (m, 1 H, CH), 1.92Ϫ1.82 (m, 2 H, CH₂), 1.47 (s,

3 H, CH₃), 1.39 (s, 3 H, CH₃), 1.29 (s, 3 H, CH₃), 1.27 (s, 3 H,

CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 111.9 (s, C), 110.4 (s, C), 85.6

(d, J ϭ 151 Hz, CHO), 84.1 (d, J ϭ 146 Hz, CHO), 83.3 (d, J ϭ

155 Hz, CHO), 81.3 (d, J ϭ 156 Hz, CHO), 61.4 (t, J ϭ 141 Hz,

CH₂OH), 46.8 (d, J ϭ 120 Hz, CH), 30.7 (t, J ϭ 125 Hz, CH₂),

27.7 (q, J ϭ 127 Hz, CH₃), 26.7 (q, J ϭ 127 Hz, CH₃), 25.4 (q, J ϭ

127 Hz, CH₃), 24.4 (q, J ϭ 127 Hz, CH₃). MS (CI, NH₃); m/z (%):

259 (M^ϩϩ 1], 243 (47), 227 (1), 185 (39), 153 (5), 143 (22), 125

(52), 113 (15), 95 (55), 85 (19). Ϫ C₁₃H₂₂O₅(258.31): calcd C 60.45,

H 8.58; found C 60.53, H 8.45.

