Phenanthridines. IV. Pschorr reactions with sulphonamides derived from N-o-aminobenzylaniline: Synthesis of 4-bromophenanthridine and formationof 6-Phenyl-7H-dibenzo[d,f]-[1,2]-thiazepine-5-dioxide

Abstract

The copper-catalysed decomposition of diazotized N-o-aminobenzyl-N-benzenesulphonylaniline (IIIb) yielded 5-benzenesulphonyl-5,6-dihydrophenanthri. dine (IIa) in lower yield than the Pschorr cyclization of N-benzenesulphonyl-N-benzyl-o-phenylenediamine (IIIa) previously studied. However, only one major by-product, 6-phenyl-7H-dibenzo[d,f]-[1,2]-thiazepine-5-dioxide (VIa) was formed from (IIIb). Pschorr cyclization of N-o-aminobenzyl-N-p-toluenesulphonyl-o-bromoaniline (IIIc) gave 4-bromophenanthridine (Ic) and 6-(2-bromophenyl)-2-methyl-7H-dibenzo[d,f]-[1,2]-thiazepine-5-dioxide (VIc). When this cyclization was carried out after diazotization with 30% excess sodium nitrite, N-benzyl-N-p-toluenesulphonyl-o-bromoaniline (IIIg) was also formed.