Organotin iodide hydride: Chemoselective 1,4-hydrostannations of conjugated enones in the presence of aldehydes and subsequent intermolecular aldol reactions

Full text of DOI:10.1021/jo951500r

3
76
J . Org. Chem. 1996, 61, 376-379
Or ga n otin Iod id e Hyd r id e: Ch em oselective
,4-Hyd r osta n n a tion s of Con ju ga ted
En on es in th e P r esen ce of Ald eh yd es a n d
Su bsequ en t In ter m olecu la r Ald ol Rea ction s
conjugated enones could be accomplished in preference
to the reduction of aldehydes, the subsequent aldol
reaction of the resulting metal enolates could be expected.
Organotin hydrides appear to be good candidates for this.
They appear to act as soft Lewis acids leading to 1,4-
addition,7 and the resulting tin enolates can be expected
1
,8
Takayo Kawakami, Masato Miyatake,
Ikuya Shibata, and Akio Baba*
9
to show pronounced reactivity toward aldehydes. Quite
recently, Enholm and co-workers have reported the
Department of Applied Chemistry, Faculty of Engineering,
Osaka University, 2-1 Yamadaoka, Suita, Osaka 565, J apan
3
selective 1,4-hydrostannation of cyclic enones by Bu SnH
under free radical conditions and a subsequent intramo-
lecular aldol reaction.10 In this paper, we demonstrate
Received August 14, 1995
that Bu SnIH reagents accomplish the selective 1,4-
2
reduction of conjugated enones 1, irrespective of coexist-
ent aldehydes, and a subsequent diastereoselective in-
termolecular aldol reaction.
The 1,2- and 1,4- regiochemistry of the reduction of
conjugated enones has been intensively investigated with
a variety of reductants.1 Recently, efforts have been
Tin iodide hydride reagents can be prepared by the two
directed toward chemoselective reductions of conjugated
enones with tolerance by susceptible functional groups.
As exhibited in the reductions with NaBH , a general
4
methods shown in eq 1, to obtain pure Bu
2
SnIH (reagent
SnIH and Bu SnI
reagent B).12 The former (1 mmol) was synthesized by
mixing Bu SnH (0.5 mmol) and Bu SnI (0.5 mmol) at
room temperature in THF (1 mL). The latter (1 mmol)
was prepared by mixing Bu SnH (1 mmol) and Bu SnI
(1 mmol) at room temperature in THF (1 mL). The
complete formation of the Bu SnIH species was spectro-
1
1
A) or an equimolar mixture of Bu
2
3
(
order of reactivity among carbonyl groups is conjugated
enones < ketones < conjugated enals < aldehydes.2,3 Not
2
2
2
2
in keeping with this general reactivity order of aldehydes
3
2
2
and conjugated enones, it is notable that the Luche
4
reagent (NaBH
4
/LnCl
3
), even in the presence of alde-
2
13
hydes, can reduce conjugated enones to furnish allylic
1
119
alcohols in 1,2-fashion.5 No selective 1,4-reduction of
scopically confirmed by H, C, and Sn NMR.
conjugated enones in the presence of aldehydes has been
demonstrated, to our knowledge, although reductions by
copper hydride tolerate the presence of ketone moieties
in the same substrate.6 If the 1,4-hydrometalation of
(
1) The selective 1,2-reduction of conjugated enones has been carried
a,b
c-f
out by aluminum hydrides such as LiAlH
boron hydrides such as 9-BBN-H and NaBH . On the other hand,
4
and DIBAL-H,
and
The selective 1,4-reduction of conjugated enone 1a took
place with either of these reagents (entries 1 and 2 in
Table 1). Moreover, good enhancement of yield was
achieved with reagent B, possibly because of the as-
g,h
i,j
4
the selective 1,4-reductions have been accomplished by silicon
k-n
o-r
s-v
hydrides,
copper hydrides,
iron hydrides,
and organoborohy-
w,x
drides such as L- and K-Selectride. (a) Hudlicky, M. Reductions in
Organic Chemistry; J ohn Wiley & Sons, Inc.: New York, 1984; pp 119-
sistance of a soft Lewis acid, Bu
1, these results are in sharp contrast with the original
tin hydrides, Bu SnH and Bu SnH. The former showed
SnI.13 As shown in Table
3
1
1
21. (b) Balachander, N.; Wang, S. S.; Sukenik, N. Tetrahedron Lett.
