Effect of substituents in directing the formation of benzochlorins and isobacteriochlorins in porphyrin and chlorin systems.

[GRAPHICS] A first synthesis of free-base fluorinated benzochlorins by acid catalyzed cyclization of 20-(2-trisiloxy-trifluoromethylvinyl)octaethylporphyrin is achieved, Under similar reaction conditions, the purpurin-18-N-hexylimide analogues produced the corresponding fluorinated and nonfluorinated ethylidene-substituted isobacteriochlorins and fluorinated chlorin, respectively. The structure of the porphyrin based fluorinated benzochlorin was also confirmed by X-ray analysis.