Chiral ketone catalyzed highly chemo- and enantioselective epoxidation of conjugated enynes

Full text of DOI:10.1021/jo9907639

7
646
J . Org. Chem. 1999, 64, 7646-7650
Ch ir a l Keton e Ca ta lyzed High ly Ch em o-
Sch em e 1
a n d En a n tioselective Ep oxid a tion of
Con ju ga ted En yn es
Zhi-Xian Wang, Guo-An Cao, and Yian Shi*
Department of Chemistry, Colorado State University,
Fort Collins, Colorado 80523
Received May 7, 1999
Chiral alkynyloxiranes are very useful synthetic in-
termediates. The alkynyl group is a synthetically versa-
tile functional group, and it provides a controlling group
1
,2
for regioselective opening of the epoxide (Scheme 1).
In addition, some important natural products contain
alkynyloxiranes (for example, the antitumor agent neo-
the asymmetric epoxidation of enynes using ketone 1 as
catalyst and Oxone as oxidant.9
3
carzinostatin ). Enantioselective epoxidation of enynes
would provide a direct approach to alkynyloxiranes.4,5
Recently we reported a highly enantioselective epoxi-
dation method for trans- and trisubstituted olefins using
a fructose-derived ketone 1 as catalyst and Oxone as
6
oxidant. In an effort to expand the scope of this epoxi-
dation, we have been investigating the feasibility of
chemo- and enantioselective epoxidation of enynes with
this catalyst (eq 1). Although dioxiranes are known to
(1)
7
be able to epoxidize C-C triple bonds, chemoselective
epoxidation of the enynes using dimethyldioxirane has
Resu lts a n d Discu ssion
8
been observed. Herein we report our detailed studies on
The enyne substrates were readily synthesized by
known procedures. The substituted 6-membered cyclic
enynes were prepared from commercially available 1-ethy-
nylcyclohexene (Table 1, entries 3-5). The other cyclic
enynes were prepared by reacting a ketone and an
acetylide to give the propargyl alcohol, which was then
converted to its carbonate. The resulting carbonate was
converted to an enyne by Pd(0) catalyst.10 The acyclic
enynes were prepared from readily available R,â-unsat-
(
1) For some leading references on synthetic applications of alky-
nyloxiranes, see: (a) Alexakis, A.; Marek, I.; Mangeney, P.; Normant,
J . F. Tetrahedron 1991, 47, 1677. (b) Marshall, J . A.; DuBay, W. J . J .
Am. Chem. Soc. 1992, 114, 1450. (c) Marshall, J . A.; Pinney, K. G. J .
Org. Chem. 1993, 58, 7180. (d) Marshall, J . A.; Tang, Y. J . Org. Chem.
1
994, 59, 1457. (e) Mukai, C.; Sugimoto, Y-i.; Ikeda, Y.; Hanaoka, M.
Tetrahedron Lett. 1994, 35, 2183. (f) Aurrecoechea, J . M.; Solay, M.
Tetrahedron Lett. 1995, 36, 2501. (g) Piotti, M. E.; Alper, H. J . Org.
Chem. 1997, 62, 8484. (h) Aurrecoechea, J . M.; Alonso, E.; Solay, M.
Tetrahedron 1998, 54, 3833. (i) Aurrecoechea, J . M.; Solay, M.
Tetrahedron 1998, 54, 3851. (j) Bernard, N.; Chemla, F.; Normant, J .
F. Tetrahedron Lett. 1998, 39, 6715.
1
1
urated aldehydes using the Corey-Fuchs procedure.
(2) For some leading references on synthetic transformations of
homopropargyl alcohols, see: (a) Murray, T. F.; Samsel, E. G.; Varma,
V.; Norton, J . R. J . Am. Chem. Soc. 1981, 103, 7520. (b) McDonald, F.
E.; Gleason, M. M. J . Am. Chem. Soc. 1996, 118, 6648. (c) Marko, I.
E.; Dobbs, A. P.; Scheirmann, V.; Chelle, F.; Bayston, D. J . Tetrahedron
Lett. 1997, 38, 2899.
Our investigation started with 1-ethynylcyclohexene
as the test substrate (Table 1, entry 1). Subjecting this
enyne to the epoxidation conditions led to a chemoselec-
tive epoxidation of the double bond. The analysis of the
epoxide using chiral GC (Chiraldex B-TA column) showed
93% ee. Further studies demonstrated that the acetylene
could bear different substituents such as alkyl, TMS, and
ester groups (Table 1, entries 3-5). The epoxidation could
(
3) For a leading reference, see: Myers, A. G.; Hammond, M.; Wu,
Y.; Xiang, J .-N.; Harrington, P. M.; Kuo, E. Y. J . Am. Chem. Soc. 1996,
18, 10006.
4) For leading references on asymmetric epoxidations of enynes
1
(
directed by hydroxy groups, see: (a) J ohnson, R. A.; Sharpless, K. B.
In Catalytic Asymmetric Synthesis; Ojima, I., Ed.; VCH: New York,
1
1
993; Chapter 4.1. (b) Katsuki, T.; Martin, V. S. Org. React. 1996, 48,
.
