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Organocatalysed Asymmetric Direct Mannich Reaction of Acetophenone Derivatives and Dibenzo[ b , f ][1,4]oxazepines with Azetidine‐2‐carboxylic Acid
Author(s) -
Ren YuanYuan,
Wang YouQing,
Liu Shuang,
Pan Kun
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402446
Subject(s) - chemistry , acetophenone , mannich reaction , enantioselective synthesis , azetidine , ketone , yield (engineering) , carboxylic acid , organic chemistry , medicinal chemistry , combinatorial chemistry , stereochemistry , catalysis , materials science , metallurgy
An enantioselective direct Mannich reaction of different acetophenone derivatives with various substituted seven‐membered cyclic imines using ( S )‐azetidine‐2‐carboxylic acid as an organocatalyst is described, which provides an efficient access to optically active 11‐substituted‐10,11‐dihydrodibenzo[ b , f ][1,4]oxazepine derivatives with 87–95 % ee . For α,β‐unsaturated ketone benzalacetone, the desired Mannich product was obtained with 72 % ee . A plausible transition state is established to explain the observed absolute stereochemistry of the Mannich products. The reaction can also be performed on a gram scale with no adverse effects on the yield and enantioselectivity. Furthermore, some simple transformations involving the Wittig olefination and the decarboxylative reduction of the Mannich products were performed.