A Stereospecific Access to Allylic Systems Using Rhodium(II)-Vinyl Carbenoid Insertion into Si-H, O-H, and N-H Bonds

Article abstract of DOI:10.1021/jo961952j

Rhodium-catalyzed decomposition of α-vinyldiazoesters in the presence of silanes, alcohols, ethers, amines, and thiols have been shown to produce the corresponding α-silyl, α-hydroxy, α-alkoxy, α-amino, and α-thioalkoxy esters in generally good yield with a complete retention of the stereochemistry of the double bond of the diazo precursor. An extension of the process in homochiral series has also been devised using either a chiral auxiliary attached to the ester function or achiral α-vinyldiazoesters and Doyle's chiral catalyst Rh₂(MEPY)₄. In the former approach, pantolactone as chiral auxiliary gave diastereoselectivities of up to 70%, while the second approach produced the desired allylsilane with ee as high as 72%. On the other hand, Rh₂(MEPY)₄-catalyzed insertion into the O-H bond of water led to poor or no enantioselectivity in good agreement with recent literature reports.

Full text of DOI:10.1021/jo961952j

1630
J . Org. Chem. 1997, 62, 1630-1641
A Ster eosp ecific Access to Allylic System s Usin g
Rh od iu m (II)-Vin yl Ca r ben oid In ser tion in to Si-H, O-H, a n d N-H
Bon d s
Priyadarshanie Bulugahapitiya, Yannick Landais,* Liliana Parra-Rapado,
Denis Planchenault, and Vale´ry Weber
Institut de Chimie Organique, Universite´ de Lausanne, Colle`ge Prope´deutique,
1015 Lausanne-Dorigny, Switzerland
Received October 17, 1996X
Rhodium-catalyzed decomposition of R-vinyldiazoesters in the presence of silanes, alcohols, ethers,
amines, and thiols have been shown to produce the corresponding R-silyl, R-hydroxy, R-alkoxy,
R-amino, and R-thioalkoxy esters in generally good yield with a complete retention of the
stereochemistry of the double bond of the diazo precursor. An extension of the process in homochiral
series has also been devised using either a chiral auxiliary attached to the ester function or achiral
R-vinyldiazoesters and Doyle’s chiral catalyst Rh2(MEPY)4. In the former approach, pantolactone
as chiral auxiliary gave diastereoselectivities of up to 70%, while the second approach produced
the desired allylsilane with ee as high as 72%. On the other hand, Rh2(MEPY)4-catalyzed insertion
into the O-H bond of water led to poor or no enantioselectivity in good agreement with recent
literature reports.
Sch em e 1
In tr od u ction
The stereocontrolled electrophilic functionalization of
chiral allylic systems is one of the most powerful ways
to generate complex targets having several new stereo-
genic centers.1 1,2-Stereocontrol in acyclic and cyclic
allylic systems has been thoroughly studied and the
transfer of chirality from the allylic center to proximal
prochiral centers is usually efficient (Scheme 1). Several
models have been developed over the last 20 years to
account for the stereochemical outcome of these electro-
philic processes, and it is now possible to predict with
confidence the stereochemical outcome of the reaction.2
However, such a transfer of chirality is only possible
providing that both the geometry of the allylic double
bond and the absolute configuration of the allylic chiral
center have been perfectly set up prior to functionaliza-
tion. In this context, we recently reported a straightfor-
ward entry to (Z) and (E)-allylsilanes 1 where both the
configuration of the double bond and that of the chiral
allylic center would be controlled.3 It was shown that a
putative vinylrhodium carbenoid species 2, generated in
situ through Rh2(OAc)4-catalyzed decomposition of ste-
reochemically defined (E) or (Z)-vinyldiazoesters 3, in-
serted into the Si-H bond of a silane stereospecifically
with retention of the geometry of the starting double
bond. We report here that the strategy is of general
utility and can be applied to the stereospecific prepara-
tion of other allylic systems such as allylic amines,
alcohols, and thioethers, through insertion into N-H,
O-H, and S-H bonds, respectively. A study on the
control of the absolute configuration of the chiral allylic
center is also described. Two different routes for control-
ling the stereochemistry at the allylic center have been
devised for this purpose. The first route involves the
insertion of a vinyldiazoester where the chirality is
located on the ester function. In this case, we have
observed that readily available pantolactone (as a chiral
auxiliary) is the best choice. In the second approach, we
have investigated the use of achiral vinyldiazoesters and
optically active rhodium catalysts, such as Doyle’s Rh2-
(MEPY)4.4 Encouraging levels of stereocontrol have been
observed for the first time in these insertions using chiral
catalysts.
X Abstract published in Advance ACS Abstracts, February 15, 1997.
(1) (a) Masamune, S.; Choy, W.; Petersen, J . S.; Sita, L. R. Angew.
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31. (e) Ager, D. J .; East, M. B. Tetrahedron 1992, 48, 2803.
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Organic Compounds; J ohn Wiley & Sons: New York, 1994. (b) Houk,
K. N.; Paddon-Row, M. N.; Rondan, N. G.; Wu, Y.-D.; Brown, F. K.;
Spellmeyer, D. C.; Metz, J . T.; Li, Y.; Loncharich, R. J . Science 1986,
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1.
Discu ssion
Syn th esis of (E)- a n d (Z)-Vin yld ia zoester s. Vinyl-
diazomethanes have been used in various contexts in the
(4) (a) Doyle, M. P. Recl. Trav. Chim. Pays-Bas 1991, 110, 305. (b)
Doyle, M. P. In Catalytic Asymmetric Synthesis; Ojima, I., Ed.; VCH:
New York, 1993; p 63. (c) Padwa, A.; Austin, D. J . Angew. Chem., Int.
Ed. Engl. 1994, 33, 1797.
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1994, 35, 9549. (b) Ganem, B. Chemtracts, Org. Chem. 1995, 8, 51.
S0022-3263(96)01952-4 CCC: $14.00 © 1997 American Chemical Society

Rhodium(II)-Vinyl Carbenoid Insertion
J . Org. Chem., Vol. 62, No. 6, 1997 1631
Sch em e 2
Sch em e 3
analogous Z-isomers has so far appeared. The most
straightforward access to diazoesters 7 involves the
treatment of â,γ-unsaturated esters 6 with a diazo-
transfer reagent (mesyl azide8 (MsN3) or acetylbenzene-
sulfonyl azide9 (ABSA)) in the presence of a base (DBU
or NEt3), according to the Davies procedure (Scheme 2).6
The uncommon â,γ-unsaturated acids 5a -c and 5f-h
prepared using a reported method from aldehydes 4a -
e,10 were esterified and submitted to diazo-transfer
reaction to afford esters 7a -h in good overall yield
(Scheme 2). 1H NMR and capillary GC showed that this
sequence afforded the E isomer as the sole product.
past,5 including the synthesis of divinylcyclopropanes and
more recently their analogues, i.e., vinyldiazoesters 3
have been introduced by Davies and co-workers6 in a
cyclopropanation-Cope rearrangement sequence to pro-
vide an efficient route to seven-membered rings and
tropane skeletons. Surprisingly, only one example of
insertion of these vinylmetal carbenoids into the O-H
bond has been reported before our investigations.6d
Moreover, while the preparation of (E)-vinyldiazoesters
is well documented,6,7 no report concerning the stereo-
control occurring during the diazo-transfer process with
We were also pleased to find that (Z)-â,γ-unsaturated
esters 6i,j led with complete stereocontrol (within the
1
limits of detection of H NMR and capillary GC) to the
desired (Z)-vinyldiazoesters 7i,j in excellent overall yield
and that no isomerization or migration of the double bond
occurred in our conditions.10b This represents the first
and indeed a general route to this kind of diazo precursor.
The ester function in 7i was easily introduced through
the sequence depicted below with the geometry of the
olefin being secured during the hydrogenation of the
triple bond (Scheme 3).
(5) (a) Salomon, R. G.; Salomon, M. F.; Heyne, T. R. J . Org. Chem.
1975, 40, 756. (b) Salomon, R. G.; Salomon, M. F.; Kachinski, J . L. C.
J . Am. Chem. Soc. 1977, 99, 1043. (c) Mueller, L. G.; Lawton, R. G. J .
Org. Chem. 1979, 44, 4741. (d) Franck-Neumann, M.; Dietrich-
Buchecker, M. Tetrahedron 1978, 34, 2797. (e) Schneider, M. P.; Rau,
A. J . Am. Chem. Soc. 1979, 101, 4426. (f) Schneider, M. P.; Goldbach,
M. J . Am. Chem. Soc. 1980, 102, 6114. (g) Mandai, T.; Hara, K.;
Kawada, M.; Nokami, J . Tetrahedron Lett. 1983, 24, 1517.
(6) (a) Davies, H. M. L.; Clark, T. J .; Smith, H. D. Tetrahedron Lett.
1985, 25, 5659. (b) Davies, H. M. L.; Clark, T. J .; Alligood, D. B.;
Eiband, G. R. Tetrahedron 1987, 43, 4265. (c) Davies, H. M. L.; Young,
W. B.; Smith, H. D. Tetrahedron Lett. 1989, 30, 4653. (d) Davies, H.
M. L.; Smith, H. D.; Korbor, O. Tetrahedron Lett. 1987, 28, 1853. (e)
Davies, H. M. L.; Oldenburg, C. E. M.; McAfee, M. J .; Nordahl, J . G.;
Henretta, J . P.; Romines, K. R. Tetrahedron Lett. 1988, 29, 975. (f)
Davies, H. M. L.; Clark, T. J .; Church, L. A. Tetrahedron Lett. 1989,
30, 5057. (g) Davies, H. M. L.; McAfee, M. J .; Oldenburg, C. E. M. J .
Org. Chem. 1989, 54, 930. (h) Davies, H. M. L.; Huby, N. J . S.;
Cantrell, W. R.; Olive, J . L. J . Am. Chem. Soc. 1993, 115, 9468. (i)
Davies, H. M. L. Tetrahedron 1993, 49, 5203 and references cited. (j)
Wulff, W. D.; Yang, D. C.; Murray, C. K. J . Am. Chem. Soc. 1988, 110,
2653. (k) Davies, H. M. L.; Clark, T. J .; Smith, H. D. J . Org. Chem.
1991, 56, 3817. (l) Padwa, A.; Kulkarni, Y. S.; Zhang, Z. J . Org. Chem.
1990, 55, 4144. (m) Davies, H. M. L.; Saikali, E.; Young, W. B. J . Org.
Chem. 1991, 56, 5696. (n) Davies, H. M. L.; Hu, B. J . Org. Chem. 1992,
57, 3186. (o) Davies, H. M. L.; Peng, Z.-Q.; Houser, J . H. Tetrahedron
Lett. 1994, 35, 8939.
Ster eosp ecific Syn th esis of (E) a n d (Z)-Allylsi-
la n es. Our first insertion experiments were carried out
by slowly adding styryldiazoester 7a to a suspension of
silane in CH2Cl2 and a catalytic amount of Rh2(OAc)4.
The desired allylsilane 8a was thus formed in 70% yield
1
after evaporation of the solvent, and the H NMR of the
crude reaction mixture indicated that 8a was pure
enough to be used without further purifications (Scheme
4, Table 1, entry 1). The protocol could be simplified to
a large extent by simply mixing the diazoester and the
silane in CH2Cl2 and then adding a catalytic amount of
Rh2(OAc)4. The deep red coloration of the diazo precursor
vanished over a period of 20 min, indicating that the
diazo precursor was no longer present in the reaction
mixture. Consequently, in contrast to what is usually
(8) Taber, D. F.; Ruckle, R. E., J r.; Hennessy, M. J . J . Org. Chem.
1986, 51, 4077.
(9) Baum, J . S.; Shook, D. A.; Davies, H. M. L.; Smith, H. D. Synth.
Commun. 1987, 17, 1709.
(10) (a) Bunce, R. A.; Reeves, H. D. J . Chem. Educ. 1990, 67, 69.
(b) Galatsis, P.; Manwell, J . J .; Millan, S. D. Tetrahedron Lett. 1996,
37, 5261 and references cited therein.
(7) (a) Regitz, M.; Menz, F. Chem. Ber. 1968, 101, 2622. (b) Ye, T.;
McKervey, M. A. Chem. Rev. 1994, 94, 1091. For a recent synthesis
of R-diazoesters, see: Taber, D. F.; You, K.; Song, Y. J . Org. Chem.
1995, 60, 1093.