1
also extend to many other enynes. The H NMR spectra
of the crude reaction mixtures in all cases were very clean
and showed that the epoxidations chemoselectively oc-
curred at the double bond. Among cyclic enynes, the 5-
and 12-membered systems gave somewhat lower ee than
the 6- and 8-membered systems. Most of the tested acyclic
disubstituted and trisubstituted enynes gave high enan-
tioselectivities. In contrast to certain isolated trisubsti-
(
5) For leading references on asymmetric epoxidations of enynes
using (salen)Mn(III), see: (a) Lee, N. H.; J acobsen, E. N. Tetrahedron
Lett. 1991, 32, 6533. (b) Brandes, B. D.; J acobsen, E. N. J . Org. Chem.
994, 59, 4378. (c) Hamada, T.; Irie, R.; Katsuki, T. Synlett 1994, 479.
d) Sasaki, H.; Irie, R.; Hamada, T.; Suzuki, K.; Katsuki, T. Tetrahedron
994, 50, 11827. (e) Hamada, T.; Daikai, K.; Irie, R.; Katsuki, T. Synlett
995, 407.
1
(
1
1
(6) (a) Tu, Y.; Wang, Z.-X.; Shi, Y. J . Am. Chem. Soc. 1996, 118,
9
6
806. (b) Wang, Z.-X.; Tu, Y.; Frohn, M.; Shi, Y. J . Org. Chem. 1997,
2, 2328. (c) Wang, Z.-X.; Tu, Y.; Frohn, M.; Zhang, J .-R.; Shi, Y. J .
Am. Chem. Soc. 1997, 119, 11224. (d) Frohn, M.; Dalkiewicz, M.; Tu,
Y.; Wang, Z.-X.; Shi, Y. J . Org. Chem. 1998, 63, 2948. (e) Wang, Z.-X.;
Shi, Y. J . Org. Chem. 1998, 63, 3099. (f) Zhu, Y.; Tu, Y.; Yu, H.; Shi,
Y. Tetrahedron Lett. 1998, 39, 7819. (g) Tu, Y.; Wang, Z.-X.; Frohn,
M.; He, M.; Yu, H.; Tang, Y.; Shi, Y. J . Org. Chem. 1998, 63, 8475.
(8) Wang, X.; Ramos, B.; Rodriguez, A. Tetrahedron Lett. 1994, 35,
6977.
(9) For a preliminary report of a portion of this work, see: Cao, G.-
A.; Wang, Z.-X.; Tu, Y.; Shi. Y. Tetrahedron Lett. 1998, 39, 4425.
(10) Manai, T.; Tsujiguchi, Y.; Matsuoka, S.; Tsuji, J . Tetrahedron
Lett. 1993, 34, 7615.
(
7) (a) Curci, R.; Fiorentino, M.; Fusco, C.; Mello, R. Tetrahedron
Lett. 1992, 33, 7929. (b) Murray, R. W.; Singh, M. J . Org. Chem. 1993,
8, 5076.
5
(11) Corey, E. J .; Fuchs, P. L. Tetrahedron Lett. 1972, 3769.
1
0.1021/jo9907639 CCC: $18.00 © 1999 American Chemical Society
Published on Web 09/08/1999

Notes
J . Org. Chem., Vol. 64, No. 20, 1999 7647
Ta ble 1. Asym m etr ic Ep oxid a tion of En yn es Ca ta lyzed by Keton e 1 & en t-1a
a
All reactions except entries 9-11 were carried out with substrate (1 equiv), ketone (0.3 equiv), Oxone (1.38 equiv), and K2CO3 (5.8
equiv) in CH3CN-DMM-aqueous K2CO3/AcOH solution (prepared by adding 0.5 mL of AcOH to 100 mL of 0.1 M aqueous K2CO3, pH
b
9
.3) (1:2:2, v/v). The reaction was run with substrate (1 equiv), ketone (0.5 equiv), Oxone (2.07 equiv), and K2CO3 (8.7 equiv) in CH3CN-
c
DMM-aqueous K2CO3/AcOH solution (1:2:2, v/v). The epoxides were purified by flash chromatography and gave satisfactory spectroscopic
d
e
characterization. Enantioselectivity was determined by chiral GC (Chiraldex B-TA column). Enantioselectivity was determined by
f
1
chiral GC (Chiraldex B-TA column) after desilylation. Enantioselectivity was determined by H NMR shift analysis of the epoxide products
directly with Eu(hfc)3. Enantioselectivity was determined by chiral HPLC (Chiralcel OD). Enantioselectivity was determined by chiral
GC (Chiraldex G-TA column). The absolute configuration was determined by a correlation of the epoxide with a prepared authentic
sample (see text). The absolute configuration was tentatively assumed by analogy based on the spiro reaction mode.
g
h
i
j
tuted olefins,6c the enantioselectivity for the trisubstitued
enynes is certainly high, which indicates that the alkyne
groups are beneficial for chiral induction.
shown in eq 2. The chiral epoxy alcohol obtained from
the epoxidation of the allylic alcohol was oxidized to the
aldehyde, which was subsequently converted to the
alkyne.13 In all of these cases, the configurations obtained
To determine the absolute configurations of the ep-
oxides, correlations of representative cyclic, disubstituted,
and trisubstituted enyne epoxides (Table 1, entries 1, 2,
6
,14
are consistent with the spiro transition state.
