1,2-Ferrocenedilazaphosphinines 3:A New Class fo Planar Chiral Ligands for Cu-Catalyzed Cyclopropanation

• Published in: Bulletin of the Korean Chemical Society 2002, Vol.23 (12), p.1702-1708
• Main Authors: Paek, Seung-Hwan, Co, Thanh Thien, Lee, Dong-Ho, Park, Yu-Chul, Kim, Tae-Jeong
• Format: Article
• Language: Korean
• ISSN: 0253-2964; 1229-5949

The synthesis and catalytic application of a new class of a new class of planar chiral ferrocenes, 1,2-ferrocenediylazaphosphinines (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.