a

solution of the three preceding diastereomers (0.330 g,

˚

0.46 mmol) in anhydrous CH₂Cl₂(10 mL) was added 4 A molecu-

lar sieves, NaOAc (85 mg, 1 mmol) and pyridinium dichromate

(0.754 g, 2 mmol). After 16 hours at room temp., ether (10 mL) was

added and the resulting suspension was filtered. The solvents were

evaporated under vacuum and the crude product was purified by

chromatography through silica gel (Petroleum ether/EtOAc, 9:1) af-

fording 0.190 g (59%) of the carba-C-disaccharide 40 as a 1:1 mix-

ture of two diastereomers 40a and 40b. 40a (0.1 g, 31%): [α]_D²⁵ϭ

Ϫ9.76, c ϭ 0.5, CHCl₃. Ϫ IR (film, KBr): ν˜ ϭ 3064 cm^Ϫ1, 3031,

2987, 2935, 1720 (CϭO), 1497, 1454, 1381, 1246, 1211, 1060, 860,

1

736, 698. Ϫ H NMR (CDCl₃): δ ϭ 7.36Ϫ7.17 (m, 15 H, aromatic

H), 4.85 (dd, J ϭ 12 Hz, 1 H, OCH_aH_bPh), 4.75Ϫ4.51 (m, 7 H, 2

ϫ CHO and 5 ϫ OCH_aH_bPh), 4.44 (dd, J ϭ 2.9, 5.6 Hz, 1 H, H₁Ј),

4.41Ϫ4.36 (m, 2 H, 2 ϫ CHO), 3.78Ϫ3.74 (m, 2 H, CH₂OBn),

3.72Ϫ3.65 (m, 1 H, H₃Ј), 3.56Ϫ3.54 (m, 2 H, 2 ϫ CHO), 3.08 (dd,

J ϭ 10.3, 18.1 Hz, 1 H, CH_aH_bCO), 2.80 (dd, J ϭ 4.7, 18.1 Hz, 1

H, CH_aH_bCO), 2.66 (ddd, J ϭ 3.1, 4.5, 13.3 Hz, 1 H, CH_aH_b),

2.52Ϫ2.46 (m, 1 H, CH), 1.79 (ddd, J ϭ 5.8, 10.3, 13.3 Hz, 1 H,

CH_aH_b), 1.47 (s, 3 H, CH₃), 1.38 (s, 3 H, CH₃), 1.30 (s, 3 H, CH₃),

1.24 (s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 210.2 (s, CϭO),

138.2 (s, aromatic C), 128.4 (d, aromatic CH), 128.3 (d, aromatic

CH), 127.8 (d, aromatic CH), 128.7 (d, aromatic CH), 127.6 (d,

aromatic CH), 127.5 (d, aromatic CH), 111.8 (s, C), 110.3 (s, C),

84.8 (d, CHO), 84.1 (d, CHO), 81.7 (d, CHO), 81.4 (d, CHO), 77.0

(d, CHO), 76.6 (d, CHO), 76.7 (d, CHO), 76.1 (d, CHO), 74.5 (t,

CH₂O), 73.4 (t, CH₂O), 71.5 (t, CH₂O), 68.9 (t, CH₂O), 44.3 (d,

CH), 36.9 (t, CH₂), 28.9 (t, CH₂), 27.8 (q, CH₃), 26.6 (q, CH₃),

Carba-Aldehyde (39): To

a solution of (COCl)₂(0.13 mL,

25.5 (q, CH₃), 24.3 (q, CH₃). MS (CI, NH₃); m/z (%): 691 [M^ϩ

ϩ

1.5 mmol) in dry CH₂Cl₂(5 mL) at Ϫ40°C was added DMSO

(0.21 mL, 3 mmol) and after 5 minutes, a solution of the alcohol

38 (0.193 g, 0.75 mmol) in CH₂Cl₂(2 mL). The solution was al-

lowed to warm to Ϫ10°C over a period of 20 minutes and Et₃N

(1.1 mL, 7.5 mmol) was added. Water (5 mL) was then added at

room temp. and the organic layer was decanted. The aqueous layer

was extracted with CH₂Cl₂and the combined extracts were washed

with brine, dried with MgSO₄and the solvent evaporated under

vacuum. The residue was purified by chromatography through sil-

ica gel (Petroleum ether/EtOAc, 9:1) affording 0.164 g of the alde-

hyde 39 (85%). Ϫ IR (film, KBr): ν˜ ϭ 2988 cm^Ϫ1, 2936, 2726, 1725

(CϭO), 1456, 1381, 1245, 1212, 1161, 1059, 858, 808, 738, 699. Ϫ

¹H NMR (CDCl₃): δ ϭ 9.84 (s, 1 H, CHO), 4.79 (t, J ϭ 5.2 Hz, 1

H, OCH), 4.59 (d, J ϭ 5.3 Hz, 1 H, OCH), 4.42Ϫ4.39 (m, 2 H, 2

ϫ OCH), 2.85 (ddd, J ϭ 1.2, 9.6, 17.9 Hz, 1 H, CH_aH_bCHO), 2.72

(ddd, J ϭ 1, 5.1, 17.9 Hz, 1 H, CH_aH_bCHO), 2.53Ϫ2.47 (m, 1 H,

CH), 1.47 (s, 3 H, CH₃), 1.39 (s, 3 H, CH₃), 1.29 (s, 3 H, CH₃),

1.27 (s, 3 H, CH₃). MS (CI, NH₃); m/z (%): 274 [M^ϩϩ 18], 257

[M^ϩϩ 1], 241 (44), 229 (1), 216 (11), 199 (40), 183 (19), 152 (3),

123 (13), 95 (13), 85 (9).

17], 615 (2), 507 (1), 436 (1), 229 (2), 91 (100). HRMS [M ϩ Na]