4
, 9, 10, 12, 13, 15, and 16) were made with authentic
(13) M u¨ ller, S.; Liepold, B.; Roth, G. J .; Bestmann, H. J . Synlett
996, 521.
1
samples prepared from epoxy alcohols with known
(14) For leading references on the transition states of the dioxirane-
configuration.6
e,12
In the cases of silyl-substituted ep-
mediated epoxidation, see: (a) Baumstark, A. L.; McCloskey, C. J .
Tetrahedron Lett. 1987, 28, 3311. (b) Baumstark, A. L.; Vasquez, P.
C. J . Org. Chem. 1988, 53, 3437. (c) Bach, R. D.; Andres, J . L.;
Owensby, A. L.; Schlegel, H. B.; McDouall, J . J . W. J . Am. Chem. Soc.
1992, 114, 7207. (d) Yang, D.; Wang, X.-C.; Wong, M.-K.; Yip, Y.-C.;
Tang, M.-W. J . Am. Chem. Soc. 1996, 118, 11311. (e) Houk, K. N.;
Liu, J .; DeMello, N. C.; Condroski, K. R. J . Am. Chem. Soc. 1997, 119,
10147. (f) J enson, C.; Liu, J .; Houk, K. N.; J orgensen, W. L. J . Am.
Chem. Soc. 1997, 119, 12982.
oxides, the comparisons were made after the silyl groups
were removed by TBAF. A represetative reaction se-
quence for the preparation of the authentic sample is
(12) Gao, Y.; Hanson, R. M.; Klunder, J . M.; Ko, S. Y.; Masamune,
H.; Sharpless, K. B. J . Am. Chem. Soc. 1987, 109, 5765.

7
648 J . Org. Chem., Vol. 64, No. 20, 1999
Notes
Sch em e 2
(2)
2 4
combined extracts were washed with brine, dried (Na SO ),
concentrated, and purified by flash chromatography (pentane-
It is widely believed that the spiro transition state is
favored due to a stabilizing interaction of an oxygen lone
pair of the dioxirane with the π* orbital of the olefin.
In the present case, the conjugation of an alkyne to the
olefin results in a lowering of the olefin’s LUMO. As a
result, the overlap of the oxygen lone pair with the olefin’s
LUMO in the spiro transition state becomes even more
favorable. Previously we have shown that the main
1a,5b
ether, 1:0 to 10:1 v/v) to give (R,R)-1-ethynylcyclohexene oxide
as a colorless oil (0.48 g, 78% yield, 93% ee) (Table 1, entry 1).
1
4c,e
23
[R]
D
3
) +22.36 (c 0.93, CHCl ).
1
a ,5b
(S,S)-1-Eth yn ylcycloh exen e Oxid e
(Ta ble 1, en tr y 2).
).
R,R)-1-(1′-P r op yn yl)cycloh exen e Oxid e (Ta ble 1, en tr y
2
3
Colorless oil. [R]
D
) -22.44 (c 1.1, CHCl
3
(
1
3
2
1
). En yn e. Colorless liquid. H NMR δ: 5.99 (br s, 1H), 2.10-
13
.03 (m, 4H), 1.93 (s, 3H), 1.64-1.53 (m, 4H). C NMR δ: 133.1,
21.1, 82.7, 81.6, 29.6, 25.6, 22.5, 21.7, 4.11.
2
3
competing transition state with this system is the planar
Ep oxid e. Colorless oil. [R]
2249 cm H NMR δ: 3.27 (br s, 1H), 2.10 (dt, J ) 15.1, 6.0
Hz, 1H), 2.00-1.85 (m, 3H), 1.82 (s, 3H), 1.44-1.16 (m, 4H).
D
3
) +14.8 (c 1.02, CHCl ). IR:
transition state B (Scheme 2).6c The competition between
-1
1
spiro A and planar B is affected by the steric bulk of
substituents on the olefin. Higher ee can be obtained by
1
3
C NMR δ: 80.0, 78.6, 60.1, 50.7, 30.1, 24.4, 19.6, 19.1, 3.8. Anal.
Calcd for C 12O: C, 79.37; H, 8.88. Found: C, 79.51; H, 8.73.
R,R)-1-(Tr im eth ylsilyleth yn yl)cycloh exen e Oxide (Table
9
H
decreasing the size of R
a
(favoring spiro A) and increasing
(
the size of R (disfavoring planar B). The epoxidation of
c
-1 1
1
, en tr y 4). En yn e. IR: 2146 cm . H NMR δ: 6.18 (br s, 1H),
13
the enynes in Table 1 is expected to proceed via spiro
transition states C and D. The sterically less demanding
acetylene groups should favor the spiro transition states,
particularly spiro C.
In summary, we have found that the epoxidation of
conjugated enynes using a fructose-derived chiral ketone
2.15-2.05 (m, 4H), 1.67-1.52 (m, 4H), 0.18 (s, 9H). C NMR δ:
1
36.4, 120.9, 107.5, 91.0, 29.3, 25.8, 22.4, 21.6, 0.29.
