Chiral nickelacycles

IV. DEVELOPMENT OF CHIRAL NICKELACYCLES AS AMINO ACID SYNTHONS... 

This isomerization reaction leads to the buildup of a new stereogenic center. Therefore, addition of a chiral diphosphine may lead to the formation of an optically active product. Addition of the chiral bidentate diphosphine (5, -2,3-bis(diphenylphosphino)butane (5,S)-chiraphos) to a CHjCIj solution of the six-membered ring nickelacycle derived from glutaric anhydride leads to a mixture of diastereomers with a 16% diastereomeric excess favoring the R configuration (Scheme 5). However, on standing at 24 °C, the mixture of diastereomers equilibrates favoring the thermodynamically more stable S nickelacycle isomer with 52% diastereomeric excess. 

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