986, 27, 4849-4852. (c) Wilson, K. E.; Seidner, R. T.; Masamune, S.
J . Chem. Soc., Chem. Commun. 1970, 213-214. (d) Ashby, E. C.; Lin,
J . J . Tetrahedron Lett. 1976, 3865-3868. (e) Antus, S.; Gottsegen, A.;
N o´ gradi, M. Synthesis 1981, 574-576. (f) Zoretic, P.; Golen, J . A. J .
Org. Chem. 1981, 46, 3555-3558. (g) Krishnamurthy, S.; Brown, H.
C. J . Org. Chem. 1975, 40, 1864-1865. (h) Krishnamurthy, S.; Brown,
H. C. J . Org. Chem. 1977, 42, 1197-1201. (i) J ohnson, M. R.; Rickborn,
B. J . Org. Chem. 1970, 35, 1041-1045. (j) Komiya, S.; Tsutsumi, O.
Bull. Chem. Soc. J pn. 1987, 60, 3423-3424. (k) Ojima, I.; Nihonyanagi,
M.; Kogure, T.; Kumagai, M.; Horiuchi, S.; Nakatsugawa, K. J .
Organomet. Chem. 1975, 94, 449-461. (l) Keinan, E.; Greenspoon, N.
Tetrahedron Lett. 1985, 26, 1353-1356. (m) Keinan, E.; Greenspoon,
N. J . Am. Chem. Soc. 1986, 108, 7314-7325. (n) Schmidt, T. Tetra-
hedron Lett. 1994, 35, 3513-3516. (o) Boeckman, J . R. K.; Michalak,
R. J . Am. Chem. Soc. 1974, 96, 1623-1625. (p) Semmelhack, M. F.;
Stauffer, R. D. J . Org. Chem. 1975, 40, 3619-3621. (q) Semmelhack,
M. F.; Stauffer, R. D.; Yamashita, A. J . Org. Chem. 1977, 42, 3180-
2
2
3
a lack of regioselectivity (entry 4), and the latter had poor
reducing ability toward 1a (entry 5). Other dibutyltin
halide hydrides prepared in a manner similar to reagent
B also effected the selective 1,4-reduction (entries 6 and
7
), although the corresponding fluoride reagent predomi-
nantly promoted 1,2-reduction to furnish the allylic
alcohol 3a in 36% yield (entry 8). When 1,4-dinitroben-
zene (DNB) was added as a radical scavenger, little effect
on the 1,4-reduction of 1a was observed (entry 3). This
suggests that 1,4-hydrostannation by organotin iodide
hydride proceeds by an ionic reaction path.
Table 2 lists the reductions of conjugated enones 1b-e
with reagent B in THF at ambient temperature. All runs
demonstrated complete 1,4-selectivity to provide the
3
188. (r) Tsuda, T.; Fujii, T.; Kawasaki, K. Saegusa, T. J . Chem. Soc.,
Chem. Commun. 1980, 1013-1014. (s) Noyori, R.; Umeda, I.; Ishigami,
T. J . Org. Chem. 1972, 37, 1542-1545. (t) Collman, J . P.; Finke, R.
G.; Matlock, P. L.; Wahren, R.; Brauman, J . I. J . Am. Chem. Soc. 1970,
9
8, 4685-4687. (u) Collman, J . P.; Finke, R. G.; Matlock, P. L.; Wahren,
R.; Komoto, R. G.; Brauman, J . I. J . Am. Chem. Soc. 1978, 100, 1119-
1
1
140. (v) Boldrini, G. P.; Umani-Ronchi, A. J . Organomet. Chem. 1979,
71, 85-88. (w) Ganem, B. J . Org. Chem. 1975, 40, 146-147. (x)
(7) For example: Lefout, J . M. Tetrahedron 1978, 34, 2597-2605.
(8) The palladium-catalyzed tributyltin hydride reduction of conju-
gated carbonyl compounds provided saturated ketones. (a) Keinan, E.;
Gleize, P. A. Tetrahedron Lett. 1982, 23, 477-480. (b) Four, P.; Guibe,
F. Tetrahedron Lett. 1982, 23, 1825-1828.
Fortunato, J . M.; Ganem, B. J . Org. Chem. 1976, 41, 2194-2200.