2
3
Ep oxid e. Colorless oil. [R]
170 cm
D
) +11.7 (c 1.02, CHCl
3
). IR:
-
1
1
2
1
. H NMR δ: 3.31 (t, J ) 2.4 Hz, 1H), 2.1 (dt, J )
5.2, 6.2 Hz, 1H), 1.99 (ddd, J ) 15.2, 7.5, 5.7 Hz, 1H), 1.88 (td,
13
J ) 6.3, 2.4 Hz, 2H), 1.44-1.16 (m, 4H), 0.14 (s, 9H). C NMR
δ: 106.0, 87.0, 60.3, 50.5, 29.7, 24.3, 19.6, 19.0, -0.03. Anal. Calcd
1
as catalyst and Oxone as oxidant is highly chemo-,
for C11
H
18OSi: C, 67.98; H, 9.34. Found: C, 67.95; H, 9.13.
(
R,R)-1-[(E t h oxyca r b on yl)et h yn yl]cycloh exen e Oxid e
enantioselective, and stereospecific. The alkyne groups
are beneficial for the enantioselectivity due to both
electronic and steric effects. The availability of these
enantiomerically enriched enyne epoxides provides op-
portunities for potential synthetic applications.
-1 1
(
Ta ble 1, en tr y 5). En yn e. IR: 2207, 1708, 1625 cm . H NMR
δ: 6.39 (br s, 1H), 4.18 (q, J ) 7.2 Hz, 2H), 2.13-2.07 (m, 4H),
1
1
.62-1.53 (m, 4H), 1.26 (t, J ) 7.2 Hz, 3H). 13C NMR δ: 154.3,
42.0, 118.5, 88.3, 78.7, 61.8, 28.2, 26.0, 22.0, 21.2, 14.1.
Ep oxid e. Colorless oil. [R]23 ) +9.1 (c 0.78, CHCl ). IR: 2240,
D
3
-
1 1
1
2
1
713 cm . H NMR δ: 4.23 (q, J ) 7.2 Hz, 2H), 3.42 (br s, 1H),
.16 (dt, J ) 15.3, 6.2 Hz, 1H), 2.06 (ddd, J ) 15.3, 6.7, 5.8 Hz,
H), 2.00-1.90 (m, 2H), 1.49-1.19 (m, 4H), 1.30 (t, J ) 7.2 Hz,
Exp er im en ta l Section
1
3
Gen er a l Meth od s. Oxone was purchased from Aldrich (it has
been found that the oxidation activity of the purchased Oxone
occasionally varies with different batches). All glassware used
for the epoxidation was carefully washed to be free of any trace
metals which catalyze the decomposition of Oxone. Elemental
analyses were performed by M-H-W Laboratories, Phoenix, AZ.
Silica gel 60 of E-Merck Co. was employed for all flash chroma-
tography.
3H). C NMR δ: 153.2, 87.0, 73.6, 62.3, 60.0, 49.4, 28.7, 24.0,
19.2, 18.6, 14.1. Anal. Calcd for C11
Found: C, 68.19; H, 7.00.
14 3
H O : C, 68.02; H, 7.27.
(R,R)-1-[3′-(ter t-Bu tyld im eth ylsiloxy)-1′-p r op yn yl]cyclo-
p en ten e Oxid e (Ta ble 1, en tr y 6). En yn e. Colorless liquid.
-
1
1
IR: 2225, 1634 cm . H NMR δ: 6.02 (br s, 1H), 4.46 (s, 2H),
2.48-2.42 (m, 4H), 1.90 (quintet, J ) 7.5 Hz, 2H), 0.92 (s, 9H),
0.14 (s, 6H). 13C NMR δ: 137.9, 124.4, 89.2, 82.5, 52.5, 36.4, 33.4,
26.1, 23.4, 18.6, -4.85.
Gen er a l Ep oxid a tion P r oced u r e. To a mixture of 1-ethy-
nylcyclohexene (0.53 g, 5 mmol) and ketone 1 (0.387 g, 1.5 mmol)
2
3
Ep oxid e. Colorless oil. [R]
D
3
) -7.5 (c 1.75, CHCl ). IR: 2242
-
1 1
in DMM-CH
AcOH (prepared by adding 0.5 mL AcOH to 100 mL of 0.1 M
aqueous K CO , pH 9.3) (25 mL) and a catalytic amount of Bu
NHSO . After the mixture was cooled to -10 °C, a solution of
Oxone (4.25 g, 6.9 mmol) in 20 mL of aqueous Na
(EDTA) (4 ×
(4.0 g, 29 mmol) in 20 mL of
3
CN (40 mL, 2:1 v/v) were added aqueous K
2
CO
3
/
cm . H NMR δ: 4.33 (s, 2H), 3.61 (s, 1H), 2.13 (dd, J ) 13.9,
8.3 Hz, 1H), 1.98 (dd, J ) 13.9, 8.3 Hz, 1H), 1.79 (ddd, J ) 13.9,
10.4, 8.4 Hz, 1H), 1.75-1.31 (m, 3H), 0.89 (s, 9H), 0.09 (s, 6H).
