Synthesis of some nitrogen–arsenic heterocycles : 5,10-dihydro-5,10-o-benzenophenarsazine (azarsatriptycene), 10,11-dihydro-5-phenyl-5H-di-benzo[b,f][1,4]azarsepine, and 2,3-dihydro-1,2-diphenyl-1H-benz[c]-azarsole

Abstract

10,11-Dihydro-5-phenyl-5H-dibenzo[b,f][1,4]azarsepine (1) and 1,2-dihydro-1,2-diphenyl-1H-benz[c]azarsole (7) are formed in low yield in the reaction between o-lithio-N-(o-lithiobenzyl)aniline and dichloro(phenyl) arsine. Azarsatriptycene (12) is prepared by cyclising 10-(2-chlorophenyl)-5,10-dihydrophenarsazine with an excess of lithium diethylamide in ether. The triptycene is a neutral compound which resists quaternisation and is unaffected by acids and bases. The arsenic–carbon bond is cleaved by treatment with sodamide in hexamethylphosphoramide to give 5,5′,10,10′-tetrahydro-5,5′-diphenyl-10,10′-oxydiphenarsazine (10).