1514
H. Tokuyama et al.
LETTER
(15) Mori, Y.; Seki, M. Heterocycles 2002, 58, 125.
Acknowledgment
(16) Typical Procedure: To a solution of thiol ester 1 (1.00 g,
4.48 mmol), PdCl2(dppf) (365 mg, 0.448 mmol), CuI (1.45
g, 7.61 mmol), and tri-2-furylphosphine (260 mg, 1.12
mmol) in a mixture of DMF (7.5 mL) and Et3N (1.5 mL) was
added 1-hexyne (1.02 mL, 892 mmol) at r.t. After stirring for
3 h at 50 °C, Celite was added to the mixture and the
resulting suspension was stirred for 5 min. The mixture was
diluted with Et2O (50 mL) and the reaction was quenched by
addition of H2O (50 mL). The mixture was filtered through
a pad of Celite and separated. The aqueous layer was
extracted with Et2O (20 mL × 2). The combined organic
extracts were washed with brine (20 mL), dried over anhyd
MgSO4 and concentrated in vacuo. Purification by flash
column chromatography on silica gel (40 g, 5–8% Et2O/
hexanes) gave 1.03 g (4.21 mmol, 94%) of a,b-alkynyl
ketone 2 as a brown oil. Compound 2: IR(film): 2958, 2871,
2214, 1671, 1513, 1247, 1178, 1036, 825 cm–1. 1H NMR
(400 MHz, CDCl3): d = 7.11 (d, J = 8.3 Hz, 2 H), 6.82 (d,
J = 8.5 Hz, 2 H), 3.78 (s, 3 H), 2.92 (t, J = 6.8 Hz, 2 H), 2.83
(t, J = 7.1 Hz, 2 H), 2.37 (t, J = 6.8 Hz, 2 H), 1.58–1.52 (m,
2 H), 1.46–1.40 (m, 2 H), 0.93 (t, J = 7.3 Hz, 3 H). 13C NMR
(100 MHz, CDCl3): d = 187.1, 158.0, 132.4, 129.2, 113.9,
94.8, 80.8, 55.2, 47.3, 29.7, 29.1, 21.9, 18.6, 13.5. HRMS
(FAB): m/z calcd for C16H20O2: 244.1463. Found: 244.1458.
(17) The reaction using trimethylsilylacetylene gave only
recovered starting material 1.
This work was supported in part by the Ministry of Education,
Science, Sports, and Culture, Japan. H.T. thanks PRESTO, JST for
financial support.
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O
SEt
n-Bu
Ar
Figure 1
(12) Tokuyama, H.; Yokoshima, S.; Yamashita, T.; Fukuyama,
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(21) The yield of 2 increased as the amount of CuI increased. The
yields of 2 with no CuI, 0.5, 1.0, 1.5, 2.0, and 2.5 equiv are
11%, 25%, 33%, 62%, 65%, and 87%, respectively.
However, addition of more than 3.0 equiv of CuI did not
improve the yield.
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Synlett 2003, No. 10, 1512–1514 © Thieme Stuttgart · New York