H NMR δ: 83.1, 81.5, 65.1, 55.9, 51.9, 31.7, 27.6, 26.0, 19.2,
24 2
18.4, -4.9. Anal. Calcd for C14H O Si: C, 66.61; H, 9.58.
2
3
4
-
1
3
4
2
-4
1
0
M) and a solution of K
2
CO
3
Found: C, 66.83; H, 9.47.
water were added dropwise simultaneously from separate
syringes via syringe pump(s) over 3 h. The reaction was then
quenched by adding pentane (40 mL) and water (30 mL). The
aqueous layer was extracted with pentane (3 × 40 mL). The
(R,R)-1-[3′-(ter t-Bu t yld im et h ylsiloxy)-1′-p r op yn yl]cy-
cloocten e Oxid e (Ta ble 1, en tr y 7). En yn e. Colorless oil. IR:
2214, 1639 cm . H NMR δ: 6.07 (t, J ) 8.3 Hz, 1H), 4.44 (s,
2H), 2.31-2.27 (m, 2H), 2.17-2.14 (m, 2H), 1.59-1.49 (m, 8H),
-
1
1

Notes
J . Org. Chem., Vol. 64, No. 20, 1999 7649
0
5
.93 (s, 9H), 0.14 (s, 6H). 13C NMR δ: 137.8, 123.6, 87.5, 84.9,
2.5, 30.0, 29.9, 28.6, 27.1, 26.6, 26.2, 26.0, 18.5, -4.83.
δ: 6.16 (dt, J ) 15.9, 7.2 Hz, 1H), 5.50 (d, J ) 15.9 Hz, 1H),
4.20 (s, 2H), 3.38 (s, 3H), 2.09 (q, J ) 7.2 Hz, 2H), 1.42 (sextet,
2
3
13
Ep oxid e. Colorless oil. [R]
D
) +9.2 (c 1.2, CHCl
3
). IR: 2248
J ) 7.2 Hz, 2H), 0.91 (t, J ) 7.2 Hz, 3H). C NMR δ: 145.6,
-
1 1
cm . H NMR δ: 4.32 (s, 2H), 3.05 (dd, J ) 10.4, 4.2 Hz, 1H),
109.2, 85.4, 83.4, 60.6, 57.7, 35.2, 22.0, 13.7.
Ep oxid e. Colorless oil. [R]23
) -2.5 (c 1.14, CHCl
). H NMR
1
2
0
2
.16 (dt, J ) 13.7, 3.3 Hz, 2H), 1.78-1.16 (m, 10H), 0.89 (s, 9H),
D
3
1
3
.10 (s, 6H). C NMR δ: 84.5, 81.4, 63.6, 53.8, 51.9, 30.6, 27.2,
6.5, 26.2, 25.9, 25.87, 25.3, 18.4, -4.93. Anal. Calcd for
δ: 4.11 (s, 2H), 3.37 (s, 3H), 3.14 (br s, 1H), 3.10 (m, 1H), 1.58-
1.44 (m, 4H), 0.97 (t, J ) 7.2 Hz, 3H). 13C NMR δ: 83.4, 79.6,
C
17
H
30
O
2
Si: C, 69.33; H, 10.27. Found: C, 69.58; H, 10.58.
60.5, 60.0, 57.9, 45.3, 33.8, 19.1, 14.0. Anal. Calcd for C
C, 70.10; H, 9.15. Found: C, 70.22; H, 9.39.
9 14 2
H O :
(
R,R)-1-[3′-(ter t-Bu t yld im et h ylsiloxy)-1′-p r op yn yl]cy-
clod od ecen e Oxid e (Ta ble 1, en tr y 8). En yn e. Colorless oil.
IR: 2215, 1633 cm . H NMR δ: 5.79 (t, J ) 7.7 Hz, 1H), 4.51
(R ,R )-3-E t h yl-2-m e t h yl-2-(t r im e t h ylsilyle t h yn yl)ox-
ir a n e (Ta ble 1, en tr y 15). En yn e. Colorless oil. IR: 2146 cm .
-
1
1
-1
1
(
s, 2H), 2.31 (td, J ) 6.5, 4.1 Hz, 2H), 2.18 (t, J ) 5.9 Hz, 2H),
H NMR δ: 5.92 (td, J ) 7.4, 1.4 Hz, 1H), 2.08 (qd, J ) 7.6, 7.4
1
6
2
.57-1.51 (m, 4H), 1.40-1.29 (m, 12H), 0.93 (s, 9H), 0.15 (s,
13
Hz, 2H), 1.77 (d, J ) 0.6 Hz, 3H), 0.98 (t, J ) 7.6 Hz, 3H), 0.18
13
H). C NMR δ: 140.3, 122.0, 92.0, 83.6, 52.6, 36.4, 30.4, 27.2,
6.4, 26.1, 26.0, 25.5, 24.9, 24.8, 24.5, 24.4, 18.5, -4.85.
(s, 9H). C NMR δ: 141.4, 117.5, 108.8, 89.9, 22.0, 17.1, 13.6,
0.31.
