Stereocontrol in organic synthesis using silicon-containing compounds. A formal synthesis of prostaglandins controlling the stereochemistry at C-15 using a silyl-to-hydroxy conversion following a stereochemically convergent synthesis of an allylsilane

DOI: 10.1039/a804276d

Source and publish data:

Journal of the Chemical Society. Perkin transactions I p. 2687 - 2700 (1998)

Update date:2022-07-30

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Authors:

Fleming, Ian

Winter, Stephen B. D.

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Article abstract of DOI:10.1039/a804276d

Hydrosilylation of isoprene with chloro(diphenyl)silane gave (Z)-chloro(2-methylbut-2-enyl)-diphenylsilane 7. The cuprate reagent derived from this chloride underwent conjugate addition to methyl cinnamate 11, 1,2-silylcupration with hex-1-yne 16 and allene 18, and allylic displacement reactions with 1-vinylcyclohexyl acetate 20 and (Z)-1-cyclopentyloct-2-en-1-yl acetate 22. The silyl group in each of the products was converted into a hydroxy, with the removal of the 2-methylbut-2-enyl group taking place under much milder acidic conditions than those needed to remove the phenyl group from the dimethyl(phenyl)silyl group, and making this group suitable for the conversion of an allylsilane into an allyl alcohol. A stereospecifically anti conjugate displacement of the allylic benzoate group in (Z)-(1S,5R,6R,7R,1′S)-7-benzoyloxy-6-(1′-benzoyloxyoct-2′- enyl)-2-oxabicyclo[3.3.0]octan-3-one 52, and a stereospecifically syn conjugate displacement of the carbamate group in (Z)-(1S,5R,6R,7R,1′R)-7-benzoyloxy-6-(1′-N-phenylcarbamoyloxyoct- 2′-enyl)-2-oxabicyclo[3.3.0]octan-3-one 51, gave stereo-convergently the same allylsilane (1′ E,2″Z)-(1S,5S,6R,7R,3′S)-7-benzoyloxy-6-[3′-(2″- methylbut-2″-enyl)-diphenylsilyloct-1′-enyl]-2-oxabicyclo[3.3.0] octan-3-one 53. Silyl-to-hydroxy conversion gave the allyl alcohol (E)-(1S,5S,6R,7R,3′S)-7-benzoyloxy-6-(3′-hydroxyoct-1′-enyl)- 2-oxabicyclo[3.3.0]octan-3-one 54, having the relative and absolute stereochemistry at C-15 of the prostaglandins.

Full text of DOI:10.1039/a804276d

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Stereocontrol in organic synthesis using silicon-containing

compounds. A formal synthesis of prostaglandins controlling the

stereochemistry at C-15 using a silyl-to-hydroxy conversion following

a stereochemically convergent synthesis of an allylsilane

Ian Fleming* and Stephen B. D. Winter

Department of Chemistry, Lensﬁeld Road, Cambridge, UK CB2 1EW

Hydrosilylation of isoprene with chloro(diphenyl)silane gave (Z)-chloro(2-methylbut-2-enyl)-

diphenylsilane 7. The cuprate reagent derived from this chloride underwent conjugate addition to

methyl cinnamate 11, 1,2-silylcupration with hex-1-yne 16 and allene 18, and allylic displacement

reactions with 1-vinylcyclohexyl acetate 20 and (Z)-1-cyclopentyloct-2-en-1-yl acetate 22. The silyl group

in each of the products was converted into a hydroxy, with the removal of the 2-methylbut-2-enyl group

taking place under much milder acidic conditions than those needed to remove the phenyl group from

the dimethyl(phenyl)silyl group, and making this group suitable for the conversion of an allylsilane

into an allyl alcohol. A stereospeciﬁcally anti conjugate displacement of the allylic benzoate group in

(Z)-(1S,5R,6R,7R,1ЈS)-7-benzoyloxy-6-(1Ј-benzoyloxyoct-2Ј-enyl)-2-oxabicyclo[3.3.0]octan-3-one 52,

and a stereospeciﬁcally syn conjugate displacement of the carbamate group in (Z)-(1S,5R,6R,7R,1ЈR)-7-

benzoyloxy-6-(1Ј-N-phenylcarbamoyloxyoct-2Ј-enyl)-2-oxabicyclo[3.3.0]octan-3-one 51, gave stereo-

convergently the same allylsilane (1ЈE,2ЉZ)-(1S,5R,6R,7R,3ЈS)-7-benzoyloxy-6-[3Ј-(2Љ-methylbut-2Љ-enyl)-

diphenylsilyloct-1Ј-enyl]-2-oxabicyclo[3.3.0]octan-3-one 53. Silyl-to-hydroxy conversion gave the allyl

alcohol (E)-(1S,5R,6R,7R,3ЈS)-7-benzoyloxy-6-(3Ј-hydroxyoct-1Ј-enyl)-2-oxabicyclo[3.3.0]octan-3-one

54, having the relative and absolute stereochemistry at C-15 of the prostaglandins.

Introduction

Having developed a method for converting the phenyldimethyl-

silyl group into a hydroxy with retention of conﬁguration,¹and

also a stereoselective synthesis of allylsilanes from allylic alco-

hols,²we were faced with a problem in trying to combine these

two methods. We had in mind that we might be able to control

the stereochemistry at C-15 in the synthesis of prostaglandin

F_2α1, a long-standing problem, which has excited several solu-

tions.^3,4We had the methods for setting up a silyl group [Si] at

C-15 with high levels of regio- and stereo-speciﬁcity in either

sense from either or both of the diastereoisomeric propargyl

(prop-2-ynyl) alcohols 3 and 4 obtained by nucleophilic attack

on a C-13 aldehyde 5 (Scheme 1). Our method was not depend-

ent upon any stereoselectivity in the formation of the mixture

of propargyl alcohols 3 and 4. It was only necessary to be able

to separate the diastereoisomers, in order to achieve con-

vergence by submitting each to a different protocol, as used

already in our synthesis of the Prelog–Djerassi lactone.⁵How-

ever, there was a fundamental problem in the idea when we

started the work described in this paper—we could not use our

standard phenyldimethylsilyl group as [Si] in the allylsilane 2,

because the essential ﬁrst step in the silyl-to-hydroxy conversion

is to remove the phenyl group with an electrophile. Any attempt

to attack the phenyl ring would not be able to compete with

attack at C-13 of the double bond of the allylsilane. Several

silyl groups have been developed to overcome this type of

problem, notably Tamao and Ito’s diisopropylamino-⁶and

alkoxy-(dimethyl)silyl groups,⁷Chan’s (dimethyl)pyrrolidino-

methylsilyl group,⁸Hayashi and Hiyama’s ﬂuoro(diphenyl)silyl

group,⁹Landais’ phenylthiocyclopropyl(dimethyl)silyl group¹⁰

and Roush’s¹¹and Kocienski’s¹²various furyl(dimethyl)silyl

groups, all of which allow an allylsilane to be converted into an

allyl alcohol, but none of which allows the silyl group to be

introduced using the powerful silylcuprate chemistry. Taber has

solved the problem recently, retaining the phenyldimethylsilyl

group, and hence the capacity to use its cuprate—he found that

Birch reduction of the phenyl group and treatment with ﬂuor-

ide ion removed it, but he has not actually carried out the

CO₂H

[Si]

CHO

Scheme 1

sequence with an allylsilane.¹³We tried unsuccessfully to

remove the phenyl ring of the phenyldimethylsilyl group by

converting it into its chromiumtricarbonyl complex—the

complex was formed, but the allyl group remained more

reactive than the phenyl.¹⁴Another solution to the problem has

been developed by Tamao and Ito, with their diethylamino-

(diphenyl)silyl group, which can be made into a cuprate

reagent,¹⁵while we developed the (Z)-2-methylbut-2-

J. Chem. Soc., Perkin Trans. 1, 1998

2687

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enyl(diphenyl)silyl group¹⁶and applied it to a prostaglandin

synthesis.¹⁷We report all our work on this group in full here and

in the following paper.

CO₂Me

Ph₂Si

OLi

OMe

Results and discussion

iii

The two essential features that we needed were that the silyl

group should have a substituent that is attacked by an electro-

phile more readily than the double bond of the allylsilane 2,

and that the silyl group should also be capable of being

delivered as a cuprate into the organic structure. It was the

second requirement that gave us most trouble, for we found that

a wide variety of aryldimethylsilyl groups, with aryl groups

more susceptible to electrophilic attack than phenyl, could not

be prepared as chlorides,¹⁸or the chlorides would only give,

when they were stirred with lithium, disilanes and not silyl-

lithium reagents.¹⁹It appears to be more or less essential to have

at least one unsubstituted phenyl group, as Tamao and Ito

found with their group, and we found with the group that we

eventually succeeded with.

Ph₂Si

CO₂Me

90%

89% 93:7

i, iii

CO₂Me

Ph₂Si

CO₂Me

The (Z)-2-methylbut-2-enyl(diphenyl)silyl group

15 90% 80:20

The key was provided by a report from Ojima and Kumagai

of the regio- and stereo-selective hydrosilylation of isoprene

with chloro(dimethyl)silane.²⁰We found, similarly, that hydro-

silylation of isoprene using chloro(diphenyl)silane 6 and the

same catalyst in a sealed tube gave the silyl chloride 7 with high

selectivity and in high yield. Although clean, this silyl chloride

proved to be difﬁcult to purify, distillation causing decomp-

osition, but even in its slightly crude state it was easily con-

verted into, successively, the disilane 8, the lithium reagent 9,

and the cuprate 10 (Scheme 2). It appeared to be best not to

i, iii

Ph₂

91%

i, iii

•

Ph₂Si

19 89%

+ Ph₂SiHCl

SiPh₂Cl

94%

Ph₂Si SiPh₂

Ph₂

OAc

21 82%

iii

OAc

SiPh₂)₂CuCN Li₂

SiPh₂Li

(

C₅H₁₁-n

Ph₂Si

Scheme 2 Reagents: i, PdCl₂(PhCN)₂cat., Ph₃P; ii, Li, THF; iii, CuCN

C₅H₁₁-n

isolate the disilane 8, which could be obtained in 64% yield,

even though its crystallinity gave an opportunity to purify the

reagent—once isolated, it needed sonication and powdered

lithium to cleave it. It was better to continue stirring the silyl

chloride 7 with lithium shot as usual, even though the disilane

must have been an intermediate.²¹An alternative route to the

silyl chloride, which does allow some puriﬁcation by distil-

lation, is described in the following paper.

OCONHPh

78% from 22

64% from 23

iv, v, vi

C₅H₁₁-n

Scheme 3 Reagents: i, 10; ii, NH₄Cl, H₂O; iii, MeI; iv, BuLi; v, CuI,

Ph₃P; vi, 9

We tested the cuprate reagent, to make sure that it reacted

with each of the substrates that we already knew the phenyl-

dimethylsilylcuprate reacted with, namely α,β-unsaturated

esters 11 and 14, a terminal acetylene 16, allene 18 and the

allylic acetate 20. The reactions all worked well (Scheme 3), and

were suitable for the alkylation and the protonation protocol

with the esters 11 and 14, giving the diastereoisomeric esters 13

and 15, respectively. Moving closer to the prostaglandin prob-

lem, the silylcuprate 10 also reacted with the allylic acetate

22 to give the allylsilane 24 with the substitution pattern of the

prostaglandin sidechain, and showing the expected regio-

selectivity for allylic displacement with an acetate having a cis

double bond and the larger substituent at the oxygen-bearing

end of the allylic system.²With a slightly different protocol,

assembling the cuprate on the allylic carbamate 23, the reagent

gave the same allylsilane 24. The reagent appeared in every way

to be similar in its reactivity, regioselectivity and stereoselectiv-

ity to the corresponding phenyldimethylsilylcuprate reagent.

We used the ester 12 to test methods for converting the silyl

into a hydroxy group. We had been hopeful that peracid alone,

MCPBA, for example, or peracetic acid in acetic acid, would do

both jobs at once—the removal of the allyl group by epoxide

formation and easy loss of the silyl group, followed immediately

by the silyl-to-hydroxy oxidation step. Unfortunately, we were

2688

J. Chem. Soc., Perkin Trans. 1, 1998

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unable to ﬁnd conditions that gave anything other than com-

plex mixtures of products. We turned therefore to stepwise

methods (Scheme 4). Protodesilylation was easily accomplished

SiPh₂X

33 a X = OH 46%

b X = OMe 49%

Ph₂

ii, iii, iv

iii

Ph₂SiOH

Ph₂SiOMe

NO₂

Ph₂Si

CO₂Me

48%

49%

NO₂

42%

or v, ii

i or ii

Ph₂SiF

SiPh₂X

CO₂Me

CO₂R

35 a X = OH 51%

b X = OMe 49%

a R = Me

i, iii

100%

77% from 25; 80% (iv) from 12

c X = F

100%

Ph₂

b R = H 88% (v,ii) from 12

or v

36 60% (i,iii)

59% (v)

Ph₂Si

CO₂Me

SiPh₂OR

C₅H₁₁-n

a R = H

b R = Me

i, ii

70:30 100%

Ph₂Si

Ph₂SiOH

i, iii

C₅H₁₁-n

CO₂Me

65%

CO₂Me

or v

C₅H₁₁-n

33%

44%

38 57% (i, iii)

67% (v)

Scheme 4 Reagents: i, BF₃ؒ2AcOH, CH₂Cl₂; ii, H₂O₂, KF, NaHCO₃,

MeOH, THF; iii, HCl, MeOH, H₂O; iv, KBr, AcOOH, AcOH, NaOAc;

v, H₂SO₄, MeOH

Scheme 5 Reagents: i, HCl, MeOH, H₂O; ii, BF₃ؒ2AcOH, CH₂Cl₂;

iii, H₂O₂, KF, NaHCO₃, MeOH, THF; iv, 2,4-dinitrophenylhydrazine;

v, KBr, H₂O₂, KF, THF, MeOH

under mild conditions, typically with the boron triﬂuoride–

acetic acid complex in dichloromethane (ca. 0.05 ) at Ϫ10 ЊC

for ﬁve minutes, giving the ﬂuoride 25, or with dilute meth-

anolic hydrochloric acid (ca. 0.3 ) at room temperature for

three hours. In the latter case, the product mixture was about

half silanol 26 and half silyl ether 27, even though the propor-

tion of water present must have been only about 4%. We do not

know whether this is a kinetic or a thermodynamic result, and

comment only that it is known that hydroxide ion is a better

nucleophile for silicon than the corresponding alkoxide ion.²²

The oxidation step could be carried out using Tamao’s condi-

tions in the usual way, to give the alcohol 28a. Our one-pot

procedure 12→28a using bromine, generated in situ in buffered

peracetic acid also worked well, as did a one-pot procedure

carrying out the protodesilylation with sulfuric acid in meth-

anol, and then basifying the mixture with sodium hydrogen

carbonate and adding potassium ﬂuoride and hydrogen per-

oxide, except that this gave us the acid 28b instead of the ester.

The protodesilylation–oxidation sequence applied to the alkyl-

ated esters 13, however, did not go to completion under the

standard conditions. We isolated the silanol 30 in comparable

amounts to the alcohol 29, indicating that the phenyl groups

slow the oxidation down marginally. Increasing the time for the

oxidation of the diastereoisomeric ester 15 from one day to

three, and topping up the hydrogen peroxide each day, gave

almost complete conversion to the alcohol 31, but we still

isolated a small amount of the silanol 32. No doubt this could

be remedied by even longer or stronger treatment with the

oxidising agent.

anol gave the silanols 33a, 35a and 37a, and the silyl ethers 33b,

35b and 37b. Protodesilylation of the allylsilane 21 with the

boron triﬂuoride–acetic acid complex gave the silyl ﬂuoride 35c.

One- or two-pot oxidations gave hexanal, as its 2,4-dinitro-

phenylhydrazone 34, and, most signiﬁcantly, the allylic alcohols

36 and 38. For the last of these, we also found new, essentially

neutral conditions, with a combination of potassium bromide

in hydrogen peroxide to create the electrophilic brominating

agent, and potassium ﬂuoride and hydrogen peroxide to carry

out the oxidation step.

The prostaglandin C-15 problem

With all the exploratory work in hand, we turned to the main

task: to synthesise an allylsilane of the type 2 from an aldehyde

5. We chose the aldehyde 40 to be the aldehyde 5 that we would

actually use. The protecting groups, both for the C-9 and the

C-11 hydroxy groups were esters, limiting us to protocols using

cis double bonds derived from the triple bond. Our earlier

method, used in the syntheses of the Prelog–Djerassi lactone

and of dihydronepetalactone, and which we shall not be able

to apply here, required that we reduce the triple bond of one

diastereoisomer to a trans double bond using lithium alu-

minium hydride, and the ester and lactone groups would not be

compatible with this protocol. However, we had by this time

developed protocols for convergence using a stereospeciﬁcally

syn displacement for one diastereoisomer and a stereospeciﬁc-

ally anti displacement for the other, with a cis double bond in

each, avoiding the need for lithium aluminium hydride.

We then tested the protodesilylation and oxidation condi-

tions, in various combinations on the other allylsilanes (Scheme

5). Protodesilylations of the allylsilanes 17, 21 and 24 in meth-

We prepared the aldehyde 40 in essentially quantitative

yield from the alcohol 39, already known from the work of

Uskokovic²³and Kovâcs.²⁴The aldehyde was, not surprisingly,

J. Chem. Soc., Perkin Trans. 1, 1998

2689

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exceptionally susceptible to elimination of the β-benzoate

group, so that the oxidation was rather dependent upon the

virtues of the Dess–Martin periodinane. We also found that the

addition of the acetylenic nucleophile gave less of the elimin-

ation product when the cerium reagent was used, and, as

expected, the addition was only slightly stereoselective, giving

the pair of diastereoisomers 41 and 42, which we were not able

to separate, in a ratio of 63:37 (Scheme 6). Thus the elegantly

BzO

43 63%

44 37%

CHO

BzO

40 100%

OBz

OCONHPh

48 85%

23%

47 100%

iv, v, vi

iii

(71% recovered)

87%

BzO

Ph₂Si

72% 63:37

iii

vii, viii

BzO

43 63%

44 37%

BzO

50 66%

Scheme 7 Reagents: i, PhCOCl, Et₃N, DMAP; ii, PhNCO, Et₃N; iii,

10; iv, BuLi; v, CuI; vi, 9; vii, BF₃ؒ2AcOH; viii, H₂O₂, KF, MeOH

enough material to carry out the silyl-to-hydroxy conversion

into the known ‘unnatural’ prostaglandin precursor 50. The

carbamate 51 and the benzoate 52 gave the diastereoisomeric

allylsilane 53 (Scheme 8), for which we found a slightly different

protocol for the conversion of the carbamate 51 into the

allylsilane 53: addition of the lithium salt of the carbamate to

the 1:1 silylcopper reagent gave a 53% yield, with 29% of

recovered carbamate, which represents a 77% yield overall.

