Formation of the steroidal C-25 chiral center via the asymmetric alkylation methodology.
A novel approach for the preparation of steroids containing a chiral center at C-25 is reported. The key stereochemistry inducing step was asymmetric alkylation of pseudoephenamine amides of steroidal C-26 acids. The reaction proceeded with high diastereoselectivity (dr > 99 : 1). The developed methodology was successfully applied to the synthesis of (25R)- and (25S)-cholestenoic acids as well as (25R)- and (25S)-26-hydroxy brassinolides.
Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Kuprevich st., 5/2, 220141 Minsk, Belarus. vz@iboch.bas-net.by.
Yu V
YV
Ermolovich
V N
VN
Zhabinskii
V A
VA
Khripach
D000478:Alkylation; D000577:Amides; D000662:Amphetamines / Q000737:chemistry*; D060406:Brassinosteroids / Q000138:chemical synthesis*; D002782:Cholestenes / Q000138:chemical synthesis*; D015394:Molecular Structure; D013237:Stereoisomerism
D000577:Amides; D000662:Amphetamines; D060406:Brassinosteroids; D002782:Cholestenes; C514718:cholestenoic acid; C587965:pseudoephenamine