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E. Bernacka et al. / Tetrahedron Letters 42 (2001) 5093–5094
Table 1. a-Amidoalkyl sulfones 2 and BOC-amines 4a
Entry
R
2 Yield (%)b
2 Mp (°C)
4 Yield (%)b
4 Mp (°C)c
a
b
c
d
e
f
g
h
i
Ph
65
77
68
77
54
76
69
76
80
177–178 (–)
174–175 (–)
179–180 (–)
183–185 (–)
148–150 (–)
88–90 (–)
73
71
87
91
82
77
87.5
82
73
52–53 (52–53)12
71–74 (75–76)13
48–50 (50–50.5)14
65–68 (72.5–73)13
48–51 (–)
p-Cl-C6H4
p-MeO-C6H4
p-Me-C6H4
2-Furyl
Me
Et
i-Pr
c-C6H11
d
(–)
(–)
(–)
d
114–6 (114–115)11
109–111 (–)
151–154 (–)
d
41–44 (50–51)15
a All new compounds were fully characterized by MS, IR and 1H NMR spectra.
b Yields of crude products.
c Mps of crude products. Literature mps are given in parentheses.
d Low-melting solid.
References
toluenesulfinate (3.57 g, 20 mmol), water (40 ml),
methanol (20 ml) and formic acid (5 ml) was stirred for
ca. 15 min until it became homogeneous and then left for
24 h at room temperature. The crystalline sulfone 2 was
filtered off with suction, washed successively with water
(30 ml), and ether (30 ml) and dried over P2O5. Sulfones
2a–d were washed only with water (30 ml) and then dried.
Crude 2 were spectroscopically pure (1H NMR). Analyti-
cally pure samples were obtained by crystallization from
ethyl acetate (2a–c), ethyl acetate-hexane (2d,e,h), etha-
nol–hexane (2i), and ether–hexane (2f,g).
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9. Experimental conditions for the preparation of 2: A
mixture of aldehyde
1 (20 mmol), crude t-butyl
carbamate10 (2.34 g, 20 mmol), anhydrous sodium p-
.