Silyl-to-hydroxy conversion gave the known ‘natural’ alcohol

54, completing our long held ambition to control the stereo-

chemistry of an allylic alcohol by taking advantage of the

versatility of our convergent stereocontrolled methods for

setting up allylsilanes.

46 74%

᎐

Scheme 6 Reagents: i, Dess–Martin; ii, C₅H₁₃C᎐CCeCl₂; iii, H₂, Pd,

MnCl₂, quinoline, MeOH; iv, K₂CO₃, MeOH

᎐

short method in which allylic acetates are transposed in a tran-

sition metal-catalysed suprafacial 1,3 shift would not have been

easy to apply here, since, like our own earlier method, it requires

different double bond geometries with which to achieve con-

vergence.⁴Fortunately, we were no longer obliged to separate

the propargylic alcohols—we could delay the separation until

we had the cis-allylic alcohols. Lindlar reduction gave the pair

of alcohols 43 and 44, which we were able to separate, and to

which we were able to assign structures by converting the minor

alcohol 44 into the known alcohol 46,⁴and the mixture of

the two alcohols 43 and 44 into a mixture of the alcohols 45 and

46.

From each of the allylic alcohols 43 and 44, we prepared the

carbamates 48 and 51 and the benzoates 47 and 52 (Schemes 7

and 8). The benzoate 47 and the carbamate 48 gave the

same allylsilane 49 (Scheme 7) when subjected to our standard

protocols. The yield was rather low (23%) with the three-step

procedure assembling the cuprate on the carbamate 48, convert-

ing it into the allylsilane 49, but the two procedures gave us

Experimental

Light petroleum refers to the fraction bp 40–60 ЊC. Basic

ammonium chloride refers to saturated aqueous ammonium

chloride (9 parts) to which saturated aqueous ammonia (1 part)

has been added. Ether refers to diethyl ether.

Chlorodiphenylsilane 6

Method 1.²⁵Diphenylsilane (4.4 cm³, 23.7 mmol) and chloro-

triphenylmethane (6.97 g, 25.0 mmol) were reﬂuxed in dry ben-

zene (100 cm³) for 24 h under argon. The mixture was cooled,

ﬁltered quickly and the residue washed with cold dry pentane.

2690

J. Chem. Soc., Perkin Trans. 1, 1998

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pressure to give the chlorosilane (8.1 g, 94%), which was used

without further puriﬁcation; ν_max(ﬁlm)/cm^Ϫ11660 (C᎐C), 1600

᎐

(Ph) and 1120 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.70 (4 H, br d,

J 7.5, o-SiPh₂), 7.52–7.42 (6 H, m, m- and p-SiPh₂), 5.24 (1 H, br

q, J 6.7, CHMe), 2.39 (2 H, s, SiCH₂), 1.63 (3 H, t, J 1.4,

MeC᎐CH) and 1.40 (3 H, d, J 6.6, CHMe); δ (63 MHz; CDCl )

᎐

BzO

134.6, 133.9, 130.7, 130.3, 128.2, 119.8, 26.3, 23.1 and 14.2;

m/z 288 [19%, M^ϩ(³⁷Cl)], 286 [49, M^ϩ(³⁵Cl)] and 77 (12, Ph)

(Found: C, 71.3; H, 6.5; Cl, 12.5%; M^ϩ, 286.0943 and 288.0912.

C₁₇H₁₉SiCl requires C, 71.2; H, 6.7; Cl, 12.4%; C₁₇H₁₉Si³⁵Cl

requires M, 286.0945 and C₁₇H₁₉Si³⁷Cl requires M, 288.0915).

43 63%

44 37%

(Z)-(2-Methylbut-2-enyl)diphenylsilyllithium 9

Method 1. (Z)-Chloro(2-methylbut-2-enyl)diphenylsilane

(0.745 g, 0.5 cm³, 2.6 mmol) was stirred vigorously for 2 h with

lithium shot (0.068 g, 9.8 mmol) in dry THF (5 cm³) at 0 ЊC

under argon. The deep red solution was stored overnight in a

freezer at Ϫ18 ЊC and used within a few days. The molarity

was determined by the double titration method of Gilman as

modiﬁed by Whitesides.²¹

BzO

OCONHPh

OBz

51 96%

52 99%

Method 2. A mixture of the disilane 8 (0.88 g, 1.75 mmol)

and lithium powder (0.04 g, 6 mmol) in dry THF (5 cm³) was

sonicated for 2 h at 0 ЊC under argon. The resulting deep red

solution of silyllithium reagent was then stored overnight in a

freezer at Ϫ18 ЊC. Double titration indicated almost quanti-

tative conversion.

iii, iv

53%

84%

(29% recovered)

(Z,Z)-1,2-Bis(2-methylbut-2-enyl)-1,1,2,2-tetraphenyldisilane 8

Freshly prepared silyllithium reagent 9 (0.74 mmol) was added

dropwise to a stirred solution of the chlorosilane 7 (0.289 g,

1.01 mmol) in dry THF (5 cm³) at 0 ЊC under argon. After

stirring at this temperature for 4 h the reaction was quenched

with water (10 cm³) and the mixture ﬁltered through Celite and

extracted with light petroleum (3 × 10 cm³). The organic layers

were combined, washed with brine (10 cm³), dried (MgSO₄) and

concentrated under reduced pressure. The residue was chrom-

atographed (SiO₂, EtOAc–hexane, 5:95) to give the disilane

(0.24 g, 64%) as prisms, mp 110–111 ЊC (from hexane); R_f

BzO

Ph₂Si

vi, vii

(EtOAc–hexane, 1:9) 0.49; ν_max(CH₂Cl₂)/cm^Ϫ11661 (C᎐C),

᎐

BzO

1587 (Ph) and 1103 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.40 (8 H, br

d, J 5.5, 2 × o-SiPh₂), 7.34–7.19 (12 H, m, 2 × m- and p-SiPh₂),

4.98 (2 H, br q, J 6.4, 2 × C᎐CHMe), 2.21 (4 H, s, 2 × SiCH ),

᎐

54 60%

1.40 (6 H, t, J 1.3, 2 × MeC᎐CH) and 1.16 (6 H, d, J 6.7,

᎐

2 × C᎐CHMe); δ (100 MHz; CDCl ) 136.2, 135.4, 133.0, 129.0,

᎐

Scheme 8 Reagents: i, PhNCO, Et₃N; ii, PhCOCl, Et₃N, DMAP; iii,

BuLi; iv, C₅H₉Ph₂SiCu; v, 10; vi, BF₃ؒ2AcOH; vii, H₂O₂, KF, MeOH

127.6, 118.2, 26.4, 18.9 and 13.7; m/z 502 (9%, M^ϩ) and 433

(100, M Ϫ CH CMe᎐CHMe) (Found: C, 81.2; H, 7.6%; M^ϩ,

᎐

502.2513. C₃₄H₃₈Si₂requires C, 81.2; H, 7.6%; M, 502.2512).

The organic layers were combined and concentrated under

reduced pressure. Kugelrohr distillation of the residue (2 distil-

lations were necessary, 150 ЊC at 7 mmHg) (lit.,²⁵143 ЊC at 10

mmHg) gave the chlorosilane²⁵(4.55 g, 88%), ν_max(ﬁlm)/cm^Ϫ1

2140 (Si–H), 1580 (Ph) and 1120 (Si–Ph); δ_H(250 MHz; CDCl₃)

7.82 (4 H, br d, J 7.5, o-SiPh₂), 7.67–7.47 (6 H, m, m- and

p-SiPh₂) and 5.91 (1 H, s, SiH).

Characterisation of the silyllithium reagent

(Z)-(2-Methylbut-2-enyl)diphenylsilane. Freshly prepared

silyllithium reagent 9 (4.1 mmol) was poured into water and the

mixture extracted with ether (3 × 15 cm³). The organic layers

were combined, washed with brine (10 cm³), dried (MgSO₄) and

concentrated under reduced pressure. The residue was chroma-

tographed (SiO₂, EtOAc–hexane, 2:98) to give the silane (0.081

g, 20%); R_f(EtOAc–hexane, 2:98) 0.34; ν_max(ﬁlm)/cm^Ϫ12140

Method 2.²⁶Diphenylsilane (14.1 cm³, 76.1 mmol) was stirred

with a suspension of copper() chloride (20.2 g, 150 mmol,

dried at 120 ЊC under vacuum) and copper() iodide (0.3 g, 1.6

mmol) in dry ether (250 cm³) under nitrogen at room temper-

ature for 4 d, ﬁltered and concentrated under reduced pressure.

Distillation of the residue gave the chlorosilane²⁵(9.5 g, 57%),

(Si–H), 1670 (C᎐C) and 1600 (Ph); δ (250 MHz; CDCl ) 7.56 (4

᎐

H, br d, J 7.6, o-SiPh₂), 7.43–7.31 (6 H, m, m- and p-SiPh₂), 5.12

(1 H, br q, J 6.4, CHMe), 4.89 (1 H, t, J 4.0, SiH), 2.09 (2 H, d,

J 4.0, SiCH ), 1.62 (3 H, t, J 1.4, MeC᎐CH) and 1.36 (3 H, d,

᎐

bp 95–96 ЊC at 0.5 mmHg; identical (IR, H NMR) with the

J 6.7, CHMe); m/z 252 (19%, M^ϩ), 251 (16, M Ϫ H) and 183

(100, Ph₂SiH) (Found: M^ϩ, 252.1323. C₁₇H₂₀Si requires M,

252.1334).

earlier sample. This method, although lower yielding, was the

easier, and gave a cleaner product.

(Z)-(2-Methylbut-2-enyl)diphenylsilylmethanol. Formalde-

hyde gas (prepared by heating paraformaldehyde) in a stream

of argon was bubbled through a solution of freshly prepared

silyllithium reagent 9 (0.94 mmol) at room temperature. Mild

reﬂuxing was observed and the deep red solution changed col-

our to a light grey within 5 min. The mixture was poured into

water and extracted with ether (3 × 15 cm³). The organic layers

(Z)-Chloro(2-methylbut-2-enyl)diphenylsilane 7

Chlorodiphenylsilane 6 (6.58 g, 30 mmol), freshly distilled iso-

prene (2.18 g, 32 mmol), triphenylphosphine (0.04 g, 0.15

mmol) and bis(benzonitrile)palladium dichloride (0.025 g,

0.065 mmol) were heated in a sealed tube under argon at 70 ЊC

for 7 h. The excess isoprene was evaporated off under reduced

J. Chem. Soc., Perkin Trans. 1, 1998

2691

View Article Online

were combined, washed with brine (10 cm³), dried (MgSO₄) and

concentrated under reduced pressure. The residue was chrom-

atographed (SiO₂, EtOAc–hexane, 1:4) to give the alcohol

(0.145 g, 55%); R_f(EtOAc–hexane, 1:9) 0.16; ν_max(ﬁlm)/cm^Ϫ1

J 14.1, SiCH H ), 1.28 (3 H, t, J 1.4, MeC᎐CH), 1.11 (3 H,

᎐

A B

d, J 6.7, C᎐CHMe) and 0.87 (3 H, d, J 6.3, MeCHCO); m/z

᎐

428 (37%, M^ϩ), 413 (29, M Ϫ Me), 397 (58, M Ϫ OMe) and

359 (100, M Ϫ CH CMe᎐CHMe) (Found: M^ϩ, 428.2168.

᎐

3394 (br OH), 1662 (C᎐C), 1589 (Ph) and 1113 (SiPh); δ (250

C₂₈H₃₂SiO₂requires M, 428.2172).

᎐

MHz; CDCl₃) 7.66 (4 H, br d, J 5.5, o-SiPh₂), 7.47–7.24 (6 H,

m, m- and p-SiPh₂), 5.21 (1 H, br q, J 6.7, CHMe), 4.65 (1 H, br

s, OH), 3.98 (2 H, s, CH₂O), 2.23 (2 H, s, CH₂C), 1.61 (3 H,

Methyl (Z)-(2RS,3SR)-2-methyl-3-(2-methylbut-2-enyl)-

diphenylsilyl-3-phenylpropanoate 15

t, J 1.4, MeC᎐CH) and 1.50 (3 H, d, J 6.8, CHMe); m/z 282

Methyl 2-methylcinnamate (0.158 g, 0.90 mmol) in THF (1 cm³)

was added dropwise to a stirred solution of freshly prepared

bis-silylcuprate reagent 10 (0.97 mmol) at Ϫ78 ЊC under argon.

The mixture was stirred at this temperature for 1 h, then

allowed to warm slowly to 0 ЊC and stirred at this temperature

for a further 1 h. The mixture was cooled to Ϫ78 ЊC, quenched

with basic aqueous ammonium chloride (10 cm³), ﬁltered

through Celite and extracted with ether (3 × 10 cm³). The

organic layers were combined, washed with basic aqueous

ammonium chloride (5 cm³) and brine (5 cm³), dried (MgSO₄)

and concentrated under reduced pressure. The residue, in which

the diastereoisomers 15 and 13 were present in a ratio of 80:20,

was chromatographed (SiO₂, EtOAc–hexane, 1:9) to give the

β-silyl ester 15 (0.250 g, 65%) as prisms, mp 75–77 ЊC (from

hexane); R_f(EtOAc–hexane, 1:9) 0.31; ν_max(ﬁlm)/cm^Ϫ11740

᎐

(25%, M^ϩ), 251 (19, M Ϫ CH₂OH) and 213 (100, M Ϫ CH₂-

CMe᎐CHMe) (Found: M^ϩ, 282.1449. C H SiO requires M,

᎐

18 22

282.1440).

Lithium

(Z)-bis[(2-methylbut-2-enyl)diphenylsilyl]cyano-

cuprate 10. Freshly prepared silyllithium reagent 9 (2.6 mmol)

was added to a stirred suspension of dry copper() cyanide

(0.096 g, 1.07 mmol) in dry THF (3 cm³) at 0 ЊC under argon.

The red-black mixture was stirred at this temperature for 25

min, and used immediately.

Methyl (Z)-3-(2-methylbut-2-enyl)diphenylsilyl-3-phenyl-

propanoate 12

Methyl cinnamate (0.152 g, 0.94 mmol) in THF (1 cm³) was

added dropwise to a stirred solution of freshly prepared bis-

silylcuprate reagent 10 (1 mmol) at Ϫ78 ЊC under argon and the

mixture stirred at this temperature for 1 h and then at 0 ЊC for

a further 2 h. The mixture was quenched with basic aqueous

ammonium chloride (10 cm³), ﬁltered through Celite and

extracted with ether (3 × 10 cm³). The combined organic layers

were washed with basic aqueous ammonium chloride (5 cm³)

and brine (5 cm³), dried (MgSO₄) and concentrated under

reduced pressure. The residue was chromatographed (SiO₂,

EtOAc–hexane, 15:85) to give the β-silyl ester (0.35 g, 90%) as

prisms, mp 70–71 ЊC (from hexane); R_f(EtOAc–hexane, 15:85)

0.41; ν_max(ﬁlm)/cm^Ϫ11738 (C᎐O), 1663 (C᎐C), 1599 (Ph) and

(C᎐O), 1640 (C᎐C), 1600 (Ph) and 1110 (Si–Ph); δ (250 MHz;

᎐

CDCl₃) 7.64 (2 H, br d, J 7.6, o-SiPh_APh_B), 7.55 (2 H, br d,

J 7.7, o-SiPh_APh_B), 7.48–7.37 (3 H, m, m- and p-SiPh_APh_B),

7.36–7.27 (3 H, m, m- and p-SiPh_APh_B), 7.22–7.10 (3 H, m,

m- and p-CPh), 6.98 (2 H, br d, J 8.3, o-CPh), 4.78 (1 H, br q,

J 6.7, C᎐CHMe), 3.27 (3 H, s, OMe), 3.12 (1 H, d, J 11.7,

᎐

PhCHSi), 2.86 (1 H, dq, J 11.7 and 6.9, CHCO), 1.67 (1 H, d,

J 14.7, SiCH_AH_B), 1.52 (1 H, d, J 14.7, SiCH_AH_B), 1.28 (3 H, t,

J 1.3, MeC᎐CH), 1.14 (3 H, d, J 6.9, MeCHCO) and 0.99 (3 H,

᎐

d, J 6.7, C᎐CHMe); m/z 428 (23%, M^ϩ), 413 (36, M Ϫ Me), 397

(67, M Ϫ OMe) and 359 (100, M Ϫ CH CMe᎐CHMe) (Found:

᎐

1100 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.51–7.29 (10 H, m, SiPh₂),

7.16-7.08 (2 H, m, m- and p-CPh), 6.86 (1 H, br d, J 9.4, o-CPh),

4.90 (1 H, br q, J 6.4, CHMe), 3.46 (3 H, s, OMe), 3.36 (1 H, dd,

J 12.3 and 3.4, PhCHSi), 2.82 (1 H, dd, J 16.1 and 3.4, CH_AH_B-

CO), 2.62 (1 H, dd, J 16.1 and 12.3, CH_AH_BCO), 1.85 (2 H, s,

M^ϩ, 428.2206. C₂₈H₃₂SiO₂requires M, 428.2172) (Found: C,

78.3; H, 7.5. C₂₈H₃₂SiO₂requires C, 78.5; H, 7.5%), and the

β-silyl ester 13 (0.097 g, 25%), identical (TLC, IR, H NMR)

with the ester above.