2
3
1
23
Ep oxid e. Colorless oil. [R]
D
) -31.8 (c 1.2, CHCl
3
). H NMR
Ep oxid e. Colorless oil. [R]
) -8.1 (c 1.0, CHCl ). IR: 2175
D
3
-
1 1
δ: 4.37 (s, 2H), 3.00 (dd, J ) 9.6, 2.6 Hz, 1H), 2.34-2.27 (m,
H), 2.09-2.04 (m, 2H), 1.76-1.11 (m, 16H), 0.91 (s, 9H), 0.12
cm . H NMR δ: 3.10 (t, J ) 6.3 Hz, 1H), 1.55 (qd, J ) 7.6, 6.3
13
2
Hz, 2H), 1.48 (s, 3H), 1.06 (t, J ) 7.6 Hz, 3H), 0.164 (s, 9H).
NMR δ: 106.4, 86.5, 66.2, 51.1, 21.8, 18.3, 10.4, -0.05. Anal.
Calcd for C10 OSi: C, 65.87; H, 9.95. Found: C, 65.70; H, 9.76.
C
1
3
(
2
s, 6H). C NMR δ: 84.8, 81.9, 66.0, 56.6, 51.9, 35.9, 29.7, 27.2,
6.8, 25.9, 25.8, 25.3, 25.2, 24.3, 23.6, 23.5, 18.4, -5.0. Anal.
Calcd for C21 Si: C, 71.94; H, 10.92. Found: C, 71.79; H,
H
18
H
38
O
2
(R,R)-2-Met h yl-3-p h en yl-2-(t r im et h ylsilylet h yn yl)ox-
ir a n e (Ta ble 1, en tr y 16). En yn e. Colorless oil. A mixture of
1
0.73.
R,R)-2-P h en yl-3-(tr im eth ylsilyleth yn yl)oxir an e (Table
, en tr y 9). En yn e. Colorless oil. IR: 2167, 2120 cm . H NMR
5
a
1
1
(
E and Z isomers (E/ Z ) 2.8/1 by H NMR). H NMR δ
-
1 1
1
(E)-isomer: 7.3-7.2 (m, 5H), 6.81 (br s, 1H), 1.96 (s, 3H), 0.14
(s, 9H). H MR δ (Z)-isomer: 7.3-7.2 (m, 5H), 6.45 (br s, 1H),
δ: 7.37-7.25 (m, 5H), 6.99 (d, J ) 16.4 Hz, 1H), 6.16 (d, J )
1
1
1
6.4 Hz, 1H), 0.22 (s, 9H). 13C NMR δ: 142.6, 136.3, 128.92,
1.97 (s, 3H), 0.16 (s, 9H).
28.89, 126.5, 108.2, 104.6, 97.1, 0.2.
23
Ep oxid e. Colorless oil. [R]
D
3
) +103.7 (c 1.05, CHCl ). IR:
2
3
Ep oxid e. Colorless oil. [R]
D
) +140.1 (c 0.52, CHCl
3
). IR:
-1
1
2
1
1
7
179, 1605 cm
. H NMR δ: 7.4-7.25 (m, 5H), 4.29 (s, 1H),
13
-
1 1
2
1
1
176 cm . H NMR δ: 7.36-7.25 (m, 5H), 4.03 (d, J ) 2.0 Hz,
H), 3.34 (d, J ) 2.0 Hz, 1H), 0.205 (s, 9H). C NMR δ: 135.9,
28.9, 128.8, 125.8, 101.4, 90.0, 60.4, 49.7, -0.11.
.29 (s, 3H), 0.22 (s, 9H). C NMR δ: 134.5, 128.4, 128.2, 126.9,
1
3
05.8, 87.4, 65.2, 53.5, 17.9, 0.01. Anal. Calcd for C14
2.99; H, 7.87. Found: C, 72.88; H, 7.89.
H18OSi: C,
(
R,R)-2-[(ter t-Bu t yld im et h ylsilyl)et h yn yl]-3-p h en ylox-
(
R,R)-3-Bu tyl-2-eth yn yl-2-p r op yloxir a n e (Ta ble 1, en tr y
ir a n e (Ta ble 1, en tr y 10). En yn e. Colorless oil. IR: 2166, 2120
-1
1
1
7). En yn e. Colorless oil. IR: 3309, 2094, 1636 cm . H NMR
-
1 1
cm . H NMR δ: 7.38-7.26 (m, 5H), 6.99 (d, J ) 16.3 Hz, 1H),
δ: 5.96 (t, J ) 7.6 Hz, 1H), 2.74 (s, 1H), 2.11 (t, J ) 7.3 Hz, 2H),
6
1
.18 (d, J ) 16.3 Hz, 1H), 0.98 (s, 9H), 0.16 (s, 6H). 13C NMR δ:
42.5, 136.3, 128.9, 126.5, 108.4, 105.2, 95.4, 26.4, 16.9, -4.37.
2
1
.10 (dt, J ) 7.6, 7.3 Hz, 2H), 1.53 (sextet, J ) 7.3 Hz, 2H), 1.38-
.29 (m, 4H), 0.92 (t, J ) 7.3 Hz, 3H), 0.89 (t, J ) 7.3 Hz, 3H).
