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Construction of contiguous tetrasubstituted chiral carbon stereocenters via direct catalytic asymmetric aldol and mannich‐type reactions
Author(s) -
Matsunaga Shigeki,
Yoshino Tatsuhiko
Publication year - 2011
Publication title -
the chemical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.61
H-Index - 78
eISSN - 1528-0691
pISSN - 1527-8999
DOI - 10.1002/tcr.201100020
Subject(s) - stereocenter , aldol reaction , chemistry , schiff base , catalysis , enantioselective synthesis , electrophile , mannich reaction , organic chemistry , organocatalysis , ketone , medicinal chemistry , combinatorial chemistry , stereochemistry
Abstract Catalytic asymmetric synthesis of unnatural amino acids with vicinal tetrasubstituted chiral carbon stereocenters is described. In the first part, direct catalytic asymmetric aldol reaction of simple non‐activated ketone electrophiles with α‐substituted α‐isothiocyanato ester donors was realized. A Mg/Schiff base catalyst promoted the aldol reaction, and α‐amino‐β‐hydroxy esters were obtained in up to 98% ee and 98:2 d.r. In the second part, the Mg/Schiff base catalyst and a Sr/Schiff base catalyst were utilized for stereodivergent direct asymmetric Mannich‐type reaction of ketimines. The Mg/Schiff base catalyst gave syn ‐α,β‐diamino esters, while the Sr/Schiff base catalyst produced anti ‐α,β‐diamino esters in good to high enantioselectivity, up to 97% ee . DOI 10.1002/tcr.201100020