SiCH ), 1.41 (3 H, t, J 1.5, MeC᎐CH) and 1.08 (3 H, d, J 6.7,

(1E,2ЈZ)-Hex-1-enyl(2Ј-methylbut-2Ј-enyl)diphenylsilane 17

Hex-1-yne (0.29 cm³, 2.5 mmol) was added dropwise to a stirred

solution of freshly prepared bis-silylcuprate reagent 10 (3.1

mmol) at Ϫ78 ЊC under argon. The mixture was stirred at this

temperature for 1 h and then at room temperature overnight.

The mixture was quenched with basic aqueous ammonium

chloride (10 cm³), ﬁltered through Celite and extracted with

light petroleum (3 × 10 cm³). The organic layers were com-

bined, washed with basic aqueous ammonium chloride (5 cm³)

and brine (5 cm³), dried (MgSO₄) and concentrated under

reduced pressure. The residue was chromatographed (SiO₂,

hexane) to give the vinylsilane (0.76 g, 91%); R_f(EtOAc–hexane,

᎐

CHMe); m/z 414 (5%, M^ϩ), 345 (100, M Ϫ CH CMe᎐CHMe)

᎐

and 251 (20, M Ϫ CHPhCH₂CO₂Me) (Found: C, 78.3; H,

7.4%; M^ϩ, 414.2010. C₂₇H₃₀SiO₂requires C, 78.2; H, 7.3%; M,

414.2015).

Methyl (Z)-(2RS,3RS)-2-methyl-3-(2-methylbut-2-enyl)-

diphenylsilyl-3-phenylpropanoate 13

Methyl cinnamate (0.123 g, 0.76 mmol) in THF (1 cm³) was

added dropwise to a stirred solution of freshly prepared bis-

silylcuprate reagent 10 (0.95 mmol) at Ϫ78 ЊC under argon. The

mixture was stirred at this temperature for 1 h, then at 0 ЊC for a

further 1 h and then cooled to Ϫ78 ЊC. Methyl iodide (0.3 cm³,

4.82 mmol) in THF (1 cm³) was added dropwise and the mix-

ture allowed to warm slowly to room temperature and stirred

overnight. The mixture was quenched with basic aqueous

ammonium chloride (10 cm³), ﬁltered through Celite and

extracted with ether (3 × 10 cm³). The organic layers were

combined, washed with basic aqueous ammonium chloride

(5 cm³) and brine (5 cm³), dried (MgSO₄) and concentrated

under reduced pressure. The residue was chromatographed

(SiO₂, EtOAc–hexane, 1:9) to give the β-silyl ester (0.288 g,

89%, as a 93:7 mixture with its diastereoisomer 15); R_f(EtOAc–

hexane, 1:9) 0.40; ν_max(ﬁlm)/cm^Ϫ11745 (C᎐O), 1665 (C᎐C),

1:9) 0.58; ν_max(ﬁlm)/cm^Ϫ11670 (C᎐C), 1600 (Ph) and 1120

᎐

(Si–Ph); δ_H(250 MHz; CDCl₃) 7.68 (4 H, br d, J 7.1, o-SiPh₂),

7.51–7.36 (6 H, m, m- and p-SiPh₂), 6.16 (1 H, dt, J 18.5 and

5.8, SiC᎐CH), 6.02 (1 H, d, J 18.6, SiCH᎐C), 5.15 (1 H, br q,

᎐

J 6.5, C᎐CHMe), 2.25 (2 H, q, J 6.5, C᎐CCH ), 2.18 (2 H, s,

᎐

SiCH ), 1.62 (3 H, t, J 1.4, MeC᎐CH), 1.62–1.31 (4 H, m,

᎐

CH CH Me), 1.40 (3 H, d, J 6.6, C᎐CHMe) and 0.95 (3 H, t,

᎐

J 7.0, CH₂Me); m/z 334 (56%, M^ϩ) and 265 (100, M Ϫ CH₂-

CMe᎐CHMe) (Found: M^ϩ, 334.2115. C H Si requires M,

᎐

23 30

334.2117).

(Z)-Propen-2-yl(2-methylbut-2-enyl)diphenylsilane 19

᎐

1600 (Ph) and 1115 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.69 (2 H, br

d, J 7.8, o-SiPh_APh_B), 7.44 (2 H, br d, J 6.6, o-SiPh_APh_B), 7.42–

7.36 (3 H, m, m- and p-SiPh_APh_B), 7.33–7.23 (3 H, m, m- and

p-SiPh_APh_B), 7.15–7.08 (3 H, m, m- and p-CPh), 6.84 (2 H, br d,

Condensed allene (0.04 cm³at Ϫ78 ЊC, 0.87 mmol) in dry THF

(10 cm³) was added dropwise to a stirred solution of freshly

prepared bis-silylcuprate reagent 10 (2.5 mmol) at Ϫ78 ЊC under

argon. The mixture was stirred at this temperature for 1 h and

then at room temperature overnight. The mixture was quenched

with basic aqueous ammonium chloride (10 cm³), ﬁltered

through Celite and extracted with light petroleum (3 × 10 cm³).

J 7.9, o-CPh), 4.81 (1 H, br q, J 6.4, C᎐CHMe), 3.07 (3 H, s,

᎐

OMe), 3.04 (1 H, d, J 10.7, PhCHSi), 2.96 (1 H, dq, J 10.8 and

6.3, CHCO), 1.76 (1 H, d, J 14.1, SiCH_AH_B), 1.73 (1 H, d,

2692

J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online

The organic layers were combined, washed with basic aqueous

ammonium chloride (5 cm³) and brine (5 cm³), dried (MgSO₄)

and concentrated under reduced pressure. The residue was

chromatographed (SiO₂, hexane) to give the vinylsilane (0.225 g,

The washing was extracted with ether (10 cm³), the organic

layers combined, washed with brine (10 cm³), dried (Na₂SO₄)

and concentrated under reduced pressure to give the allyl alco-

hol (1.175 g, 100%); R_f(EtOAc–hexane, 1:4) 0.40; ν_max(ﬁlm)/

89%); R_f(hexane) 0.62; ν_max(ﬁlm)/cm^Ϫ11662 (C᎐C), 1617

cm^Ϫ13360 (br OH) and 1650 (C᎐C); δ (250 MHz; CDCl ) 5.49

᎐

(C᎐C), 1588 (Ph) and 1109 (Si–Ph); δ (250 MHz; CDCl ) 7.54

(1 H, dt, J 11.1 and 7.1, C᎐CHCH ), 5.38 (1 H, tt, J 11.0

᎐

(4 H, br d, J 7.4, o-SiPh₂), 7.44–7.31 (6 H, m, m- and p-SiPh₂),

5.87 (1 H, br s, C᎐CH H ), 5.44 (1 H, br s, C᎐CH H ), 5.07

and 1.3, CH᎐CHCH ), 4.20 (1 H, t, J 8.3, CHOH), 2.23–1.25

᎐

[18 H, m, (CH₂)₄CHCHO, (CH₂)₄Me and OH] and 0.88 (3 H,

t, J 6.8, Me); m/z 196 (55%, M^ϩ), 127 (87, M Ϫ C₅H₉), 109 (83,

M Ϫ C₅H₉Ϫ H₂O) and 57 [100, Me(CH₂)₃] (Found: M^ϩ,

196.1832. C₁₃H₂₄O requires M, 196.1878).

᎐

(1 H, br q, J 6.3, C᎐CHMe), 2.19 (2 H, s, SiCH ), 1.91 (3 H, t,

᎐

J 1.4, MeC᎐CH ), 1.60 (3 H, t, J 1.4, MeC᎐CH) and 1.26 (3 H,

᎐

dd, J 6.7 and 0.4, C᎐CHMe); m/z 292 (54%, M^ϩ), 251 (32,

᎐

M Ϫ MeC᎐CH ) and 223 (100, M Ϫ CH CMe᎐CHMe)

᎐

(Found: M^ϩ, 292.1646. C₂₀H₂₄Si requires M, 292.1647).

(Z)-1-Cyclopentyloct-2-en-1-yl acetate 22

Acetic anhydride (0.04 cm³, 0.42 mmol), (Z)-1-cyclopentyloct-

2-en-1-yl (0.063 g, 0.32 mmol) and 4-dimethylaminopyridine

(0.044 g, 0.36 mmol) were stirred in dry dichloromethane

(5 cm³) under nitrogen at room temperature overnight. Ether

(5 cm³) and hydrochloric acid (1 mol dm^Ϫ3in H₂O, 5 cm³) were

added, and the organic layer washed with aqueous sodium

hydroxide (1 mol dm^Ϫ3, 5 cm³) and brine (5 cm³), dried (MgSO₄)

and concentrated under reduced pressure. The residue was

chromatographed (SiO₂, EtOAc–hexane, 5:95) to give the acet-

ate (0.064 g, 85%); R_f(EtOAc–hexane, 1:9) 0.47; ν_max(ﬁlm)/

(Z)-(2-Cyclohexylideneethyl)(2-methylbut-2-enyl)diphenylsilane

1-Vinylcyclohexyl acetate²⁷(0.032 g, 0.19 mmol) was added

dropwise to a stirred solution of freshly prepared bis-silyl-

cuprate reagent 10 (0.28 mmol) at Ϫ78 ЊC under argon. The

mixture was stirred at this temperature for 1 h and then at 0 ЊC

for 30 min. The mixture was quenched with basic aqueous

ammonium chloride (10 cm³), ﬁltered through Celite and

extracted with ether (3 × 10 cm³). The organic layers were com-

bined, washed with basic aqueous ammonium chloride (5 cm³)

and brine (5 cm³), dried (MgSO₄) and concentrated under

reduced pressure. The residue was chromatographed (SiO₂,

hexane) to give the allylsilane (0.056 g, 82%); R_f(EtOAc–

cm^Ϫ11740 (C᎐O); δ (250 MHz; CDCl ) 5.53 (1 H, dt, J 10.7

᎐

and 7.4, C᎐CHCH ), 5.41 (1 H, dd, J 9.3 and 8.3, CHOAc),

᎐

5.27 (1 H, ddt, J 10.8, 9.3 and 1.5, CH᎐CHCH ), 2.21–2.04 (3

᎐

H, m, CHCHOAc and C᎐CHCH ), 2.02 (3 H, s, OMe),

᎐

hexane, 2:98) 0.46; ν_max(ﬁlm)/cm^Ϫ11670 (C᎐C), 1600 (Ph) and

᎐

1.75–1.43 [6 H, m, (CH₂)₃Me], 1.41–1.12 [8 H, m, (CH₂)₄-

CHCHOAc)] and 0.87 (3 H, t, J 6.7, CH₂Me); m/z 238 (10%,

M^ϩ), 196 (40, M Ϫ CH₂CO), 179 (33, M Ϫ OAc) and 127

(100, M Ϫ CH₂CO Ϫ C₅H₉) (Found: M^ϩ, 238.1939. C₁₅H₂₆O₂

requires M, 238.1933).

1120 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.55 (4 H, br d, J 5.4,

o-SiPh₂), 7.41–7.29 (6 H, m, m- and p-SiPh₂), 5.15 (1 H, t, J 8.1,

C᎐CHCH ), 5.08 (1 H, br q, J 6.7, CHMe), 2.09 (2 H, s,

᎐

CH CMe), 2.01 (2 H, d, J 8.2, SiCH CH᎐C), 2.01–1.99 [2 H,

᎐

m, (CH ) (CH ) C᎐C], 1.90 [2 H, t, J 6.0, (CH ) (CH ) C᎐C],

᎐

2 B

1.52 (3 H, t, J 1.4, MeC᎐CH), 1.33 (3 H, d, J 6.7, CHMe) and

᎐

1.43–1.19 [6 H, m, (CH ) CH C᎐C]; m/z 360 (53%, M^ϩ), 290

(Z)-1-Cyclopentyloct-2-en-1-yl N-phenylcarbamate 23

᎐

Phenyl isocyanate (0.2 cm³, 1.8 mmol), the allyl alcohol (0.193

g, 0.985 mmol) and triethylamine (0.2 cm³, 1.4 mmol) were

stirred in dry dichloromethane (2 cm³) under nitrogen at room

temperature for 2.5 h. The mixture was quenched with water

(5 cm³) and extracted with dichloromethane (5 × 5 cm³). The

organic layers were combined, washed with aqueous hydro-

chloric acid (0.1 mol dm^Ϫ3, 3 cm³) and brine (3 cm³), dried

(MgSO₄) and concentrated under reduced pressure. The residue

was chromatographed (SiO₂, EtOAc–hexane, 1:4) to give the

carbamate (0.278 g, 82%); R_f(EtOAc–hexane, 1:4) 0.58;

(82, M Ϫ Me C᎐CHMe) and 183 (100, Ph SiH) (Found: M^ϩ,

᎐

360.2273. C₂₅H₃₂Si requires M, 360.2273).

1-Cyclopentyloct-2-yn-1-ol

Butyllithium (1.1 mol dm^Ϫ3in hexane, 2.4 cm³, 2.6 mmol) was

added dropwise to a stirred solution of hept-1-yne (0.34 cm³,

0.88 mmol) in dry THF (20 cm³) at Ϫ78 ЊC under nitrogen.

After stirring at this temperature for 5 min, cyclopentane-

carbaldehyde²⁸(0.258 g, 2.6 mmol) in dry THF (2 cm³) was

added via a cannula and the solution was stirred at this tem-

perature for a further 15 min. The mixture was poured onto

saturated aqueous ammonium chloride (20 cm³) and extracted

with ethyl acetate (4 × 30 cm³). The organic layers were com-

bined, washed with brine (10 cm³), dried (MgSO₄) and concen-

trated under reduced pressure. The residue was chromato-

graphed (SiO₂, EtOAc–hexane, 15:85) to give the propargyl

alcohol (0.422 g, 84%); R_f(EtOAc–hexane, 1:4) 0.40; ν_max(ﬁlm)/

ν_max(ﬁlm)/cm^Ϫ13321 (br NH), 1704 (C᎐O) and 1601 (Ph);

᎐

δ_H(250 MHz; CDCl₃) 7.37 (2 H, d, J 7.5, o-Ph), 7.32–7.25 (2 H,

m, m-Ph), 7.01 (1 H, br t, J 7.2, p-Ph), 6.52 (1 H, br s, NH), 5.57

(1 H, dt, J 10.4 and 7.4, C᎐CHCH ), 5.42 (1 H, dd, J 9.4 and

᎐

7.4, CHO), 5.33 (1 H, ddt, J 10.4, 9.4 and 1.5, CH᎐CHCH ),

᎐

2.21 (2 H, br q, J 7.2, CH C᎐C), 2.09 (1 H, sextet, J 7.7,

᎐

CHCHO), 1.81–1.18 [14 H, m, (CH₂)₄CHCHO) and (CH₂)₃Me]

and 0.87 (3 H, t, J 6.5, Me); m/z 315 (9%, M^ϩ), 271 (19,

M Ϫ CO₂) and 179 (69, M Ϫ OCONHPh) (Found: M^ϩ,

315.2197. C₂₀H₂₉NO₂requires M, 315.2198).

cm^Ϫ13350 (br OH) and 2240 (C᎐C); δ (250 MHz; CDCl ) 4.21

᎐

(1 H, br d, J 6.9, CHOH), 2.18 (2 H, td, J 7.0 and 1.9, CH C᎐C),

᎐

2.13 (1 H, sextet, J 7.5, CHCHOH), 1.75–1.28 [15 H, m,

(CH₂)₄CHCHOH, (CH₂)₃Me and OH] and 0.88 (3 H, t, J

7.0, Me); m/z 194 (57%, M^ϩ), 179 (68, M Ϫ Me), 165 (51,

M Ϫ CH₂Me), 151 (33, M Ϫ CH₂CH₂Me), 138 [13, M Ϫ

(CH₂)₃Me] and 125 (100, M Ϫ C₅H₉) (Found: M^ϩ, 194.1722.

C₁₃H₂₂O requires M, 194.1722).

(1E,2ЈZ)-1-Cyclopentyloct-1-en-3-yl-2Ј-methylbut-2Ј-enyl-

(diphenyl)silane 24

Method 1. Butyllithium (1.43 mol dm^Ϫ3in hexane, 0.28 cm³,

0.40 mmol) was added dropwise to a stirred solution of the

carbamate 23 (0.114 g, 0.36 mmol) in dry THF (2 cm³) at 0 ЊC

under nitrogen. After stirring at this temperature for 2 min the

solution was added via a cannula to a vigorously stirred slurry

of dry copper() iodide (0.069 g, 0.362 mmol) and triphenyl-

phosphine (0.191 g, 0.73 mmol) in dry ether (3 cm³) at 0 ЊC

under nitrogen. The mixture was stirred at this temperature for

a further 45 min forming a yellow slurry. The silyllithium

reagent 9 (0.40 mmol) was added dropwise to the slurry and the

mixture stirred at 0 ЊC for 3 h and then at room temperature for

a further 12 h. The mixture was quenched with basic aqueous

(Z)-1-Cyclopentyloct-2-en-1-ol

A 50 cm³round bottomed ﬂask containing the propargyl alco-

hol (1.163 g, 6 mmol), modiﬁed Lindlar catalyst (Pd ϩ MnCl₂)²⁹

(0.033 g) and quinoline (0.09 g) in heptane (15 cm³), at

room temperature with vigorous stirring, was alternately

evacuated and then ﬂushed with nitrogen 4 times, and the pro-

cedure repeated with hydrogen. The mixture was stirred under

an atmosphere of hydrogen overnight, ﬁltered through Celite

and then washed with aqueous hydrochloric acid (10%, 10 cm³).

