Unusual preference for ketone and reversal of chemoselectivity in Lewis acid-catalyzed aldol reaction of ketene silyl acetal

被引:27
作者
Chen, JX [1 ]
Sakamoto, K [1 ]
Orita, A [1 ]
Otera, J [1 ]
机构
[1] Okayama Univ Sci, Dept Appl Chem, Okayama 7000005, Japan
关键词
D O I
10.1021/jo981218v
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Ketene silyl acetals undergo facile reaction with ketones in the presence of a Lewis acid such as (C6F5)(2)SnBr2, TMSOTf, or Sc(OTf)(3). This unique reactivity allows ketones to react in preference to aldehydes or acetals in competitive aldol-type reactions. Upon treatment with keto aldehydes or keto acetals, ketene silyl acetals provide single products derived from the exclusive reaction with the ketonic function. Particularly noteworthy is the discrimination of ketones from aldehydes in naked forms. It has been proved that such bias results from the differentiated recognition of ketone and aldehyde carbonyls. The ternary system consisting of ketene silyl acetal, carbonyl, and an appropriate Lewis acid is crucial for achieving the effective differentiation.
引用
收藏
页码:9739 / 9745
页数:7
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