1632 J . Org. Chem., Vol. 62, No. 6, 1997
Bulugahapitiya et al.
Ta ble 1. Syn th esis of Allylsila n es 8a -k (Sch em e 4)
Sch em e 5
entry
7a
R3Si
8a
% yieldc
1
2
3
4
5
6
7
8
9
7a
7a
7a
7a
7a
7b
7b
7d
7f
PhMe2Si
8a
8b
8c
8d
8e
8f
8g
8h
8i
70
72
45
85
76
80
61
76
87
98
97
(Thien)Me2Sib
(Me3Si)3Si
(i-PrO)Me2Si
(i-Pr)2FSi
PhMe2Si
(Thien)Me2Sib
PhMe2Si
PhMe2Si
allylMe2Si
(BrCH2)Me2Si
10
11
7a
7a
8j
8k
a
b
E/Z > 98: < 2. (Thien)Me2Si:(5-methylthienyl)dimethylsilyl.
c Estimated yield from 1H NMR after evaporation of the solvent
and the excess of silane.
reacts cleanly in the presence of the presumed rhodium-
vinylcarbenoid species without competitive sulfur ylide14
or cyclopropanation reactions15 (entries 2 and 7). Inter-
estingly, the insertion using an allylsilane (i.e. allylSiMe2H,
entry 10) produced the desired ester 8j in excellent yield
without a trace of cyclopropanation products. This
demonstrates that insertion into the Si-H bond is a more
favorable process than cyclopropanation, at least when
one has to deal with monosubstituted olefinic silanes.
Insertion into the Si-H of (bromomethyl)silane (entry
11) also led to R-silylester 8k which might be a useful
synthon for further radical functionalization.16
Sch em e 4
observed with R-alkyldiazoesters,11 vinyldiazoesters do
not seem to dimerize under our reaction conditions, so
that the concentration of the diazo precursor in the
medium is no longer a problem. Other vinyldiazoesters
undergo the insertion process with generally good yields
(Table 1). Although the products obtained are generally
clean enough to be used as such, distillation of the
allylsilane can be performed, and is preferable to chro-
matography over silica gel which results in extensive
desilylation. Different substituents on the silane have
been used, demonstrating that the insertion process can
accommodate nearly any kind of silicon group. This is
of importance from the perspective of the oxidation of the
C-Si bond into the corresponding C-OH bond, since
Tamao, Kumada, and Fleming12 in their pioneering
studies have clearly shown that an activating group on
the silicon is generally required for this oxidation to take
place. For instance, alkoxysilane can be introduced by
this route via insertion using (i-PrO)SiMe2H (entry 4).
It is noteworthy that ethyldiazoacetate gave poor yields
on reaction with the same silane, indicating again a
contrasting reactivity of vinyldiazoesters compared to
their alkyl analogues. (Me3Si)3SiH also led to the desired
silane although in moderate yield (entry 3). This silane
is often used as an alternative to Bu3SnH due to the low
bond energy of the Si-H bond. Therefore, it is a good
reducing agent, which explains the large amount of ester
6a formed through reduction of 7a .13 The insertion into
the unusual (i-Pr)2SiFH, prepared from the corresponding
chlorosilane, gave rise to the unstable R-silylester 8e in
good yield (entry 5). The thiophene-silane reagent also
Finally, a recent report by Davies et al.6d mentioned
that the insertion of the vinylrhodium carbenoid gener-
ated from 7k into the O-H bond of water did occur in
good yield but was followed by a migration of the allylic
double bond to form the corresponding R-hydroxy-R,â-
unsaturated ester (Scheme 5). Such a double bond
migration was not observed during the insertion into the
Si-H bond, since treatment of 7k with PhMe2SiH in the
presence of Rh2(OAc)4 produced the expected allylsilane
8l in 70% yield and not the vinylsilane. 8l could not be
purified due to extensive desilylation, but its structure
1
was unambiguously assigned from its H NMR spectrum.
We next tackled the critical question of the stereose-
lectivity of the insertion process. (E)- and (Z)-vinyldia-
zoesters 7c-e and 7i,j were thus submitted to the same
reaction conditions as those described above. Examina-
tion of the crude reaction mixture in both cases unam-
biguously revealed that the insertion process is stereospe-
cific leading to (Z)- and (E)-allylsilanes 8m -p in good
yields, with retention of the geometry of the double bond
(Scheme 6). The retention of the stereochemistry sup-
ports the hypothesis of a concerted mechanism for the
insertion into the Si-H bond,17 similar to the one
proposed by Doyle for metal-carbenoid insertion into the
C-H bond.18 A stepwise organometallic process would
probably involve isomerization or migration of the double
bond, leading to a conjugated ester through i.e. oxidative
addition onto the Si-H bond and formation of an hy-
drido-rhodium complex.11e,19
(11) (a) Bagheri, V.; Doyle, M. P.; Taunton, J .; Claxton, L. E. J . Org.
Chem. 1988, 53, 6158. (b) Andrey, O.; Landais, Y.; Planchenault, D.
Tetrahedron Lett. 1993, 34, 2927. (c) Andrey, O.; Landais, Y.;
Planchenault, D.; Weber, V. Tetrahedron 1995, 51, 12083. (d) Landais,
Y.; Planchenault, D. Tetrahedron 1995, 51, 12097. (e) Landais, Y.;
Planchenault, D. Tetrahedron Lett. 1994, 35, 4565. (f) Barnier, J .-P.;
Blanco, L. J . Organomet. Chem. 1996, 514, 67.
(12) For reviews on the oxidation of the C-Si bond, see: (a) J ones,
G. R.; Landais, Y. Tetrahedron 1996, 52, 7599. (b) Fleming, I.
Chemtracts, Org. Chem. 1996, 9, 1. (c) Tamao, K.; Ishida, N.; Tanaka,
T.; Kumada, M. Organometallics 1983, 2, 1694. (d) Fleming, I.;
Henning, R.; Parker, D. C.; Plaut, H. E.; Sanderson, P. E. J . J . Chem.
Soc., Perkin Trans. 1 1995, 317. However, a recent report mentioned
that oxidation of nonactivated SiMe3 group can also be carried out,
albeit in modest yield, see: Smitrovich, J .-H.; Woerpel, K. A. J . Org.
Chem. 1996, 61, 6044.
(14) (a) Doyle, M. P. In Comprehensive Organometallic Chemistry
II: A Review of the Literature 1982-1994; Abel, E. W., Stone, F. G. A.,
Wilkinson, G., Eds.; Pergamon: Oxford, 1995; p 421. (b) Doyle, M. P.
Acc. Chem. Res. 1986, 19, 348.
(15) (a) Schenck, G. O.; Steinmetz, R. Ann. Chem. 1963, 668, 19.
(b) Mu¨ller, E.; Kessler, H.; Fricke, H.; Suhr, H. Tetrahedron Lett. 1963,
16, 1047.
(16) (a) Bols, M.; Skrydstrup, T. Chem. Rev. 1995, 95, 1253. (b)
Stork, G. Bull. Soc. Chim. Fr. 1990, 675.
(17) Landais, Y.; Parra-Rapado, L.; Planchenault, D.; Weber, V.
Tetrahedron Lett. 1997, 38, 229.
(18) Doyle, M. P.; Westrum, L. J .; Wendelmoed, N. E. W.; See, M.
M.; Boone, W. P.; Bagheri, V.; Pearson, M. M. J . Am. Chem. Soc. 1993,
115, 958.
(13) (a) Chatgilialoglu, C. Acc. Chem. Res. 1992, 25, 188. (b)
Chatgilialoglu, C. Chem. Rev. 1995, 95, 1229.

Rhodium(II)-Vinyl Carbenoid Insertion
J . Org. Chem., Vol. 62, No. 6, 1997 1633
Ta ble 2. In ser tion of Rh od iu m -Vin yl Ca r ben oid in to
N-H a n d O-H Bon d s (Sch em e 8)
Sch em e 6
entry
7a
condb
RX
14a
%yieldc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
7a
7b
7c
7g
7h
7i
7a
7c
7i
7a
7a
7a
7c
7i
A
A
A
A
A
A
B
B
B
C
D
E
HO
HO
HO
HO
HO
HO
EtO
MeO
MeO
RO
PhO
PhNH
PhNH
PhNH
14a
14b
14c
14d
14e
14f
14g
14h
14i
14j
14k
14l
14m
14n
77
54
53
63
32
50
75
65
65
52
40
68
62
70
E
E
Sch em e 7
a
b
E/Z or Z/E ratio >98:<2. Conditions: A, wet ether, 1 h, rt,
B, ROH (solvent), 15 min, rt; C, ROH:CF3CH2OH (10 equiv),
benzene, 5 min, reflux; D, PhOH (5 equiv), benzene, 1 h, reflux;
E, PhNH2 (5 equiv), benzene, 10 min, reflux. c Isolated yield after
purification by chromatography.
Sch em e 8
amines and alcohols has never been reported. We
therefore extended our methodology to the insertion into
O-H and N-H bonds and showed that similarly to the
insertion into the Si-H bond, the process is stereospecific
leading to (Z)- and (E)-allylic amines, alcohols, and ethers
in good yields (Scheme 8, Table 2).
The reactions were performed starting from vinyldia-
zoesters 7a -i under conditions which differ slightly from
those described for the insertion into the Si-H bond.
Insertion into the O-H bond of H2O was best carried out
in wet ether at room temperature (entries 1-6), affording
the expected allylic alcohols in 32-77% yield. With
EtOH and MeOH, the insertion occurred at room tem-
perature when the reagent is also the solvent (entries
7-9). Such conditions are not convenient for the less
nucleophilic CF3CH2OH or PhOH, so in these cases, the
reaction was best performed in benzene under reflux,
producing the ethers in moderate yields (40-50%) (en-
tries 10 and 11). More interestingly, the (E)-ester 7c and
(Z)-ester 7i, gave rise to the corresponding (E)- and (Z)-
allylic alcohols 14c and 14f in good yields (entries 3 and
6), stereospecifically with retention of the geometry of the
double bond. Similar behavior was observed during
insertion into the O-H bond of alcohols (entries 8 and
9). The contrasting yields summarized in entries 4 and
We also extended our methodology to the synthesis of
allylsilane ketone 10 and dienylsilane 13 which were
obtained in 65% and 72% yield, respectively, from the
corresponding diazo precursors 96k and 126k (Scheme 7).
Again, it is important to note that the R-silylketone was
obtained pure enough to be used without further purifi-
cations since it was found very sensitive to chromatog-
raphy and distillation.11a,20 The R-silylketone was thus
directly reduced using DIBAH to afford the more stable
syn-â-hydroxysilane 11 in reasonable yield as a single
diastereoisomer.
In ser tion of Rh od iu m -Vin yl Ca r ben oid s in to
N-H, O-H, a n d S-H Bon d s. The decomposition of
R-diazoesters catalyzed by metal complexes in the pres-
ence of an amine or an alcohol is known to produce,
through insertion into the N-H and O-H bond, respec-
tively, the corresponding R-amino and R-hydroxy es-
ters.21,22 Surprisingly, however, the application of this
methodology to the stereoselective synthesis of allylic
(21) For metallo-carbene insertion into N-H bonds: see: (a) Paulis-
sen, R.; Hayez, E.; Hubert, A. J .; Teyssie´, P. Tetrahedron Lett. 1974,
607. (b) Nicoud, J .-F.; Kagan, H. Tetrahedron Lett. 1971, 2065. O-H
bonds: (a) Cox, G. C.; Miller, D. J .; Moody, C. J .; Sie, E.-R.H.B.;
Kulagowski, J . J . Tetrahedron 1994, 50, 3195. (c) Haigh, D. Tetrahe-
dron 1994, 50, 3177. (c) Aller, E.; Cox, G. G.; Miller, D. J .; Moody, C.
J . Tetrahedron Lett. 1994, 35, 5949. (d) Landais, Y.; Planchenault, D.
Synlett 1995, 1191. (e) Cox, G. G.; Moody, C. J .; Austin, D. J .; Padwa,
A. Tetrahedron 1993, 49, 5109.
(22) (a) Demonceau, A.; Hubert, A. J .; Noels, A. F. In Metal Promoted
Selectivity in Organic Synthesis; Noels, A. F., Graziani, M., Hubert,
A. J ., Eds.; Kluwer Academic Publ.: Dordrecht, Netherlands, 1991; p
237. (b) Paulissen, R.; Reimlinger, H.; Hayez, E.; Hubert, A. J .; Teyssie´,
P. Tetrahedron Lett. 1973, 2233. (c) Petiniot, N.; Anciaux, A. J .; Noels,
A. F.; Hubert, A. J .; Teyssie´, P. Tetrahedron Lett. 1978, 1239. (d) Noels,
A. F.; Demonceau, A.; Petiniot, N.; Hubert, A. J .; Teyssie´, P. Tetrahe-
dron 1982, 38, 2733.
(19) (a) Hill, J . E.; Nile, T. A. J . Organomet. Chem. 1977, 137, 293.
(b) Brockmann, M.; Dieck, T. H.; Klaus, J . J . Organomet. Chem. 1986,
301, 209. (c) Lappert, M. F.; Maskell, R. K. J . Organomet. Chem. 1984,
264, 217. (d) Bergens, S. H.; Noheda, P.; Whelan, J .; Bosnich, B. J .
Am. Chem. Soc. 1992, 114, 2128. (e) Brown, J . M.; Lloyd-J ones, G. C.
J . Am. Chem. Soc. 1994, 116, 866. (f) Hiyama, T.; Kusumoto, T. In
Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon Press: Oxford, 1991; p 763. (g) Tamao, K.; Nakagawa, Y.;
Ito, Y. Organometallics 1993, 12, 2297. (h) Horn, K. A. Chem. Rev.
1995, 95, 1317.
(20) The R-silylketone might undergo Brook rearrangement, al-
though we have not isolated the corresponding silyl enol ether. The
parent vinylketone is sometimes present in small amount as
a
byproduct and could be formed either through desilylation of 10 or
hydrolysis of a silyl enol ether.