C₄₀H₄₈O₉Na: calcd. 695.3190; found: 695.3191. Ϫ 40b (90 mg,

28%): [α]_D²⁵ϭ ϩ27.7, c ϭ 0.46, CHCl₃. Ϫ IR (film, KBr): ν˜ ϭ

3064 cm^Ϫ1, 3031, 2987, 2935, 1720 (CϭO), 1603, 1496, 1454, 1382,

1211, 1059, 911, 860, 734, 698. Ϫ ¹H NMR (CDCl₃): δ ϭ

7.36Ϫ7.16 (m, 15 H, aromatic H), 4.84 (dd, J ϭ 11.1 Hz, 1 H,

OCH_aH_bPh), 4.74Ϫ4.51 (m, 7 H, 2 ϫ CHO, 5 ϫ OCH_aH_bPh),

4.41Ϫ4.34 (m, 3 H, 3 ϫ CHO), 3.76Ϫ3.74 (m, 2 H, CH₂OBn),

3.67Ϫ3.62 (m, 2 H, 2 ϫ CHO), 3.58Ϫ3.57 (m, 1 H, CHO), 3.14

(dd, J ϭ 10.3, 18.1 Hz, 1 H, CH_aH_bCO), 2.75 (dd, J ϭ 4.6, 18.1 Hz,

1 H, CH_aH_bCO), 2.62 (ddd, J ϭ 3.0, 4.4, 13.2 Hz, 1 H, CH_aH_b),

2.51Ϫ2.46 (m, 1 H, CH), 1.79 (ddd, J ϭ 5.9, 10.2, 13.2 Hz, 1 H,

CH_aH_b), 1.47 (s, 3 H, CH₃), 1.32 (s, 3 H, CH₃), 1.30 (s, 3 H, CH₃),

1.19 (s, 3 H, CH₃). Ϫ ¹³C NMR (CDCl₃): δ ϭ 210.4 (s, CϭO),

138.4 (s, aromatic C), 138.0 (s, aromatic C), 128.4 (d, aromatic CH),

128.3 (d, aromatic CH), 128.2 (d, aromatic CH), 127.8 (d, aromatic

CH), 127.7 (d, aromatic CH), 127.6 (d, aromatic CH), 111.9 (s, C),

110.2 (s, C), 85.0 (d, CHO), 84.1 (d, CHO), 81.5 (d, CHO), 77.8

(d, CHO), 77.2 (d, CHO), 77.1 (d, CHO), 76.7 (d, CHO), 75.6 (d,

CHO), 74.4 (t, CH₂O), 73.4 (t, CH₂O), 71.6 (t, CH₂O), 68.9 (t,

CH₂O), 44.2 (d, CH), 36.5 (t, CH₂), 29.2 (t, CH₂), 27.7 (q, CH₃),

26.5 (q, CH₃), 25.5 (q, CH₃), 24.2 (q, CH₃). Ϫ MS (CI, NH₃); m/z

(%): 691 [M^ϩϩ 17], 615 (1), 436 (1), 91 (100). HRMS [M ϩ Na]

C₄₀H₄₈O₉Na: calcd. 695.3190; found: 695.3192.

Carba-Disaccharide (40a؊b): Into a dry 25 mL three-necked flask

equipped with a thermometer, an inlet for argon and a septum was

introduced the 3-deoxyglucosyltributylstannane^[32a](0.346 g,

0.5 mmol,) in anhydrous THF (10 mL). A 1.5  solution of nBuLi

Eur. J. Org. Chem. 2000, 401Ϫ418

417

Y. Landais, L. Parra-Rapado

FULL PAPER

[14]

[15]

[16]

J. B. Lambert, W. J. Schulz, P. H. Mueller, K. Kobayashi, J. Am.

Chem. Soc. 1984, 106, 792Ϫ793.

Acknowledgments

We gratefully acknowledge the Swiss National Science Foundation

for financial support through the CHiral2 program. We thank Ms

C. Glanzmann and Dr. R. Angelaud for technical assistance.

Acids such as pTsOH or BF₃ϪOEt₂gave mostly Peterson elim-

ination.

D. B. Collum, F. Mohamadi, J. S. Hallock, J. Am. Chem. Soc.

1983, 105, 6882Ϫ6889.

[17] [17a]

Y. Landais, D. Planchenault, V. Weber, Tetrahedron Lett.

1995, 36, 2987Ϫ2990. Ϫ ^[17b]Y. Landais, D. Planchenault, Syn-

lett 1995, 1191Ϫ1193.

[18]

[1]

O. Andrey, C. Glanzmann, Y. Landais, L. Parra-Rapado, Tetra-

hedron 1997, 53, 2835Ϫ2854.

Y. Landais, L. Parra-Rapado, Tetrahedron Lett. 1996, 37,

1205Ϫ1208.