J. Chem. Soc., Perkin Trans. 1, 1998

2693

View Article Online

ammonium chloride (10 cm³), ﬁltered through Celite and

extracted with light petroleum (3 × 10 cm³). The organic layers

were combined, washed with basic aqueous ammonium chlor-

ide (5 cm³) and brine (5 cm³), dried (MgSO₄) and concentrated

under reduced pressure. The residue was chromatographed

(SiO₂, hexane) to give the allylsilane (0.098 g, 64%); R_f(EtOAc–

364 (25%, M^ϩ), 345 (62, M Ϫ F) and 201 (100, Ph₂SiF) (Found:

M^ϩ, 364.1296. C₂₂H₂₁SiO₂F requires M, 364.1291).

Methyl 3-(hydroxydiphenylsilyl)-3-phenylpropanoate 26 and

methyl 3-(methoxydiphenylsilyl)-3-phenylpropanoate 27

Hydrochloric acid (10 mol dm^Ϫ3, 5 drops) and the allylsilane 12

(0.05 g, 0.12 mmol) were reﬂuxed in methanol (5 cm³) for 1 h.

The solvent was evaporated under reduced pressure and the

residue taken up in ether (10 cm³), washed with aqueous

sodium hydrogen carbonate (2 cm³) and brine (2 cm³), dried

(MgSO₄) and concentrated under reduced pressure. The residue

was chromatographed (SiO₂, EtOAc–hexane, 1:4) to give

successively the methoxysilane 27 (0.022 g, 49%); R_f(EtOAc–

hexane, 1:9) 0.40; ν_max(ﬁlm)/cm^Ϫ11660 (C᎐C) and 1110 (Si–Ph);

᎐

δ_H(250 MHz; CDCl₃) 7.57–7.47 (4 H, m, o-SiPh₂), 7.41–7.27

(6 H, m, m- and p-SiPh ), 5.24 (1 H, dd, J 15.3 and 7.0, CH᎐

᎐

CHCHSi), 5.13 (1 H, dd, J 15.3 and 9.1, CH᎐CHCHSi), 4.95

᎐

(1 H, br q, J 6.5, C᎐CHMe), 2.35 (1 H, sextet, J 7.4, CHCH᎐

᎐

CHCHSi), 2.13–2.02 (1 H, m, C᎐CHCHSi), 2.08 (1 H, d, J 13.8,

᎐

SiCH_AH_B), 2.02 (1 H, d, J 13.7, SiCH_AH_B), 1.72–1.37 [8 H, m,

(CH ) CHCH᎐CHCHSi], 1.48 (3 H, t, J 1.4, MeC᎐CH), 1.24–

hexane, 1:9) 0.44; ν_max(ﬁlm)/cm^Ϫ11738 (C᎐O) and 1113 (Si–

᎐

1.09 [8 H, m, (CH ) Me], 1.17 (3 H, d, J 6.7, C᎐CHMe) and

Ph); δ_H(250 MHz; CDCl₃) 7.54 (2 H, br d, J 5.5, o-SiPh_APh_B),

7.48–7.20 (8 H, m, m-, p-SiPh₂and o-SiPh_APh_B), 7.16–7.04

(3 H, m, m- and p-CPh), 6.95 (2 H, br d, J 8.0, o-CPh), 3.47

(3 H, s, OMe), 3.46 (3 H, s, OMe), 3.31 (1 H, dd, J 11.1 and 4.7,

PhCHSi), 2.87 (1 H, dd, J 16.2 and 4.7, CH_AH_BCO) and 2.77

(1 H, dd, J 16.2 and 11.1, CH_AH_BCO); m/z 376 (64%, M^ϩ)

and 213 (100, Ph₂SiOMe) (Found: M^ϩ, 376.1530. C₂₃H₂₄SiO₃

requires M, 376.1495), and the silanol 26 (0.021 g, 48%), R_f

(EtOAc–hexane, 1:9) 0.13; ν_max(ﬁlm)/cm^Ϫ13440 (br OH), 1715

᎐

0.82 (3 H, t, J 6.7, CH₂Me); δ_C(100 MHz; CDCl₃) 135.7, 135.0,

134.7, 134.6, 132.7, 128.9, 127.7, 127.2, 117.5, 43.5, 33.2,

31.3, 30.3, 28.8, 28.5, 26.3, 24.9, 22.5, 17.9 and 14.0; m/z 361

(20%, M Ϫ C₅H₉) and 183 (100, Ph₂SiH) (Found: M^ϩϪ C₅H₉,

361.2347. C₂₅H₃₃Si requires M, 361.2351), and the recovered

carbamate 23 (0.021 g, 18%).

Method 2. Freshly prepared silyllithium reagent 9 (0.27

mmol) was added dropwise to stirred slurry of dry copper()

iodide (0.044 g, 0.23 mmol) in dry ether (1.5 cm³) and tri-

phenylphosphine (0.120 g, 0.46 mmol) at 0 ЊC under argon. The

mixture was stirred at this temperature for 20 min. Butyllithium

(1.34 mol dm^Ϫ3in hexane, 0.17 cm³, 0.23 mmol) was added

dropwise to a stirred solution of the carbamate 23 (0.072 g, 0.23

mmol) in dry THF (1 cm³) at 0 ЊC under argon. After stirring at

this temperature for 2 min the solution was added via a cannula

to the silylcopper reagent at 0 ЊC. The mixture was stirred at this

temperature for a further 4 h. The reaction was quenched with

basic aqueous ammonium chloride (1 cm³) and the mixture ﬁl-

tered through Celite and extracted with light petroleum (3 × 5

cm³). The organic layers were combined, washed with basic

aqueous ammonium chloride (3 cm³) and brine (3 cm³), dried

(MgSO₄) and concentrated under reduced pressure. The residue

was chromatographed (SiO₂, light petroleum) to give the

(C᎐O), 1600 (Ph) and 1116 (Si–Ph); δ (250 MHz; CDCl ) 7.57

᎐

(2 H, br d, J 7.5, o-SiPh_APh_B), 7.45–7.28 (8 H, m, m-, p-SiPh₂

and o-SiPh_APh_B), 7.19–7.06 (3 H, m, m- and p-CPh), 6.98 (2 H,

br d, J 6.5, o-CPh), 3.50 (3 H, s, OMe), 3.21 (1 H, dd, J 8.6 and

6.5, PhCHSi), 2.87 (1 H, dd, J 16.4 and 6.6, CH_AH_BCO) and

2.84 (1 H, dd, J 16.4 and 8.7, CH_AH_BCO); m/z 362 (26%, M^ϩ)

and 199 (100, Ph₂SiOH) (Found: M^ϩ, 362.1312. C₂₂H₂₂SiO₃

requires M, 362.1318).

Methyl 3-hydroxy-3-phenylpropanoate 28a

Method 1. Boron triﬂuoride–acetic acid complex (0.04 cm³,

0.16 mmol) was added dropwise to a stirred solution of the

allylsilane 12 (0.051 g, 0.12 mmol) in dichloromethane (5 cm³)

at room temperature under argon. After 30 seconds the mixture

was quenched with sodium hydrogen carbonate (0.175 g, 2.1

mmol) and the solvent evaporated under reduced pressure.

THF (4 cm³), methanol (4 cm³), potassium ﬂuoride (0.03 g, 0.5

mmol) and hydrogen peroxide (30%, 1 cm³, 8.7 mmol) were

added and the mixture was stirred for 3 d at room temperature,

with further hydrogen peroxide (30%, 1 cm³) added each day.

The mixture was poured into water and extracted with dichloro-

methane (5 × 10 cm³). The organic layers were combined,

washed with brine (5 cm³), dried (MgSO₄) and concentrated

under reduced pressure. The residue was chromatographed

(SiO₂, EtOAc–hexane, 1:4) to give the alcohol³⁰(0.017 g, 77%);

R_f(EtOAc–hexane, 1:4) 0.17; ν_max(CDCl₃)/cm^Ϫ13601 (OH),

allylsilane (0.068 g, 69%), identical (TLC, IR, H NMR) with

the earlier sample, and the recovered carbamate 23 (0.014 g,

19%).

Method 3. The allylic acetate 22 (0.048 g, 0.2 mmol) in dry

ether–pentane (1:1, 2 cm³) was added dropwise to a mixture of

the silylcuprate reagent 10 (0.2 mmol) and triphenylphosphine

(0.053 g, 0.2 mmol) and the mixture stirred at 0 ЊC for a further

45 min. The mixture was quenched with basic aqueous ammo-

nium chloride (1 cm³), ﬁltered through Celite and extracted

with light petroleum (3 × 3 cm³). The organic layers were com-

bined, washed with basic aqueous ammonium chloride (2 cm³)

and brine (2 cm³), dried (MgSO₄) and concentrated under

reduced pressure. The residue was chromatographed (SiO₂,

hexane) to give a mixture of the allylsilane and another isomer

(0.067 g, 78%, 4:1).

3510 (br OH), 1726 (C᎐O) and 1605 (Ph); δ (250 MHz; CDCl )

᎐

7.37–7.25 (5 H, m, Ph), 5.14 (1 H, ddd, J 8.0, 4.3 and 3.5,

CHOH), 3.72 (3 H, s, OMe), 3.23 (1 H, d, J 3.4, OH), 2.76 (1 H,

dd, J 16.4 and 8.4, CH_AH_BCO) and 2.72 (1 H, dd, J 16.4 and

4.5, CH_AH_BCO).

Methyl 3-(ﬂuorodiphenylsilyl)-3-phenylpropanoate 25

Method 2. Peracetic acid (36–40% in AcOH, 0.7 cm³, 3.5

mmol) was added dropwise to a stirred mixture of the

allylsilane 12 (0.287 g, 0.69 mmol), potassium bromide (0.099 g,

0.83 mmol) and sodium acetate (0.17 g, 2 mmol) in acetic acid

(3.5 cm³) at 0 ЊC. The mixture was allowed to warm to room

temperature and more peracetic acid (2.1 cm³, 10.5 mmol) and

sodium acetate (0.5 g, 6 mmol) were added and the mixture

stirred overnight. The mixture was quenched with aqueous

sodium thiosulfate solution (25%), the aqueous layer saturated

with salt and the mixture extracted with ethyl acetate (5 × 10

cm³). The combined organic layers were washed with saturated

aqueous sodium hydrogen carbonate (5 cm³) and brine (5 cm³),

dried (Na₂SO₄) and concentrated under reduced pressure. The

residue was chromatographed (SiO₂, EtOAc–hexane, 1:4) to

give the alcohol (0.099 g, 80%), identical (TLC, ¹H NMR) with

the earlier sample.

Boron triﬂuoride–acetic acid complex (0.05 cm³, 0.2 mmol) was

added dropwise to a stirred solution of the allylsilane 12 (0.057

g, 0.14 mmol) in dichloromethane (5 cm³) at 0 ЊC under argon.

TLC indicated that the reaction was complete almost immedi-

ately. The mixture was poured into water and extracted with

dichloromethane (2 × 15 cm³). The organic layers were com-

bined and washed with saturated aqueous sodium hydrogen

carbonate (10 cm³), dried (MgSO₄) and concentrated under

reduced pressure to give the ﬂuorosilane (crude yield 0.050 g,

100%); R_f(EtOAc–hexane, 1:4) 0.34; ν_max(ﬁlm)/cm^Ϫ11745

(C᎐O), 1600 (Ph), 1130 (Si–Ph) and 850 (Si–F); δ (250 MHz;

᎐

CDCl₃) 7.57 (2 H, br d, J 5.7, o-SiPh_APh_B), 7.48–7.27 (8 H,

m, m-, p-SiPh₂and o-SiPh_APh_B), 7.18–7.11 (3 H, m, m- and

p-CPh), 7.04 (2 H, br d, J 6.4, o-CPh), 3.49 (3 H, s, OMe), 3.35

(1 H, q, J 7.5, PhCHSi) and 2.88 (2 H, d, J 7.6, CH₂CO); m/z

2694

J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online

Methyl (2RS,3RS)-2-methyl-3-hydroxy-3-phenylpropanoate 29

and methyl (2RS,3RS)-2-methyl-3-(hydroxydiphenylsilyl)-3-

phenylpropanoate 30

Aqueous sodium thiosulfate (25%) was added to consume

the excess hydrogen peroxide and the mixture acidiﬁed with

aqueous hydrochloric acid (1 mol dm^Ϫ3). The mixture was

poured into water (5 cm³) and extracted with ether (5 × 10 cm³).

The organic layers were combined, washed with brine (5 cm³),

dried (MgSO₄) and concentrated under reduced pressure. The

residue was chromatographed (SiO₂, EtOAc–hexane, 1:1) to

give the acid³⁰(0.031 g, 88%); R_f(MeOH–CH₂Cl₂, 1:9) 0.26;

δ_H(250 MHz; CDCl₃) 7.38–7.25 (5 H, m, Ph), 5.15 (1 H, dd,

J 8.8 and 4.1, CHOH), 5.72 (2 H, br s, OH), 2.83 (1 H, dd,

J 16.6 and 8.8, CH_AH_BCO) and 2.76 (1 H, dd, J 16.7 and 4.1,

CH_AH_BCO).

Boron triﬂuoride–acetic acid complex (0.07 cm³, 0.25 mmol)

was added dropwise to a stirred solution of the allylsilane 13

(0.214 g, 0.5 mmol) in dichloromethane (5 cm³) at room tem-

perature under argon. After 5 min the reaction was quenched

with sodium hydrogen carbonate (0.2 g, 2.4 mmol) and the

solvent evaporated under reduced pressure. THF (4 cm³),

methanol (4 cm³), potassium ﬂuoride (0.03 g, 0.5 mmol) and

hydrogen peroxide (30%, 1 cm³, 8.7 mmol) were added and the

mixture was stirred for 24 h at room temperature. The mixture

was poured into water (5 cm³) and extracted with dichloro-

methane (5 × 10 cm³). The organic layers were combined,

washed with brine (5 cm³), dried (MgSO₄) and concentrated

under reduced pressure. The residue was chromatographed

(SiO₂, EtOAc–hexane, 1:9) to give the alcohol³¹29 (0.032 g,

33%); R_f(EtOAc–hexane, 1:9) 0.07; ν_max(CDCl₃)/cm^Ϫ13603

(E)-Hydroxy(hex-1-enyl)diphenylsilane 33a and (E)-methoxy-

(hex-1-enyl)diphenylsilane 33b

Hydrochloric acid (10 mol dm^Ϫ3, 2 drops) was stirred with the

allylsilane 17 (0.023 g, 0.069 mmol) in methanol (3 cm³) at room

temperature for 2 h. The reaction was quenched with sodium

hydrogen carbonate and the solvent evaporated under reduced

pressure. The residue was taken up in ether (5 cm³), dried

(MgSO₄) and concentrated under reduced pressure. Preparative

TLC (EtOAc–hexane, 1:4) gave, successively, the methoxysilane

33b (0.010 g, 49%); R_f(EtOAc–hexane, 1:4) 0.69; ν_max(ﬁlm)/

(OH), 3510 (br OH), 1736 (C᎐O), 1604 (Ph) and 1587 (Ph);

᎐

δ_H(250 MHz; CDCl₃) 7.38–7.26 (5 H, m, Ph), 4.73 (1 H, d, J 8.6,

CHOH), 3.72 (3 H, s, OMe), 2.95 (1 H, br s, OH), 2.81 (1 H, qn,

J 7.2, CHMe) and 0.99 (3 H, d, J 7.2, CHMe) and the silanol 30

(0.082 g, 44%); R_f(EtOAc–hexane, 1:9) 0.14; ν_max(CDCl₃)/cm^Ϫ1

3649 (OH), 3530 (br OH), 1720 (C᎐O), 1599 (Ph) and 1590

cm^Ϫ11620 (C᎐C) and 1120 (Si–Ph); δ (250 MHz; CDCl ) 7.65–

᎐

(Ph); δ_H(250 MHz; CDCl₃) 7.58 (2 H, br d, J 7.7, o-SiPh_APh_B),

7.44 (2 H, br d, J 7.5, o-SiPh_APh_B), 7.40–7.31 (3 H, m, m- and

p-SiPh_APh_B), 7.28–7.22 (3 H, m, m- and p-SiPh_APh_B), 7.16–7.11

(3 H, m, m- and p-CPh), 6.97 (2 H, br d, J 6.5, o-CPh), 3.28

(3 H, s, OMe), 3.12 (1 H, dq, J 11.0 and 6.6, CHMe), 2.96 (1 H,

d, J 11.0, SiCH) and 1.04 (3 H, d, J 6.7, CHMe).

