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Direct Organocatalytic Asymmetric Mannich Addition of 3‐Substituted‐2 H ‐1,4‐Benzoxazines: Access to Tetrasubstituted Carbon Stereocenters
Author(s) -
Wang YouQing,
Zhang Yongna,
Pan Kun,
You Junxiong,
Zhao Jin
Publication year - 2013
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201300654
Subject(s) - stereocenter , chemistry , enantioselective synthesis , mannich reaction , adduct , organocatalysis , acetone , carbon fibers , yield (engineering) , alcohol , catalysis , proline , organic chemistry , stereochemistry , combinatorial chemistry , amino acid , materials science , composite number , metallurgy , composite material , biochemistry
Abstract 3‐Substituted‐2 H ‐1,4‐benzoxazines undergo a highly enantioselective direct Mannich reaction with acetone in the presence of an L ‐proline catalyst at room temperature. The corresponding N‐heterocycles with α‐tetrasubstituted carbon stereocenters were obtained in good yields (48–92%) and excellent enantioselectivity (up to >99% ee ). Furthermore, a novel modification involving the diastereoselective reduction of the Mannich adduct was carried out leading to the formation of a 1,3‐amino alcohol with a chiral tetrasubstituted carbon stereocenter in high yield.