1634 J . Org. Chem., Vol. 62, No. 6, 1997
Bulugahapitiya et al.
Sch em e 9
Sch em e 11
Sch em e 10
5 suggests that the reaction is also sensitive to electronic
effects, with electron-withdrawing substituents on the
diazo precursor probably slowing down the insertion
process. Electron-withdrawing groups on the alcohol
chain (CF3) similarly led to a lower yield of the corre-
sponding allylic ether (entry 10). This is a trend which
we have already noticed during our recent studies on
Si-H bond insertion.17 The mechanism of the insertion
of metal-carbenoid species into O-H bonds is not known
with certainty, but the above observations fit well with
the hypothesis of a nucleophilic attack of the alcohol onto
the electrophilic carbenoid center.23
Insertion into the N-H bond of aniline was found to
go to completion after only 10 min in benzene under
reflux, leading to R-aminoesters in good yield. As ob-
served for the Si-H and O-H bonds, the insertion
process occurs stereospecifically with retention of the
double bond geometry (Table 2, entries 13 and 14), thus
giving a straightforward access to unusual R-aminoesters
having a vinyl group on the chiral center.
Insertion into the S-H bond was also investigated with
less success,24 giving modest yields of the corresponding
R-phenylthio ester (Scheme 9) along with a byproduct
which we have not been able to purify. The phenylthio
allylic derivative was isolated as the alcohol 15 after
reduction of the ester function. The presence of the
double bond onto which thiophenol can readily add might
be at the origin of this disappointingly low yield. Finally,
the thioether 15 can be oxidized, affording the expected
allylsulfone 16 in nearly quantitative yield. Such a
synthon could be particularly useful as a precursor of
allylstannes or for the generation of functionalized pol-
yanions.25
allylic center. Two different procedures were envisaged,
starting either from a diazoester having a chiral auxiliary
attached to the ester function (i.e. I, Scheme 10) or from
a prochiral racemic vinyldiazoester with a chiral catalyst
(i.e. II). The second approach has recently been inves-
tigated in O-H insertion reactions and led to very
disappointing results.26 However, this is an attractive
possibility since the insertion process is virtually absent
without catalyst and hence is likely to occur within the
rhodium complex framework, thereby forcing both pro-
tagonists (the carbenoid species and the X-H bond) to
meet in a chiral environment. High levels of enantiose-
lectivity during these investigations would therefore
strongly support the hypothesis that the rhodium catalyst
and its ligands are intimately bound to the carbenoid
center during the insertion.
The choice of pantolactone as a chiral auxiliary was
dictated by prior results in our group and the pioneering
work of Davies and co-workers6h who demonstrated that
excellent diastereoselectivities could be attained using
this chiral auxiliary during cyclopropanation reactions.
Such high levels of stereoselectivity is attributed to a
favored coordination of the electrophilic carbenoid center
with the carbonyl group of pantolactone. A stabilization
and a rigidification of the transition state would then lead
to higher diastereofacial differentiation. We report here
that pantolactone is also an efficient chiral auxiliary for
rhodium-carbenoid insertion reactions even if our dia-
stereoselectivities do not compete with those reported by
Davies for cyclopropanations.
Asym m etr ic Access to Allylic System s. Having a
straightforward method for controlling the stereochem-
istry of the allylsilane double bond, we were next
concerned with the control of the stereochemistry at the
The diazo precursors 18a -d were prepared in 40-55%
overall yield, by condensation of acids 5a ,d ,e and com-
mercial hex-3-enoic acid with pantolactone in the pres-
ence of DCC and DMAP, followed by the diazo transfer
process (Scheme 11). Using this esterification protocol,
(23) (a) Miller, D. J .; Moody, C. J . Tetrahedron 1995, 51, 10811. (b)
Aller, E.; Brown, D. S.; Cox, G. G.; Miller, D. J .; Moody, C. J . J . Org.
Chem. 1995, 60, 4449.
(24) (a) Moyer, M. P.; Feldman, P. L.; Rapoport, H. J . Org. Chem.
1985, 50, 5223. (b) Brunner, H.; Wutz, K.; Doyle, M. P. Monatsh.
Chem. 1990, 121, 755.
(25) Simpkins, N. S. Sulfones in Organic Synthesis; Pergamon:
Oxford, 1993.
(26) Ferris, L.; Haigh, D.; Moody, C. J . Tetrahedron Lett. 1996, 37,
107.

Rhodium(II)-Vinyl Carbenoid Insertion
J . Org. Chem., Vol. 62, No. 6, 1997 1635
Ta ble 3. Syn th esis of Allylsila n es, Allylic Alcoh ols, a n d
Sch em e 13
Eth er s 19a -g (Sch em e 11)
entry
diazoa
producta
dec
%yieldd
1
2
3
4
5
6
7
18a
18a
18bb
18c
18d
18a
18a
19a
19b
19cb
19d
19e
19f
32
34
50
70
44
50
5
70
55
67
75
65
75
75
19g
a
b
E/Z or Z/E ratio >98:<2. E/Z ratio 96:4. c de was estimated
from 1H NMR of the crude reaction mixture. Isolated yield after
d
flash chromatography.
Sch em e 12
20a ,b.30 Oxidative cleavage of the C-Si bond, with
retention of configuration,12 finally afforded the desired
diols 21a ,b.31 In contrast to what we observed previously
with menthol or analogues,28 the reduction of the ester
function occurred with partial epimerization at the allylic
center. Nevertheless, we were able to demonstrate
unambiguously that the allylsilanes 19a -d all possessed
the S absolute configuration irrespective of the geometry
of the diazo precursor (Scheme 13).
the geometry of the olefin was thus left unchanged in
contrast to the condensation of the chiral auxiliary with
the acyl chloride derivative which leads to partial isomer-
ization of the double bond.27 18a -d were then treated
as above (PhMe2SiH or (Me3Si)3SiH) to afford the corre-
sponding allylsilanes 19a -e in good yields and with
diastereoselectivities as high as 70% (Scheme 11, Table
3).
Similarly, 18a and 18d were submitted to the Rh2-
(OAc)4 decomposition in the presence of H2O and MeOH,
to afford the corresponding esters 19f and 19g as a
diastereoisomeric mixture (Scheme 11, Table 3, entries
6 and 7). With 19f, we have been able to separate both
diastereoisomers using flash chromatography (19fa and
19fb). Surprisingly, as the diastereoselectivity of the
insertion into the O-H bond of H2O was on the same
order of magnitude as that observed for insertion into
the Si-H bond, the diastereoselectivity of the insertion
process into the O-H bond of MeOH was very low. This
is in good agreement with the recent investigations of
Moody et al. on the insertion of menthyl-derived diazo-
esters into MeOH.32 As for the Si-H insertion process,
the mechanism is presently unknown, and a rationaliza-
tion of our stereoselectivity is therefore compromised.
Moreover, comparison between insertion in H2O and
MeOH could be misleading if one looks at the difference
in reaction conditions. Water is used as a reagent, but
methanol is also the solvent for the reaction. The
conversion of ester 19f into the corresponding methyl
ester 22 as depicted in Scheme 14 allowed us to assign
the S absolute configuration for the major isomer 19fa .
Consequently, insertion into Si-H and O-H bonds
occurs with the same topicity, and it is likely that the
coordination proposed for the former (Scheme 12) is also
operative for the latter. Again, higher diastereoselec-
tivities were found with pantolactone as a chiral auxiliary
compared to menthol, but, as mentioned previously with
As the mechanism of the insertion is not known with
certainty, it is premature to give a definitive rationaliza-
tion of our stereoselectivities. However, model reactions
using menthol as chiral auxiliary gave much lower
diastereoselectivities than pantolactone, hence we as-
sume that electronic and not just steric effects are
involved during the insertion process. Stabilization of
the transition state through coordination of the carbenoid
center with the carbonyl of the pantolactone might be
invoked (vide supra), with the vinylrhodium carbenoid
probably in a s-trans-s-trans conformation and the silane
approaching on the opposite face relative to the panto-
lactone (Scheme 12). Both methyl groups on the chiral
auxiliary then occupy a position where the steric interac-
tions between them and the “rhodium-acetate-wall” are
minimized.6h It should be emphasized that (Z)-olefins led
to slightly higher diastereoselectivities than (E)-olefins
(compare entries 3 and 4). We also observed that
changing from PhMe2SiH (entry 1) to (Me3Si)3SiH (entry
2) did not alter the diastereoselectivity, indicating that
the size of the silane had little influence. This is in good
agreement with our previous observations made during
a study of insertions in the alkyl series.28 We attribute
the low sensitivity of rhodium carbenoids toward struc-
tural changes and steric effects to the occurrence of an
early transition state, a hypothesis which has been
consistently put forward in carbene transfer processes.17,29
The absolute configuration of the allylsilanes 19a -d
was determined by a three-step sequence: the hydroge-
nation of the double bond of 19a , 19c, and 19d , followed
by reduction of the ester group, gave the â-hydroxysilanes
(29) (a) Wee, A. G. H.; Liu, B. Tetrahedron Lett. 1996, 37, 145. (b)
Mu¨ller, P.; Fernandez, D. Helv. Chim. Acta 1995, 78, 947. (c) Doyle,
M. P.; Griffin, J . H.; Bagheri, V.; Dorow, R. L. Organometallics 1984,
3, 53. (d) Doyle, M. P.; Wang, L. C.; Loh, K.-L. Tetrahedron Lett. 1984,
25, 4087. Recent studies in our group on the mechanism of the Si-H
insertion corroborate the hypothesis of a mechanism involving an early
transition state with the development of partial positive charge on the
silicon center.17
(30) Hydrogenation of the double bond of 19c and 19d led to
products with the same configuration, indicating that the topicity of
the insertion reaction was identical for (E) and (Z)-diazo precursors.
(31) (a) J eong, K.-S.; Sjo¨, P.; Sharpless, K. B. Tetrahedron Lett. 1992,
33, 3833. (b) Regeling, H.; Chittenden, G. J . F. Carbohydr. Res. 1991,
216, 79. (c) Corey, E. J .; Link, J . O. Tetrahedron Lett. 1992, 33, 3431.
(32) Cox, G. G.; Haigh, D.; Hindley, R. M.; Miller, D. J .; Moody, C.
J . Tetrahedron Lett. 1994, 35, 3139.
(27) A 30-50% isomerization of the double bond was observed under
these conditions with the (Z)-hex-3-enoic acid.
(28) Landais, Y.; Planchenault, D. Tetrahedron 1997, in press.

1636 J . Org. Chem., Vol. 62, No. 6, 1997
Bulugahapitiya et al.
Ta ble 4. Rh 2(5S-MEP Y)4-Ca ta lyzed In ser tion in to Si-H
a n d O-H Bon d s (Sch em e 15)
Sch em e 16
entry
diazo
product
eea
%yield
1
2
3
7a
7b
7a
23a
23b
14a
72
52
8
30b
32b
59c
Measured from the 1H NMR of the corresponding Mosher’s
esters and by capillary GC. b Isolated overall yield (two steps) after
flash chromatography. c Isolated yield of the R-hydroxy ester 14a
after flash chromatography.
a
Sch em e 14
generated from 7a , into the Si-D bond of PhMe2SiD. The
insertion process was found to occur with virtually
complete incorporation of deuterium (limit of detection
of 1H NMR). This route thus offers an easy entry to
deuterium labeled allylsilanes which would be difficult
to prepare using other known methods. Similarly, inser-
tion into the O-D bond of D2O and EtOD gave the
desired R-deutero-R-alkoxy esters 26a ,b in 54% and 62%
yield, respectively, with complete incorporation of deu-
terium (Scheme 16).
Sch em e 15
The insertion into the Si-H bond was found to give
reasonable enantioselectivity36,37 with Rh2(5S-MEPY)4
(Table 4, entries 1 and 2) . On the opposite and in good
agreement with literature reports,26 nearly no selectivity
was observed on insertion of 7a into the O-H bond of
H2O (entry 3). This suggests that insertion of metal-
carbenoid species into polar (O-H and N-H) and non-
polar bonds (C-H and Si-H) involves intermediates of
different nature. The metal and its chiral ligands might
be partially dissociated from the carbenoid center in the
former case, and on the opposite might be more inti-
mately bound to the reactive carbenoid center in the
second case hence contributing more efficiently to the
stereocontrol. The good level of enantioselectivity reached
with Si-H insertion represents a useful alternative to
the nonselective O-H bond insertion since the silicon
group can be regarded as an OH equivalent.12 Finally,
we also tested Rh2(MEOX)4 and found this catalyst to be
poorly reactive, leading to no enantioselectivity at all. It
must be emphasized though that both Rh2(5S-MEPY)4
and Rh2(MEOX)4 are much less reactive than Rh2(OAc)4
and therefore require much longer reaction times. None-
theless, these few examples demonstrate that this strat-
egy is of interest and will certainly deserve much more
attention in the future. The search for a more reactive
and more selective catalyst is therefore needed to further
enhance the value of this methodology. Work along these
lines is now in progress in our group.
the R-silylesters 19a and 19c,d , while the removal of
pantolactone in 19fa occurred in good yield it was also
accompanied by partial epimerization.
As shown above, the pantolactone can lead to useful
diastereoselectivities, indeed the best which have been
so far reported in such insertion reactions, but the
epimerization during the DIBAH reduction and the loss
of pantolactone (only in the silicon series) somewhat limit
the utility of this approach. Several attempts to over-
come this problem have not so far been successful. For
instance, pig liver esterase treatment of the ester 19a
led exclusively to desilylation and more surprisingly
without further hydrolysis of the ester function of the
desilylated product.33
We thus turned our attention to the use of chiral
rhodium catalysts (model II, Scheme 10). Asymmetric
4
insertions were carried out using Doyle’s Rh2(5S-MEPY)4
34
and Rh2(MEOX)4 under the conditions described previ-
ously for Rh2(OAc)4 (Scheme 15, Table 4). The resulting
R-silylesters were directly submitted to reduction using
LiAlH4 in ether affording the corresponding alcohols
23a ,b35 in modest overall yields (Scheme 15). The
enantiomeric excesses were then measured either on the
1
crude alcohols (GC or HPLC) or from the H NMR of the
Mosher’s esters of the alcohols, assuming that no race-
mization had occurred during the reduction of the ester
function. This was unambiguously demonstrated through
reduction of R-deutero-R-silylester 24 which gave the
desired deutero-alcohol 25 in 64% yield (from 7a ) with
no incorporation of hydrogen at C-2 (Scheme 16). 24 was
prepared by insertion of the rhodium-vinyl carbenoid
(36) A preliminary account of these results has been presented:
Chiral 2 symposium, (03-29-1995), Gwatt (Switzerland).
(37) For other asymmetric routes to R-silylcarbonyl compounds,
see: (a) Enders, D.; Nakai, S. Helv. Chim. Acta 1990, 73, 1833. (b)
Enders, D.; Nakai, S. Chem. Ber. 1991, 24, 219. (c) Bhushan, V.;
Lohray, B. B.; Enders, D. Tetrahedron Lett. 1993, 34, 5067. (d) Gilloir,
F.; Malacria, M. Tetrahedron Lett. 1992, 33, 3859. (e) Le Bideau, F.;
Gilloir, F.; Nilsson, Y.; Aubert, C.; Malacria, M. Tetrahedron Lett. 1995,
36, 1641. (f) Paquette, L. A.; Maynard, J . D.; Ra, C. S.; Hoppe, M. J .
Org. Chem. 1989, 54, 1408. (g) Paquette, L. A.; Gilday, J . P.; Ra, C.
S.; Hoppe, M. J . Org. Chem. 1988, 53, 704. (h) Gilday, J . P.; Gallucci,
J . C.; Paquette, L. A. J . Org. Chem. 1989, 54, 1399. (i) Le Bideau, F.;
Aubert, C.; Malacria, M. Tetrahedron: Asym. 1995, 6, 697. (j) Le
Bideau, F.; Gilloir, F.; Nilsson, Y.; Aubert, C.; Malacria, M. Tetrahedron
1996, 52, 7487. (k) Enders, E.; Lohray, B. B.; Burkamp, F.; Bhushan,
V.; Hett, R. Liebigs. Ann. Chem. 1996, 189.
(33) (a) Azerad, R. Bull. Soc. Chim. Fr. 1995, 132, 17. (b) Wong,
C.-H.; Whitesides, G. M. Enzymes in Synthetic Organic Chemistry;
Pergamon: Oxford, 1994.
(34) Doyle, M. P.; Eismont, M. Y.; Protopopova, M. N.; Kwan, M.
M. Y. Tetrahedron 1994, 50, 1665.
(35) The absolute configuration of alcohol 23a was determined as
follows: hydrogenation of the double bond and oxidation of the C-Si
bond of 23a afforded the known diol 21a possessing the S config-
uration.31c 23b was assumed to possess the same absolute configu-
ration as 23a .