[19] [19a]

[2] [2a]

G. R. Jones, Y. Landais, Tetrahedron 1996, 52, 7599Ϫ7662.

I. Fleming, Chemtracts, Org. Chem. 1996, 9, 1Ϫ64. Ϫ

K. Tamao, Advances In Silicon Chemistry 1996, 3, 1Ϫ62.

W. R. Roush, P. T. Grover, X. Lin, Tetrahedron Lett. 1990,

[19b]

[2b]

Ϫ

31, 7563Ϫ7566 Ϫ

W. R. Roush, P. T. Grover, Tetrahedron

[19c]

[2c]

Lett. 1990, 31, 7567Ϫ7570 Ϫ

W. R. Roush, P. T. Grover,

[20]

J. B. Lambert, Tetrahedron 1990, 46, 2677Ϫ2689.

Tetrahedron 1992, 48, 1981Ϫ1998.

^{[21] [21a]}L. Agrofoglio, E. Suhas, A. Farese, R. Condom, S. R. Chal-

[3]

[4]

^[3a]H-U. Reissig, The Chemistry of the Cyclopropyl Group (Eds.:

land, R. A. Earl, R. Guedj, Tetrahedron 1994, 50, 10611Ϫ10670

S. Patai, Z. Rappoport), John Wiley & Sons Ltd., London,

[21b]

[3b]

and references cited therein. Ϫ

Y. Cheng, D. Dutschman,

1987, pp 375Ϫ443. Ϫ

F. A. Carey, R. J. Sundberg, in: Ad-

E. De Clercq, A. Jones, S. Rahim, G. Verhelst, R. Walker, Mol.

Pharmacol. 1981, 20, 230Ϫ233.

vanced Organic Chemistry, 3rd Ed., Plenum: New-York, 1991,

part A, p. 157.

[22]

^[4a]M. Ochiai, K. Sumi, E. Fujita, Chem. Lett. 1982, 79Ϫ80. Ϫ

C. Desgranges, G. Razaka, F. Drouillet, H. Bricaud, P. Herdew-

ijn, E. De Clerq, Nucleic Acids Res. 1984, 12, 2081Ϫ2090.

[4b]

M. Ochiai, K. Sumi, E. Fujita, M. Shiro, Tetrahedron Lett.

[23] [23a]

[4c]

P. Herdewijn, E. De Clerq, J. Balzarini, H. Vanderhaeghe,

1982, 23, 5419Ϫ5422. Ϫ

M. Ochiai, K. Sumi, E. Fujita,

[23b]

[4d]

J. Med. Chem. 1985, 28, 1385Ϫ1386. Ϫ

R. Cookson, P.

Chem. Pharm. Bull. 1983, 31, 3931Ϫ3938. Ϫ

I. Fleming, P.

[4e]

Dudfield, R. Newton, P. Ravenscroft, D. Scopes, J. Cameron,

E. J. Sanderson, N. K. Terrett, Synthesis 1992, 69Ϫ74. Ϫ

P.

Mohr, Tetrahedron Lett. 1995, 36, 7221Ϫ7224. Ϫ ^[4f]J. S. Panek,

Eur. J. Med. Chem. Chim. Ther. 1985, 20, 375Ϫ377.

[24] [24a]

M. A. Sperman, J. E. Damen, T. Kolodka, A. H. Green-

R. M. Garbaccio, N. F. Jain, Tetrahedron Lett. 1994, 35,

[4g]

berg, J. C. Jamieson, J. A. Wright, Cancer Lett. 1991, 57, 7Ϫ13.

6453Ϫ6456. Ϫ

I. Ryu, A. Hirai, H. Suzuki, N. Sonoda, S.

[24b]

Murai, J. Org. Chem. 1990, 55, 1409Ϫ1410. Ϫ ^[4h]M. Kihihara,

S. Yokoyama, H. Kakuda, T. Momose, Tetrahedron Lett. 1995,

36, 6907Ϫ6910.

