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Paper | Special issue | Vol 30, No. 2, 1990, pp.1091-1099
Published online, 1st January, 1970
DOI: 10.3987/COM-89-S105
Introduction of a New Concept: "d-Orbital Participation in Asyammetric Recognition" (DOPAR) for Use with CD Absorption Data of Dithiolane Derivatives

Tetsuichi Shibata,* Yoichi Iitaka, and Seiichi Inayama

*Pharmaceutical Institute, School of Medicine, Keio University, Shinanomachi 35, Shinjuku, Tokyo 160-0016, Japan

Abstract

An empirical correlation between the signs of circular dichroism (cd) absorption (at 237 and 252 nm) and the absolute configuration of two asymmetric carbons in a compound containing a dithiolane ring was elucidated by use of two types of molecular orbital calculation (MOC) (CNDO/2 and ab initio with STO-3G* set). These used the atom coordinate from X-ray crystallography of α-tetrahydro-L-α-santonin ethylene dithioacetal. The contributions of both the 3d-orbital of sulfur atom and the 2p-orbitals of asymmetric carbons in LUMO (excited state) in the results of MOC were shown to be relatively large. These results suggested that "d-orbital participation in asymmetric recognition" (DOPAR) would help explain the cd absorption data of the compound. The calculated/observed rations (c/o ratio) of two transition energy differences in the CD absorption were 2.7 CNDO/2 and 3.5 in the ab initio, respectively.