Rhodium(II)-Vinyl Carbenoid Insertion
J . Org. Chem., Vol. 62, No. 6, 1997 1637
and then heated at 50 °C for 2 h. The solution was treated
with water at 0 °C and then extracted with ether. The
combined extracts were washed with brine and dried over
MgSO4, and the solvents were evaporated in vacuo. Distilla-
tion (70 °C, 0.15 mbar) gave hept-3-ynol (6.3 g, 82%) as a
colorless oil. To a stirred solution of the preceding alcohol (1.27
g, 9 mmol) in freshly distilled acetone (25 mL) was added
dropwise at -5 °C, over a period of 30 min, a solution of the
J ones reagent (5.05 mL, 13.6 mmol). After the addition was
complete, the mixture was stirred at rt for 3 h and then treated
with water. The solution was extracted with ether, and the
combined extracts were dried over MgSO4 and evaporated in
vacuo to afford hept-3-ynoic acid (1.07 g, 77%) used in the next
step without further purification. To a stirred solution of hept-
3-ynoic acid (1 g, 6.48 mmol) in dry ether (10 mL) was added
dropwise, at 0 °C, an ethereal solution of diazomethane until
no starting material could be detected by TLC. The solvent
was evaporated in vacuo to give methyl hept-3-ynoate (1.1 g,
100%) used in the next step without further purification. The
preceding ester (1 g, 5.94 mmol), Lindlar catalyst (100 mg),
and quinoline (two drops) in dry hexane (10 mL) were stirred
under an hydrogen atmosphere at rt for 4 h. After filtration
of the catalyst through Celite, evaporation of the solvent in
vacuo, and flash chromatography of the residue (petroleum
ether/ethyl acetate 9:1), 6i was obtained as a colorless oil (1.04
g, 100%) (63% overall yield from heptyne): 1H NMR δ 5.65-
5.46 (2H, m), 3.68 (3H, s), 3.10 (2H, d, J ) 5.8 Hz), 2.07-1.98
(2H, m), 1.43-1.22 (6H, m), 0.88 (3H, t, J ) 6.7 Hz); IR (film)
3030, 2960, 1740, 1430, 1260, 1200, 1020 cm-1; MS m/ z (%):
169 (M+ - 1, 59), 133 (41), 112 (43), 97 (98), 83 (96), 71 (100).
Anal. Calcd for C10H18O2: C 70.55, H 10.66. Found: C 70.45,
H 10.52.
Con clu sion
We have demonstrated here that the extension of our
methodology to the rhodium-vinyl carbenoid insertion
into O-H, N-H, and S-H bonds provides an easy and
stereospecific access to chiral R-hydroxy, R-alkoxy, R-ami-
no, and R-thioalkoxy allylic systems. The development
of an asymmetric approach to the synthesis of these
allylic synthons has been carried out using either a chiral
auxiliary such as pantolactone attached to the ester
function or, more attractively, using chiral catalysts such
as Doyle’s Rh2(5S-MEPY)4. In the latter approach,
enantioselectivities up to 72% were obtained, which to
our knowledge is the best selectivity attained so far in
such insertions.38 Finally, it is worth underlining the
large difference in enantioselectivities obtained with
substrate 7a upon insertion into Si-H and O-H bonds
with the same chiral catalyst (Table 4). This obviously
calls for a distinct mechanism for insertion into polar
O-H and N-H bonds and nonpolar Si-H and C-H
bonds.17,18,23 Although this appears conceivable, studies
reported to date along with the results herein are not
sufficient yet for one to draw definitive conclusions.
Exp er im en ta l Section
Elemental analyses were performed by the I. Beetz labora-
tory, W-8640 Kronach (Germany). CH2Cl2 was distilled from
CaH2. THF and ether were distilled from sodium and ben-
zophenone. 4d ,e were prepared according to a reported
procedure.39 5d ,e are commercially available (Fluka). Com-
bustion analysis of allylsilanes 8c,e,j,k ,l,o have not been
provided due to their relative instability. Analysis and
spectroscopic data of corresponding alcohols are available as
Supporting Information.
Gen er a l P r oced u r e for th e P r ep a r a tion of th e r-Dia zo-
â,γ-u n sa tu r a ted Ester s 7.6k To a stirred solution of 6 (21
mmol) and ABSA (31.5 mmol) in acetonitrile (80 mL) was
added dropwise at 0 °C DBU (31.5 mmol). The reaction
mixture was stirred at rt for 30 min and then treated with a
saturated solution of NH4Cl. The solution was extracted with
ether, and the combined extracts were washed with a satu-
rated solution of NaCl and dried over MgSO4. Evaporation of
the solvent in vacuo and chromatography of the residue
(petroleum ether/ethyl acetate 6:4) gave 7 as an orange-red
oil.
Gen er a l P r oced u r e for th e P r ep a r a tion of th e â,γ-
Un sa tu r a ted Ester s 6. A solution of aldehyde 4 (0.17 mmol),
malonic acid (0.19 mmol), and triethylamine (29 mL) was
refluxed 1 h then cooled to rt. The solution was extracted with
ether, and the combined extracts were washed with a 1 M HCl
solution and then treated wth 5% NaOH. The aqueous layer
was washed with ether and then acidified with 1 M HCl (pH
1). The solution was extracted with ether, the combined
extracts were washed with a saturated solution of NaCl and
dried over MgSO4, and the solvent was evaporated in vacuo.
The resulting acid 5 was then dissolved in EtOH (100 mL),
and one drop of concentrated H2SO4 was added. The solution
was refluxed for 3 h. After cooling at 0 °C, the mixture was
treated with a saturated solution of NaHCO3 and extracted
with ether. The combined extracts were washed with brine
and dried (MgSO4), and the solvent was evaporated in vacuo.
Chromatography of the residue (petroleum ether/ethyl acetate
98:2) gave 6 as a colorless oil.
Eth yl (E)-2-d ia zon on -3-en oa te (7c) (72%): 1H NMR δ
5.73 (1H, dt, J ) 1.4 and 15.9 Hz), 5.31 (1H, dt, J ) 7.0 and
15.9 Hz), 4.26 (2H, q, J ) 7.1 Hz), 2.16 (2H, ddt, J ) 1.4, 7.0
and 7.0 Hz), 1.30 (3H, t, J ) 7.1 Hz), 1.46-1.18 (6H, m), 0.89
(3H, t, J ) 6.8 Hz); IR (CHCl3) 3020, 2960, 2100, 1700, 1470,
1380, 1320, 1110, 960 cm-1; MS m/ z (%): 211 (M+ + 1, 54),
210 (M+, 27), 193 (20), 181 (31), 168 (52), 165 (54), 154 (100),
135 (20), 121 (23), 108 (71), 79 (43). Anal. Calcd for
C11H18O2N2: C 62.83, H 8.63, N 13.32. Found: C 63.00, H
8.53, N 13.14.
Meth yl (Z)-2-d ia zon on -3-en oa te (7i) (71%): 1H NMR δ
5.62-5.45 (2H, m), 3.80 (3H, s), 2.08-1.98 (2H, m), 1.47-1.21
(6H, m), 0.89 (3H, t, J ) 6.5 Hz); IR (film) 2970, 2930, 2870,
2100, 1710, 1440, 1300, 1200, 1120, 1020 cm-1; MS m/ z (%):
196 (M+, 5), 169 (100), 168 (29), 131 (44), 111 (44), 97 (63), 81
(88), 71 (40). Anal. Calcd for C10H16O2N2: C 61.20, H 8.22,
N 14.27. Found: C 61.17, H 8.25, N 14.27.
Eth yl (E)-n on -3-en oa te (6c) (76%): 1H NMR δ 5.62-5.44
(2H, m), 4.13 (2H, q, J ) 7.1 Hz), 3.01 (2H, d, J ) 5.4 Hz),
2.06-1.98 (2H, m), 1.43-1.18 (6H, m), 1.27 (3H, t, J ) 7.1
Hz), 0.88 (3H, t, J ) 6.8 Hz); IR (film) 2970, 2940, 2870, 1740,
1460, 1250, 1160, 970 cm-1
. Anal. Calcd for C11H20O2: C
Gen er a l P r oced u r e for th e P r ep a r a tion of Allylsila n es
8. To a stirred solution of diazoester 7 (2.3 mmol) and
dimethylphenylsilane (4.6 mmol) in dry CH2Cl2 (20 mL) was
added at rt Rh2(OAc)4 (0.01 mmol). The mixture was stirred
at rt for 20 min, and the solvent was evaporated in vacuo.
Kugelrohr distillation of the residue gave 8 as a colorless oil.
Eth yl (E)-2-(dim eth ylph en ylsilyl)-4-ph en ylbu t-3-en oate
(8a ) (70%): 1H NMR δ 7.53-7.19 (10H, m), 6.40 (1H, dd, J )
10.0 and 16.0 Hz), 6.12 (1H, d, J ) 16.0 Hz), 4.03 (1H, dq, J
) 7.1 and 10.1 Hz), 3.99 (1H, dq, J ) 7.1 and 10.1 Hz), 3.24
(1H, d, J ) 10.0 Hz), 1.11 (3H, t, J ) 7.1 Hz), 0.44 (6H, s); IR
(CHCl3) 3000, 1700, 1650, 1600, 1380, 1300, 1260, 1160, 1130,
980, 830 cm-1; MS m/ z (%): 324 (M+, 24), 145 (17), 144 (100),
135 (73), 116 (33), 115 (50), 105 (16), 91 (20), 75 (18). Anal.
Calcd for C20H24O2Si: C 74.03, H 7.45, Si 8.66. Found: C
73.97, H 7.32, Si 8.75.
71.70, H 10.94. Found: C 71.55, H, 10.77.
Meth yl (Z)-Non -3-en oa te (6i). To a stirred solution of
heptyne (5 g, 52 mmol) in HMPA (25 mL) was added dropwise,
at 0 °C, a 1.6 M solution of n-BuLi in hexane (31.2 mL, 6.55
mmol). The solution was stirred at rt for 15 min and at 50 °C
for 30 min. Oxirane (3.82 mL, 78 mmol) was then added at
-50 °C, and the mixture was allowed to warm to rt over 1 h
(38) While this work was submitted, an article on asymmetric Si-H
insertion of phenyldiazoacetate appeared, reporting enantioselectivities
of up to 50%, see: Buck, R. T.; Doyle, M. P.; Drysdale, M. J .; Ferris,
L.; Forbes, D. C.; Haigh, D.; Moody, C. J .; Pearson, N. D.; Zhou, Q.-L.
Tetrahedron Lett. 1996, 37, 7631.
(39) Rosowsky, A.; Mota, C. E.; Wright, J . E.; Freisheim, J .-H.;
Heusner, J . J .; McCormak, J . J .; Queener, S. F. J . Med. Chem. 1993,
36, 3103.

