Synlett 2014; 25(20): 2964-2965
DOI: 10.1055/s-0034-1379541
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© Georg Thieme Verlag Stuttgart · New York

Heterocyclic Ketene Aminals

Li-Fen Yang
Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091, P. R. of China   eMail: yanglifenhgn@163.com
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Publikationsdatum:
19. November 2014 (online)

Introduction

Heterocyclic ketene aminals (HKAs) are important precursors in organic synthesis of a variety of heterocyclic compounds. HKAs are conjugated with electron-donating amino groups and an electron-withdrawing carbonyl group, as well as a highly polarized double bond (C=C).1 This leads to higher electron density of the α-carbon (C3) than that of the secondary amino groups (N1 and N5) and makes the reaction at the α-carbon very easy. HKAs have four nucleophilic sites (N1, N5, C3, O6). As a result, they are usually used as regioselective building blocks. Especially, they can serve as bis-nucleophiles (C3 and N1) and react with bis-electrophiles to synthesize the fused heterocycles. HKAs can be easily prepared from the corresponding acetophenone and diamine (Scheme [1]).

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Scheme 1 Synthesis of heterocyclic ketene aminals