1064
A. Wada et al.
LETTER
(11) In the case of trisubstituted olefins 5d and 5e, its stereo-
(6) Engler, T. A.; Sampath, U.; Naganathan, S.; Velde, D. V.;
Takuasgawa, F. J. Org. Chem. 1989, 54, 5712.
chemistry was determined after conversion to the
corresponding aldehyde by oxidation, respectively. See:
Wada, A.; Hiraishi, S.; Takamura, N.; Date, T.; Aoe, K.; Ito,
M. J. Org. Chem. 1997, 62, 4343.
(7) Subramanian, L. R.; Bentz, H.; Hanack, M. Synthesis 1973,
293.
(8) 1H NMR data of enol nonaflate 2a are as follows: (300 MHz,
CDCl3) : 0.97 (6 H, s, Me 2), 1.42–1.50 (2 H, m, CH2),
1.56–1.62 (2 H, m, CH2), 1.68 (3 H, s), 2.02 (2 H, t, J = 7
Hz), 6.21 (1 H, d, J = 12 Hz, =CH), 6.46 (1 H, d, J = 16 Hz,
=CH).
(12) Typical coupling procedure: To a stirred solution of enol
nonaflate (2a, 0.5 mmol), acetylene (6, 1 mmol),
diisopropylamine (2 mmol, 200 mg), and CuI (15 mol%, 35
mg) in benzene (3 mL) was added Pd(PPh3)4 (10 mol%, 58
mg) all at once under nitrogen. After stirring for an indicated
period in Table 2, the reaction was quenched with saturated
aqueous NH4Cl solution (3 mL) and extracted with ether (10
mL 3). The extracts were washed with saturated aqueous
NaCl solution (10 mL) and then dried over Na2SO4. The
solvent was removed under reduced pressure and the residue
was purified by column chromatography on a silica gel to
produce the coupled product 7.
(9) Farina, V.; Krishnan, B. J. Am. Chem. Soc. 1991, 113, 9585.
(10) Typical coupling procedure: To a stirred solution of enol
nonaflate (2a, 1 mmol),(vinyl)tributylstannane (4, 1.5
mmol), and AsPh3 (20 mol%, 60 mg) in DMF (2 mL) was
added Pd2dba3-CHCl3 adduct (2.5 mol%, 26 mg) all at once
under nitrogen. After stirring for an indicated period in
Table 1, the reaction was quenched with saturated aqueous
NH4Cl solution (3 mL) and extracted with diethyl ether (10
mL 3). The extracts were washed with saturated aqueous
NaCl solution (10 mL) and then dried over Na2SO4. The
solvent was removed under reduced pressure and the residue
was purified by column chromatography on silica gel to
afford the coupled product 5.
7a: IR (CHCl3) cm–1: 3608, 3450, 2932, 2209, 1604; 1H
NMR (300 MHz, CDCl3) : 1.00 (6 H, s, Me 2), 1.40–1.47
(2 H, m, CH2), 1.56–1.61 (3 H, m, CH2 and OH), 1.70 (3 H,
s, Me), 1.99 (2 H, t, J = 6 Hz, CH2), 4.41 (2 H, d, J = 4 Hz,
CH2), 5.47 (1 H, dt, J = 16.5, 2 Hz, =CH), 6.59 (1 H, d, J =
16 Hz, =CH); HRMS (EI) C14H20O: requires 204.1513,
found 204.1520.
5a: IR (CHCl3) cm–1: 3610, 3446, 2969, 1647; 1H NMR (300
MHz, CDCl3) : 1.00 (6 H, s, Me 2), 1.40–1.46 (2 H, m,
CH2), 1.56–1.62 (3 H, m, CH2 and OH), 1.69 (3 H, s, Me),
2.02 (2 H, t, J = 7 Hz, CH2), 4.19 (2 H, t, J = 7 Hz, CH2), 5.78
(1 H, dt, J = 15, 6 Hz, =CH), 6.03 (1 H, dd, J = 16, 10 Hz,
=CH), 6.14 (1 H, d, J = 16 Hz, =CH), 6.31 (1 H, ddt, J = 15,
10, 1 Hz, =CH); HRMS (EI) C14H22O: requires 206.1669,
found 206.1667.
(13) In the case of 13C-labeled aldehyde 1, there was no
reappearance of the peak for the conversion to the
corresponding enol triflate. On the contrary, there was no
trouble in preparation of the enol nonaflate.
Synlett 2002, No. 7, 1061–1064 ISSN 0936-5214 © Thieme Stuttgart · New York