(
2) (a) Adams, C. Synth. Commun. 1984, 14, 1349-1353. (b) Ward,
D. E.; Rhee, C. K. Can. J . Chem. 1989, 67, 1206-1211.
3) Zn(BH
cannot reduce conjugated enones but conjugated enals
and ketones: Sarkar, D. C.; Das, A. R.; Ranu, B. C. J . Org. Chem.
990, 55, 5799-5801.
4) (a) Luche, J . L. J . Am. Chem. Soc. 1978, 100, 2226-2227. (b)
(
4
)
2
(9) (a) Stille, J . K.; Shenvi, S. Tetrahedron Lett. 1982, 23, 627-630.
(b) Kobayashi, K.; Kawanisi, M.; Hitomi, T.; Kozima, S. Chem. Lett.
1983, 851-854.
1
(
(10) Enholm, E. J .; Xie, Y.; Abbound, A. J . Org. Chem. 1995, 60,
1112-1113.
Luche, J . L.; Rodriguez-Hahn, L.; Crabb e´ , P. J . Chem. Soc., Chem.
Commun. 1978, 601-602. (c) Luche, J . L.; Gemal, A. L. J . Am. Chem.
Soc. 1979, 101, 5848-5849. (d) Gemal, A. L.; Luche, J . L. J . Am. Chem.
Soc. 1981, 103, 5454-5459.
(11) (a) Neumann, W. P.; Pedain, J . Tetrahedron Lett. 1964, 2461-
2465. (b) Sawyer, A. K.; Brown, J . E.; Hanson, E. L. J . Organomet.
Chem. 1965, 3, 464-471.
(
(
5) Gemal, A. L.; Luche, J . L. J . Org. Chem. 1979, 44, 4187-4189.
(12) Sawyer, A. K.; Brown, J . E. J . Organomet. Chem. 1966, 5, 438-
445.
6) (a) Tsuda, T.; Hayashi, T.; Satomi, H.; Kawamoto, T.; Saegusa,
T. J . Org. Chem. 1986, 51, 537-540. (b) Lipshuts, B. H.; Ung, C. S.;
Sengupta, S. Synlett 1970, 64-66.
(13) In the reaction with Bu
3 3 4
SnH/Pd(PPh ) , the yield increased
using ZnCl as the coactivating Lewis acid catalyst.
8b
2
0
022-3263/96/1961-0376$12.00/0 © 1996 American Chemical Society

Notes
J . Org. Chem., Vol. 61, No. 1, 1996 377
Ta ble 1. Red u ction s of Ch a lcon e 1a by Va r iou s Tin
Hyd r id es
Ta ble 4. In ter m olecu la r Ald ol Rea ction s of Con ju ga ted
a
En on es 1 w ith Ald eh yd es 4 by Usin g Rea gen t B
yield, %
entry enone 1 aldehyde 4
conditions
rt, 2 h
yield, % syn:antib
entry
“Sn-H”
Reagent Aa
Reagent B
Reagent B- DNB
Bu2SnH2
2a
3a
1
2
3
4
5
6
7
1a
1a
1b
1d
1d
1d
1d
4a
4a
4a
4a
4a
4b
4c
6, 68
6, 47
7, 53
8, 74
8, 55
9, 74
38:62
80:20
91:9
89:11
90:10
>99:1
92:8
1
2
3
4
5
6
7
8
69
91
77
18
19
53
86
5
0
0
0
45
0
0
-30 °C f rt, 3 h
-30 °C f rt, 3 h
-30 °C f rt, 3 h
-30 °C f rt, 3 h
-30 °C f rt, 3 h
b
b,c
c
Bu3SnH
b
Bu2SnBrH-Bu3SnBr
-30 °C f rt, 3 h 10, 67
b
Bu2SnClH-Bu3SnCl
0
36
b
a
Bu2SnFH-Bu3SnF
3 2 2
Enone 1 1 mmol, aldehyde 4 1 mmol, Bu SnH 1 mmol, Bu SnI
mmol, THF 1 mL. b Determined by 400 MHz 1H NMR. 1d 1
c
1
a
Chalcone 1a 1 mmol, Bu2SnH2 0.5 mmol, Bu2SnI2 0.5 mmol,
THF 1 mL. Chalcone 1a 1 mmol, Bu3SnH 1 mmol, Bu2SnX2 1
mmol, 4a 1 mmol, Bu2SnH2 0.5 mmol, Bu2SnI2 0.5 mmol, THF 1
mL.
b
c
mmol, THF 1 mL. DNB 0.1 mmol.