1638 J . Org. Chem., Vol. 62, No. 6, 1997
Bulugahapitiya et al.
Eth yl (E)-2-(d im eth yl(5-m eth ylth ien -2-yl)silyl)-4-p h en -
ylbu t-3-en oa te (8b): 1H NMR δ 7.34-7.18 (5H, m), 7.09 (1H,
d, J ) 3.4 Hz), 6.86-6.84 (1H, m), 6.42 (1H, dd, J ) 10.0 and
16.0 Hz), 6.20 (1H, d, J ) 16.0 Hz), 4.12 (1H, dq, J ) 7.1 and
10.1 Hz), 4.06 (1H, dq, J ) 7.1 and 10.1 Hz), 3.23 (1H, d, J )
10.0 Hz), 2.54 (3H, d, J ) 0.6 Hz), 1.20 (3H, t, J ) 7.1 Hz),
0.44 (3H, s), 0.43 (3H, s); IR (film) 2970, 2920, 1710, 1640,
1600, 1440, 1370, 1250, 1000, 960, 750, 700 cm-1; MS m/ z
(%): 362 (M+ + NH4+, 6), 344 (8), 264 (41), 247 (100), 218 (10),
155 (11), 144 (23), 91 (27), 74 (16). Anal. Calcd for C19H24O2-
SiS: C 66.24, H 7.02, Si 8.15, S 9.31. Found: C 66.40, H 6.99,
Si 8.11, S 9.26.
E t h yl (E)-2-(Tr is(t r im et h ylsilyl)silyl)-4-p h en ylbu t -3-
en oa te (8c): 1H NMR δ 7.48-7.16 (5H, m), 6.46 (1H, dd, J )
10.6 and 15.9 Hz), 6.25 (1H, d, J ) 15.9 Hz), 4.42-4.06 (2H,
m), 3.38 (1H, d, J ) 10.6 Hz), 1.28 (3H, t, J ) 6.9 Hz), 0.234
(9H, s), 0.232 (9H, s), 0.206 (9H, s); IR (film) 3061, 2950, 1717,
1640, 1600, 1500, 1400, 1367, 1250, 840, 750 cm-1; MS m/ z
(%): 437 (M+, 1), 363 (44), 317 (15), 219 (23), 173 (19), 115
(27), 73 (100).
Eth yl (E)-2-(d im eth yl(isop r op yloxy)silyl)-4-p h en ylbu t-
3-en oa te (8d ): 1H NMR δ 7.38-7.17 (5H, m), 6.48 (1H, dd, J
) 9.7 and 16.0 Hz), 6.31 (1H, d, J ) 16.0 Hz), 4.20 (1H, dq, J
) 7.1 and 10.1 Hz), 4.15 (1H, dq, J ) 7.1 and 10.1 Hz), 4.08
(1H, sept, J ) 6.1 Hz), 3.20 (1H, d, J ) 9.7 Hz), 1.30 (3H, t, J
) 7.1 Hz), 1.17 (6H, d, J ) 6.1 Hz), 0.26 (3H, s), 0.25 (3H, s);
IR (film) 2980, 2950, 1710, 1640, 1590, 1440, 1370, 1250, 1140,
1030, 970, 750 cm-1; MS m/ z (%): 307 (M+ + 1, 100), 261 (45),
247 (68), 219 (19). Anal. Calcd for C17H26O3Si: C 66.62, H
8.55. Found: C 66.72, H 8.46.
Hz), 3.01 (1H, d, J ) 10.0 Hz), 2.05-1.94 (2H, m), 1.08 (3H, t,
J ) 7.1 Hz), 0.92 (3H, t, J ) 7.4 Hz), 0.38 (6H, s); IR (CHCl3)
2960, 1710, 1460, 1430, 1370, 1250, 1160, 1120, 910, 840, 820
cm-1; MS m/ z (%): 276 (M+, 31), 199 (32), 194 (18), 135 (79),
129 (24), 123 (22), 96 (100), 95 (23), 91 (20), 81 (72), 76 (23).
Anal. Calcd for C16H24O2Si: C 69.52, H 8.75, Si 10.16.
Found: C 69.56, H 8.73, Si 10.07.
Meth yl (Z)-2-(d im eth ylp h en ylsilyl)n on -3-en oa te (8o):
1H NMR δ 7.53-7.48 (2H, m), 7.40-7.32 (3H, m), 5.61 (1H,
ddt, J ) 1.8, 11.3 and 11.3 Hz), 5.32 (1H, ddt, J ) 0.9, 8.7 and
11.3 Hz), 3.53 (3H, s), 3.38 (1H, dd, J ) 0.9 and 11.0 Hz), 1.88-
1.55 (2H, m), 1.38-1.08 (6H, m), 0.85 (3H, t, J ) 6.6 Hz), 0.40
(3H, s), 0.39 (3H, s); IR (CHCl3) 3020, 2960, 2870, 1720, 1640,
1430, 1400, 1300, 1255, 1155, 1060, 820 cm-1; MS m/ z (%):
305 (M+ + 1, 6), 228 (16), 227 (100), 170 (3), 135 (4), 91 (3), 89
(5), 74 (5). Anal. Calcd for C18H28O2Si: C 71.00, H 9.27, Si
9.22. Found: C 71.15, H 9.14, Si 9.04.
Eth yl (Z)-2-(d im eth ylp h en ylsilyl)h ex-3-en oa te (8p ): 1H
NMR δ 7.53-7.49 (2H, m), 7.39-7.31 (3H, m), 5.60 (1H, ddt,
J ) 1.5, 11.0 and 11.0 Hz), 5.30 (1H, dt, J ) 7.0 and 11.0 Hz),
4.01-3.91 (2H, m), 3.36 (1H, d, J ) 11.0 Hz), 1.91-1.82 (1H,
m), 1.71-1.62 (1H, m), 1.10 (3H, t, J ) 7.1 Hz), 0.81 (3H, t, J
) 7.5 Hz), 0.40 (6H, s); IR (CHCl3) 2970, 2940, 2870, 1700,
1460, 1370, 1260, 1120, 1080, 840 cm-1; MS m/ z (%): 276 (M+,
16), 231 (10), 199 (14), 135 (64), 105 (13), 96 (100), 81 (29).
Anal. Calcd for C16H24O2Si: C 69.52, H 8.75, Si 10.16.
Found: C 69.51, H 8.69, Si 10.08.
(E)-5-P h en yl-3-(d im et h ylp h en ylsilyl)p en t -4-en -2-on e
(10). To a stirred solution of Rh2(OAc)4 (5 mg, 0.01 mmol) and
dimethylphenylsilane (0.5 mL, 3.22 mmol) in dry CH2Cl2 (2
mL) was added using a syringe pump (0.3 mmol/h) a solution
of 96k (0.3 g, 1.61 mmol) in dry CH2Cl2 (4 mL) at rt. When the
addition was complete, the solvent was evaporated in vacuo
to afford 10 (crude yield: 65%) which was used in the next
step without further purification. 1H NMR δ 7.67-7.20 (10H,
m), 6.53 (1H, ddd, J ) 1.5, 10.1 and 16 Hz), 6.17 (1H, d, J )
16 Hz), 3.65 (1H, d, J ) 10.1 Hz), 2.48 (3H, s), 0.46 (3H, s),
0.45 (3H, s); IR (film) 3069, 2959, 1719, 1592, 1450, 1252, 881,
833 cm-1; MS m/ z (%): 294 (M+, 68), 267 (64), 233 (52), 205
(25), 135 (100), 105 (67), 91 (51).
E t h yl
(E)-2-(flu or od iisop r op ylsilyl)-4-p h en ylb u t -3-
en oa te (8e): 1H NMR δ 7.40-7.22 (5H, m), 6.47 (1H, dd, J )
9.8 and 16 Hz), 6.39 (1H, dd, J ) 1.7 and 16 Hz), 4.19 (2H, q,
J ) 7.2 Hz), 3.48 (1H, d, J ) 9.8 Hz), 1.38-1.24 (2H, m), 1.30
(3H, t, J ) 7.2 Hz), 1.16-1.10 (12H, m); IR (film) 3082, 2950,
1721, 1642, 1600, 1496, 1464, 1253, 1147, 883, 835 cm-1; MS
m/ z (%): 338 (4), 322 (M+, 4), 251 (3), 144 (100), 115 (68), 93
(18).
Eth yl (E)-2-(a llyld im eth ylsilyl)-4-p h en ylbu t-3-en oa te
(8j): 1H NMR δ 7.38-7.23 (5H, m), 6.47 (1H, dd, J ) 10.2
and 16 Hz), 6.28 (1H, d, J ) 16 Hz), 5.86-5.74 (1H, m), 4.97-
4.91 (2H, m), 4.19 (1H, q, J ) 7.2 Hz), 4.18 (1H, q, J ) 7.2
Hz), 3.16 (1H, d, J ) 9.8 Hz), 1.68 (2H, d, J ) 8.1 Hz), 1.30
(3H, t, J ) 7.2 Hz), 0.15 (3H, s), 0.14 (3H, s); IR (film) 3079,
2977, 1717, 1629, 1597, 1251, 968, 740 cm-1; MS m/ z (%): 273
(M+ - 1, 1), 247 (44), 219 (11), 159 (7), 144 (100), 129 (7), 115
(62), 103 (29), 91 (9).
Eth yl (E)-2-((br om om eth yl)dim eth ylsilyl)-4-ph en ylbu t-
3-en oa te (8k ): 1H NMR δ 7.38-7.23 (5H, m), 6.44 (1H, dd, J
) 9.8 and 16 Hz), 6.34 (1H, d, J ) 16 Hz), 4.19 (2H, q, J ) 7.2
Hz), 3.29 (1H, d, J ) 9.8 Hz), 2.57 (2H, s), 1.30 (3H, t, J ) 7.2
Hz), 0.29 (3H, s), 0.27 (3H, s); IR (film) 3059, 2979, 1718, 1640,
1600, 1250, 900, 700 cm-1; MS m/ z (%): 342 (M+ + 1, 11),
341 (M+, 6), 247 (3), 190 (3), 144 (87), 115 (100), 91 (10).
Dieth yl (E)-2-(d im eth ylp h en ylsilyl)p en t-3-en e-1,5-d io-
a te (8l): 1H NMR δ 7.60-7.34 (5H, m), 7.18 (1H, dd, J ) 10.3
and 15.7 Hz), 5.60 (1H, dd, J ) 0.61 and 15.7 Hz), 4.18 (4H, q,
J ) 7.1 Hz), 3.29 (1H, d, J ) 10.3 Hz), 1.28 (6H, t, J ) 7.1
Hz), 0.45 (6H, s); IR (film) 3070, 2979, 1720, 1606, 1250, 881,
700 cm-1; MS m/ z (%): 321 (M+ + 1, 14), 320 (6), 259 (40),
235 (46), 219 (9), 165 (8), 135 (100), 114 (21).
(2R*,3R*)-(E)-5-P h en yl-3-(d im eth ylp h en ylsilyl)p en t-4-
en ol (11). To a solution of 10 (193 mg, 0.65 mmol) in dry THF
(10 mL) was added dropwise, at -100 °C, a 1 M solution of
DIBAH in toluene (1.31 mL, 1.31 mmol). The mixture was
stirred at -100 °C for 2 h and then treated with a 1 M solution
of HCl. The aqueous layer was extracted with ether, the
combined extracts were washed with 1 M HCl and brine and
dried over MgSO4, and the solvents were evaporated in vacuo.
Chromatography of the residue (petroleum ether/ethyl acetate/
NEt3 98:1.5:0.5) gave syn alcohol 11 (122 mg, 63%) as a
colorless oil: 1H NMR δ 7.61-7.55 (2H, m), 7.42-7.19 (8H,
m), 6.32 (1H, d, J ) 15.7 Hz), 6.12 (1H, dd, J ) 10.5 and 15.7
Hz), 4.0 (1H, dq, J ) 6.4 and 6.4 Hz), 2.22 (1H, dd, J ) 6.6
and 10.5 Hz), 1.50 (1H, s), 1.21 (3H, d, J ) 6.3 Hz), 0.41 (3H,
s), 0.40 (3H, s); 13C NMR δ 137.9, 134.1, 130.8, 129.2, 128.5,
127.9, 127.5, 126.8, 125.9, 69.0, 44.5, 23.2, -2.9, -3.6; IR (film)
3430, 3070, 2970, 1600, 1490, 1250, 1120, 840, 820, 740 cm-1
;
MS m/ z (%): 145 (11), 144 (69), 135 (40), 129 (100), 115 (11),
105 (7), 91 (13). Anal. Calcd for C19H24OSi: C 76.97, H 8.16,
Si 9.47. Found: C 77.00, H 8.29, Si 9.65.
Meth yl (3E,5E)-2-Diazo-6-ph en ylh exa-3,5-dien oate (12).
Prepared according to reference 6k. 1H NMR δ 7.42-7.22 (5H,
m), 6.89 (1H, ddd, J ) 1.0, 8.5 and 15.6 Hz), 6.48 (1H, d, J )
15.6 Hz), 6.51-6.08 (2H, m), 3.85 (3H, s); IR (CHCl3) 3010,
2950, 2100, 1700, 1600, 1420, 1370, 1310, 980 cm-1; MS m/ z
(%): 228 (M+, 43), 227 (43), 195 (61), 157 (62), 141 (90), 128
Eth yl (E)-2-(d im eth ylp h en ylsilyl)n on -3-en oa te (8m ):
1H NMR δ 7.51-7.47 (2H, m), 7.39-7.32 (3H, m), 5.59 (1H,
ddt, J ) 1.3, 10.0 and 15.4 Hz), 5.20 (1H, dt, J ) 7.0 and 15.3
Hz), 4.01 (1H, dq, J ) 7.1 and 10.7 Hz), 3.93 (1H, dq, J ) 7.1
and 10.8 Hz), 3.02 (1H, d, J ) 10.0 Hz), 2.01-1.93 (2H, m),
1.40-1.16 (6H, m), 1.08 (3H, t, J ) 7.1 Hz), 0.88 (3H, t, J )
6.8 Hz), 0.38 (6H, s); IR (CHCl3) 2970, 2870, 1720, 1600, 1470,
1380, 1260, 1180, 1100, 820 cm-1; MS m/ z (%): 318 (M+, 37),
273 (13), 261 (26), 241 (30), 155 (17), 135 (100), 95 (15), 81
(52). Anal. Calcd for C19H30O2Si: C 71.64, H 9.49, Si 8.82.
Found: C 71.91, H 9.41, Si 8.54.
(73), 115 (100), 91 (98), 77 (35), 73 (77). Anal. Calcd for C13
-
H12O2N2: C 68.41, H 5.30, N 12.27. Found: C 68.47, H 5.21,
N 12.22.
Meth yl (3E,5E)-6-p h en yl-2-(d im eth ylp h en ylsilyl)h exa -
3,5-d ien oa te (13): 1H NMR δ 7.52-7.17 (10H, m), 6.81-6.71
(1H, m), 6.38 (1H, d, J ) 15.6 Hz), 6.01-5.97 (2H, m), 3.55
(3H, s), 3.22-3.19 (1H, m), 0.44 (3H, s), 0.43 (3H, s); IR (CHCl3)
2950, 1710, 1630, 1490, 1440, 1360, 1260, 920 cm-1; MS m/ z
(%): 354 (M+ + NH4+, 13), 337 (M+ + 1, 41), 305 (37), 259
Eth yl (E)-2-(d im eth ylp h en ylsilyl)h ex-3-en oa te (8n ): 1H
NMR δ 7.51-7.47 (2H, m), 7.39-7.31 (3H, m), 5.59 (1H, dd, J
) 10.0 and 15.4 Hz), 5.23 (1H, dt, J ) 6.4 and 15.4 Hz), 4.01
(1H, dq, J ) 7.1 and 10.9 Hz), 3.94 (1H, dq, J ) 7.1 and 10.9