7.51 (4 H, m, o-SiPh₂), 7.49–7.28 (6 H, m, m- and p-SiPh₂), 6.30

(1 H, dt, J 18.7 and 6.2, C᎐CHCH ), 5.97 (1 H, dt, J 18.7 and

᎐

1.4, SiCH᎐C), 3.57 (3 H, s, OMe), 2.22 (2 H, br q, J 6.5,

᎐

C᎐CHCH ), 1.62–1.01 (4 H, m, CH CH Me) and 0.92 (3 H, t,

᎐

J 7.3, CHMe); m/z 296 (14%, M^ϩ), 239 (32, M Ϫ C₄H₉) and 213

(100, Ph₂SiOMe) (Found: M^ϩ, 296.1603. C₁₉H₂₄SiO requires

M, 296.1596) and the silanol 33a (0.009 g, 46%), R_f(EtOAc–

hexane, 1:4) 0.31; ν_max(ﬁlm)/cm^Ϫ13620 (br OH), 1600 (Ph) and

1120 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.63–7.57 (4 H, m, o-SiPh₂),

7.45–7.33 (6 H, m, m- and p-SiPh₂), 6.32 (1 H, dt, J 18.7 and

6.2, C᎐CHCH ), 5.97 (1 H, dt, J 18.7 and 1.4, SiCH᎐C), 2.20

Methyl (2RS,3SR)-2-methyl-3-hydroxy-3-phenylpropanoate 31

and methyl (2RS,3SR)-2-methyl-3-(hydroxydiphenylsilyl)-3-

phenylpropanoate 32

Boron triﬂuoride–acetic acid complex (0.04 cm³, 0.14 mmol)

was added dropwise to a stirred solution of the allylsilane

15 (0.051 g, 0.12 mmol) in dichloromethane (5 cm³) at room

temperature under argon. After 30 seconds the reaction was

quenched with sodium hydrogen carbonate (0.175 g, 2.1 mmol)

and the solvent evaporated under reduced pressure. THF (4

cm³), methanol (4 cm³), potassium ﬂuoride (0.03 g, 0.5 mmol)

and hydrogen peroxide (30%, 1 cm³, 8.7 mmol) were added

and the mixture was stirred for 3 d at room temperature, with

further hydrogen peroxide (30%, 1 cm³) added each day. The

mixture was poured into water (5 cm³) and extracted with

dichloromethane (5 × 10 cm³). The organic layers were com-

bined, washed with brine (5 cm³), dried (MgSO₄) and concen-

trated under reduced pressure. The residue was chromato-

graphed (SiO₂, EtOAc–hexane, 1:4) to give, successively, the

alcohol³¹31 (0.015 g, 65%); R_f(EtOAc–hexane, 1:4) 0.21;

᎐

(2 H, br q, J 6.5, C᎐CHCH ), 1.55–1.11 (5 H, m, CH CH Me

᎐

and OH) and 0.92 (3 H, t, J 6.7, Me); m/z 282 (13%, M^ϩ),

225 (51, M Ϫ C₄H₉) and 199 (100, Ph₂SiOH) (Found: M^ϩ,

282.1441. C₁₈H₂₂SiO requires M, 282.1440).

Hexanal 2,4-dinitrophenylhydrazone 34

Boron triﬂuoride–acetic acid complex (0.2 cm³, 0.8 mmol) was

added dropwise to a stirred solution of the allylsilane 17 (0.207

g, 0.62 mmol) in dichloromethane (15 cm³) at Ϫ10 ЊC under

argon. After 5 min the reaction was quenched with sodium

hydrogen carbonate (0.29 g, 3.5 mmol) and the solvent evapor-

ated under reduced pressure. THF (6 cm³), methanol (6 cm³),

potassium ﬂuoride (0.15 g, 2.5 mmol) and hydrogen peroxide

(30%, 2 cm³, 17.4 mmol) were added and the mixture was

stirred at room temperature overnight. A solution of 2,4-

dinitrophenylhydrazine (0.25 g, 1.3 mmol) and sulfuric acid

(98%, 0.5 cm³) in methanol (5 cm³) was added dropwise and the

mixture stirred for a further 1 h at room temperature. The sol-

vents were evaporated under reduced pressure and the residue

taken up in ether (10 cm³), washed with aqueous sodium

hydroxide (1 mol dm^Ϫ3, 2 cm³), and brine (2 cm³), dried

(MgSO₄) and concentrated under reduced pressure to give the

hydrazone (0.073 g, 42%) as yellow prisms, mp 107–108 ЊC

(from EtOH) (lit.,³²108 ЊC); ν_max(CDCl₃)/cm^Ϫ13307 (NH), 1619

ν_max(CDCl₃)/cm^Ϫ13607 (OH), 3530 (br OH), 1719 (C᎐O) and

᎐

1605 (Ph); δ_H(250 MHz; CDCl₃) 7.38–7.26 (5 H, m, Ph), 5.11

(1 H, d, J 4.0, CHOH), 3.67 (3 H, s, OMe), 2.95 (1 H, br s, OH),

2.79 (1 H, dq, J 7.1 and 4.1, CHMe) and 0.99 (3 H, d, J 7.2,

CHMe) and the silanol 32 (0.004 g, 9%), R_f(EtOAc–hexane,

1:4) 0.30; ν_max(CDCl₃)/cm^Ϫ13650 (OH), 3480 (br OH), 1732

(C᎐O), 1598 (Ph) and 1590 (Ph); δ (250 MHz; CDCl ) 7.67

᎐

(2 H, br d, J 6.9, o-SiPh_APh_B), 7.45–7.11 (11 H, m, m-, p-SiPh₂,

m-, p-CPh and o-SiPh_APh_B), 7.04 (2 H, br d, J 7.5, o-CPh), 3.61

(1 H, br s, OH), 3.46 (3 H, s, OMe), 3.15 (1 H, qn, J 7.1,

PhCHSi), 2.95 (1 H, d, J 7.3, SiCH) and 1.17 (3 H, d, J 7.0,

CHMe).

(C᎐N), 1594 (Ar), 1520 (NO ) and 1336 (NO ); δ (250

᎐

MHz; CDCl₃) 11.01 (1 H, s, NH), 9.13 (1 H, d, J 2.5, 3-ArH),

8.29 (1 H, dd, J 9.5 and 2.5, 5-ArH), 7.92 (1 H, d, J 9.6, 6-ArH),

7.53 (1 H, t, J 5.4, CH᎐N), 2.33–2.22 (2 H, m, CH C᎐N), 1.71–

᎐

3-Hydroxy-3-phenylpropanoic acid 28b

1.55 (2 H, m, CH CH C᎐N), 1.43-1.28 (4 H, m, CH CH Me)

᎐

2 2 2 2

and 1.00–0.83 (3 H, m, Me).

Sulfuric acid (98%, 5 drops) was stirred with the allylsilane 12

(0.088 g, 0.21 mmol) in methanol (5 cm³) at room temperature

for 3 h. The reaction was quenched with sodium hydrogen carb-

onate (0.175 g, 2.1 mmol). THF (5 cm³), potassium ﬂuoride

(0.03 g, 0.5 mmol) and hydrogen peroxide (30%, 1 cm³, 8.7

mmol) were added and the mixture was reﬂuxed overnight.

Hydroxy(2-cyclohexylideneethyl)diphenylsilane 35a and

methoxy(2-cyclohexylideneethyl)diphenylsilane 35b

Hydrochloric acid (10 mol dm^Ϫ3, 2 drops) was stirred with the

allylsilane 21 (0.031 g, 0.086 mmol) in methanol (3 cm³) at room

J. Chem. Soc., Perkin Trans. 1, 1998

2695

View Article Online

temperature for 3 h. The reaction was quenched with sodium

hydrogen carbonate and the solvent evaporated under reduced

pressure. The residue was taken up in ether (5 cm³), dried

(MgSO₄) and concentrated under reduced pressure. Preparative

TLC (EtOAc–hexane, 1:4) gave, successively, the methoxysilane

35b (0.013 g, 49%); R_f(EtOAc–hexane, 1:4) 0.63; ν_max(CH₂Cl₂)/

cm^Ϫ11580 (Ph) and 1100 (Si–Ph); δ_H(250 MHz; CDCl₃) 7.59

(4 H, br d, J 7.3, o-SiPh₂), 7.45–7.31 (6 H, m, m- and p-SiPh₂),

(0.013 g, 0.03 mmol) were stirred in a mixture of THF and

methanol (1:1, 4 cm³) at room temperature for 3 h. The reac-

tion was quenched with sodium hydrogen carbonate and the

solvent evaporated under reduced pressure. The residue was

taken up in ether (10 cm³), washed with water (2 cm³) and brine

(2 cm³), dried (MgSO₄) and concentrated under reduced pres-

sure to give a 5:2 mixture of the silanol 37a and the methoxy-

silane 37b (0.014 g); δ_H(250 MHz; CDCl₃) 7.64–7.49 (4 H, m,

o-SiPh₂), 7.41–7.31 (6 H, m, m- and p-SiPh₂), 5.27–5.16 (2 H, m,

5.15 (1 H, t, J 8.2, C᎐CH), 3.54 (3 H, s, Me), 2.06 (2 H, d, J 8.2,

᎐

SiCH ), 2.05–1.91 [2 H, m, (CH ) (CH ) C᎐C], 1.93 [2 H, t,

CH᎐CH), 3.05 (3 H, s, OMe 37b), 2.36 (1 H, sextet, J 7.4,

᎐

2 B

᎐

J 5.9, (CH ) (CH ) C᎐C], 1.43–1.33 (4 H, m, 2 × CH CH -

CHCH᎐CHCHO), 2.20–2.03 (1 H, m, SiCHCH ), 1.72–1.06

᎐

C᎐C) and 1.30–1.12 (2 H, m, CH CH CH C᎐C); m/z 322 (76%,

[16 H, m, 2 × (CH₂)₄] and 0.83 (3 H, t, J 6.7, CH₂Me).

᎐

M^ϩ), 291 (9, M Ϫ OMe) and 213 (100, Ph₂SiOMe) (Found: M^ϩ,

322.1767. C₂₁H₂₆SiO requires M, 322.1753) and the silanol 35a

(0.014 g, 51%), R_f(EtOAc–hexane, 1:4) 0.33; ν_max(CH₂Cl₂)/

cm^Ϫ13610 (br OH); δ_H(250 MHz; CDCl₃) 7.64 (4 H, br d, J 7.4,

o-SiPh₂), 7.48–7.33 (6 H, m, m- and p-SiPh₂), 5.20 (1 H, t, J 8.3,

(E)-1-Cyclopentyloct-1-en-3-ol 38

Method 1. Hydrochloric acid (10 mol dm^Ϫ3, 4 drops) and the

allylsilane 24 (0.105 g, 0.24 mmol) were stirred in a mixture of

THF and methanol (1:1, 8 cm³) at room temperature over-

night. The reaction was quenched with sodium hydrogen carb-

onate (0.145 g, 1.73 mmol). Potassium ﬂuoride (0.030 g, 0.5

mmol) and hydrogen peroxide (30%, 1 cm³, 8.7 mmol) were

added and the mixture was stirred at room temperature for 12

h. Additional hydrogen peroxide (1 cm³) was added and the

mixture was reﬂuxed for 6 h. The excess hydrogen peroxide was

quenched with sodium sulﬁte and the mixture acidiﬁed with

aqueous hydrochloric acid (1 mol dm^Ϫ3). The organic solvents

were evaporated off under reduced pressure. The aqueous resi-

due was extracted with ether (4 × 5 cm³) and the organic layers

combined, washed with brine (2 cm³), dried (MgSO₄), and con-

centrated under reduced pressure. The residue was chromato-

graphed (SiO₂, EtOAc–hexane, 7:93) to give the alcohol³⁴

(0.022 g, 57%); R_f(EtOAc–hexane, 1:4) 0.38; ν_max(CDCl₃)/cm^Ϫ1

C᎐CH), 2.50 (1 H, br s, OH), 2.09–1.99 (6 H, m, 3 × CH C᎐C),

᎐

1.55–1.47 (4 H, m, 2 × CH CH C᎐C) and 1.38–1.22 (2 H, m,

᎐

CH CH CH C᎐C); m/z 308 (59%, M^ϩ) and 199 (100, Ph SiOH)

᎐

(Found: M^ϩ, 308.1590. C₂₀H₂₄SiO requires M, 308.1596).

Fluoro(2-cyclohexylideneethyl)diphenylsilane 35c

Boron triﬂuoride–acetic acid complex (0.04 cm³, 0.16 mmol)

was added dropwise to a stirred solution of the allylsilane 21

(0.058 g, 0.16 mmol) in dichloromethane (5 cm³) at Ϫ10 ЊC

under argon. After 5 min the reaction was quenched with

sodium hydrogen carbonate (0.17 g, 2.0 mmol) and the mixture

washed with water (5 cm³) and extracted with dichloromethane

(2 × 15 cm³). The organic layers were combined, washed with

brine (5 cm³), dried (MgSO₄) and concentrated under reduced

pressure to give the crude ﬂuorosilane (0.050 g, 100%); R_f

(EtOAc–hexane, 1:4) 0.46; δ_H(250 MHz; CDCl₃) 7.78–7.60

(4 H, m, o-SiPh₂), 7.59–7.25 (6 H, m, m- and p-SiPh₂), 5.17 (1 H,

3605 (OH) and 1667 (C᎐C); δ (250 MHz; CDCl ) 5.60 (1 H, dd,

᎐

J 15.4 and 7.3, C᎐CHCHOH), 5.41 (1 H, dd, J 15.3 and 7.5,

᎐

CH᎐CHCHOH), 4.01 (1 H, q, J 6.5, CHOH), 2.43 (1 H, sextet,

᎐

t, J 8.2, C᎐CH), 2.36–2.03 (6 H, m, 3 × CH C᎐C) and 1.75–1.19

J 7.8, CHCH᎐CHCHOH), 1.79–1.20 [17 H, m, 2 × (CH ) and

᎐

2 4

᎐

[6 H, m, (CH ) CH C᎐C].

OH] and 0.87 (3 H, t, J 6.6, CH₂Me).

᎐

Method 2. Hydrogen peroxide (30%, 2 cm³, 17.4 mmol),

sodium hydrogen carbonate (0.163 g, 1.94 mmol), potassium

ﬂuoride (0.045 g, 0.78 mmol), potassium bromide (0.092 g, 0.77

mmol) and the allylsilane 24 (0.105 g, 0.24 mmol) were reﬂuxed

in a mixture of THF and methanol (1:1, 8 cm³) for 12 h. The

excess hydrogen peroxide was quenched with sodium sulﬁte.

The mixture was acidiﬁed with aqueous hydrochloric acid

(1 mol dm^Ϫ3) and the organic solvents evaporated off under

reduced pressure. The aqueous residue was extracted with ether

(4 × 5 cm³) and the organic layers combined, washed with brine

(2 cm³), dried (MgSO₄), and concentrated under reduced pres-

sure. The residue was chromatographed (SiO₂, EtOAc–hexane,

7:93) to give the alcohol (0.051 g, 67%), identical (TLC, IR, ¹H

NMR) to the earlier sample.

2-Cyclohexylideneethanol 36

Method 1. Hydrochloric acid (10 mol dm^Ϫ3, 9 drops) was

stirred with the allylsilane 21 (0.104 g, 0.28 mmol) in a THF–

methanol mixture (1:1, 8 cm³) at room temperature for 3 h. The

reaction was quenched with sodium hydrogen carbonate (0.350

g, 4.2 mmol). Potassium ﬂuoride (0.060 g, 1.0 mmol) and

hydrogen peroxide (30%, 1 cm³, 8.7 mmol) were added and the

mixture was reﬂuxed for 3 h. The mixture was poured into

water (5 cm³) and extracted with dichloromethane (5 × 10 cm³).

The organic layers were combined, washed with brine (5 cm³),

dried (MgSO₄) and evaporated under reduced pressure. The

residue was chromatographed (SiO₂, EtOAc–hexane, 1:4) to

give the alcohol³³(0.022 g, 60%); R_f(EtOAc–hexane, 1:4) 0.27;

ν_max(CDCl₃)/cm^Ϫ13330 (br OH) and 1667 (C᎐C); δ (250 MHz;

᎐

CDCl ) 5.34 (1 H, br t, J 7.1, C᎐CH), 4.12 (2 H, d, J 7.1,

(1S,5R,6R,7R)-7-Benzoyloxy-6-formyl-2-oxabicyclo[3.3.0]-

octan-3-one 40

᎐

CH O), 2.17 [2 H, br s, (CH ) (CH ) C᎐C], 2.09 [2 H, br s,

᎐

2 B

(CH ) (CH ) C᎐C], 1.54 [6 H, br s, (CH ) CH C᎐C] and 1.23

(1 H, v br s, OH).

(1S,5R,6R,7R)-7-Benzoyloxy-6-hydroxymethyl-2-oxabicyclo-

[3.3.0]octan-3-one 39^{23,24,35–37}[mp 116–117 ЊC (lit.,³⁷115–

116 ЊC) (Found: C, 65.3; H, 5.8. C₁₅H₁₆O₅requires C, 65.2; H,

5.8%)] (0.559 g, 2 mmol) in dry dichloromethane (4 cm³) was

added via a cannula to a solution of Dess–Martin periodinane³⁸

(1 g, 2.4 mmol) in dry dichloromethane (8 cm³) at 0 ЊC under

argon. The reaction was allowed to warm to room temperature

for 1 h, after which a white precipitate had formed. Ether (20

cm³) was added and the mixture was cooled to 0 ЊC. Sodium

thiosulfate (4 g) and saturated aqueous sodium hydrogen car-

bonate (20 cm³) were added and the mixture warmed to room

temperature and stirred for a further 10 min after which the

precipitate had gone. The mixture was extracted with ether

(3 × 10 cm³) and the organic layers combined, washed with sat-

urated aqueous sodium hydrogen carbonate (5 cm³) and brine

(5 cm³), dried (Na₂SO₄) and concentrated under reduced pres-

sure to give the aldehyde³⁷(0.555 g, 100%), which was used

᎐

Method 2. The allylsilane 21 (0.18 g, 0.5 mmol), sodium

hydrogen carbonate (0.25 g, 3 mmol), potassium ﬂuoride (0.058

g, 1 mmol), potassium bromide (0.12 g, 1 mmol) and hydrogen

peroxide (30%, 2 cm³, 17.4 mmol) were reﬂuxed in a THF–

methanol mixture (1:1, 10 cm³) overnight. Water (5 cm³) was

added and the mixture extracted with ethyl acetate (2 × 20 cm³).

The combined organic layers were washed with brine (5 cm³),

dried (MgSO₄) and evaporated under reduced pressure. The

residue was chromatographed (SiO₂, EtOAc–hexane, 1:4) to

give the alcohol (0.037 g, 59%) identical (TLC, ¹H NMR) with

the earlier sample.

