Electron impact induced cyclizations in 4†chioro†3†(N†aryliminomethyl) (2H) benzopyrans and benzothiopyrans

Intramolecular substitutions leading to cyclizations with the ejection of chlorine have been noticed during mass spectral fragmentation of 4‐chloro‐3‐(N‐aryliminomethyl) (2H) benzopyrans and benzothiopyrans. Very interesting ortho effects involving intramolecular substitutions have also been observed in 6‐methyl‐4‐diloro‐3‐[N‐(2‐methoxyphenyliminomethyl)] (2H) benzopyran and 6‐methyl‐4‐chloro‐3‐[N‐(2‐chlorophenyliminomethyl)]‐(2H) benzopyran. The proposed fragmentation mechanisms have been supported by the accurate mass measurements and linked scan studies. Copyright © 1987 John Wiley & Sons, Ltd.