Ta ble 2. Red u ction s of Va r iou s Con ju ga ted En on es by
enolate had been expected to be quenched. In contrast,
Bu
3
SnH reduced aldehyde 4a to 5a in 80% yield (eq 2).
a
Rea gen t B
entry
R1
R2
1
conditions
yield %
1
2
3
4
Ph
Me
Ph
Me
Ph
H
1b
1c
1d
1e
rt, 2 h
rt, 2.5 h
rt, 1 h
rt, 2 h
2b, 72
2c, 67
2d , 63
cis-cyclohexenone
2e, 42 (4)b
a
Enone 1 1 mmol, Bu3SnH 1 mmol, Bu2SnI2 1 mmol, THF 1
mL. b Cyclohexanol.
These results suggested that reagent B would be a good
candidate for an intermolecular aldol reaction by the tin
enolate (C), as illustrated in eq 3. As expected, when a
Ta ble 3. Red u ction s of Ald eh yd es 4 by Va r iou s Tin
a
Hyd r id es
2 2 3
mixture of 1a and 4a was treated with Bu SnI and Bu -
SnH in THF at ambient temperature, aldol product 6 was
obtained in 68% yield (entry 1 in Table 4). However, the
entry
aldehyde 4
“Sn-H”
yield of 5, %
3
1
2
3
4
5
6
R ) Ph
(4a )
(4a )
(4a )
(4a )
(4b)
(4c)
Reagent A
Reagent B
Bu3SnH
Bu2SnH2
Reagent B
Reagent B
5a , 5
5a , 6
5a , 93
5a , 100
5b, 31
5c, 17
3
R ) Ph
3
R ) Ph
3
R ) Ph
3
R ) c-hex
3
R ) i-Pr
a
Aldehyde 4 1 mmol, SnH reagent 1 mmol, MeOH 1 mL.
corresponding ketones 2b-e; no allylic alcohols arising
from 1,2-reduction were detected. In the case of cyclo-
hexenone 1e (entry 4), 4% of cyclohexanol was formed,
plausibly generated by further reduction of the 1,4-
reduction product.
Next we examined the reduction of aldehydes by these
tin reagents. As shown in Table 3, the reagents A and
B showed quite low reducing ability (entries 1 and 2),
diastereoselectivity obtained at ambient temperature was
not satisfactory (syn:anti ) 38:62). The striking depen-
dency of the diastereoselectivity on reaction temperature
is indicated in entries 1 and 2 (Table 4). Excellent syn-
selectivity was observed at -30 °C f rt (entry 2). This
3 2 2
while either Bu SnH or Bu SnH readily reduced ben-
zaldehyde 4a to benzyl alcohol 5a (entries 3 and 4).
Reagent B also exhibited poor reactivity toward cyclo-
hexanecarboxaldehyde 4b and isobutyraldehyde 4c (en-
tries 5 and 6).
This interesting outcome prompted us to try a competi-
tive reduction of a conjugated enone and an aldehyde.
When an equimolar mixture of 1b (1 mmol) and benzal-
dehyde 4a (1 mmol) was treated with reagent B in MeOH
3
diastereoselectivity is not due to the Lewis acid, Bu SnI
in reagent B, because the alternative use of reagent A
also gave 8 with high syn-selectivity (entry 5).1 It can
be presumed that a (Z)-enolate is generated by the 1,4-
4
1
5
hydrostannation of 1d when in an s-cis conformation
and that the resulting (Z)-enolate gives the syn aldol
(14) It has been reported that the reaction of tributylstannyl enolate,
(
1 mL) at ambient temperature, the selective 1,4-reduc-
tion of 1b produced ketone 2b in 61% yield without any
,2-reduction, while benzyl alcohol 5a was furnished in
analogous to the tin enolate C arising from 1,4-hydrostannation of 1c,
9
with 4a gave moderate anti-selectivity at low temperature.