(E)-Hydroxy(1-cyclopentyloct-1-en-3-yl)diphenylsilane 37a and

(E)-methoxy(1-cyclopentyloct-1-en-3-yl)diphenylsilane 37b

Hydrochloric acid (10 mol dm^Ϫ3, 6 drops) and the allylsilane 24

2696

J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online

immediately without further puriﬁcation; R_f(Et₂O) 0.10; δ_H(250

(2 H, d, J 7.7, o-Ph), 7.55 (1 H, br t, J 7.5, p-Ph), 7.43 (2 H, br t,

J 7.7, m-Ph), 5.57 (1 H, dt, J 11.0 and 7.3, C᎐CHCH ), 5.46

MHz; CDCl ) 9.81 (1 H, s, CH᎐O), 7.97 (2 H, br d, J 7.1, o-Ph),

᎐

7.55 (1 H, br t, J 7.2, p-Ph), 7.43 (2 H, br t, J 7.5, m-Ph), 5.74 (1

H, br d, J 5.4, CHOBz), 5.13 (1 H, br t, J 6.3, CHOCOCH₂),

(1 H, dd, J 10.9 and 8.7, CH᎐CHCH ), 5.36 (1 H, dt, J 6.1 and

᎐

3.4, CHOBz), 5.08 (1 H, t, J 6.4, CHOCOCH₂), 4.55 (1 H, ddd,

J 8.6, 5.3 and 3.3, CHOH), 3.17–3.09 (1 H, m, CHCH₂CO₂),

2.93 (1 H, dd, J 18.2 and 10.3, CH_AH_BCO₂), 2.55 (1 H, dd,

J 18.3 and 2.3, CH_AH_BCO₂), 2.45 (1 H, dt, J 15.6 and 6.0,

CH_AH_BCOBz), 2.35 (1 H, br d, J 15.6, CH_AH_BCOBz), 2.18

3.57–3.46 (1 H, m, CHCH CO), 3.19 (1 H, br s, CHCH᎐O),

᎐

2.97 (1 H, dd, J 18.5 and 10.9, CH_AH_BCO₂), 2.53–2.43 (1 H, m,

CH_AH_BCOBz), 2.47 (1 H, dd, J 18.5 and 2.5, CH_AH_BCO₂) and

2.04 (1 H, dt, J 16.0 and 5.7, CH_AH_BCOBz).

(1 H, br q, J 4.6, CHCHOBz), 2.15–1.96 (2 H, m, CH C᎐C),

᎐

(1S,5R,6R,7R,1ЈS)-7-Benzoyloxy-6-(1Ј-hydroxyoct-2Ј-ynyl)-2-

oxabicyclo[3.3.0]octan-3-one 41 and (1S,5R,6R,7R,1ЈR)-7-

benzoyloxy-6-(1Ј-hydroxyoct-2Ј-ynyl)-2-oxabicyclo[3.3.0]octan-

3-one 42

1.36 (2 H, quintet, J 7.7, C᎐CHCH CH ), 1.33–1.22 (4 H, m,

᎐

2 2

CH₂CH₂Me) and 0.86 (3 H, t, J 6.8, Me); δ_C(100 MHz; CDCl₃)

176.9, 166.3, 134.3, 133.3, 129.7, 129.6, 128.5, 85.0, 78.3, 67.4,

59.0, 38.7, 38.6, 36.7, 31.5, 29.2, 27.8, 22.4 and 14.0 (Found: C,

70.9; H, 7.5. C₂₅H₂₈O₅requires C, 70.9; H, 7.6%), and the

(1ЈS)-allyl alcohol 44 (0.192 g, 37%); R_f(Et₂O) 0.37; [α]_DϪ38.8

n-Butyllithium (1.43 mol dm^Ϫ3in hexane, 2.8 cm³, 4 mmol) was

added dropwise to a stirred solution of hept-1-yne (0.52 cm³, 4

mmol) in dry THF (25 cm³) at Ϫ78 ЊC under argon. After stir-

ring at this temperature for 10 min, the solution was added via a

cannula to a slurry of cerium trichloride (dried at 140 ЊC at 0.1

mmHg for 4 h) in dry THF (2 cm³) also at Ϫ78 ЊC under argon.

The mixture was stirred at this temperature for 1 h and then at

0 ЊC for 30 min forming a yellow coloured slurry. The aldehyde

40 (0.555 g, 2 mmol) in dry THF (7 cm³) was added slowly via

a cannula to this slurry at Ϫ78 ЊC, and the mixture stirred for

30 min. The reaction was quenched with saturated aqueous

ammonium chloride (10 cm³) and the mixture extracted with

ether (3 × 20 cm³). The organic layers were combined, washed

with brine (10 cm³), dried (MgSO₄) and concentrated under

reduced pressure. The residue was chromatographed (SiO₂,

EtOAc–light petroleum, 1:1) to give the propargyl alcohols 41

and 42 (0.537 g, 72%) in a 5:3 ratio, which were inseparable by

(c 1.4, CHCl₃); ν_max(ﬁlm)/cm^Ϫ13450 (br OH), 1772 (C᎐O), 1719

᎐

(C᎐O) and 1601 (Ph); δ (400 MHz; CDCl ) 7.97 (2 H, d, J 7.1,

᎐

o-Ph), 7.53 (1 H, br t, J 7.4, p-Ph), 7.42 (2 H, br t, J 7.7, m-Ph),

5.59 (1 H, dt, J 11.0 and 7.4, C᎐CHCH ), 5.53 (1 H, dt, J 5.6

᎐

and 2.7, CHOBz), 5.42 (1 H, dd, J 10.9 and 9.2, CH᎐CHCH ),

᎐

5.04 (1 H, t, J 5.8, CHOCOCH₂), 4.41 (1 H, dd, J 8.8 and 7.2,

CHOH), 2.89 (1 H, dd, J 17.5 and 10.2, CH_AH_BCO₂), 2.88–2.78

(1 H, m, CHCH₂CO₂), 2.54 (1 H, dd, J 17.5 and 1.4, CH_AH_B-

CO₂), 2.44 (1 H, dt, J 15.8 and 5.7, CH_AH_BCOBz), 2.38 (1 H, br

d, J 15.8, CH_AH_BCOBz), 2.28–2.24 (1 H, m, CHCHOBz), 2.17–

1.97 (2 H, m, CH C᎐C), 1.36 (2 H, quintet, J 7.2, C᎐CHCH -

᎐

CH₂), 1.33–1.20 (4 H, m, CH₂CH₂Me) and 0.85 (3 H, t, J 6.8,

Me); δ_C(100 MHz; CDCl₃) 176.8, 166.2, 134.9, 133.3, 129.72,

129.67, 129.2, 128.5, 85.1, 77.6, 67.8, 59.3, 40.6, 38.7, 36.7,

31.5, 29.2, 27.8, 22.5 and 14.0; m/z 372 (16%, M^ϩ), 355

(41, M Ϫ OH), 354 (34, M Ϫ H₂O), 301 [23, M Ϫ (CH₂)₄Me],

chromatography; R_f(Et₂O) 0.44; ν_max(ﬁlm)/cm^Ϫ13452 (br OH),

᎐

2360 (C᎐C), 1770 (C᎐O), 1715 (C᎐O), 1602 (Ph) and 1584 (Ph);

275 [66, M Ϫ CH᎐CH(CH ) Me], 250 (36, M Ϫ BzOH), 232

᎐

2 4

᎐

δ_H(250 MHz; CDCl₃) 8.00 (2 H, br d, J 7.6, o-Ph), 7.55 (1 H, br

t, J 7.4, p-Ph), 7.43 (2 H, br t, J 7.5, m-Ph), 5.46 (1 H, dt, J 6.7

and 3.5, CHOBz), 5.05 (1 H, br t, J 5.6, CHOCOCH₂), 4.64–

4.58 (1 H, m, CHOH major), 4.58-4.51 (1 H, m, CHOH minor),

3.14–3.01 (1 H, m, CHCH₂CO₂), 2.93 (1 H, dd, J 17.9 and 9.8,

CH_AH_BCO₂), 2.63 (1 H, dd, J 18.0 and 2.0, CH_AH_BCO₂), 2.54

(1 H, dt, J 16.9 and 6.2, CH_AH_BCOBz), 2.45–2.30 (2 H, m,

CH_AH_BCOBz and CHCHCOH), 2.18 (2 H, td, J 7.0 and 2.0,

(60, M Ϫ BzOH Ϫ H₂O) and 105 (100, PhCO^ϩ) (Found: M^ϩ,

372.1915. C₂₂H₂₈O₅requires M, 372.1937).

(Z)-(1S,5R,6R,7R,1ЈS)-7-Hydroxy-6-(1Ј-hydroxyoct-2Ј-enyl)-2-

oxabicyclo[3.3.0]octan-3-one 46

Potassium carbonate (0.037 g, 0.27 mmol) was added to a

stirred solution of the benzoate 44 (0.069 g, 0.185 mmol) in

methanol (1 cm³). The mixture was stirred at room temperature

overnight and then acidiﬁed with aqueous hydrochloric acid

(3 mol dm^Ϫ3). The solvent was evaporated under reduced pres-

sure and the residue taken up in ether (5 cm³), dried (MgSO₄),

and concentrated under reduced pressure. The residue was

chromatographed (SiO₂, EtOAc) to give the diol⁴(0.035 g,

74%); R_f(EtOAc) 0.38; [α]_Dϩ28.9 (c 1.0, CHCl₃); ν_max(CDCl₃)/

cm^Ϫ13608 (OH), 3450 (br OH), 1765 (C᎐O) and 1655 (C᎐C);

᎐

C᎐CCH major), 2.13 (2 H, td, J 7.1 and 2.0, C᎐CCH minor),

᎐

1.53–1.35 (2 H, m, C᎐CCH CH ), 1.35–1.23 (4 H, m, CH CH -

᎐

Me) and 0.92–0.82 (3 H, m, Me); δ_C(100 MHz; CDCl₃) 176.6,

171.2, 166.5, 133.5, 133.4, 133.3, 129.7, 129.6, 128.6, 128.5,

88.0, 87.4, 85.0, 84.8, 84.7, 78.8, 78.5, 77.7, 77.2, 66.7, 63.0,

62.2, 60.4, 59.2, 59.0, 40.4, 39.6, 39.1, 38.9, 38.5, 38.3, 36.6,

36.4, 35.8, 31.1, 28.20, 28.15, 27.2, 22.1, 21.1, 19.1, 18.6, 14.2

and 13.9; m/z 248 (80%, M Ϫ BzOH), 230 (24, M Ϫ BzOH Ϫ

H₂O) and 105 (100, PhCO^ϩ) (Found: M^ϩϪ BzOH, 248.1432.

C₂₂H₂₆O₅Ϫ BzOH requires M, 248.1412).

᎐

δ (250 MHz; CDCl ) 5.57 (1 H, dt, J 11.1 and 7.4, C᎐CHCH ),

᎐

5.36 (1 H, br t, J 10.3, CH᎐CHCH ), 4.84 (1 H, dt, J 7.2

᎐

and 4.0, CHOCOCH ), 4.38 (1 H, t, J 9.0, C᎐CCHOH), 4.20

᎐

(1 H, q, J 7.3, CH₂CHOH), 2.66 (1 H, dd, J 18.5 and 9.8,

CH_AH_BCO₂), 2.57–2.35 (3 H, m, CH_AH_BCO₂, CHCH₂CO₂and

(Z)-(1S,5R,6R,7R,1ЈR)-7-Benzoyloxy-6-(1Ј-hydroxyoct-2Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one 43 and (Z)-(1S,5R,6R,

7R,1ЈS)-7-benzoyloxy-6-(1Ј-hydroxyoct-2Ј-enyl)-2-oxabicyclo-

[3.3.0]octan-3-one 44

CH H COH), 2.19–1.79 (4 H, m, CH C᎐C, CH H COH and

᎐

CHCHCOH), 1.37–1.23 [6 H, m, (CH₂)₃Me] and 0.86 (3 H, t,

J 6.7, Me); δ_C(100 MHz; CDCl₃) 176.8, 134.5, 129.8, 82.5, 76.0,

71.4, 57.7, 40.3, 39.6, 35.2, 31.5, 29.3, 27.9, 22.5 and 14.0; m/z

268 (13%, M^ϩ), 250 (39, M Ϫ H₂O), 232 (25, M Ϫ 2H₂O), 197

[81, M Ϫ (CH₂)₄Me], 179 [51, M Ϫ (CH₂)₄Me Ϫ H₂O] and 161

[15, M Ϫ (CH₂)₄Me Ϫ 2H₂O] (Found: M^ϩ, 268.1674. C₁₅H₂₄O₄

requires M, 268.1675).

The propargyl alcohols 41 and 42 (0.521 g, 1.41 mmol), the

modiﬁed Lindlar catalyst (Pd ϩ MnCl₂)²⁹(0.020 g) and quino-

line (0.030 g) in dry methanol (15 cm³) were alternately evacu-

ated and ﬂushed with argon (4 ×) and the procedure repeated

with hydrogen, at room temperature with vigorous stirring. The

mixture was stirred under hydrogen overnight, ﬁltered through

Celite and concentrated under reduced pressure. The residue

was taken up in ether (20 cm³), washed with aqueous hydro-

chloric acid (0.1 mol dm^Ϫ3, 5 cm³), brine (5 cm³), dried (MgSO₄)

and concentrated under reduced pressure. The residue was

chromatographed (SiO₂, EtOAc–light petroleum, 3:7) to give

the (1ЈR)-allyl alcohol 43 (0.325 g, 63%), mp 66–67 ЊC (from

EtOAc–light petroleum); R_f(Et₂O) 0.34; [α]_DϪ139.5 (c 1.1,

(Z)-(1S,5R,6R,7R,1ЈR)-7-Hydroxy-6-(1Ј-hydroxyoct-2Ј-enyl)-2-

oxabicyclo[3.3.0]octan-3-one 45 and (Z)-(1S,5R,6R,7R,1ЈS)-7-

hydroxy-6-(1Ј-hydroxyoct-2Ј-enyl)-2-oxabicyclo[3.3.0]octan-3-

one 46

These were prepared by the same method using a mixture of the

benzoates 43 and 44 (0.029 g, 0.08 mmol, ratio 1:2), potassium

carbonate (0.015 g, 0.1 mmol) and methanol (0.5 cm³) to give

an inseparable mixture of the diols⁴45 and 46 (0.015 g, 72%) in

a 1:2 ratio, identical (TLC, IR) with the diol above; δ_H(250

CHCl₃); ν_max(ﬁlm)/cm^Ϫ13492 (br OH), 1747 (C᎐O), 1714

᎐

(C᎐O), 1602 (Ph) and 1584 (Ph); δ (400 MHz; CDCl ) 7.99

᎐

J. Chem. Soc., Perkin Trans. 1, 1998

2697

View Article Online

MHz; CDCl ) 5.57 (1 H, dt, J 11.0 and 7.5, C᎐CHCH ), 5.36

g, 0.185 mmol) and triethylamine (0.03 cm³, 0.21 mmol) were

᎐

(1 H, br t, J 10.2, CH᎐CHCH ), 4.84 (1 H, dt, J 7.2 and 3.9,

stirred in dry dichloromethane (1 cm³) under argon at room

temperature overnight. The mixture was diluted with ether (10

cm³) and the organic layer washed with water (1 cm³), aqueous

hydrochloric acid (1 mol dm^Ϫ3, 1 cm³), saturated aqueous

sodium hydrogen carbonate (1 cm³) and brine (1 cm³), dried

(MgSO₄) and concentrated under reduced pressure. The residue

was chromatographed (SiO₂, EtOAc–light petroleum, 1:5 and

then 1:1) to give the carbamate (0.077 g, 85%); R_f(Et₂O) 0.70;

ν_max(CHCl₃)/cm^Ϫ13431 (NH), 1771 (C᎐O), 1718 (C᎐O) and

᎐

CHOCOCH ), 4.37 (1 H, t, J 9.1, C᎐CCHOH), 4.20 (1 H, q,

᎐

J 7.2, CH₂CHOH), 2.66 (1 H, dd, J 18.5 and 9.9, CH_AH_BCO₂),

2.57–2.34 (3 H, m, CH_AH_BCO₂, CHCH₂CO₂and CH_AH_B-

COH), 2.20–1.78 (4 H, m, CH C᎐C, CH H COH and

᎐

CHCHCOH), 1.40–1.18 [6 H, m, (CH₂)₃Me] and 0.88 (3 H, t,

J 6.7, Me); δ_C(100 MHz; CDCl₃) 177.2 (minor), 176.8 (major),

134.5 (major), 134.4 (minor), 129.8 (major), 129.6 (minor), 83.6

(minor), 82.5 (major), 76.0 (major), 74.3 (minor), 71.4 (major),

67.8 (minor), 59.1 (minor), 57.7 (major), 40.8 (minor), 40.3

(major), 39.6 (major), 38.9 (minor), 35.9 (minor), 35.2 (major),

31.5, 29.3, 27.9, 22.5 and 14.0.

᎐

1602 (Ph); [α]_DϪ94.6 (c 1.07 CHCl₃); δ_H(400 MHz; CDCl₃) 7.99

(2 H, d, J 7.2, o-Bz), 7.55 (1 H, t, J 7.4, p-Bz), 7.43 (2 H, t, J 7.7,

m-Bz), 7.38–7.25 (4 H, m, o- and m-PhN), 7.05 (1 H, t, J 7.2,

p-PhN), 6.69 (1 H, br s, NH), 5.71 (1 H, dt, J 10.8 and 7.5,

(Z)-(1S,5R,6R,7R,1ЈR)-7-Benzoyloxy-6-(1Ј-benzoyloxyoct-2Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one 47

C᎐CHCH ), 5.56 (1 H, t, J 8.9, CHOCON), 5.49 (1 H, dt, J 5.9

᎐

and 3.1, CHOBz), 5.38 (1 H, dd, J 10.8 and 9.5, CH᎐CHCH ),

᎐

Benzoyl chloride (0.06 cm³, 0.5 mmol), the alcohol 43 (0.119 g,

0.32 mmol), triethylamine (0.07 cm³, 0.5 mmol) and 4-di-

methylaminopyridine (0.005 g, 0.04 mmol) were stirred in dry

dichloromethane (2 cm³) under argon at room temperature

overnight. The mixture was diluted with ether (10 cm³) and

quenched with hydrochloric acid (1 mol dm^Ϫ3, 2 cm³). The

mixture was extracted with ether (3 × 1 cm³) and the organic

layers combined, washed with saturated aqueous sodium

hydrogen carbonate (1 cm³) and brine (1 cm³), dried (MgSO₄)

and concentrated under reduced pressure. The residue was

chromatographed (SiO₂, EtOAc–light petroleum, 1:1) to give

the dibenzoate (0.152 g, 100%); R_f(Et₂O) 0.63; [α]_DϪ36.8 (c

1.36, CHCl₃); ν_max(ﬁlm)/cm^Ϫ11770 (C᎐O), 1714 (C᎐O), 1602

5.06 (1 H, t, J 6.0, CHOCOCH₂), 2.92 (1 H, dd, J 17.8 and 10.4,

CH_AH_BCO₂), 2.88–2.79 (1 H, m, CHCH₂CO₂), 2.58 (1 H, dd,

J 17.8 and 1.3, CH_AH_BCO₂), 2.56–2.42 (2 H, m, CH_AH_BCOBz

and CHCHC᎐C), 2.35 (1 H, d, J 15.7, CH H COBz), 2.30–

᎐

2.05 (2 H, m, CH C᎐C), 1.52–1.21 (6 H, m, CH CH CH ) and

᎐

0.86 (3 H, t, J 6.9, Me); δ_C(100 MHz; CDCl₃) 176.4, 165.8,

152.6, 137.5, 137.2, 133.3, 129.7, 129.2, 129.1, 128.6, 124.9,

84.4, 77.0, 70.3, 57.0, 40.1, 38.5, 36.3, 31.5, 29.1, 28.1, 22.5 and

14.0; m/z 491 (23%, M^ϩ), 354 (28, M Ϫ PhNHCO₂H), 233 (87,

M Ϫ PhNHCO₂H Ϫ BzOH) and 105 (100, PhCO) (Found:

M^ϩ, 491.2267. C₂₉H₃₃NO₆requires M, 491.2308).