2
3
Ep oxid e. Colorless oil. [R]
D
) +147.3 (c 0.75, CHCl
175 cm . H NMR δ: 7.36-7.25 (m, 5H), 4.02 (d, J ) 2.0 Hz,
H), 3.35 (d, J ) 2.0 Hz, 1H), 0.954 (s, 9H), 0.138 (s, 6H). 13
3
). IR:
13
C NMR δ: 140.3, 122.1, 86.3, 74.1, 32.6, 31.5, 28.2, 22.6, 21.6,
-
1 1
2
1
1
4.1, 13.8.
Ep oxid e. Colorless oil. [R]
C
23
D
3
) -3.08 (c 0.91, CHCl ). IR:
NMR δ: 135.9, 128.9, 128.8, 125.8, 102.1, 88.3, 60.4, 49.8, 26.2,
6.7, -4.6. Anal. Calcd for C16 22OSi: C, 74.36; H, 8.58.
Found: C, 74.31; H, 8.45.
R,R)-2-P h en yl-3-(1′-p r op yn yl)oxir a n e (Ta b le 1, en t r y
-1 1
3
1
7
2
307, 2116 cm . H NMR δ: 3.14 (t, J ) 5.6 Hz, 1H), 2.29 (s,
H), 1.70-1.33 (m, 10H), 0.99 (t, J ) 7.0 Hz, 3H), 0.93 (t, J )
1
H
13
.0 Hz, 3H). C NMR δ: 83.9, 70.8, 65.0, 54.5, 33.6, 28.7, 27.8,
(
2.7, 19.1, 14.2, 14.1. Anal. Calcd for C11H18O: C, 79.47; H, 10.91.
-
1 1
1
(
1
1
1). En yn e. Colorless oil. IR: 2216 cm . H NMR δ: 7.37-7.25
Found: C, 79.43; H, 10.75.
m, 5H), 6.86 (d, J ) 16.3 Hz, 1H), 6.13 (dq, J ) 16.3, 2.2 Hz,
(
R ,R )-3-Bu t yl-2-p r op yl-2-(t r im e t h ylsilyle t h yn yl)ox-
H), 2.01 (d, J ) 2.2 Hz, 3H). 13C NMR δ: 140.3, 136.7, 128.9,
-1
ir a n e (Ta ble 1, en tr y 18). En yn e. Colorless oil. IR: 2143 cm
.
28.5, 126.3, 109.0, 88.5, 79.1, 4.75.
Ep oxid e. Colorless oil. [R]
1
H NMR δ: 5.93 (t, J ) 7.5 Hz, 1H), 2.09 (t, J ) 7.3 Hz, 2H),
2
3
D
3
) +154.5 (c 0.8, CHCl ). IR:
2
.08 (dt, J ) 7.5, 7.3 Hz, 2H), 1.53 (qt, J ) 7.5, 7.3 Hz, 2H),
.36-1.26 (m, 4H), 0.92 (t, J ) 7.5 Hz, 3H), 0.89 (t, J ) 7.5 Hz,
-
1 1
2
1
1
243 cm . H NMR δ: 7.37-7.24 (m, 5H), 3.97 (d, J ) 1.7 Hz,
13
1
3
3
H), 3.29 (m, 1H), 1.88 (d, J ) 1.7 Hz, 3H). C NMR δ: 136.1,
13
H), 0.17 (s, 9H). C NMR δ: 139.8, 123.2, 108.0, 90.7, 32.7,
28.7, 128.7, 125.7, 80.9, 75.7, 60.1, 49.9, 3.8. Anal. Calcd for
1.6, 28.2, 22.6, 21.7, 14.1, 13.9, 0.3.
C
11
H
10O: C, 83.51; H, 6.37. Found: C, 83.24; H, 6.40.
23
Ep oxid e. Colorless oil. [R]
D
3
) +7.16 (c 1.41, CHCl ). IR:
(
R,R)-2-P r op yl-3-(tr im eth ylsilyleth yn yl)oxir a n e (Ta ble
-1 1
2
1
9
1
1
169 cm . H NMR δ: 3.12 (t, J ) 5.5 Hz, 1H), 1.66-1.37 (m,
0H), 0.98 (t, J ) 7.0 Hz, 3H), 0.92 (t, J ) 7.0 Hz, 3H), 0.16 (s,
H). C NMR δ:105.5, 87.8, 65.5, 55.0, 33.8, 28.8, 28.0, 22.7,
9.3, 14.3, 14.2, 0.05. Anal. Calcd for C14
0.99. Found: C, 70.44; H, 11.07.
-1 1
1
, en tr y 12). En yn e. Colorless oil. IR: 2176, 2143 cm . H NMR
δ: 6.22 (dt, J ) 15.9, 7.1 Hz, 1H), 5.51 (dt, J ) 15.9, 1.4 Hz,
H), 2.08 (tdd, J ) 7.4, 7.1, 1.4 Hz, 2H), 1.42 (sextet, J ) 7.4
Hz, 2H), 0.91 (t, J ) 7.4 Hz, 3H), 0.184 (s, 9H). C NMR δ: 146.3,
09.9, 104.4, 92.7, 35.3, 22.0, 13.8, 0.19.