(15) (a) Boldrini, G. P.; Mancini, F.; Tagliavini, E.; Trombini, C.;
1
Ronchi, A. U. J . Chem. Soc., Chem. Commun. 1990, 1680-1681. (b)
Boldrini, G. P.; Bortolotti, M.; Mancini, F.; Tagliavini, E.; Trombini,
C.; Ronchi, A. U. J . Org. Chem. 1991, 56, 5820-5826.
only 9% yield (eq 2). Surprisingly, the aldol product 7
was also obtained in spite of the MeOH solventsthe tin

3
78 J . Org. Chem., Vol. 61, No. 1, 1996
Notes
product under conditions of kinetic control.16 The enones
Hz), 6.38 (dd, 1H, J ) 16.11 and 6.35 Hz), 6.68 (d, 1H, J ) 16.11
1
3
3
Hz), 7.20-7.44 (m, 10H); C NMR (CDCl ) δ 75.1, 126.3, 126.6,
1
b and 1d also provided the aldol products 7 and 8,
1
27.8, 127.8, 128.5, 128.6, 130.5, 131.5, 136.5, 142.8; HRMS calcd
respectively, with high syn-selectivities (entries 3 and 4).
Moreover, cyclohexanecarboxaldehyde 4b and isobutyral-
dehyde 4c behaved similarly (entries 6 and 7).
for C15 14O 210.1045, found 210.1038.
H
Butyrophenone (2b) [495-40-9], 4-phenyl-2-butanone (2c)
2550-26-7], propiophenone (2d ) [93-55-0], cyclohexanone (2e)
[
In conclusion, Bu
2
SnIH reagents selectively reduce
[108-94-1], cyclohexanol [108-93-0] were identified in comparison
with commercially available samples.18
conjugated enones 1 in the presence of aldehydes at
ambient temperature. In addition, a subsequent aldol
reaction proceeds with syn-selectivity at -30 °C. Further
work on related systems including the characterization
of the tin enolates C is underway.
P r eced u r e for t h e Com p et it ive R ea ct ion b et w een
En on es a n d Ald eh yd es. To the solution of Bu
in 1 mL of MeOH were added 1b (1 mmol) and 4a (1 mmol).
Bu SnH (1 mmol) was added, and the solution was stirred for 2
2 2
SnI (1 mmol)
3
h. After quenching with MeOH (5 mL), volatiles were removed
under reduced pressure. The residue was subjected to column
chromatography, eluting with hexane-EtOAc (9:1) to give
mainly ketone 2b (61%); benzyl alcohol 5a (9%) and aldol product
7 (8%) were also detected.
Exp er im en ta l Section
An a lysis. 1H, 13C, and 119Sn NMR spectra were recorded at
1
13
4
00, 100, and 149 MHz, respectively. Samples for H and
NMR spectra of produced ketones and aldols were examined in
deuteriochloroform (CDCl ) containing 0.03% (w/v) of tetra-
C
Rep r esen ta tive P r eced u r e for th e Ald ol-Typ e Rea ction .
To the solution of Bu SnI (1 mmol) in 1 mL of THF were added
2
2
3
conjugated enone 1 (1 mmol) and aldehyde 4 (1 mmol). Bu3-
SnH (1 mmol) was added at -30 °C, and the solution was stirred
for 3 h with warming to room temperature. After quenching
with MeOH (5 mL), volatiles were removed under reduced
pressure. The residue was subjected to column chromatography
eluting with hexane-EtOAc (1:2) to give the corresponding
products 6-10. Further purification was performed by TLC
eluting with hexane-EtOAc (1:1).
1
13
119
methylsilane. Samples for H, C, and
tin hydrides were examined in tetrahydrofuran-d
Sn NMR spectra of
containing
8
tetramethyltin. GLC analyses were performed using FFAP and
OV-1 (2-m x 3-mm) columns. Column chromatography was
performed by using Wakogel C-200 mesh silica gel. Preparative
TLC was carried out on Wakogel B-5F silica gel. Yields were
1
determined by H NMR or GLC using internal standards.
