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Synthesis of α-Stereogenic Amides and Ketones by Enantioselective Conjugate Addition of 1,4-Dicarbonyl But-2-enes

✍ Scribed by Zhiyong Jiang; Yuanyong Yang; Yuanhang Pan; Yujun Zhao; Hongjun Liu; Choon-Hong Tan

Publisher
John Wiley and Sons
Year
2009
Tongue
English
Weight
265 KB
Volume
15
Category
Article
ISSN
0947-6539

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✦ Synopsis

Abstract

Constructing α‐stereogenic amides and ketones: The highly regioselective and enantioselective conjugate addition of 1,3‐dicarbonyl compounds to 1,4‐dicarbonyl but‐2‐enes has been developed with the chiral bicyclic guanidine as catalyst (ee values up to 97 %; see scheme).magnified image

In the conjugate addition reaction of a α,β‐unsaturated compound, the new stereogenic center is created in the β‐position. In contrast, conjugate addition to 1,4‐dicarbonyl but‐2‐enes will generate an α‐stereogenic center with respect to one of the carbonyl groups, which informally, can be considered as an inversion of normal reactivity patterns or Umpolung. In this paper, we demonstrate that chiral bicyclic guanidine can catalyze the addition of 1,3‐dicarbonyl compounds to 1,4‐dicarbonyl but‐2‐enes [(E)‐4‐oxo‐4‐arylbutenamides and (E)‐4‐oxo‐4‐arylbutenones] with high regioselectivity and enantioselectivity (ee values up to 97 %).

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