The circular dichroism of some 2,2′-bridged biphenyls. The absolute configuration of (+)-6,7-diphenyldibenzo[e,g][1,4]diazocine-3,10-dicarboxylic acid

Abstract

The principal features of the c.d. (solutions in dioxan) of (+)-6,7-diphenyldibenzo[e,g][1,4]diazocine-3,10-di-carboxylic acid (1a), of (S)-(+)-1,12-dimethyl-6,7-diphenyldibenzo[e,g][1,4]diazocine (1b), and of (S)-(+)-1,11-dimethyl-6-phenyl-5H-dibenzo[d,f][1,3]diazepine (6a) are a positive long-wave Cotton effect and a negative short-wave conjugation band Cotton effect; the (+)-dicarboxydiazocine has been assigned the S-configuration. The u.v. spectra of several 6,7-diphenyldibenzo[e,g][1,4]diazocines and 6-phenyl-5H-dibenzo-[d,f][1,3]diazepines are given. The c.d. (solutions in dimethyl sulphoxide; above 250 nm) of (S)-(+)-1,11-dimethyl-5H-dibenzo[d,f][1,3]diazepin-6(7H)-one (8a) shows two negative Cotton effects.