Ma ter ia ls. Tributyltin hydride (Bu
dihydride (Bu SnH ) were, respectively, prepared by the reduc-
tion of tributyltin chloride (Bu SnCl) and dibutyltin dichloride
THF and toluene were freshly
3
SnH) and dibutyltin
syn - a n d a n ti-2-Ben zyl-1,3-d ip h en yl-3-h yd r oxyp r op a n -
2
2
1
-on e (6): colorless liquid, purified by TLC with hexane-EtOAc
-1
1
3
(1:1): IR (neat) 3400 and 1658 cm
;
H NMR (CDCl
3
) syn δ
1
7
2 2 4
(Bu SnCl ) with LiAlH .
3
.07 (dd, 1H, J ) 3.90 and 13.67 Hz), 3.18 (dd, 1H, J ) 10.74
distilled over sodium benzophenone ketyl. All reactions were
carried out under dry nitrogen.
P r ep a r a tion of Or ga n otin Iod id e Hyd r id es. Reagent A
and 13.67 Hz), 3.35 (d, 1H, J ) 1.47 Hz), 4.00-4.07 (m, 1H),
13
5
.08 (d, 1H, J ) 4.39 Hz), 6.93-7.95 (m, 15H); C NMR (CDCl
syn δ 33.5, 55.6, 74.0, 126.0, 126.2, 127.6, 128.1, 128.2, 128.2,
128.3, 128.9, 133.0, 137.3, 139.3, 141.6, 205.5; H NMR (CDCl3)
3
)
(
1 mmol) was synthesized by mixing Bu
Bu SnI (0.5 mmol) in THF. Reagent B (1 mmol) was preparated
by mixing Bu SnH (1 mmol) and Bu SnI (1 mmol) in THF. We
2
SnH
2
(0.5 mmol) and
1
2
2
a n ti δ 2.87 (dd, 1H, J ) 6.35 and 13.68 Hz), 3.03 (dd, 1H, J )
8.79 and 13.68 Hz), 3.52 (d, 1H, J ) 6.84 Hz), 4.07-4.12 (m,
1H), 4.95 (dd, 1H, J ) 5.86 and 6.84 Hz), 6.94-7.94 (m, 15H);
3
2
2
spectrocopically confirmed that these reagents were immediately
formed even at -50 °C.
13C NMR (CDCl ) a n ti δ 36.6, 54.7, 75.4, 126.1, 126.3, 127.7,
3
Rea gen t A (8.00 M in THF-d
8
): 1H NMR (rt) δ 6.41 (Sn-H,
128.1, 128.3, 128.4, 128.4, 128.9, 133.0, 138.0, 138.5, 142.6, 204.7.
1J ( Sn- H) ) 2060 Hz, J ( Sn- H) ) 1968 Hz); C NMR
119
1
1
117
1
13
1
13
H and C NMR data of syn-6 were consistent with the ones
1
119
13
1
117
13
(
rt) δ 14.1, 17.3 ( J ( Sn- C
R
) ) 408 Hz, J ( Sn- C
R
) ) 390
reported previously: Boldrini, G. P.; Bortolotti, M.; Mancini, G.;
Tagliavini, E.; Trombini, C.; Umani-Ronchi, A. J . Org. Chem.
3
13
2
13
Hz), 26.7 ( J (Sn- C ) ) 74 Hz), 29.7 ( J (Sn- C ) ) 29 Hz);
γ
â
1
19
Sn NMR (rt) δ -76.3 (d).
Rea gen t B (8.00 M in THF-d
1
991, 56, 5820-5826. Registry No. syn-6, 132455-70-0; anti-6,
1
18
8
): H NMR (rt) Bu
2
Sn IH δ
135414-46-9.
