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C 2 ‐Symmetric Fluorous Diamines and Diimines as Ligands for Metal‐Catalysed Asymmetric Cyclopropanation of Styrene
Author(s) -
Shepperson Ian,
Quici Silvio,
Pozzi Gianluca,
Nicoletti Marcello,
O’Hagan David
Publication year - 2004
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.200400436
Subject(s) - cyclopropanation , chemistry , enantiopure drug , styrene , cobalt , copper , catalysis , diamine , yield (engineering) , metal , polymer chemistry , rhodium , organic chemistry , medicinal chemistry , copolymer , enantioselective synthesis , polymer , materials science , metallurgy
Perfluoroalkyl‐substituted, enantiopure C 2 ‐symmetric N and N,O ligands showing affinity either for standard organic solvents or perfluorocarbons have been conveniently prepared from readily available precursors. Preformed cobalt( II ) and in‐situ‐generated copper( I ) complexes of these ligands were tested as catalysts in the metal‐catalysed cyclopropanation of styrene with diazoacetates. Under optimised reaction conditions, which include the use of a fluorous biphasic system and short reaction times, the copper complex of a C 2 ‐symmetric diamine afforded promising results (yield = 77%, trans / cis = 67:33, ee of the trans isomer = 62%) and could be easily separated from the products by simply decanting the fluorous phase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)