Ϫ

B. Winchester, G. W. J. Fleet, Glycobiology 1992, 2,

199Ϫ210. Ϫ ^[24c]M. J. Humphries, K. Matsumoto, S. L. White,

K. Olden, Proc. Natl. Acad. Sci. U.S.A. 1986, 46, 1752Ϫ1756.

[24d]

Ϫ

P. B. Anzeveno, L. J. Creemer, J. K. Daniel, C.-H. R.

[5] [5a]

P. F. Hudrlik, D. Peterson, J. Am. Chem. Soc. 1975, 97,

King, P. S. Liu, J. Org. Chem. 1989, 54, 2539Ϫ2542. Ϫ ^[24e]T. W.

[5b]

1464Ϫ1468. Ϫ

P. F. Hudrlik, D. Peterson, R. J. Rona, J.

Miller, B. H. Arison, G. Albers-Schonberg, Biotech. and Bioeng.

Org. Chem. 1975, 40, 2263Ϫ2264.

[24f]

1973, 15, 1075Ϫ1080. Ϫ

I. Miwa, H. Hara, J. Okuda, T.

[6]

For a preliminary account, see: Y. Landais, L. Parra-Rapado,

[24g]

Suami, S. Ogawa, Biochem. Intern. 1985, 11, 809Ϫ816. Ϫ

C. S. Wilkox, J. J. Gaudino, J. Am. Chem. Soc. 1986, 108,

3102Ϫ3104.

Tetrahedron Lett. 1996, 37, 1209Ϫ1212.

[7] [7a]

B. Giese, Radicals in organic Synthesis: Formation of Car-

bonϪCarbon Bonds, Pergamon Press, 1986 and references cited

[25]

For comprehensive reviews on the total synthesis of carba-sug-

[7b]

therein. Ϫ

L. S. Hegedus, Palladium in Organic Synthesis,

[25a]

ars and carba-C-disaccharides, see:

T. Suami, Top. Curr.

M. H. D. Postema, Tetra-

D. E. Levy, C. Tang, in:

in: Organometallics in Synthesis

Ϫ A manual, (Ed.: M.

[25b]

Chem. 1990, 154, 257Ϫ283. Ϫ

Schlosser), John Wiley & Sons Ltd, 1994, chapter 5 and refer-

[25c]

hedron 1992, 48, 8545Ϫ8599. Ϫ

ences cited therein.

The Chemistry of C-Glycosides; Tetrahedron Organic Chemistry

series, Pergamon, Elsevier Science Ltd., 1995.

E. W. Colvin, Silicon Reagents in Organic Synthesis, Academic

Press Ltd, 1988, chapter 5 and references cited therein.

H. C. Kolb, M. S. vanNieuwenhze, K. B. Sharpless, Chem. Rev.

1994, 94, 2483Ϫ2547.

V. van Rheenen, R. C. Kelly, D. Y. Cha, Tetrahedron Lett.

1976, 1973Ϫ1976.

R. Angelaud, Y. Landais, Tetrahedron Lett. 1997, 38,

8841Ϫ8844.

[8] [8a]

J. Furukawa, N. Kawabata, J. Nishimura, Tetrahedron Lett.

[8b]

1966, 3353Ϫ3354. Ϫ

J. Nishimura, N. Kawabata, J. Furu-

[26]

[27]

[28]

[29]

kawa, Tetrahedron 1969, 25, 2647Ϫ2569. For more recent re-

ports, see: Ϫ ^[8c]T. Morikawa, H. Sasaki, R. Hanai, A. Shibuya,

[8d]

T. Taguchi, J. Org. Chem. 1994, 59, 97Ϫ103. Ϫ

A. B. Char-

[8e]

ette, H. Lebel, J. Org. Chem. 1995, 60, 2966Ϫ2967. Ϫ

M.

Lautens, P. H. M. Delanhe, J. Org. Chem. 1995, 60, 2474Ϫ2487.

[9] [9a]

E. D. Mihelich, K. Daniels, D. J. Eickhoff, J. Am. Chem.

Soc. 1981, 103, 7690Ϫ7692. Ϫ ^[9b]R. W. Hoffmann, Chem. Rev.

1989, 89, 1841Ϫ1860.

[30]

[31]

C. L. Hill, G. M. Whitesides, J. Am. Chem. Soc. 1974, 870Ϫ876.

R. A. Field, A. H. Haines, E. J. T. Chrystal, Bioorg. Med. Chem.

Lett. 1991, 1, 667Ϫ672.