1
119
1
1
117
1
6
.37 (Sn-H, J ( Sn- H) ) 2046 Hz, J ( Sn- H) ) 1955 Hz);
1 119 13
syn - a n d a n ti-1,3-Dip h en yl-2-eth yl-3-h yd r oxyp r op a n -1-
on e (7): colorless liquid, purified by TLC with hexane-EtOAc
1
1
3
3
C NMR (rt) Bu
2
Sn IH δ 14.2, 17.2 ( J ( Sn- C
R
) ) 404 Hz,
) ) 74 Hz,
) ) 29 Hz); Bu Sn I δ
) ) 311 Hz),
) ) 63 Hz), 29.8
Sn IH δ -76.3 (d);
117
13
3
119
13
J ( Sn- C
R
) ) 387 Hz), 26.8 ( J ( Sn- C
γ
-1
(
2
)
(
18 2
1:1); IR (neat) 3250 and 1640 cm ; HRMS calcd for C17H O
117
13
2
13
J ( Sn- C
γ
) ) 70 Hz), 29.8 ( J (Sn- C
â
3
1
54.1307, found 254.1304; H NMR (CDCl
3
) syn δ 0.77 (t, 3H, J
1
119
13
1
117
13
1
2
(
R R
4.2, 17.4 ( J ( Sn- C ) ) 325 Hz, J ( Sn- C
3 119 13 3 117 13
7.57 Hz), 1.72-1.99 (m, 2H), 3.39 (br, 1H), 3.74 (m, 1H), 5.37
7.2 ( J ( Sn- C
γ
) ) 66 Hz, J ( Sn- C
γ
13
d, 1H, J ) 4.88 Hz), 7.16-7.86 (m, 10H); C NMR (CDCl
3
) syn
2
13
119
J (Sn- C
Sn I δ 80.5 (s).
Rep r esen ta tive P r eced u r e for th e 1,4-Selective Red u c-
tion of En on es. To the solution of Bu SnI (1 mmol) in 1 mL
of THF was added Bu SnH (1 mmol). The mixture was stirred
â
) ) 24 Hz); Sn NMR (rt) Bu
2
δ 12.0, 20.6, 54.2, 73.8, 126.1, 127.3, 127.7, 128.1, 128.2, 128.5,
Bu
3
37.4, 142.1, 205.0; 1H NMR (CDCl
1
7
(
3
) a n ti δ 0.78 (t, 3H, J )
.33 Hz), 1.46-1.75 (m, 2H), 3.29 (br, 1H), 3.76 (m, 1H), 4.99
13
2
2
3
d, 1H, J ) 7.33 Hz), 7.16-7.92 (m, 10H); C NMR (CDCl ) a n ti
3
δ 11.5, 23.6, 54.3, 75.6, 126.3, 127.7, 128.2, 128.3, 128.5, 133.1,
at rt for 10 min. Conjugated enone 1a (1 mmol) was added, and
the solution was stirred until the Sn-H absorption disappeared
in the IR spectra. After quenching the reaction with MeOH (5
mL), volatiles were removed under reduced pressure. The
residue was subjected to column chromatography eluting with
hexane-EtOAc (9:1) to give the product 2a . Further purification
was performed by TLC eluting with hexane-EtOAc (10:1).
1
38.2, 142.7, 205.6.
syn - a n d a n ti-1,3-Dip h en yl-3-h yd r oxy-2-m eth ylp r op a n -
1
-on e (8): colorless liquid, purified by TLC with hexane-EtOAc
-1
16 2
(1:1); IR (neat) 3000 and 1705 cm ; HRMS calcd for C16H O
1
2
3
40.1151, found 240.1148; H NMR (CDCl ) syn δ 1.12 (d, 3H,
J ) 7.33 Hz), 3.63 (qd, 1H, J ) 7.33 and 2.93 Hz), 5.17 (d, 1H,
J ) 2.93 Hz), 7.25-7.95 (m, 10H); C NMR (CDCl
4
2
4
13
3
) syn δ 11.1,
1
,3-Dip h en ylp r op a n on e (2a ): white solid; mp 68.7-70.3 °C;
7.0, 73.1, 126.0, 127.3, 128.2, 128.5, 128.8, 133.6, 135.6, 141.8,
-
1 1
IR (KBr) 1665 cm ; H NMR (CDCl
Hz), 3.30 (t, 2H, J ) 7.32 Hz), 7.18-7.97 (m, 10H); C NMR
CDCl ) δ 30.1, 40.4, 126.1, 128.0, 128.4, 128.5, 128.6, 133.0,
36.8, 141.3, 199.2; HRMS calcd for C15 14O 210.1045, found
10.1024.
,3-Dip h en yl-2-p r op en ol (3a ): colorless liquid, purified by
3
) δ 3.07 (t, 2H, J ) 7.32
1
05.8; H NMR (CDCl ) a n ti δ 1.00 (d, 3H, J ) 7.32 Hz), 3.88-
3
1
3
.07 (m, 1H), 4.93 (d, 1H, J ) 7.81 Hz), 7.25-7.99 (m, 10H).
