| Abstract: | Various N-(2-haloaryl)methyl]pyridinium, N-(arylmethyl)-2-halopyridinium and N-(2-halobenzyl)iso-quinolinium salts have been synthesized and their intramolecular photocyclization reactions studied. Upon irradiation the aqueous solution of N-(2-haloaryl)methyl]pyridinium, and N-arylmethyl-2-halopyridinium salts 1, 2 were cyclized to give isoindolium salts. In contrast to the pyridinium salts 1, 2 , the aqueous solution of N-(2-halobenzyl)isoquinolinium salts 3 appear not to undergo photocyclization. N-Benzyl-2-chloropyridinium salts 1c is more reactive than N-(2-chlorobenzyl)pyridinium salt 1a in the photocyclization. N-(2-Chlorobenzyl)-2-chloropyridinium salt 1d is three times more reactive than 1c . A mechanism of π-complex formation of the halogen moiety of the pyridinium ring with the phenyl ring is suggested for the reactive pyridinium salt. The triplet energy of the isoquinolinium salts 3 is tool low to photocyclize. |
