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.