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Communication | Special issue | Vol 30, No. 1, 1990, pp.241-246
Published online, 1st January, 1970
DOI: 10.3987/COM-89-S16
■ Investigation of Stereochemical Control for Steroid Side Chain by Kinetic Protonation of Tetronate Derivatives

Toshio Honda,* Hironao Takada, Tadashi Katoh, and Masayoshi Tsubuki

*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

Stereochemical control for construction of steroidal side chains by kinetic protonation of tetronate derivatives is described. Kinetic protonation of the (22R)-tetronates (4 and 11) proceeded with the inversion of the stereochemistry at the C-22 position to afford the corresponding (22S)-tetronates (3 and 12), whereas the same treatment of 9a and 9b gave only a mixture of stereoisomers. Furthermore, isomerization of the double bond of 7a and 7b led to the formation of (20E)-olefin (8a) and (20Z)-olefin (8b) (84:16) with moderate stereoselectivity.