Rhodium(II)-Vinyl Carbenoid Insertion
J . Org. Chem., Vol. 62, No. 6, 1997 1639
(100), 231 (24), 227 (13), 152 (13), 135 (29). Anal. Calcd for
C21H24O2Si: C 74.96, H 7.19, Si 8.35. Found: C 74.97, H 7.25,
Si 8.38.
Gen er a l P r oced u r e for th e P r ep a r a tion of Allylic
Alcoh ols 14a -f. Rh2(OAc)4 (0.01 mmol) was added at rt to a
solution of 7 (6.94 mmol) in moist ether (50 mL). The mixture
was stirred at rt for 6 h, and the solvent was evaporated in
vacuo. Chromatography of the residue (petroleum ether/ethyl
acetate 9:1) gave 14 as a pale yellow oil.
6.22 (1H, dd, J ) 6.9 and 16.0 Hz), 4.71 (1H, dd, J ) 0.9 and
6.8 Hz), 4.27 (2H, q, J ) 7.1 Hz), 4.04 (1H, dq, J ) 8.6 and
12.4 Hz), 3.92 (1H, dq, J ) 8.6 and 12.5 Hz), 1.32 (3H, t, J )
7.1 Hz); IR (film) 2990, 2940, 1740, 1600, 1450, 1280, 1170,
1030, 970, 700 cm-1; MS m/ z (%): 288 (M+, 3), 259 (2), 215
(100), 169 (6), 131 (37), 115 (58), 91 (28), 77 (18). Anal. Calcd
for C14H15O3F3: C 58.33, H 5.24. Found: C 58.36, H 5.37.
Eth yl (E)-2-P h en oxy-4-p h en ylbu t-3-en oa te (14k ). To a
solution of phenol (220 mg, 2.33 mmol) and Rh2(OAc)4 (5 mg,
0.01 mmol) in dry benzene (4 mL) under reflux was added
slowly, over a period of 2 h (syringe pump), a solution of 7a
(110 mg, 0.5 mmol) in dry benzene (1 mL). After evaporation
of the solvent in vacuo, chromatography of the residue
(petroleum ether/ethyl acetate 95:5) gave 14k as a pale yellow
oil (58 mg, 40%): 1H NMR δ 7.50-7.28 (7H, m), 7.07-6.96
(3H, m), 6.92 (1H, d, J ) 16.0 Hz), 6.40 (1H, dd, J ) 6.3 and
16.0 Hz), 5.31 (1H, dd, J ) 1.3 and 6.3 Hz), 4.29 (1H, dq, J )
7.1 and 10.1 Hz), 4.25 (1H, dq, J ) 7.1 and 10.1 Hz), 1.28 (3H,
t, J ) 7.1 Hz); IR (film) 3040, 2990, 1750, 1600, 1490, 1370,
1240, 970, 700 cm-1, MS m/ z (%): 283 (M+ + 1, 15), 282 (M+,
12), 189 (33), 143 (14), 115 (100), 94 (13). Anal. Calcd for
C18H18O3: C 76.57, H 6.43. Found: C 76.47, H 6.23.
Gen er a l P r oced u r e for th e P r ep a r a tion of Allylic
Am in e 14l-n . Rh2(OAc)4 (0.01 mmol) was added at rt to a
solution of diazoester 7 (0.46 mmol) and aniline (2.3 mmol) in
dry benzene (5 mL), and the mixture was refluxed for 10 min.
After evaporation of the solvent in vacuo, chromatography of
the residue (petroleum ether/ethyl acetate 95:5) gave the allylic
amines 14l-n as a pale yellow oil.
Eth yl (E)-2-h yd r oxy-4-p h en ylbu t-3-en oa te (14a ): 1H
NMR δ 7.43-7.23 (5H, m), 6.83 (1H, dd, J ) 1.6 and 15.9 Hz),
6.26 (1H, dd, J ) 5.6 and 15.9 Hz), 4.84 (1H, ddd, J ) 1.6, 5.6
and 5.6 Hz), 4.33 (1H, dq, J ) 7.1 and 10.8 Hz), 4.26 (1H, dq,
J ) 7.1 and 10.8 Hz), 3.13 (1H, d, J ) 5.6 Hz), 1.33 (3H, t, J
) 7.1 Hz); IR (CHCl3) 3550, 3000, 1730, 1600, 1450, 1370,
1260, 1100, 1080, 1020, 860 cm-1; MS m/ z (%): 206 (M+, 8),
189 (6), 188 (6), 134 (10), 133 (100), 115 (22), 103 (16), 77 (12).
Anal. Calcd for C12H14O3: C 69.89, H 6.84. Found: C 69.96,
H 6.94.
Eth yl (E)-2-h yd r oxyn on -3-en oa te (14c): 1H NMR δ 5.89
(1H, ddt, J ) 1.4, 6.8 and 15.3 Hz), 5.50 (1H, ddt, J ) 1.5, 4.6
and 15.3 Hz), 4.58 (1H, d, J ) 4.6 Hz), 4.26 (2H, q, J ) 7.2
Hz), 2.92 (1H, s), 2.11-2.02 (2H, m), 1.42-1.27 (6H, m), 1.30
(3H, t, J ) 7.2 Hz), 0.88 (3H, t, J ) 6.7 Hz); IR (film) 3211,
3182, 2957, 1742, 1376, 1112 cm-1; MS m/ z (%): 200 (M+, 3),
183 (7), 135 (8), 125 (27), 109 (17), 99 (100), 83 (33). Anal.
Calcd for C11H20O3: C 65.95, H 10.07. Found: C 66.05, H
10.02.
Meth yl (Z)-2-h yd r oxyn on -3-en oa te (14f): 1H NMR δ
5.72 (1H, ddt, J ) 1.2, 7.5 and 10.7 Hz), 5.35 (1H, ddt, J )
1.6, 8.9 and 10.7 Hz), 4.94 (1H, d, J ) 8.9 Hz), 3.79 (3H, s),
2.23-2.16 (2H, m), 1.46-1.22 (6H, m), 0.90 (3H, t, J ) 6.8
Hz); IR (film) 3448, 2955, 1740, 1379, 1084 cm-1; MS m/ z
(%): 186 (M+, 9), 153 (3), 125 (100), 109 (46), 99 (23), 81 (34).
Anal. Calcd for C10H18O3: C 64.49, H 9.74. Found: C 64.42,
H 9.70.
Gen er a l P r oced u r e for th e P r ep a r a tion of Allylic
Meth oxy a n d Eth oxy Eth er s 14g-i. Rh2(OAc)4 (0.01 mmol)
was added at rt to a solution of 7 (0.97 mmol) in ethanol or
methanol (3 mL). The mixture was stirred at rt for 15 min,
and the solvent was evaporated in vacuo. Chromatography
of the residue (petroleum ether/ethyl acetate 95:5) gave 14 as
a pale yellow oil.
Eth yl (E)-2-(N-p h en yla m in o)n on -3-en oa te (14m ): 1H
NMR δ 7.18 (2H, dd, J ) 7.4 and 8.5 Hz), 6.74 (1H, t, J ) 7.4
Hz), 6.63 (2H, d, J ) 8.6 Hz), 5.88 (1H, dt, J ) 6.8 and 15.7
Hz), 5.52 (1H, dd, J ) 5.7 and 15.7 Hz), 4.53-4.50 (1H, m),
4.23 (2H, q, J ) 7.2 Hz), 2.10-2.02 (2H, m), 1.43-1.21 (6H,
m), 1.29 (3H, t, J ) 7.2 Hz), 0.88 (3H, t, J ) 6.6 Hz); IR (film)
2956, 1734, 1368, 1187 cm-1; MS m/ z (%): 276 (M+ + 1, 18),
275 (M+, 22), 202 (100), 144 (10), 132 (28), 117 (12), 93 (11).
Anal. Calcd for C17H25NO2: C 74.13, H 9.16, N 5.09. Found:
C 74.25, H 9.07, N 5.15.
Meth yl (Z)-2-(N-p h en yla m in o)n on -3-en oa te (14n ): 1H
NMR δ 7.18 (2H, dd, J ) 7.4 and 8.6 Hz), 6.75 (1H, t, J ) 7.4
Hz), 6.61 (2H, d, J ) 8.6 Hz), 5.73 (1H, ddt, J ) 1.2, 7.5 and
10.7 Hz), 5.31 (1H, ddt, J ) 1.7, 8.8 and 10.7 Hz), 4.84 (1H, d,
J ) 8.7 Hz), 3.75 (3H, s), 2.33-2.24 (2H, m), 1.56-1.31 (6H,
m), 0.92 (3H, t, J ) 6.6 Hz); IR (film) 3409, 3082, 2954, 1738,
1644, 1600, 1500, 1176 cm-1; MS m/ z (%): 261 (M+, 18), 202
(100), 144 (11), 132 (22), 117 (12), 93 (71). Anal. Calcd for
C16H23NO2: C 73.53, H 8.87, N 5.36. Found: C 73.52, H 8.81,
N 5.16.
Eth yl (E)-2-eth oxy-4-ph en ylbu t-3-en oate (14g): 1H NMR
δ 7.42-7.26 (5H, m), 6.78 (1H, d, J ) 15.7 Hz), 6.24 (1H, dd,
J ) 6.9 and 15.7 Hz), 4.52 (1H, dd, J ) 1.2 and 6.8 Hz), 4.25
(2H, q, J ) 7.1 Hz), 3.64 (1H, dq, J ) 7.1 and 10.1 Hz), 3.59
(1H, dq, J ) 7.1 and 10.1 Hz), 1.31 (6H, t, J ) 7.1 Hz); IR
(film) 2980, 1740, 1440, 1250, 1180, 1030, 970 cm-1; MS m/ z
(%): 253 (100), 252 (M+ + NH4+, 97), 207 (34), 206 (50), 190
(39), 189 (77), 161 (51). Anal. Calcd for C14H18O3: C 71.77,
H 7.74. Found: C 71.91, H 7.76.
(E)-4-P h en yl-2-(p h en ylth io)bu t-3-en ol (15). Rh2(OAc)4
(5 mg, 0.01 mmol) was added at rt to a solution of 7a (848 mg,
3.92 mmol) and thiophenol (0.8 mL, 7.84 mmol) in dry CH2-
Cl2 (50 mL). The mixture was stirred at rt for 40 min and
Eth yl (E)-2-m eth oxyn on -3-en oa te (14h ): 1H NMR δ 5.89
(1H, dt, J ) 6.8 and 15.4 Hz), 5.46 (1H, ddt, J ) 1.3, 7.3 and
15.4 Hz), 4.23 (2H, q, J ) 7.2 Hz), 4.19 (1H, d, J ) 7.3 Hz),
3.37 (3H, s), 2.11-2.03 (2H, m), 1.46-1.24 (6H, m), 0.88 (3H,
t, J ) 6.8 Hz); IR (film) 2956, 1734, 1368, 1187 cm-1; MS m/ z
(%): 214 (M+, 3), 213 (M+ - 1, 7), 183 (9), 159 (2), 141 (100),
125 (5), 109 (24), 85 (11). Anal. Calcd for C12H22O3: C 67.24,
H 10.35. Found: C 67.29, H 10.32.
then treated with
a saturated solution of Na2CO3. The
aqueous layer was extracted with CH2Cl2, the combined
extracts were washed with a saturated solution of Na2CO3 and
brine and drived over MgSO4, and the solvent was evaporated
in vacuo. To the residual oil in dry ether (50 mL) was added
dropwise, at 0 °C, a 1 M solution of LiAlH4 in ether (3.92 mL,
3.92 mmol). The mixture was stirred at rt for 15 h and then
treated with a 1 M HCl. The aqueous layer was extracted with
ether, the combined extracts were washed with brine and dried
over MgSO4, and the solvent was evaporated in vacuo. Flash
chromatography of the residue (petroleum ether/ethyl acetate
9.1) gave 15 as a pale yellow oil (0.3 g, 30%): 1H NMR δ 7.50-
7.45 (2H, m), 7.36-7.20 (8H, m), 6.47 (1H, d, J ) 15.8 Hz),
6.15 (1H, dd, J ) 8.5 and 15.8 Hz), 3.97-3.89 (1H, m), 3.81
(1H, dd, J ) 3.5 and 9.1 Hz), 3.75 (1H, dd, J ) 4.7 and 9.1
Hz); IR (film) 3400, 3060, 2870, 1580, 1480, 1380, 1180, 970,
700 cm-1; MS m/ z (%): 258 (M+ + 2, 2), 256 (M+, 1), 147 (64),
129 (100), 117 (22), 115 (33), 110 (28), 109 (17), 91 (77). Anal.
Calcd for C16H16OS: C 74.96, H 6.29, S 12.51. Found: C 74.81,
H 6.23, S 12.60.
Meth yl (Z)-2-m eth oxyn on -3-en oa te (14i): 1H NMR δ
5.79 (1H, ddt, J ) 0.9, 7.5 and 10.8 Hz), 5.38 (1H, ddt, J )
1.6, 9.1 and 10.8 Hz), 4.59 (1H, dd, J ) 0.9 and 8.9 Hz), 3.76
(3H, s), 3.37 (3H, s), 2.28-2.14 (2H, m), 1.47-1.20 (6H, m),
0.90 (3H, t, J ) 6.7 Hz); IR (film) 2955, 1758, 1636, 1377, 1165,
1109, 733 cm-1; MS m/ z (%): 186 (M+, 9), 168 (5), 125 (100),
109 (46), 99 (23), 81 (34). Anal. Calcd for C11H20O3: C 65.97,
H 10.07. Found: C 65.97, H 9.98.
Eth yl (E)-2-(2,2,2-Tr iflu or oeth oxy)-4-ph en ylbu t-3-en oate
(14j). Rh2(OAc)4 (5 mg, 0.01 mmol) was added at rt to a
solution of 7a (199 mg, 0.92 mmol) and 2,2,2-trifluoroethanol
(0.66 mL, 9.2 mmol) in dry benzene (5 mL), and the mixture
was then refluxed for 10 min. After evaporation of the solvent
in vacuo, chromatography of the residue (petroleum ether/ethyl
acetate 95:5) gave 14j as a pale yellow oil (135 mg, 52%): 1H
NMR δ 7.45-7.28 (5H, m), 6.81 (1H, dd, J ) 0.8 and 16.0),
(E)-4-P h en yl-2-(p h en ylsu lfon yl)bu t-3-en ol (16). To a
solution of 15 (0.2 g, 0.78 mmol) in CH2Cl2 (5 mL) was added
dropwise, at 0 °C, a 70% solution of m-CPBA (423 mg, 1.72

