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Synthesis of α‐Stereogenic Amides and Ketones by Enantioselective Conjugate Addition of 1,4‐Dicarbonyl But‐2‐enes
Author(s) -
Jiang Zhiyong,
Yang Yuanyong,
Pan Yuanhang,
Zhao Yujun,
Liu Hongjun,
Tan ChoonHong
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802601
Subject(s) - stereocenter , conjugate , enantioselective synthesis , chemistry , stereochemistry , organic chemistry , catalysis , mathematics , mathematical analysis
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).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 %).