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Prolinamides Bearing Thiourea Groups as Catalysts for Asymmetric Aldol Reactions
Author(s) -
Fotaras Stamatis,
Kokotos Christoforos G.,
Tsandi Evaggelia,
Kokotos George
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001417
Subject(s) - chemistry , thiourea , aldol reaction , catalysis , proline , yield (engineering) , organocatalysis , organic chemistry , valine , amino acid , enantioselective synthesis , biochemistry , materials science , metallurgy
Organocatalysts based on α‐amino acid amides (proline,valine, and threonine) and chiral diamines bearing thiourea groups were synthesized and their activities for aldol reactions were studied. The catalyst based on ( S )‐proline and (1 S ,2 S )‐diphenylethylenediamine proved to be an excellent catalyst, providing the products of reactions between ketones and aromatic aldehydes in high to quantitative yields and with high stereoselectivities (up to 98:2 dr and 99 % ee ). The presence of an acid additive (4‐nitrobenzoic acid) has a considerable impact on both yield and enantioselectivity.