Polymerizable mesoionic 4,6‐dioxo‐1,3‐diazines, 1. Synthesis and photochemical behavior of polystyrenes with mesoionic 4,6‐dioxo‐1,3‐diazines as pendant groups

Mesoionic 5‐alkyl‐4,6‐dioxo‐1,3‐diphenyl‐2‐(3‐vinylbenzylthio)‐1,3‐diazine ( 6 ) was prepared by condensation of alkylmalonic acid ( 5 ) with 1,3‐diphenyl‐2‐(3‐vinylbenzyl)isothiourea ( 4 ) by use of dicyclohexylcarbodiimide (DCC). Homopolymerization of 6 led to new polystyrene derivatives ( 7 ) with mesoionic 4,6‐dioxo‐1,3‐diazines as pendant groups. UV irradiation of 7 yielded polystyrene derivatives with bis(β‐lactam) moieties as pendant groups ( 8 ). The change of some physical properties during the irradiation is discussed. 5‐Heptyl‐4,6‐dioxo‐1,3‐diphenyl‐2‐(3‐methylbenzylthio)‐1,3‐diazine ( 11 ) and 4‐heptyl‐1‐(3‐methylbenzylthio)‐3,5‐dioxo‐2,6‐diphenyl‐2,6‐diazabicyclo[2.2.0]hexane ( 12 ) as low‐molecular‐weight model compounds were synthesized for structural analysis.