Steric effects in some 2,2'-bridged biphenyls

Abstract

Two types of bridged biphenyls are discussed in this thesis, 3,4:5, 6-dibenzazepinium compounds and 5,6:7,8-dibenzo-1,4-diazocines.An attempt to synthesise 2,7-dihydro-4' -methoxy-3.4:5,6-dibenzazepinium-l-spiro-1'"-piperidinium bromide is described. 2,7-Dihydro-4' ,1"-dimethoxy-3,4:5,6-dibenzazepinium-1-spiro-1'"-piperidinium iodide was synthesised in an optically active condition, but attempts to obtain it in an optically and chemically pure state v/ere not completely successful. The optical stability of the impure product was determined. Attempts to resolve or activate optically 6-methoxydiphenic acid v/ere unsuccessful. 4'1"-Dimethyl-2,3-diphenyl-5,6:7,8-dibenzo-1,4-diazocine was obtained optically active and an estimation of its optical stability was made. 2,3-Dimethyl-5,6:7,8-dibenzo-l,U-diazocine-2,3"-dicarbbxylic acid was synthesised but attempts to resolve it were unsuccessful. The optical stability of 2,3-diphenyl-5,6:7,8-dibenzo-1,4-diazocine-2',3'-dicarboxylic acid was determined.2,3,4',1"-Tetramethyl-5,6:7,8-dibenzo-1,4-diazocine and 2,3-dimethyl-5,6,:7,8-dibenzo-1,4-diazocine were synthesised. Attempts to obtain 1,2,3,4-tetrahydro-2,3-dimethyl-5,6:7,8 dibenzo-1,4-diazocine by reduction of the latter diazocine appeared to be successful, but the product was chemically unstable.