᎐

(Z)-(1S,5R,6R,7R,1ЈR)-7-Benzoyloxy-6-(1Ј-N-phenylcarb-

amoyloxyoct-2Ј-enyl)-2-oxabicyclo[3.3.0]octan-3-one 51

A similar preparation from the alcohol 43 (0.053 g, 0.14 mmol)

gave the carbamate (0.067 g, 96%); R_f(Et₂O) 0.82; [α]_DϪ39.1 (c

(Ph) and 1584 (Ph); δ_H(400 MHz; CDCl₃) 7.98 (4 H, d, J 7.7,

2 × o-Ph), 7.55 (2 H, br t, J 6.9, 2 × p-Ph), 7.43 (2 H, br t, J 6.4,

m-Ph_A), 7.41 (2 H, br t, J 7.5, m-Ph_B), 5.86 (1 H, br t, J 8.2,

0.57, CHCl₃); ν_max(CHCl₃)/cm^Ϫ13434 (NH), 1772 (C᎐O), 1729

C᎐CHCHOBz), 5.70 (1 H, dt, J 10.7 and 7.5, C᎐CHCH ), 5.50

᎐

(1 H, br t, J 10.1, CH᎐CHCH ), 5.40 (1 H, dt, J 6.0 and 3.6,

᎐

(C᎐O) and 1602 (Ph); δ (400 MHz; CDCl ) 7.98 (2 H, br d,

᎐

CH₂CHOBz), 5.12 (1 H, t, J 5.8, CHOCOCH₂), 3.07–2.98 (1 H,

m, CHCH₂CO₂), 2.92 (1 H, dd, J 18.0 and 10.0, CH_AH_BCO₂),

2.62 (1 H, dd, J 17.9 and 1.7, CH_AH_BCO₂), 2.58 (1 H, br q,

J 5.8, CHCHOBz), 2.48 (1 H, dt, J 15.8 and 6.2, CH_AH_B-

COBz), 2.36 (1 H, br d, J 15.7, CH_AH_BCOBz), 2.27 (1 H, dq,

J 7.2, o-Bz), 7.54 (1 H, br t, J 7.4, p-Bz), 7.42 (2 H, br t, J 7.7,

m-Bz), 7.34 (2 H, br d, J 7.8, o-PhN), 7.28 (2 H, br t, J 7.4,

m-PhN), 7.06 (1 H, br t, J 7.2, p-PhN), 6.77 (1 H, br s, NH),

5.68 (1 H, dt, J 10.9 and 7.5, C᎐CHCH ), 5.56 (1 H, dd, J

᎐

9.1 and 7.8, CHOCON), 5.39 (1 H, dd, J 10.8 and 9.6,

J 14.5 and 7.7, CH H C᎐C), 2.19 (1 H, dq, J 14.4 and 7.0,

᎐

CH᎐CHCH ), 5.36 (1 H, q, J 3.5, CHOBz), 5.07 (1 H, br t,

᎐

CH H C᎐C), 1.46–1.33 (2 H, m, C᎐CHCH CH ), 1.33-1.22

᎐

J 5.1, CHOCOCH₂), 3.00–2.87 (2 H, m, CHCH_AH_BCO₂), 2.57

(1 H, d, J 16.2, CH_AH_BCO₂), 2.43 (1 H, dt, J 7.1 and 4.0,

(4 H, m, CH₂CH₂Me) and 0.85 (3 H, t, J 6.7, Me); δ_C(100 MHz;

CDCl₃) 176.3, 165.8, 165.5, 136.9, 133.3, 129.9, 129.7, 129.6,

128.5, 125.0, 84.3, 70.7, 56.9, 40.0, 38.8, 36.3, 31.5, 29.1, 28.1,

22.5 and 14.0; m/z 354 (29%, M Ϫ BzOH) and 105 (100, PhCO)

(Found: M^ϩϪ BzOH, 354.1825. C₂₉H₃₂O₆Ϫ BzOH requires

M, 354.1831).

CHCHC᎐C), 2.40–2.30 (1 H, m, CH H COBz), 2.35 (1 H, br

᎐

d, J 15.9, CH H COBz), 2.29–2.09 (2 H, m, CH C᎐C), 1.45–

᎐

1.22 [6 H, m, (CH₂)₃Me] and 0.86 (3 H, t, J 6.9, Me); δ_C(100

MHz; CDCl₃) 176.5, 165.8, 152.5, 137.5, 136.9, 133.3, 129.65,

129.56, 129.1, 128.5, 125.1, 84.5, 77.3, 70.3, 57.0, 39.9, 38.7,

36.3, 31.5, 29.1, 28.1, 22.5 and 14.0; m/z 491 (1%, M^ϩ), 119

(91, PhNCO) and 105 (100, PhCO) (Found: M^ϩ, 491.2319.

C₂₉H₃₃NO₆requires M, 491.2308).

(Z)-(1S,5R,6R,7R,1ЈS)-7-Benzoyloxy-6-(1Ј-benzoyloxyoct-2Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one 52

A similar benzoylation using the alcohol 44 (0.052 g, 0.14

mmol) gave the dibenzoate (0.066 g, 99%); R_f(Et₂O) 0.65;

ν_max(CDCl₃)/cm^Ϫ11771 (C᎐O), 1717 (C᎐O) and 1602 (Ph); [α]

(1ЈE,2ЉZ)-(1S,5R,6R,7R,3ЈR)-7-Benzoyloxy-6-[3Ј-(2Љ-

methylbut-2Љ-enyl)diphenylsilyloct-1Ј-enyl]-2-oxabicyclo[3.3.0]-

octan-3-one 49

᎐

Ϫ106.9 (c 0.7, CHCl₃); δ_H(400 MHz; CDCl₃) 8.02–7.95 (4 H, m,

2 × o-Ph), 7.55 (2 H, br t, J 7.4, 2 × p-Ph), 7.45–7.38 (4 H, m,

Method 1. The dibenzoate 47 (0.152 g, 0.32 mmol) in ether

(2 cm³) was added dropwise to a stirred solution of freshly

prepared silylcuprate reagent 10 (0.35 mmol) and triphenyl-

phosphine (0.183 g, 0.7 mmol) at Ϫ78 ЊC under argon. The

solution was stirred at this temperature for 1 h and allowed to

warm to 0 ЊC over 2 h. The reaction was quenched with basic

aqueous ammonium chloride (2 cm³) and the mixture extracted

with ether (3 × 5 cm³). The organic layers were combined,

washed with basic aqueous ammonium chloride (1 cm³) and

brine (1 cm³), dried (MgSO₄) and concentrated under reduced

pressure. The residue was chromatographed (SiO₂, EtOAc–light

petroleum, 1:9) to give the allylsilane (0.169 g, 87%); R_f(Et₂O)

2 × m-Ph), 5.85 (1 H, dd, J 9.2 and 7.1, C᎐CHCHOBz), 5.73

᎐

(1 H, dt, J 10.9 and 7.5, C᎐CHCH ), 5.54–5.43 (2 H, m,

᎐

CH᎐CHCH and CH CHOBz), 5.07 (1 H, br t, J 5.7, CHOC-

᎐

OCH₂), 3.04–2.86 (2 H, m, CHCH_AH_BCO₂), 2.75–2.55 (3 H, m,

CH_AH_BCO₂, CH_AH_BCOBz and CHCHOBz), 2.35 (1 H, br d,

J 15.8, CH H COBz), 2.32–2.11 (2 H, m, CH C᎐C), 1.45–1.20

᎐

[6 H, m, (CH₂)₃Me] and 0.84 (3 H, t, J 7.0, Me); δ_C(100 MHz;

CDCl₃) 176.3, 165.7, 165.6, 137.4, 133.28, 133.26, 129.8, 129.7,

129.64, 129.57, 128.5, 124.5, 84.2, 76.9, 56.7, 40.1, 38.7, 36.3,

31.5, 29.0, 28.2, 22.5 and 14.0; m/z 354 (49%, M^ϩ) and 105 (100,

PhCO) (Found: M^ϩϪ BzOH, 354.1830. C₂₉H₃₂O₆Ϫ BzOH

requires M, 354.1831).

0.69; [α]_DϪ45.5 (c 1.03, CHCl₃); ν_max(ﬁlm)/cm^Ϫ11770 (C᎐O),

᎐

(Z)-(1S,5R,6R,7R,1ЈS)-7-Benzoyloxy-6-(1Ј-N-phenylcarb-

amoyloxyoct-2Ј-enyl)-2-oxabicyclo[3.3.0]octan-3-one 48

Phenyl isocyanate (0.025 cm³, 0.19 mmol), the alcohol 44 (0.069

1714 (C᎐O), 1662 (C᎐C), 1602 (Ph), 1586 (Ph) and 1112 (Si–

Ph); δ_H(400 MHz; CDCl₃) 7.96 (2 H, br d, J 7.9, o-Bz), 7.56–

7.43 (5 H, m, p-Bz and o-SiPh₂), 7.43–7.28 (8 H, m, m-Bz,

᎐ ᎐

2698

J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online

m- and p-SiPh ), 5.34 (1 H, dd, J 15.2 and 10.1, CH᎐CHCHSi),

ture was stirred at this temperature for 20 min. Butyllithium

᎐

5.13–5.04 (2 H, m, CHOBz and C᎐CHCHSi), 4.99 (1 H, br q,

(1.34 mol dm^Ϫ3in hexane, 0.07 cm³, 0.1 mmol) was added

dropwise to a stirred solution of the carbamate 51 (0.046 g, 0.09

mmol) in dry THF (0.8 cm³) at Ϫ78 ЊC under argon. After

stirring at this temperature for 5 min the solution was added via

a cannula to the silylcopper reagent at 0 ЊC, and the mixture

was stirred at this temperature for a further 4 h. The mixture

was quenched with basic aqueous ammonium chloride (1 cm³),

ﬁltered through Celite and extracted with light petroleum (3 × 5

cm³). The organic layers were combined, washed with basic

aqueous ammonium chloride (3 cm³) and brine (3 cm³), dried

(MgSO₄) and concentrated under reduced pressure. The residue

was chromatographed (SiO₂, EtOAc–light petroleum, 1:9) to

᎐

J 6.6, C᎐CHMe), 4.88 (1 H, dt, J 6.8 and 2.2, CHOCOCH ),

᎐

2.63 (1 H, dd, J 18.2 and 8.5, CH_AH_BCO₂), 2.59–2.41 (3 H,

m, CH_AH_BCOBz, CHCH₂CO₂and CHCH᎐CHCHSi), 2.24

᎐

(1 H, dd, J 18.2 and 1.8, CH_AH_BCO₂), 2.18 (1 H, br t, J 10.8,

C᎐CCHSi), 2.06 (1 H, d, J 13.8, CH H Si), 2.05–1.97 (1 H,

᎐

m, CH_AH_BCOBz), 2.03 (1 H, d, J 13.4, CH_AH_BSi), 1.47 (3 H, t,

J 1.3, MeC᎐CH), 1.30–0.98 [8 H, m, (CH ) Me], 1.21 (3 H, d,

᎐

J 6.6, C᎐CHMe) and 0.73 (3 H, t, J 6.9, CH Me); δ (100

᎐

MHz; CDCl₃) 176.5, 166.0, 135.7, 135.6, 134.7, 134.2, 133.9,

133.2, 132.2, 129.7, 129.6, 129.5, 129.4, 128.4, 127.6, 127.5,

127.4, 118.1, 82.8, 78.7, 54.3, 42.4, 37.4, 34.3, 31.4, 28.9, 28.8,

26.4, 22.4, 17.9, 14.0 and 13.7; m/z(CI) 624 (48%, M^ϩϩ

give the allylsilane (0.030 g, 55%), identical (TLC, H NMR)

NH ), 537 (80, M Ϫ CH MeC᎐CHMe) and 105 (100, PhCO)

with the earlier sample, and the recovered carbamate 51 (0.013

g, 29%).

᎐

(Found: M^ϩϩ NH₄, 624.3507. C₃₉H₄₆O₄Si ϩ NH₄requires M,

624.3509).

Method 2. Butyllithium (1.3 mol dm^Ϫ3in hexane, 0.02 cm³,

0.026 mmol) was added dropwise to a stirred solution of the

carbamate 48 (0.014 g, 0.029 mmol) in dry THF (1 cm³) at

Ϫ78 ЊC under argon. After stirring at this temperature for 15

min the solution was added via a cannula to a vigorously stirred

slurry of copper() bromide–dimethyl sulﬁde complex (0.006 g,

0.03 mmol) in dry ether (1.5 cm³) at 0 ЊC under argon. The

mixture was stirred at this temperature for a further 45 min. The

silyllithium reagent 9 (0.45 mol dm^Ϫ3in THF, 0.06 cm³, 0.027

mmol) was added dropwise to the slurry and the mixture stirred

at 0 ЊC for 3 h. The reaction was quenched with basic aqueous

ammonium chloride (2 cm³) and the mixture extracted with

ether (3 × 5 cm³). The organic layers were combined, washed

with basic aqueous ammonium chloride (1 cm³) and brine

(1 cm³), dried (MgSO₄) and concentrated under reduced pres-

sure. The residue was chromatographed (SiO₂, EtOAc–light

petroleum, 1:9) to give the allylsilane (0.004 g, 23%), identical

(TLC, IR, ¹H NMR) with the earlier sample, and the recovered

carbamate (0.010 g, 71%).

(E)-(1S,5R,6R,7R,3ЈR)-7-Benzoyloxy-6-(3Ј-hydroxyoct-1Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one 50

Boron triﬂuoride–acetic acid complex (0.02 cm³, 0.08 mmol)

was added dropwise to the allylsilane 49 (0.049 g, 0.08 mmol) in

dichloromethane (1 cm³) at Ϫ10 ЊC under argon. After 5 min

the reaction was quenched with sodium hydrogen carbonate

(0.04 g, 0.4 mmol) and the solvent evaporated under reduced

pressure. Methanol (1 cm³), THF (1 cm³), potassium ﬂuoride

(0.01 g, 0.17 mmol) and hydrogen peroxide (30%, 0.4 cm³, 3.5

mmol) were added to the residue and the mixture stirred at

room temperature overnight and then reﬂuxed for 2 h. The

excess hydrogen peroxide was quenched with sodium sulﬁte and

the mixture acidiﬁed with hydrochloric acid (1 mol dm^Ϫ3). The

organic solvents were evaporated off under reduced pressure

and the aqueous residue extracted with ether (4 × 5 cm³). The

organic layers were combined, washed with brine (2 cm³), dried

(MgSO₄), and concentrated under reduced pressure. The resi-

due was chromatographed (SiO₂, EtOAc–light petroleum, 1:4

and then EtOAc) to give the alcohol (0.020 g, 66%); R_f(EtOAc)

0.52; [α]_DϪ96.5 (c 1.4, CHCl₃) [lit.,³⁷(for enantiomer) ϩ98 (c

0.78, CHCl₃)]; ν_max(CH₂Cl₂)/cm^Ϫ13599 (OH), 3393 (br OH),

(1ЈE,2ЉZ)-(1S,5R,6R,7R,3ЈS)-7-Benzoyloxy-6-[3Ј-(2Љ-methyl-

but-2Љ-enyl)diphenylsilyloct-1Ј-enyl]-2-oxabicyclo[3.3.0]octan-3-

one 53

1773 (C᎐O), 1718 (C᎐O) and 1602 (Ph); δ (400 MHz; CH Cl )

᎐

7.99 (2 H, br d, J 7.9, o-Ph), 7.56 (1 H, br t, J 7.4, p-Ph), 7.43

(2 H, br t, J 7.7, m-Ph), 5.64 (1 H, dd, J 15.5 and 6.0,

Method 1. A similar preparation to Method 1 above, con-

verted the dibenzoate 52 (0.058 g, 0.12 mmol) into the allyl-

silane (0.062 g, 84%); R_f(Et₂O) 0.69; [α]_DϪ36.2 (c 1.0, CHCl₃);

ν_max(CDCl₃)/cm^Ϫ11771 (C᎐O), 1716 (C᎐O), 1602 (Ph) and

C᎐ CHCHOH), 5.55 (1 H, dd, J 15.6 and 7.5, CH᎐CHCHOH),

᎐

5.22 (1 H, q, J 6.0, CHOBz), 5.05 (1 H, td, J 6.6 and 1.6,

CHOCOCH₂), 4.08 (1 H, q, J 6.1, CHOH), 2.84 (1 H, dd, J 17.3

and 9.6, CH_AH_BCO₂), 2.82–2.76 (1 H, m, CHCH₂CO₂), 2.73

᎐

1112 (Si–Ph); δ_H(400 MHz; CDCl₃) 7.95 (2 H, br d, J 7.8, o-Bz),

7.54 (1 H, br t, J 5.4, p-Bz), 7.47–7.21 (12 H, m, m-Bz and

(1 H, br q, J 6.6, CHCH᎐CHCHOH), 2.61 (1 H, dt, J 15.4

᎐

SiPh ), 5.36 (1 H, dd, J 15.3 and 9.8, CH᎐CHCHSi), 5.08 (1 H,

and 6.7, CH_AH_BCHOBz), 2.51 (1 H, d, J 16.4, CH_AH_BCO₂),

2.22 (1 H, ddd, J 15.4, 5.2 and 1.7, CH_AH_BCHOBz), 1.60 (1 H,

br s, OH), 1.55–1.39 (2 H, m, CH₂CHOH), 1.36–1.16 [6 H, m,

(CH₂)₃Me] and 0.82 (3 H, t, J 6.4, Me); δ_C(100 MHz; CDCl₃)

176.4, 166.0, 136.5, 133.3, 129.65, 129.55, 128.5, 128.4, 83.2,

79.0, 72.4, 54.0, 42.7, 37.6, 37.3, 34.8, 31.7, 25.0, 22.5 and 14.0;

m/z 354 (9%, M Ϫ H₂O), 301 [84, M Ϫ (CH₂)₄Me], 250

(60%, M Ϫ BzOH), 179 [69, M Ϫ BzOH Ϫ (CH₂)₄Me], 105

(100, SiPh^ϩ) and 77 (76, Ph) (Found: M^ϩϪ H₂O, 354.1825.

