Polymerization of alkyl diazoacetates initiated by the amidinate/Pd system: efficient synthesis of high molecular weight poly(alkoxycarbonylmethylene)s with moderate stereoregularity

Abstract

The initiating ability of a new system, amidinate/Pd, for the polymerization of diazoacetates is described. The system is effective in affording relatively high number-average molecular weight (M_n) polymers from ethyl diazoacetate (EDA, e.g., M_n = 45 100, 44% yield) and methyl diazoacetate (MDA, e.g., M_n = 26 200, 56% yield) in moderate yield. The polymerization of n-hexyl diazoacetate (nHDA) and benzyl diazoacetate (BDA) by the amidinate/Pd system yields high M_n polymers (M_n = ca.100 000), although the yield was below 10%. The system is also effective in the copolymerization of EDA with nHDA, BDA, and cyclohexyldiazoacetate (cHDA), affording high M_n copolymers in moderate yield. NMR spectra of the products obtained with the system suggest that the polymerization proceeds with significantly higher stereoregularity compared to that with previously reported Pd-based initiating systems.