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Highly Efficient Recyclable Co III –salen Complexes in the Catalyzed Asymmetric Aminolytic Kinetic Resolution of Aryloxy/Terminal Epoxides for the Simultaneous Production of N ‐Protected 1,2‐Amino Alcohols and the Corresponding Epoxides in High Optical Purity
Author(s) -
Kureshy Rukhsana I.,
Prathap K. Jeya,
Agrawal Santosh,
Kumar Manish,
Khan Noorul H.,
Abdi Sayed H. R.,
Bajaj Hari C.
Publication year - 2009
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.200900032
Subject(s) - chemistry , kinetic resolution , ionic liquid , catalysis , enantioselective synthesis , nucleophile , metal salen complexes , epoxide , medicinal chemistry , organic chemistry
Chiral Co III –salen complexes 1 – 6 bearing different substituents at the 3,3′‐ and 5,5′‐positions of the salen unit, namely H, t Bu, morpholinomethyl, and piperidinomethyl, have been synthesized. These complexes were used as catalysts in an environmentally benign protocol for the highly enantioselective aminolytic kinetic resolution (AKR) of racemic aryloxy/terminal epoxides with various carbamates as the nucleophile in the presence of different ionic liquids at room temperature. Excellent yields (>99 % with respect to the nucleophile) of N ‐protected 1,2‐amino alcohols with high regio‐ and enantioselectivities ( ee >99 %) were achieved with the simultaneous formation of the corresponding epoxides with high chiral purity ( ee up to >99 %) and in quantitative yields with catalyst 1 in the ionic liquid [bmim]PF 6 as the reaction medium in around 5 h. The catalyst is recyclable in this ionic‐liquid‐mediated AKR process (up to six cycles with no loss of performance), and the process is five times faster than the homogeneous process performed with conventional organic solvents.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)