720 J. Am. Chem. Soc., Vol. 120, No. 4, 1998
Yasuda et al.
Chemoselective Reaction of Tin Enolate between Halides and
Carbonyls. A mixture of a tin enolate 1 (1.2 mmol) and an additive
(1.8 mmol) in a dry solvent (1 mL) was stirred for 10 min under
nitrogen. To this solution was added a mixture of halide 2 (1.0 mmol)
and carbonyls (1.0 mmol), and the resulting solution was stirred under
the reaction conditions noted in Tables 3-5. After workup of the reac-
tion mixture as above, ratios of 3 to 7 were determined by 1H NMR or
GLC.
Preparation and Measurement of NMR Samples. The samples
were prepared from tin enolate 1c (0.4 mmol) and an additive in dry
C6D6 (0.4 mL). 119Sn NMR spectra were recorded at room temperature
on a JEOL JNM-GSX-400 (149 MHz) with Me4Sn as internal standard.
Spectral Data. The spectral data of compounds 3b, e, and g were
in excellent agreement with commercial available samples, and the
compounds 3l12 and 7c27 were identified by the spectral data described
in the literature.
Figure 5. Correlation of the difference of δ(13C) between vinylic
carbons of 1c with equivalents of HMPA to tin enolate 1c.
6-Phenyl-5-hexen-2-one (3a): IR (neat) 1700 cm-1; 1H NMR (400
MHz, CDCl3) δ 7.33-7.14 (m, 5H), 6.37 (d, 1H, J ) 15.62 Hz), 6.16
(dt, 1H, J ) 15.62, 6.83 Hz), 2.54 (t, 2H, J ) 6.83 Hz), 2.43 (q, 2H,
J ) 6.83 Hz), 2.10 (s, 3H); 13C NMR (22.6 MHz, CDCl3) δ 207.1,
137.0, 130.2, 128.4, 128.1, 126.6, 125.6, 42.6, 29.5, 26.7; MS m/z 174
(M+); HRMS calcd for C12H14O 174.1045, found m/z 174.1046 (M+).
Anal. Calcd for C12H14O: C, 82.72; H, 8.10. Found: C, 82.75; H,
8.10.
different effect in the reaction with aldehyde between Bu4NBr
and HMPA (Scheme 5) can be explained by the distributing
charge on the tin complex which is either neutral or anionic.
The coordination of the anionic ligand to the tin center might
considerably weaken the interaction between the tin enolate and
carbonyl group.
2-(3-Phenyl-2-propyl)cyclohexanone (3c): IR (neat) 1700 cm-1
;
Conclusion
1H NMR (400 MHz, CDCl3) δ 7.34-7.17 (m, 5H), 6.39 (d, 1H, J )
16.11 Hz), 6.23-6.16 (m, 1H), 2.71-2.64 (m, 2H), 2.53-1.33 (m,
9H); 13C NMR (100 MHz, CDCl3) δ 212.5, 137.6, 131.6, 128.5, 128.4,
127.0, 126.0, 50.7, 42.1, 33.6; MS m/z 215 (M+ + 1), 214 (M+); HRMS
calcd for C15H18O 214.1358, found m/z 214.1355 (M+). Anal. Calcd
for C15H18O: C, 84.07; H, 8.47. Found: C, 84.23; H, 8.27.
In our search for high coordination of tin enolates, we have
studied their selective control for C-C bond formation. A five-
coordinated tin enolate can be readily formed by addition of
appropriate ligands such as the bromide anion from Bu4NBr or
HMPA where the hybridization of tin can be changed from the
four-coordinated one. In particular, bromide-anion-coordinated
tin enolates effectively couple with various halides, and they
completely lose the carbonyl addition character. The tin enolates
without a ligand intrinsically are reactive toward carbonyl but
not to halide. Therefore, the pronounced change of chemose-
lectivity observed in the anionic high coordination method is
very useful for organic syntheses.
1,5-Diphenyl-4-penten-1-one (3d): mp 59-60 °C; IR (neat) 1680
1
cm-1; H NMR (270 MHz, CDCl3) δ 7.98 (m, 2H), 7.59-7.16 (m,
8H), 6.47 (d, 1H, J ) 15.62 Hz), 6.29 (dt, 1H, J ) 15.62, 6.84 Hz),
3.15 (t, 2H, J ) 7.33 Hz), 2.66 (td, 2H, J ) 7.33, 6.84 Hz); 13C NMR
(67.9 MHz, CDCl3) δ 199.3, 137.4, 136.9, 132.0, 130.8, 129.1, 128.6,
128.5, 128.0, 127.0, 126.0, 38.2, 27.5; MS m/z 236 (M+); HRMS calcd
for C17H16O 236.1202, found m/z 236.1184 (M+). Anal. Calcd for
C17H16O: C, 86.41; H, 6.82. Found: C, 86.21; H, 6.79.