1640 J . Org. Chem., Vol. 62, No. 6, 1997
Bulugahapitiya et al.
mmol), in CH2Cl2 (5 mL). The mixture was stirred at rt for 1
h and then treated with a saturated solution of NaHCO3. The
aqueous layer was extracted with CH2Cl2, the combined
extracts were washed successively with a 5% solution of NaOH
and a 1 M solution of HCl, brine and then dried over MgSO4,
and the solvent was evaporated in vacuo. Chromatography
of the residue (CH2Cl2/MeOH 98:2) afforded 16 as a pale yellow
oil (0.22 g, 98%): 1H NMR δ 7.88-7.24 (10H, m), 6.34 (1H, d,
J ) 15.9 Hz), 6.0 (1H, dd, J ) 9.3 and 15.9 Hz), 4.27 (1H, dd,
J ) 7.2 and 12.4 Hz), 4.07 (1H, dd, J ) 4.1 and 12.4 Hz), 3.98-
3.89 (1H, m); IR (film) 3500, 3060, 2930, 1580, 1450, 1300,
1150, 970 cm-1; MS m/ z (%): 147 (62), 130 (31), 129 (100),
5.31 (2H, s), 5.22 (2H, dt, J ) 6.4 and 15.5 Hz), 3.99 (2H, s),
3.96 (2H, s), 3.17 (1H, d, J ) 10.0 Hz), 3.14 (1H, d, J ) 10.0
Hz), 2.04-1.93 (4H, m), 1.13 (3H, s), 1.02 (3H, s), 0.99 (3H, s),
0.91 (6H, t, J ) 7.4 Hz), 0.89 (3H, s), 0.47 (6H, s), 0.45 (6H, s);
IR (CHCl3) 2970, 1790, 1720, 1460, 1300, 1290, 1120, 1020,
840 cm-1; MS m/ z (%): 360 (M+, 41), 283 (3), 231 (6), 187 (14),
135 (56), 105 (9), 96 (100), 81 (47). Anal. Calcd for C20H28O4-
Si: C 66.63, H 7.83, Si 7.79. Found: C 66.40, H 7.47, Si 7.94.
19d (two diastereoisomers): 1H NMR δ 7.58-7.50 (4H, m),
7.42-7.31 (6H, m), 5.59 (2H, ddt, J ) 1.6, 11.0 and 11.0 Hz),
5.34 (2H, dt, J ) 6.8 and 11.0 Hz), 5.31 (2H, s), 3.99 (2H, s),
3.97 (2H, s), 3.50 (1H, d, J ) 11.0 Hz), 3.48 (1H, d, J ) 11.0
Hz), 1.98-1.77 (2H, m), 1.70-1.52 (2H, m), 1.14 (3H, s), 1.06
(3H, s), 1.0 (3H, s), 0.93 (3H, s), 0.80 (6H, t, J ) 7.5 Hz), 0.49
(6H, s), 0.47 (6H, s); IR (CHCl3) 2970, 1790, 1460, 1430, 1370,
1300, 1260, 1140, 1000, 910 cm-1; MS m/ z (%): 360 (M+, 41),
187 (11), 155 (11), 135 (52), 105 (8), 96 (100), 81 (46). Anal.
Calcd for C20H28O4Si: C 66.63, H 7.83, Si 7.79. Found: C
66.54, H 7.84, Si 7.74.
117 (27), 115 (20), 91 (58), 77 (20). Anal. Calcd for C16H16
-
O3S: C 66.64, H 5.59, S 11.12. Found: C 66.50, H 5.60, S
11.02.
Gen er a l P r oced u r e for th e P r ep a r a tion of th e P a n to-
la ct on e â,γ-Un sa t u r a t ed E st er s 17. A solution of 5 (15
mmol), pantolactone (15.8 mmol), DCC (16.5 mmol), and
(dimethylamino)pyridine (0.04 mmol) in dry CH2Cl2 (80 mL)
was stirred at rt for 30 min and then filtered, and the solvent
was evaporated in vacuo. Chromatography of the residue
(petroleum ether/ethyl acetate 9:1) gave 17 as a colorless oil.
17b (80%): 1H NMR δ 5.73-5.47 (2H, m), 5.37 (1H, s), 4.06
(1H, d, J ) 9.0 Hz), 4.02 (1H, d, J ) 9.0 Hz), 3.18 (2H, d, J )
6.2 Hz), 2.12-2.01 (2H, m), 1.20 (3H, s), 1.11 (3H, s), 0.99 (3H,
t, J ) 7.5 Hz); IR (CHCl3) 2970, 1800, 1740, 1460, 1300, 1240,
1020, 970 cm-1; MS m/ z (%): 227 (M+ + 1, 5), 226 (M+, 2),
131 (21), 113 (17), 99 (23), 97 (35), 96 (100), 83 (26), 81 (29),
19e (two diastereoisomers): 1H NMR δ 7.57-7.50 (4H, m),
7.42-7.31 (6H, m), 5.64-5.53 (2H, m), 5.31-5.16 (2H m), 5.30
(2H, s), 3.98 (2H, s), 3.96 (2H, s), 3.18 (1H, d, J ) 10.1 Hz),
3.15 (1H, d, J ) 10.0 Hz), 1.67-1.62 (6H, m), 1.12 (3H, s),
1.01 (3H, s), 0.99 (3H, s), 0.88 (3H, s), 0.47 (6H, s), 0.45 (6H,
s); IR (CHCl3) 2975, 1780, 1720, 1460, 1340, 1290, 1250, 1120,
960, 840 cm-1; MS m/ z (%): 346 (M+, 7), 187 (3), 135 (19),
105 (5), 83 (17), 82 (100). Anal. Calcd for C19H26O4Si: C 65.86,
H 7.56, Si 8.11. Found: C 65.92, H 7.56, Si 8.26.
71 (21); [R]25
: +3.8 (c 1.26, CHCl3). Anal. Calcd for
19f. Rh2(OAc)4 (5 mg, 0.01 mmol) was added at rt to a
solution of 18a (1.45 g, 4.82 mmol) in moist ether (40 mL).
The mixture was stirred at rt for 4 h, and the solvent was
evaporated in vacuo. Chromatography of the residue (CH2-
Cl2/MeOH 99.5:0.5) gave (2S)-alcohol 19fa as a pale yellow oil
(0.79 g, 56%): 1H NMR δ 7.44-7.23 (5H, m), 6.89 (1H, d, J )
16.0 Hz), 6.34 (1H, ddd, J ) 0.6, 5.4 and 16.0 Hz), 5.43 (1H,
s), 5.02-5.0 (1H, m), 4.09 (1H, d, J ) 9.1 Hz), 4.04 (1H, d, J
) 9.1 Hz), 3.21 (1H, s), 1.24 (3H, s), 1.14 (3H, s); IR (CHCl3)
3550, 3020, 2970, 1790, 1600, 1465, 1370, 1160, 1080, 1020,
970 cm-1; MS m/ z (%): 290 (M+, 2), 144 (17), 134 (14), 133
(100), 131 (31), 115 (32), 114 (14), 104 (18), 99 (22), 91 (17), 77
(11); [R]25D: +0.6 (c 1.45, CHCl3). Anal. Calcd for C16H18O5:
C 66.20, H 6.25. Found: C 66.15, H 6.33. (2R)-alcohol 19fb
(0.27 g, 19%): 1H NMR δ 7.42-7.27 (5H, m), 6.88 (1H, dd, J
) 1.6 and 15.9 Hz), 6.27 (1H, dd, J ) 6.0 and 15.9 Hz), 5.46
(1H, s), 5.08-5.06 (1H, m), 4.08 (1H, d, J ) 9.1 Hz), 4.04 (1H,
d, J ) 9.1 Hz), 3.18 (1H, s), 1.19 (3H, s), 1.09 (3H, s); IR (CHCl3)
D
C12H18O4: C 63.70, H 8.02. Found: C 63.85, H 7.92.
17c (83%): 1H NMR δ 5.68-5.48 (2H, m), 5.37 (1H, s), 4.06
(1H, d, J ) 9.0 Hz), 4.02 (1H, d, J ) 9.0 Hz), 3.25 (2H, d, J )
7.3 Hz), 2.14-2.02 (2H, m), 1.20 (3H, s), 1.11 (3H, s), 0.99 (3H,
t, J ) 7.5 Hz); IR (CHCl3) 3570, 3040, 2950, 2870, 1800, 1760,
1635, 1440, 1310, 1250, 1030 cm-1; MS m/ z (%): 226 (M+, 2),
131 (17), 113 (18), 99 (23), 97 (37), 96 (100), 83 (31), 71 (38);
[R]25D: +1.9 (c 1.38, CHCl3). Anal. Calcd for C12H18O4: C
63.70, H 8.02. Found: C, 63.68, H 7.89.
18b. Prepared according to the general procedure reported
for esters 7 (71%): 1H NMR δ 5.72 (1H, dt, J ) 1.4 and 15.7
Hz), 5.47 (1H, s), 5.43 (1H, dt, J ) 7.4 and 15.7 Hz), 4.08 (1H,
d, J ) 9.0 Hz), 4.04 (1H, d, J ) 9.0 Hz), 2.20 (2H, ddt, J ) 1.4,
7.4 and 7.4 Hz), 1.23 (3H, s), 1.11 (3H, s), 1.04 (3H, t, J ) 7.4
Hz); IR (CHCl3) 3550, 2950, 2870, 2100, 1800, 1720, 1660,
1480, 1380, 1280, 1010 cm-1; MS m/ z (%): 224 (4), 170 (10),
169 (48), 168 (18), 109 (17), 105 (15), 97 (59), 95 (50), 85 (56),
83 (100), 81 (55), 77 (22), 71 (75); [R]25D: -0.4 (c 1.23, CHCl3).
Anal. Calcd for C12H16O4N2: C 57.13, H 6.39. Found: C 57.60,
H 6.60.
3550, 3020, 2920, 1790, 1600, 1460, 1050, 1020, 880, 850 cm-1
;
MS m/ z (%): 290 (M+, 3), 144 (8), 134 (10), 133 (100), 131
(18), 115 (22), 114 (12), 105 (13), 99 (24), 91 (10); [R]25D: +5.1
(c 1.07, CHCl3). Anal. Calcd for C16H18O5: C 66.20, H 6.25.
Found: C 66.25, H 6.17.
18c (64%): 1H NMR δ 5.64-5.54 (2H, m), 5.46 (1H, s), 4.08
(1H, d, J ) 9.2 Hz), 4.04 (1H, d, J ) 9.2 Hz), 2.18-2.04 (2H,
m), 1.24 (3H, s), 1.12 (3H, s), 1.05 (3H, t, J ) 7.5 Hz); IR
(CHCl3) 2950, 2100, 1800, 1710, 1650, 1460, 1370, 1270, 1020,
950 cm-1; MS m/ z (%): 253 (M+ + 1, 24), 252 (M+, 16), 124
(10), 123 (100), 113 (11), 97 (39), 83 (56); [R]25D: + 1.1 (c 1.39,
CHCl3). Anal. Calcd for C12H16O4N2: C 57.13, H 6.39.
Found: C 57.29, H 6.44.
19a . Prepared according to the general procedure reported
for esters 8 (67%) (two diastereoisomers): 1H NMR δ 7.57-
7.20 (10H, m), 6.36 (2H, d, J ) 9.9 and 16.0 Hz), 6.16 (1H, d,
J ) 16.0 Hz), 6.11 (1H, d, J ) 16.0 Hz), 5.35 (2H, s), 4.01 (2H,
s), 3.98 (2H, s), 3.40 (1H, d, J ) 9.9 Hz), 3.38 (1H, d, J ) 9.9
Hz), 1.15 (3H, s), 1.05 (3H, s), 1.03 (3H, s), 0.93 (3H, s), 0.54
(6H, s), 0.52 (6H, s); IR (film) 3060, 2950, 1790, 1640, 1600,
1460, 1370, 1250, 1000, 700 cm-1; MS m/ z (T): 275 (2), 145
(25), 144 (100), 135 (7), 117 (42), 115 (34), 91 (11).
19g. Rh2(OAc)4 (5 mg, 0.01 mmol) was added at rt to a
solution of 18a (105 mg, 0.35 mmol) in methanol (10 mL). The
mixture was stirred at rt for 40 min, and the solvent was
evaporated in vacuo. Chromatography of the residue (petro-
leum ether/ethyl acetate 9:1) gave 19g as an unseparable
diastereoisomeric mixture (80 mg, 75%) (two diastereoiso-
mers): 1H NMR δ 7.48-7.23 (10H, m), 6.85 (2H, d, J ) 16.0
Hz), 6.28 (1H dd, J ) 6.6 and 16.0 Hz), 6.22 (1H, dd, J ) 7.0
and 16.0 Hz), 5.46 (1H, s), 5.43 (1H, s), 4.62 (1H, dd, J ) 1.3
and 7.1 Hz), 4.58 (1H, dd, J ) 1.4 and 6.5 Hz), 4.12-3.95 (4H,
m), 3.51 (3H, s), 3.50 (3H, s), 1.23 (3H, s), 1.17 (3H, s), 1.14
(3H, s), 1.07 (3H, s); IR (CHCl3) 2970, 2920, 1800, 1760, 1660,
1470, 1400, 1370, 1300, 1160, 1080, 970, 910 cm-1; MS m/ z
(%): 322 (M+ + NH4+, 98), 305 (M+ + 1, 7), 274 (21), 273 (100),
147 (14), 115 (7). Anal. Calcd for C17H20O5: C 67.09, H 6.62.
Found: C 66.93, H 6.58.
4-P h en yl-2-(d im eth ylp h en ylsilyl)bu ta n ol (20a ). A sus-
pension of 10% palladium on charcoal (137 mg) in 2-propanol
(10 mL) was stirred under an hydrogen atmosphere for 30 min,
and then a solution of 19a (0.45 g, 1.25 mmol) in 2-propanol
(10 mL) was added slowly. The mixture was stirred at rt for
4 h and then filtered, and the solvent was evaporated in vacuo
to give a colorless oil (0.39 g, 87%) which was used in the next
step without further purification. To a solution of the resulting
oil (0.39 g, 0.95 mmol) in dry ether (25 mL) was added dropwise
19b (two diastereoisomers): 1H NMR δ 7.53-7.22 (10H, m),
6.49 (1H, dd, J ) 10 and 16 Hz), 6.4 (1H, dd, J ) 10 and 16
Hz), 6.32 (1H, d, J ) 16 Hz), 6.29 (1H, d, J ) 16 Hz), 5.40
(2H, s), 4.04-4.00 (4H, m), 3.22 (1H, d, J ) 10 Hz), 3.21 (1H,
d, J ) 10 Hz), 1.20 (3H, s), 1.16 (3H, s), 1.13 (3H, s), 1.06 (3H,
s), 0.24-0.11 (54H, m); IR (film) 3063, 2959, 1794, 1732, 1248,
848, 754 cm-1; MS m/ z (%): 520 (M+, 0.2), 415 (3), 281 (46),
207 (33), 174 (14), 144 (56), 117 (41), 73 (100).
19c (two diastereoisomers): 1H NMR δ 7.57-7.49 (4H, m),
7.42-7.33 (6H, m), 5.56 (2H, ddt, J ) 1.4, 10.0 and 15.5 Hz),

