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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 23, Number 12
BKCSDE 23(12)
December 20, 2002 

 
Title
1,2-Ferrocenediylazaphosphinines 3: A New Class of Planar Chiral Ligands for Cu-Catalyzed Cyclopropanation
Author
Seung Hwan Paek, Thanh-Thien Co, Dong Ho Lee, Yu Chul Park, Tae-Jeong Kim
Keywords
Ferrocenediylazaphosphinines, Asymmetric cyclopropanation, Copper-catalysis
Abstract
The synthesis and catalytic application of a new class of planar chiral ferrocenes, 1,2-ferrocenediylazaphos-phinines (1 and 2) are described. They are powerful ligands for the copper(I)-catalyzed asymmetric cyclopropanation of a range of alkenes with diazo esters to exhibit an exceptionally high degree of diastereoselectivity (~100% de) in favor of trans isomers, regardless the structure of the olefins and the diazo compounds. Comparative studies between 1 and 2 reveal that the former works better in terms of diastereocontrol. In contrast, however, enantioselectivity is low with both 1 and 2 as a whole although, in certain cases with a proper combination of the olefin and the diazo ester, high optical yields (up to 100% ee) can be achieved. Other reaction parameters such as the reaction temperature and the structure of the ligand do exhibit some influence, although infinitestimal, on both chemical and optical yields.
Page
1702 - 1708
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