13
1
H26OSi: C, 70.52; H,
1
3
1
(
R,R)-3-Bu tyl-2-[(ter t-bu tyld im eth ylsilyl)eth yn yl]-2-p r o-
2
3
Ep oxid e. Colorless oil. [R]
D
) +3.9 (c 0.75, CHCl
3
). IR: 2180
p yloxir a n e (Ta ble 1, en tr y 19). En yn e. Colorless oil. IR: 2141
-
1 1
cm . H NMR δ: 3.12-3.08 (m, 2H), 1.57-1.46 (m, 4H), 0.97
-1
1
cm . H NMR δ: 5.93 (t, J ) 7.4 Hz, 1H), 2.10 (t, J ) 7.4 Hz,
1
3
(
4
t, J ) 7.2 Hz, 3H), 0.18 (s, 9H). C NMR δ: 102.2, 89.3, 60.8,
5.6, 33.9, 19.2, 14.0, -0.10. Anal. Calcd for C10 18OSi: C, 65.87;
H, 9.95. Found: C, 65.69; H, 10.01.
R,R)-2-[(ter t-Bu t yld im et h ylsilyl)et h yn yl]-3-p r op ylox-
ir a n e (Ta ble 1, en tr y 13). En yn e. Colorless oil. IR: 2175, 2142
2
1
(
1
-
H), 2.07 (q, J ) 7.4 Hz, 2H), 1.54 (tq, J ) 7.4, 7.2 Hz, 2H),
H
.37-1.26 (m, 4H), 0.94 (s, 9H), 0.92 (t, J ) 7.2 Hz, 3H), 0.88
13
td, J ) 7.2, 2.4 Hz, 3H), 0.11 (s, 6H). C NMR δ: 139.6, 123.3,
(
08.7, 88.9, 32.8, 31.7, 28.3, 26.4, 22.7, 21.8, 17.0, 14.2, 13.9,
4.2.
-
1 1
cm . H NMR δ: 6.22 (dt, J ) 15.9, 7.2 Hz, 1H), 5.51 (dt, J )
23
Ep oxid e. Colorless oil. [R]
D
) +16.7 (c 0.6, EtOH). IR: 2168
1
5.9, 1.2 Hz, 1H), 2.09 (qd, J ) 7.2, 1.2 Hz, 2H), 1.43 (sextet, J
-1 1
cm . H NMR δ: 3.12 (t, J ) 5.5 Hz, 1H), 1.69-1.33 (m, 10H),
)
6
1
7.2 Hz, 2H), 0.95 (s, 9H), 0.92 (t, J ) 7.2 Hz, 3H), 0.12 (s,
13
0
0
2
.96 (t, J ) 7.0 Hz, 3H), 0.931 (s, 9H), 0.92 (t, J ) 7.2 Hz, 3H),
H). C NMR δ: 146.1, 110.1, 105.0, 90.9, 35.4, 26.3, 22.1, 16.9,
3.9, -4.33.
13
.10 (s, 6H). C NMR δ: 106.2, 86.1, 65.4, 55.0, 33.8, 28.8, 28.0,
6.2, 26.2, 22.8, 19.3, 16.7, 14.2, -4.5. Anal. Calcd for C17
32
H -
2
3
Ep oxid e. Colorless oil. [R]
D
) +4.2 (c 1.1, CHCl
3
). IR: 2178
OSi: C, 72.79; H, 11.50. Found: C, 72.71; H, 11.67.
-
1 1
cm . H NMR δ: 3.09-3.06 (m, 2H), 1.60-1.44 (m, 4H), 0.97
1
3
(
8
t, J ) 6.9 Hz, 3H), 0.93 (s, 9H), 0.11 (s, 6H). C NMR δ: 103.0,
7.4, 60.8, 45.6, 33.9, 26.2, 19.2, 16.6, 14.0, -4.6. Anal. Calcd
for C13 24OSi: C, 69.57; H, 10.78. Found: C, 69.70; H, 10.76.
R,R)-2-(3′-Meth oxy-1′-p r op yn yl)-3-p r op yloxir a n e (Ta ble
Ack n ow led gm en t. We are grateful to the generous
financial support from the General Medical Sciences of
the National Institutes of Health (GM59705-01), the
Beckman Young Investigator Award Program, the
H
(
-1 1
1
, en tr y 14). En yn e. Colorless oil. IR: 2213, 1634 cm . H NMR

7
650 J . Org. Chem., Vol. 64, No. 20, 1999
Notes
Camille and Henry Dreyfus New Faculty Award Pro-
gram, DuPont Yound Faculty Award Program, Alfred
P. Sloan Foundation, and Colorado State University.
excess of the epoxides along with the preparation of the enyne
substrates and the authentic epoxides for the determination
of absolute configurations. This material is available free of
charge via the Internet at http://pubs.acs.org.
Su p p or tin g In for m a tion Ava ila ble: NMR spectral, GC,
and HPLC data for the determination of the enantiomeric
J O9907639