C₂₂H₂₈O₃Ϫ H₂O requires M, 354.1831).

᎐

dd, J 15.2 and 7.5, C᎐CHCHSi), 5.05 (1 H, q, J 6.1, C᎐CHMe),

᎐

4.93 (1 H, br t, J 6.7, CHOCOCH₂), 4.92 (1 H, td, J 6.7 and 1.8,

CHOBz), 2.76 (1 H, dd, J 18.3 and 9.4, CH_AH_BCO₂), 2.66–2.54

(2 H, m, CHCH CO and CHCH᎐CHCHSi), 2.49 (1 H, dt,

᎐

J 15.5 and 6.8, CH_AH_BCOBz), 2.41 (1 H, dd, J 18.3 and 1.8,

CH H CO ), 2.16 (1 H, br t, J 10.6, C᎐CCHSi), 2.07 (1 H, ddd,

᎐

J 15.4, 5.5 and 1.8, CH_AH_BCOBz), 1.97 (2 H, s, SiCH₂), 1.40

(3 H, t, J 1.4, MeC᎐CH), 1.38–1.12 [8 H, m, (CH ) Me], 1.12

᎐

(3 H, d, J 6.5, C᎐CHMe) and 0.82 (3 H, t, J 7.0, CH Me);

᎐

δ_C(100 MHz; CDCl₃) 176.6, 165.9, 135.6, 134.7, 134.1, 133.9,

133.2, 132.2, 129.7, 129.6, 129.4, 129.3, 128.4, 127.6, 127.5,

127.3, 118.0, 83.1, 79.1, 54.3, 43.0, 37.5, 34.6, 31.4, 31.2, 28.9,

28.7, 26.4, 22.6, 17.8, 14.1 and 13.6; m/z(FAB) 606 (11%, M^ϩ)

and 537 (89, M Ϫ CH MeC᎐CHMe) (Found: M^ϩ, 624.3201.

(E)-(1S,5R,6R,7R,3ЈS)-7-Benzoyloxy-6-(3Ј-hydroxyoct-1Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one 54

A similar preparation from the allylsilane 53 (0.036 g, 0.06

mmol) gave the alcohol (0.013 g, 60%); R_f(EtOAc) 0.59; [α]_D

Ϫ95.1 (c 1.0, CHCl₃) [lit.,³⁷(for enantiomer) ϩ77 (c 1.04,

᎐

C₃₉H₄₆O₄Si requires M, 624.3165).

Method 2. A similar preparation to Method 2 above, con-

verted the carbamate 51 (0.031 g, 0.063 mmol) into the allyl-

silane (0.009 g, 24%), identical (TLC, ¹H NMR) with the earlier

sample, and the recovered carbamate 51 (0.022 g, 71%).

Method 3. Freshly prepared silyllithium reagent 9 (0.11

mmol) was added dropwise to stirred slurry of dry copper()

iodide (0.018 g, 0.09 mmol) in dry ether (1 cm³) and triphenyl-

phosphine (0.049 g, 0.19 mmol) at 0 ЊC under argon. The mix-

CHCl₃)]; ν_max(CHCl₃)/cm^Ϫ13602 (OH), 1772 (C᎐O), 1716

᎐

(C᎐O) and 1602 (Ph); δ (400 MHz; CDCl ) 7.98 (2 H, br d,

᎐

J 7.9, o-Ph), 7.56 (1 H, br t, J 7.4, p-Ph), 7.44 (2 H, br t, J 7.7,

m-Ph), 5.64 (1 H, dd, J 15.5 and 5.5, C᎐CHCHOH), 5.58 (1 H,

᎐

dd, J 15.5 and 6.9, CH᎐CHCHOH), 5.24 (1 H, q, J 5.9,

᎐

CHOBz), 5.05 (1 H, td, J 6.6 and 1.9, CHOCOCH₂), 4.08 (1 H,

q, J 6.0, CHOH), 2.84 (1 H, dd, J 17.0 and 9.6, CH_AH_BCO₂),

2.82–2.77 (1 H, m, CHCH₂CO₂), 2.73 (1 H, br q, J 6.4,

J. Chem. Soc., Perkin Trans. 1, 1998

2699

View Article Online

1989; P. W. Collins and S. W. Djuric, Chem. Rev., 1993, 93, 1533;

CHCH᎐CHCHOH), 2.60 (1 H, dt, J 15.4 and 6.7, CH H -

᎐

R. Noyori, I. Tomino and M. Nishizawa, J. Am. Chem. Soc., 1979,

101, 5843; P. A. Grieco, T. Takigawa, S. L. Bongers and H. Tanaka,

J. Am. Chem. Soc., 1980, 102, 7587; S. Iguchi, H. Nakai,

M. Hayashi, H. Yamamato and K. Maruoka, Bull. Chem. Soc. Jpn.,

1981, 54, 3033; S. J. Danishefsky, M. P. Cabal and K. Chow, J. Am.

Chem. Soc., 1989, 111, 3456.

4 R. Mahrwald, H. Schick, K. K. Pivnitsky and S. Schwarz,

J. Prakt. Chem., 1990, 332, 403; H. Schick, J. Spanig, R. Mahrwald,

M. Bohle, T. Reiher and K. K. Pivnitsky, Tetrahedron, 1992, 48,

5579.

CHOBz), 2.51 (1 H, d, J 16.4, CH_AH_BCO₂), 2.22 (1 H, ddd,

J 15.4, 5.1 and 1.7, CH_AH_BCHOBz), 1.60 (1 H, br s, OH), 1.56–

1.39 (2 H, m, CH₂CHOH), 1.38–1.19 [6 H, m, (CH₂)₃Me]

and 0.85 (3 H, t, J 6.7, Me); δ_C(100 MHz; CDCl₃) 176.4, 166.1,

136.4, 133.3, 129.7, 129.6, 128.5, 128.3, 83.2, 79.0, 72.2,

54.0, 42.7, 37.6, 37.2, 34.9, 31.7, 25.0, 22.5 and 14.0; m/z 250

(37%, M Ϫ BzOH), 179 [55, M Ϫ BzOH Ϫ (CH₂)₄Me] and 77

(100, Ph) (Found: M^ϩϪ BzOH, 250.1563. C₂₂H₂₈O₅Ϫ BzOH

requires M, 250.1565).

5 I. Fleming and H.-F. Chow, J. Chem. Soc., Perkin Trans. 1, 1998,

2651.

Hydrolysis of the benzoates 50 and 54 for further

characterisation

6 K. Tamao, E. Nakajo and Y. Ito, J. Org. Chem., 1987, 52, 957.

7 K. Tamao, N. Ishida and M. Kumada, J. Org. Chem., 1983, 48,

2120; K. Tamao, T. Iwahara, R. Kanatani and M. Kumada,

Tetrahedron Lett., 1984, 25, 1909; H.-J. Gais and G. Bülow,

Tetrahedron Lett., 1992, 33, 461 and 465; W. R. Roush and P. T.

Grover, Tetrahedron, 1992, 48, 1981.

8 S. Lamothe, K. L. Cook and T. H. Chan, Can. J. Chem., 1992, 70,

1733.

9 T. Hayashi, S. Hengrasmee and Y. Matsumoto, Chem. Lett., 1990,

1377; Y. Hatanaka, K. Goda, F. Yamashita and T. Hiyama,

Tetrahedron Lett., 1994, 35, 7981.

10 R. Angelaud, Y. Landais and C. Maignan, Tetrahedron Lett., 1995,

36, 3861.

11 J. A. Hunt and W. R. Roush, J. Org. Chem., 1997, 62, 1112.

12 M. C. Norley, P. J. Kocienski and A. Faller, Synlett, 1994, 77.

13 D. F. Taber, L. Yet and R. S. Bhamidipati, Tetrahedron Lett., 1995,

36, 351; D. F. Taber, R. S. Bhamidipati and L. Yet, J. Org. Chem.

1995, 60, 5537.

14 I. Fleming, P. E. J. Sanderson and F. Zammattio, J. Chem. Res. (S),

1994, 159; J. Chem. Res. (M), 1994, 1020.

15 K. Tamao, A. Kawachi, Y. Tanaka, H. Ohtani and Y. Ito,

Tetrahedron, 1996, 52, 5765; A. Kawachi and K. Tamao, Bull. Chem.

Soc. Jpn., 1997, 70, 945.

(E)-(1S,5R,6R,7R,3ЈR)-7-Hydroxy-6-(3Ј-hydroxyoct-1Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one. Potassium carbonate

(0.006 g, 0.04 mmol) was stirred with the benzoate 50 (0.011 g,

0.03 mmol) in methanol (0.5 cm³) at room temperature for 30

min and then acidiﬁed with aqueous hydrochloric acid (1 mol

dm^Ϫ3). The solvent was evaporated off under reduced pressure

and the residue taken up in ether (5 cm³), dried (MgSO₄), and

concentrated under reduced pressure. The residue was chrom-

atographed (SiO₂, EtOAc) to give the diol^37,39(0.006 g, 76%); R_f

(EtOAc) 0.28; ν_max(CDCl₃)/cm^Ϫ13690 (OH), 3602 (OH), 3393

(br OH), 1768 (C᎐O) and 1602 (C᎐C); δ (400 MHz; CDCl )

᎐

5.64 (1 H, ddd, J 15.4, 5.9 and 0.5, C᎐CHCHOH), 5.50 (1 H,

᎐

ddd, J 15.4, 8.4 and 0.9, CH᎐CHCHOH), 4.91 (1 H, td, J 7.0

᎐

and 2.9, CHOCOCH ), 4.11 (1 H, q, J 6.1, C᎐CHCHOH), 4.00

᎐

(1 H, q, J 7.0, C᎐CHCHCHOH), 2.74 (1 H, dd, J 18.1 and 9.7,

᎐

CH_AH_BCO₂), 2.63 (1 H, br q, J 8.4, CHCH₂CO₂), 2.49 (1 H, dt,

J 14.8 and 6.9, CH_AH_BCHOBz), 2.48 (1 H, dd, J 18.1 and 1.9,

CH H CO ), 2.34 (1 H, q, J 7.8, CHCH᎐CHCHOH), 1.97

᎐

16 I. Fleming and S. B. D. Winter, Tetrahedron Lett., 1993, 34, 7287.

17 I. Fleming and S. B. D. Winter, Tetrahedron Lett., 1995, 36, 1733.

18 N. Abd.Rahman, PhD Thesis, Cambridge, 1990.

19 N. Abd.Rahman, I. Fleming and A. B. Zwicky, J. Chem. Res. (S),

1992, 292; J. Chem. Res. (M), 1992, 2401.

20 I. Ojima and M. Kumagai, J. Organomet. Chem., 1978, 157, 359.

21 I. Fleming, R. S. Roberts and S. C. Smith, J. Chem. Soc., Perkin

Trans. 1, 1998, 1209.

22 C. Eaborn and S. H. Parker, J. Chem. Soc., 1955, 126.

23 J. J. Partridge, N. K. Chadha and M. S. Uskokovic, J. Am. Chem.

Soc., 1973, 95, 7171.

24 I. Tömösközi, L. Gruber, G. Kovâcs, I. Székely and V. Simonidesz,

Tetrahedron Lett., 1976, 17, 4639.

(1 H, ddd, J 14.8, 7.2 and 2.9, CH_AH_BCHOBz), 1.64–1.47 (2 H,

m, CH₂CHOH), 1.42–1.23 [6 H, m, (CH₂)₃Me] and 0.88 (3 H, t,

J 6.8, Me).

(E)-(1S,5R,6R,7R,3ЈS)-7-Hydroxy-6-(3Ј-hydroxyoct-1Ј-

enyl)-2-oxabicyclo[3.3.0]octan-3-one. A similar hydrolysis of

the benzoate 54 (0.008 g, 0.02 mmol) gave the diol^37,39(0.004 g,

70%), R_f(EtOAc) 0.25; [α]_DϪ7.2 (c 0.3, CHCl₃) [lit.,³⁷(for

enantiomer) ϩ10 (c 2.51, CHCl₃)]; ν_max(CDCl₃)/cm^Ϫ13690

(OH), 3602 (OH), 3395 (br OH), 1768 (C᎐O) and 1602

᎐

(C᎐C); δ (400 MHz; CDCl ) 5.61 (1 H, dd, J 15.4 and 6.6,

᎐

C᎐CHCHOH), 5.56 (1 H, dd, J 15.4 and 8.4, CH᎐CHCHOH),

᎐

25 J. Y. Corey and R. West, J. Am. Chem. Soc., 1963, 85, 2430.

26 A. Kunai, T. Kawakami, E. Toyoda and M. Ishikawa,

Organometallics, 1992, 11, 2708.

27 C. R. Johnson, C. J. Cheer and D. J. Goldsmith, J. Org. Chem., 1964,

29, 3320; G. Höﬂe and W. Steglich, Synthesis, 1972, 619.

28 V. Dev, J. Chem. Educ., 1970, 47, 476.

4.89 (1 H, td, J 7.0 and 3.0, CHOCOCH₂), 4.07 (1 H, q, J 6.5,

C᎐CHCHOH), 3.96 (1 H, q, J 7.3, C᎐CHCHCHOH), 2.72

(1 H, dd, J 18.0 and 9.6, CH_AH_BCO₂), 2.62–2.46 (2 H, m,

CHCH₂CO₂and CH_AH_BCHOBz), 2.43 (1 H, dd, J 18.0 and

᎐

1.8, CH H CO ), 2.28 (1 H, q, J 8.2, CHCH᎐CHCHOH), 1.94

᎐

(1 H, ddd, J 14.8, 7.6 and 3.0, CH_AH_BCHOBz), 1.63 (1 H, br s,

OH), 1.60–1.42 (2 H, m, CH₂CHOH), 1.40–1.21 [6 H, m,

(CH₂)₃Me] and 0.88 (3 H, t, J 6.7, Me); δ_C(100 MHz; CDCl₃)

176.7, 136.8, 129.5, 82.4, 72.6, 56.3, 42.6, 39.9, 37.4, 34.2, 31.7,

25.1, 22.6 and 14.0.

29 J. Rajaram, A. P. S. Narula, H. P. S. Chawla and S. Dev, Tetrahedron,

1983, 39, 2315.

30 S. G. Davies, I. M. Dorder-Hedgecock, P. Warner, R. H. Jones and

K. Prout, J. Organomet. Chem., 1985, 285, 213.

31 T. Matsumoto, I. Tanaka and K. Fukui, Bull. Chem. Soc. Jpn., 1971,

44, 3378.

32 Vogel’s Textbook of Practical Organic Chemistry, Longman,

Harlow, England, 1989, p. 1332.

33 G. H. Kulkarni and A. A. Arbale, Synth. Commun., 1988, 18, 2147.

34 J. Nakayama and A. Hirashima, J. Am. Chem. Soc., 1990, 112,

7648.

35 E. J. Corey and R. Noyori, Tetrahedron Lett., 1970, 21, 311.

36 I. Tömösközi, L. Gruber and E. Baitz-Gács, Tetrahedron, 1992, 48,

10 345.

37 E. L. Cooper and E. W. Yankee, J. Am. Chem. Soc., 1974, 96, 5876.

38 D. B. Dess and J. C. Martin, J. Org. Chem., 1983, 48, 4155; D. B.

Dess and J. C. Martin, J. Am. Chem. Soc., 1991, 113, 7277; R. E.

Ireland and L. Liu, J. Org. Chem., 1993, 58, 2899.

Acknowledgements

We thank the SERC (now the EPSRC) for a maintenance award

(S. B. D. W.).

References

1 I. Fleming, R. Henning, D. C. Parker, H. E. Plaut and P. E. J.

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Soc., Perkin Trans. 1, 1992, 3331.

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London, 1977; A. Mitra, The Synthesis of Prostaglandins, Wiley,

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and Thromboxanes, Butterworths, London, 1982; New Synthetic

Routes to Prostaglandins and Thromboxanes, eds. S. M. Roberts and

F. Scheinmann, Academic Press, London, 1982; E. J. Corey and

X.-M. Cheng, The Logic of Chemical Synthesis, Wiley, New York,

39 R. F. Newton, D. P. Reynolds, C. F. Webb, S. N. Young,

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E. Laborde, J. Org. Chem., 1987, 52, 4898.

Paper 8/04276D

Received 5th June 1998

Accepted 22nd June 1998

2700

J. Chem. Soc., Perkin Trans. 1, 1998

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