2442
X. Wen et al. / Tetrahedron Letters 53 (2012) 2440–2443
Table 3
Cl
Scope of the benzoxazoles synthesis
O
O
NH2
OH
O
T3P (in AcOEt), DIPEA
N
O
+
R
NH
NH
°
MW, 160 C, 15 min
R
HO
8
5
4
2
Product
R
Yield (%)
95
Cl
5a
5b
5c
5d
5e
Cl
Figure 3. Structure of diamide 8.
76
73
93
91
developed through T3P-mediated microwave reactions of
o-aminobenzenethiol, o-aminophenol, and o-phenylenediamine
with diverse carboxylic acids. The method is environmentally
friendly and the work-up easy allowing final products in good to
excellent yields. It is especially suitable in medicinal chemistry to
rapidly enlarge compound library for biological evaluation.
Me
N
Cl
Acknowledgments
The authors are grateful to our institutions: Inserm, Université
de Lille 2, Institut Pasteur de Lille. X.W. wishes to express his
thanks to the National Natural Science Foundation of China (Grant
21002125), the China Scholarship Council and la Fondation Franco-
Chinoise pour la Science et ses Applications, for their support of his
postdoctoral study in France.
Table 4
Scope of the benzimidazoles synthesis
O
N
R
NH2
T3P (in AcOEt), DIPEA
+
°
HO
R
MW, 160 C, 30 min
N
NH2
H
7
6
2
Supplementary data
Product
R
Yield (%)
77
Supplementary data (synthesis procedures, characterization of
compounds comparison of commercial sets of acids, aldehydes
and alcohols, putative mechanisms) associated with this article
7a
7b
7c
Cl
77
80
Me
N
References and notes
7d
7e
7g
62
93
90
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poor conversion to cyclic compound (5a) was observed using p-
chlorobenzoic acid. Therefore stronger reaction conditions were
assayed. Microwave irradiation for 15 min at 160 °C allowed a
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In conclusion, an efficient method18 for quick preparation of
benzothiazoles, benzoxazoles, and benzimidazoles has been
11. Search performed in ACS SYMYX™ database in December 2011. See
Supplementary data for details.