Rhodium(II)-Vinyl Carbenoid Insertion
J . Org. Chem., Vol. 62, No. 6, 1997 1641
at -78 °C a 1 M solution of DIBAH in toluene (1.9 mL, 1.9
mmol). The reaction mixture was stirred at -78 °C for 1 h
and then treated with a saturated solution of NH4Cl, and the
organic layer was decanted. The aqueous layer was extracted
with ether, the combined extracts were washed with a satu-
rated solution of NH4Cl and dried over MgSO4, and the solvent
was evaporated in vacuo. Chromatography of the residue
(petroleum ether/ethyl acetate/NEt3 90:9.5:0.5) gave 20a as a
colorless oil (165 mg, 61 %): 1H NMR δ 7.57-7.50 (2H, m),
7.41-7.35 (3H, m), 7.32-7.10 (5H, m), 3.88 (1H, dd, J ) 4.5
and 10.7 Hz), 3.74 (1H, dd, J ) 6.8 and 10.7 Hz), 2.74 (1H,
ddd, J ) 7.6, 9.2 and 13.6 Hz), 2.56 (1H, ddd, J ) 6.9, 9.5 and
13.5 Hz), 1.85-1.75 (2H, m), 1.38 (1H, broad s), 1.20-1.11 (1H,
m), 0.36 (3H, s), 0.35 (3H, s); IR (CHCl3) 3630, 3010, 2950,
1250, 1110, 1080 cm-1; MS m/ z (%): 271 (10), 137 (65), 136
(19), 135 (84), 132 (33), 105 (13), 104 (33), 91 (100), 75 (16).
Anal. Calcd for C18H24OSi: C 76.00, H 8.50, Si 9.87. Found:
C 75.96, H 8.45, Si 9.81.
(E)-4-P h en yl-2-(d im eth ylp h en ylsilyl)bu t-3-en ol (23a ):
1H NMR δ 7.92-7.17 (10H, m), 6.37 (1H, dd, J ) 0.6 and 15.8
Hz), 6.10 (1H, dd, J ) 9.7 and 15.8 Hz), 3.80-3.76 (2H, m),
2.31 (1H, dt, J ) 4.6 and 9.7 Hz), 0.36 (6H, s); IR (CHCl3) 3200,
2990, 2960, 1640, 1600, 1440, 1250, 1120, 970 cm-1; MS m/ z
(%): 144 (5), 137 (18), 135 (28), 131 (13), 130 (100), 129 (32),
115 (21), 91 (16). Anal. Calcd for C21H24O2Si: C 76.54, H 7.85,
Si 9.94. Found: C 76.65, H 7.93, Si 9.93.
(E)-4-P h en yl-2-(d im eth ylp h en ylsilyl)p en t-3-en ol (23b):
1H NMR δ 7.55-7.51 (2H, m), 7.46-7.21 (8H, m), 5.66 (1H,
dq, J ) 1.2 and 11.2 Hz), 3.90-3.80 (1H, m), 3.71 (1H, dd, J
) 10.4 and 10.4 Hz), 2.56 (1H, dd, J ) 4.2, 10.4 and 11.2 Hz),
1.92 (3H, d, J ) 1.3 Hz), 0.38 (3H, s), 0.36 (3H, s); IR (CHCl3)
3580, 3150, 3000, 2960, 2870, 1600, 1500, 1460, 1120, 1100,
1040, 820 cm-1; MS m/ z (%): 201 (4), 152 (5), 145 (20), 144
(92), 143 (15), 137 (57), 135 (62), 129 (100), 91 (11). Anal. Calcd
for C19H24OSi: C 76.97, H 8.16, Si 9.47. Found: C 77.02, H
8.13, Si 9.32.
Eth yl (E)-2-Deu ter io-2-(d im eth ylp h en ylsilyl)-4-p h en -
ylbu t-3-en oa te (24). Prepared according to the general
procedure described for 8: 1H NMR δ 7.53-7.17 (10H, m), 6.40
(1H, d, J ) 16.0 Hz), 6.12 (1H, d, J ) 16.0 Hz), 4.06 (1H, dq,
J ) 7.1 and 10.1 Hz), 3.98 (1H, dq, J ) 7.1 and 10.1 Hz), 1.12
(3H, t, J ) 7.1 Hz), 0.45 (6H, s); IR (film) 3030, 2970, 1720,
1650, 1610, 1460, 1240, 1130, 980, 920, 830 cm-1; MS m/ z
(%): 343 (M+ + NH4+, 5), 326 (M+ + 1, 5), 325 (M+, 3), 249
(20), 248 (100), 220 (8), 192 (16), 145 (8), 135 (12). Anal. Calcd
for C20H25O2Si: C 73.80, H 7.74, Si 8.63. Found: C 73.71, H
7.70, Si 8.56.
2-(Dim eth ylp h en ylsilyl)h exa n ol (20b). Prepared ac-
cording to the procedure reported for 20a : 1H NMR δ 7.56-
7.50 (2H, m), 7.39-7.34 (3H, m), 3.79 (1H, dd, J ) 4.5 and
10.8 Hz), 3.68 (1H, dd, J ) 6.8 and 10.8 Hz), 1.50-1.03 (7H,
m), 0.85 (3H, t, J ) 6.9 Hz), 0.33 (6H, s); IR (CHCl3) 3620,
2960, 2870, 1415, 1250, 1110, 1020, 840 cm-1; MS m/ z (%):
169 (10), 137 (100), 135 (21), 97 (10), 83 (13), 71 (14), 69 (12),
57 (23), 55 (21). Anal. Calcd for C14H24OSi: C 71.12, H 10.23,
Si 11.88. Found: C 71.18, H 10.24, Si 11.74.
4-P h en ylbu ta n e-1,2-d iol (21a ).31a To a solution of 20a (53
mg, 0.19 mmol) in acetic anhydride (0.1 mL) and peracetic acid
(32% in acetic acid) (0.6 mL) was added, at 0 °C, Hg(OAc)2 (89
mg, 0.28 mmol). The reaction mixture was stirred at rt for 3
h, and the solvent was evaporated in vacuo. Chromatography
of the residue (CH2Cl2/MeOH 99:1) afforded 21a as a colorless
oil (13 mg, 42 %).
25. Prepared according to the procedure described for
23a ,b: 1H NMR δ 7.54-7.20 (5H, m), 6.37 (1H, d, J ) 15.9
Hz), 6.10 (1H, d, J ) 15.9 Hz), 3.84-3.73 (2H, m), 0.37 (6H,
s); IR (film) 3392, 3069, 2956, 1636, 1599, 1427, 1250, 1112,
833, 736 cm-1; MS m/ z (%): 281 (M+ - 1, 0.2), 266 (2), 135
Hexa n e-1,2-d iol (21b).31b Prepared according to the pro-
cedure reported for 21a .
(55), 131 (100), 116 (22), 91 (14). Anal. Calcd for C18H21
-
DOSi: C 76.27, H 8.18, Si 9.91. Found: C 76.40, H 8.07, Si
10.08.
Meth yl (2S)-Hyd r oxy-4-p h en ylbu ta n oa te (22).31c A sus-
pension of 10% palladium on charcoal (20 mg) in methanol
(10 mL) was stirred under an hydrogen atmosphere for 30 min,
and then a solution of alcohol 19fa (0.41 g, 1.41 mmol) in
methanol (10 mL) was added slowly. The reaction mixture
was stirred at rt for 3 h and then filtered, and the solvent was
evaporated in vacuo to give a colorless oil (0.33 g, 80%) which
was used in the next step without further purification. To a
solution of the resulting ester (0.24 g, 0.82 mmol) in THF (23
mL) was added dropwise at 0 °C a solution of LiOOH (prepared
from LiOH (36 mg, 0.86 mmol), 30% H2O2 (0.42 mL), and water
(5.8 mL)). The reaction mixture was stirred at 0 °C for 1 h,
and then a solution of NaHSO3 (0.85 g, 8.2 mmol) in water
(9.3 mL) was added slowly. The mixture was stirred at 0 °C
for 15 min, diluted with a 1 M solution of Na2S2O5, and
extracted with CH2Cl2. The combined extracts were dried over
MgSO4, and the solvent was evaporated in vacuo. The
resulting acid was dissolved in dry ether (10 mL), and an
ethereal solution of diazomethane was added until no starting
material could be detected by TLC. After evaporation of the
solvent in vacuo, chromatography of the residue (petroleum
ether/ethyl acetate 5:1) afforded pantolactone (92 mg, 86%) and
ester 22 (75 mg, 70%) as a colorless oil (56% overall yield from
19fa ).
Gen er a l P r oced u r e for th e P r ep a r a tion of Allylsila n es
23a ,b Usin g Rh 2(5S-MEP Y)4. To a stirred solution of 7a (or
7b) (0.5 mmol) and dimethylphenylsilane (1 mmol) in dry CH2-
Cl2 (5 mL) was added at rt Rh2(MEPY)4 (cat.). The mixture
was stirred at rt for 48 h, and then the solvent was evaporated
in vacuo to afford the crude optically active allylsilane 8a (or
8f) which was used in the next step without further purifica-
tion. To a solution of 8a (or 8f) (0.61 mmol) in dry ether (5
mL) was added dropwise at 0 °C a 1 M solution of LiAlH4 in
ether (0.34 mmol). The reaction mixture was stirred at 0 °C
for 30 min and then treated with 1 M HCl. The aqueous layer
was extracted with ether, the combined extracts were washed
with brine and dried over MgSO4, and the solvent was
evaporated in vacuo. Chromatography of the residue (petro-
leum ether/ethyl acetate/NEt3 95:4.5:0.5) gave 23a ,b as a pale
yellow oil.
Eth yl (E)-2-Deu ter io-2-deu ter oxy-4-ph en ylbu t-3-en oate
(26a ). Prepared according to the procedure described for 14a -
f: 1H NMR δ 7.42-7.24 (5H, m), 6.82 (1H, d, J ) 15.9 Hz),
6.26 (1H, d, J ) 15.9 Hz), 4.33 (1H, dq, J ) 7.1 and 10.8 Hz),
4.27 (1H, dq, J ) 7.1 and 10.8 Hz), 1.33 (3H, t, J ) 7.1 Hz); IR
(CH2Cl2) 3470, 3030, 2990, 1730, 1600, 1580, 1250, 1210, 1160,
1020, 970, 740, 700 cm-1; MS m/ z (%): 225 (M+ + NH3, 5),
207 (4), 190 (18), 144 (5), 135 (28), 134 (100), 116 (29), 106
(10). Anal. Calcd for C12H12O3D2: C 69.21, H 7.74. Found:
C 69.28, H 6.95.
E t h yl (E)-2-Deu t er io-2-et h oxy-4-p h en ylb u t -3-en oa t e
(26b). Prepared according to the procedure described for 14g-
i: 1H NMR δ 7.42-7.24 (5H, m), 6.78 (1H, d, J ) 16.0 Hz),
6.24 (1H, d, J ) 16.0 Hz), 4.26 (1H, q, J ) 7.1 Hz), 4.25 (1H,
q, J ) 7.1 Hz), 3.64 (1H, dq, J ) 7.1 and 10.1 Hz), 3.59 (1H,
dq, J ) 7.0 and 10.1 Hz), 1.31 (6H, t, J ) 7.0 Hz); IR (film)
2980, 1740, 1600, 1580, 1450, 1180, 1120, 1100, 970, 910, 700
cm-1; MS m/ z (%): 253 (M+ + NH4, 19), 236 (M+ + 1, 4), 235
(M+, 2), 207 (12), 206 (50), 190 (73), 162 (100), 134 (32), 116
(34). Anal. Calcd for C14H17O3D: C 71.46, H 8.14. Found: C
71.56, H 7.61.
Ack n ow led gm en t. The authors gratefully acknowl-
edge the Swiss National Science Foundation for gener-
ous support (Chiral 2). We also thank Dr. I. Eggleston
for proof-reading this article and Prof. M. P. Doyle
(Trinity University) for a generous gift of Rh2(MEOX)4
and for stimulating discussions.
Su p p or tin g In for m a tion Ava ila ble: Spectroscopic data
for compounds 6a ,b, 6d -h , 6j, 7a ,b, 7d -h , 7j, diisopropyl-
fluorosilane, 8f-i, alcohols derived from 8e, 8j, 8k , 8o, 14b,
14d ,e, 14l, 17a , 17d , 18a , 18d , 21a ,b, and 22 (6 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
J O961952J