CONFORMATION OF CHLORODIHYDROSANTONINS

Abstract

The structure and conformation of newly obtained 2β-chloro-1, 2-dihydro-l-α-santonin (1) were elucidated in comparison with those of 2α-chloro-1, 2-dihydro-(2) and 1α, 2β-dichloro-1, 2-dihydro-l-α-santonin (3) and firmly characterized by IR, NMR, MS and CD spectrometry and X-ray crystallographic analysis. While both 2β-chloro-(1) and 1α, 2β-dichloroenone (3) were found to take a half-boat conformation (A), 2α-chloroisomer (2) was shown to be in the inverted half-chair conformation (B).