Substoichiometric TiCl4-mediated vicinal difunctionalization of α,β-acetylenic ketones for the synthesis of β-halo Baylis-Hillman olefins

被引:25
作者
Wei, HX [1 ]
Gao, JJ [1 ]
Li, GG [1 ]
机构
[1] Texas Tech Univ, Dept Chem & Biochem, Lubbock, TX 79409 USA
基金
美国国家卫生研究院;
关键词
D O I
10.1016/S0040-4039(01)02020-2
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
A substoichiometric amount of titanium tetrachloride was found to be effective to promote and participate in the tandem alpha -hydroxyalkylation/beta -chlorination of alpha,beta -acetylenic ketones in the presence of (n-Bu)(4)NI. This method provides the concise synthesis of (E)-beta -halo Baylis-Hillman adducts. No beta -iodo products were detected when using this combination of halogen sources. The reaction process involves 1,4-addition of chloro anion released from TiCl4 onto alpha,beta -acetylenic ketones to give TiCl3-allenolate intermediates followed by the titanium Lewis acid-promoted carbonyl addition. Modest to good yields (53-77%) and excellent E/Z stereoselectivity (>95%) have been obtained for 10 examples. (C) 2001 Elsevier Science Ltd. All rights reserved.
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页码:9119 / 9122
页数:4
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