H NMR data of syn- and anti-8 were consistent with the ones
(
1
2
3
1
H
reported previously; Noyori, R.; Nishida, I.; Sakata, J . J . Am.
Chem. Soc. 1983, 105, 1598-1608. Registry No. syn-8, 71908-
1
18
0
3-7; anti-8, 71908-02-6.
-
1 1
TLC eluting with hexane-EtOAc (4:1); IR (neat) 3200 cm ; H
NMR (CDCl ) δ 2.12 (br, 1H), 5.37 (dd, 1H, J ) 6.35 and 2.44
syn -3-Cycloh exyl-3-h yd r oxy-2-m eth yl-1-p h en ylp r op a n -
-on e (9): colorless liquid, purified by TLC with hexane-EtOAc
3
1
-
1
22 2
(1:1); IR (neat) 3200 and 1630 cm ; HRMS calcd for C16H O
1
(
16) For example: Evans, D. A.; Nelson, J . V. J . Am. Chem. Soc.
979, 101, 6120-6123.
17) (a) Finholt, A. E.; Bond, A. C., J r.; Wilzbach, K. E.; Schlesinger,
246.1621, found 246.1623; H NMR (CDCl3) syn δ 0.88-1.79
1
(m, 10H), 1.24 (d, 3H, J ) 6.84 Hz), 2.06-2.15 (m, 1H), 3.10 (br,
(
H. I. J . Am. Chem. Soc. 1947, 69, 2692-2696. (b) Kerk, G. J . M.; Noltes,
J . G.; Luijiten, J . G. A. J . Appl. Chem. 1957, 7, 366-369.
(18) Registry numbers are provide by the author.

Notes
H), 3.64-3.71 (m, 2H), 7.26-7.97 (m, 5H); 13C NMR (CDCl
J . Org. Chem., Vol. 61, No. 1, 1996 379
1
3
)
Scientists and the Grant-in Aid for Scientific Re-
search on Priority Area of Reactive Organometallics
NO.05236102 from Ministry of Education, Science and
Culture. Thanks are due to Mrs. Y. Miyaji and Mr. H.
Moriguchi, Faculty of Engineering, Osaka University,
for assistance in obtaining NMR and HRMS spectra.
syn δ 10.5, 25.8, 26.1, 26.3, 29.2, 29.4, 40.2, 41.3, 75.4, 128.4,
1
28.8, 133.4, 135.9, 205.9.
syn - a n d a n ti-3-Isop r op yl-3-h yd r oxy-2-m eth yl-1-p h en yl-
p r op a n -1-on e (10): colorless liquid, purified by TLC with
-1
hexane-EtOAc (1:1); IR (neat) 3350 and 1640 cm ; HRMS calcd
1
for C13
0
18 2 3
H O 206.1307, found 206.1301; H NMR (CDCl ) syn δ
.96 (d, 3H, J ) 6.35 Hz), 1.03 (d, 3H, J ) 6.35 Hz), 1.25 (d, 3H,
J ) 6.83 Hz), 1.74-1.83 (m, 1H), 3.15 (d, 1H, J ) 2.44 Hz), 3.62-
3
1
.71 (m, 2H), 7.45-7.98 (m, 5H); 13C NMR (CDCl
8.9, 19.1, 30.7, 41.9, 76.6, 128.4, 128.7, 133.3, 135.9, 205.7; H
) a n ti δ 0.94 (d, 3H, J ) 6.84 Hz), 1.00 (d, 3H, J )
.84 Hz), 1.27 (d, 3H, J ) 6.84 Hz), 1.74-1.85 (m, 1H), 1.89 (br,
H), 2.97-3.00 (m, 1H), 3.56-3.62 (m, 1H), 7.45-7.98 (m, 5H);
3
) syn δ 10.8,
1
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
1
13
NMR (CDCl
3
cedures and H and C NMR and HRMS spectral data for the
products 2a , 3a , 6-10 (21 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.
6
1
1
3
3
C NMR (CDCl ) a n ti δ 15.9, 16.9, 19.9, 31.2, 42.4, 79.1, 128.5,
1
28.7, 132.8, 136.7, 206.2.
Ack n ow led gm en t. This work was supported finan-
cially by the J SPS Fellowships for J apanese J unior
J O951500R