6-Phenyl-2-hexanone (3f): IR (neat) 1700 cm-1 1H NMR (400
;
MHz, CDCl3) δ 7.28-7.15 (m, 5H), 2.63-2.59 (m, 2H), 2.45-2.41
(m, 2H), 2.10 (s, 3H), 1.63-1.59 (m, 4H); 13C NMR (22.6 MHz, CDCl3)
δ 208.5, 142.0, 128.2, 128.1, 125.6, 43.5, 35.7, 30.9, 29.8, 23.4; MS
m/z 177 (M+ + 1), 176 (M+); HRMS calcd for C12H16O 176.1201,
found m/z 176.1189 (M+). Anal. Calcd for C12H16O: C, 81.77; H,
9.15. Found: C, 81.52; H, 9.17.
Experimental Section
General. Melting points were taken on a Yanagimoto melting point
apparatus and are uncorrected. IR spectra were recorded as thin films
or as solids in KBr pellets on a Hitachi 260-30 spectrophotometer.
1H and 13C NMR spectra were obtained with a Hitachi R-90H (90 and
22.6 MHz), a JEOL JNM-GSX-270 (270 and 67.9 MHz), or a JEOL
JNM-GSX-400 (400 and 100 MHz) spectrometers, respectively, with
TMS as internal standard. Mass spectra were recorded on a JEOL JMS-
DS303 or a Shimadzu GCMS-QP2000A spectrometer. GLC analyses
were performed on a Shimadzu GC-8A with FID using a 2 m × 3 mm
column packed with SE-52. Flash chromatography was performed on
silica gel (Wakogel C-300). Bulb-to-bulb distillation (Ku¨gelrohr) was
accomplished in a Sibata GTO-250RS at the oven temperature and
pressure indicated. Yields were determined by GLC or 1H NMR using
internal standards.
Materials. THF and benzene were distilled from sodium and
benzophenone. HMPA was distilled from CaH2. Tetrabutylammonium
halides were dried in vacuo before use. Tin enolates 1a-c were
prepared by known methods.8 Halides 2a-i and 4 and carbonyls 6a-b
were commercial products.
General Procedure for Substitution of Halides with Tin Enolate.
A mixture of a tin enolate 1 (1.2 mmol) and an additive (1.8 mmol) in
dry THF (1 mL) was stirred for 10 min under nitrogen. To this solution
was added a halide 2 (1.0 mmol), and the resulting solution was stirred
under the reaction conditions noted in Tables 1 and 2. Volatiles were
removed under reduced pressure, diethyl ether (30 mL) and aqueous
NH4F (15%, 15 mL) were added, and the resulting Bu3SnF was filtered
off. The filtrate was washed with water (30 mL × 2), dried (MgSO4),
and evaporated. Flash chromatography of the resultant residue on silica
gel gave pure products.
2-Propylcyclohexanone (3h): 1H NMR (400 MHz, CDCl3) δ 2.41-
1.15 (m, 13H), 0.90 (t, 3H, J ) 6.83 Hz); 13C NMR (100 MHz, CDCl3)
δ 213.6, 50.5, 41.9, 33.8, 31.6, 28.0, 24.8, 20.3, 14.2; MS m/z 140
(M+); HRMS calcd for C9H16O 140.1201, found m/z 140.1210.
1,3-Diphenylpropan-1-one (3i): mp 68-69 °C; IR (KBr) 1660
1
cm-1; H NMR (270 MHz, CDCl3) δ 8.0-7.9 (m, 2H), 7.6-7.4 (m,
3H), 7.35-7.15 (m, 5H), 3.31 (t, 2H, J ) 7.57 Hz), 3.07 (t, 2H, J )
7.57 Hz); 13C NMR (67.9 MHz, CDCl3) δ 199.2, 141.3, 136.9, 133.0,
128.6, 128.5, 128.4, 128.0, 126.1, 40.4, 30.1; MS m/z 210 (M+, 23);
HRMS calcd for C15H14O 210.1045, found m/z 210.1042 (M+). Anal.
Calcd for C15H14O: C, 85.68; H, 6.71. Found: C, 85.48; H, 6.75.
1-Phenyl-4-penten-1-one (3j): bp 70 °C/1 mmHg; IR (neat) 1680
1
cm-1; H NMR (400 MHz, CDCl3) δ 7.97-7.95 (m, 2H), 7.58-7.54
(m, 1H), 7.48-7.44 (m, 2H), 5.96-5.86 (m, 1H), 5.09 (dd, 1H, J )
17.09, 1.46 Hz), 5.01 (dd, 1H, J ) 10.25, 1.46 Hz), 3.07 (t, 2H, J )
7.32 Hz), 2.53-2.47 (m, 2H); 13C NMR (67.9 MHz, CDCl3) δ 199.3,
137.2, 136.9, 132.9, 128.5, 127.9, 115.2, 37.7, 28.1; MS m/z 160 (M+,
3.9); HRMS calcd for C11H12O 160.0889, found m/z 160.0884 (M+).
2-Benzylcyclohexanone (3k): bp 110 °C/1 mmHg; IR (neat) 1700
1
cm-1; H NMR (270 MHz, CDCl3) δ 7.4-7.1 (m, 5H), 3.24 (dd, 1H,
J ) 13.67, 4.39 Hz), 2.65-1.25 (m, 10H); 13C NMR (67.9 MHz,
CDCl3) δ 212.5, 140.4, 129.1, 128.3, 125.9, 52.4, 42.1, 35.4, 33.4, 28.0,
(27) Hasegawa, E.; Ishiyama, K.; Horaguchi, T.; Shimizu, T. J. Org.
Chem. 1991, 56, 1631-1635.