^{[10] [10a]}I. Fleming, J. Chem. Soc., Perkin Trans 1 1992, 3363Ϫ3369.

[10b]

`

I. Fleming, J. Dunogues, R. Smithers, Org. React. 1989,

Ϫ

[32] [32a]

37, 57Ϫ575. The diastereofacial selectivity observed during the

formation of 2e؊f was rationalized invoking an attack of the

electrophile anti relative to the silicon group in a conformation

where the small H group on the allylic chiral centre occupies

the inside position, eclipsing the double bond. In this way, (Z)-

allylsilanes exhibit a higher degree of stereocontrol owing to the

high allylic strain present in the other reactive conformation. In

this case, the presence of a directing OH group is not necessary

to ensure a high degree of stereocontrol. Such a A_1,3strain is

not as pronounced with (E)-allylsilanes, explaining the low dia-

stereofacial selectivity in this case.

P. Lesimple, J.-M. Beau, P. J. Sinay¨, Carbohydr. Res. 1987,

[32b]

171, 289Ϫ300. Ϫ

V. Wittmann, H. Kessler, Angew. Chem.

Int. Ed. 1993, 32, 1091Ϫ1093.

[33]

[34]

A. J. Mancuso, D. Swern, Synthesis 1981, 165.

J.-P. Vionnet, P. Renaud, Helv. Chim. Acta 1994, 77,

1781Ϫ1790.

[35]

[36]

O. Jarreton, T. Skrydstrup, J.-F. Espinosa, J. Jimenez-Barbero,

J. M. Beau, Chem. Eur. J. 1999, 5, 430Ϫ441.

J. March, Advanced Organic Chemistry, 4th Ed. Wiley Intersci-

ence, John Wiley & Sons, 1992.

[37] [37a]

[37b]

A. Pfaltz, Acc. Chem. Res. 1993, 26, 339Ϫ345. Ϫ

D.

[11]

For a review on substrate-directable reactions, see: A. H. Hov-

eyda, D. A. Evans, G. C. Fu, Chem. Rev. 1993, 93, 1307Ϫ1370

and references cited therein.

A. Evans, K. A. Woerpel, M. J. Scott, Angew. Chem. Int. Ed.

[37c]

1992, 31, 430Ϫ432. Ϫ

M. N. Protopopova, M. P. Doyle, P.

Müller, D. Ene, J. Am. Chem. Soc. 1992, 114, 2755Ϫ2757.

O. Andrey, Y. Landais, D. Planchenault, V. Weber, Tetrahedron

1995, 51, 12083Ϫ12096.

[12] [12a]

[38]

I. Fleming, A. Barbero, D. Walter, Chem. Rev. 1997,

[12b]

2063Ϫ2192. Ϫ

A. Barbero, D. C. Blakemore, I. Fleming,

[39]

[40]

R. N. Wesley, J. Chem. Soc.,Perkin Trans 1 1997, 1329Ϫ1352.

I. Reichelt, H.-U. Reissig, Liebigs, Ann. Chem. 1984, 828Ϫ830.

P. Bulugahapitiya, Y. Landais, L. Parra-Rapado, D. Planch-

enault, V. Weber, J. Org. Chem. 1997, 62, 1630Ϫ1641.

Received 24 June, 1999

[13] [13a]

P. Kocovsky, J. Srogl, M. Pour, A. Gogoll, J. Am. Chem.

Soc. 1994, 116, 186Ϫ197. Ϫ ^[13b]P. Kocovsky, M. Pour, A. Gog-

oll, V. Hanus, M. Smrcina, J. Am. Chem. Soc. 1990, 112,

6735Ϫ6737.

[O99384]

418

Eur. J. Org. Chem. 2000, 401Ϫ418

Article Doi

Studies on the mercury-desilylation of chiral cyclopropylmethylsilanes - A stereocontrolled access to carba-sugars

DOI: 10.1002/(sici)1099-0690(200002)2000:3<401::aid-ejoc401>3.0.co;2-m

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