Investigation of the C1 polymerizability of diazoacetamide: alternating C1-cyclocopolymerization of hetero-bis(diazocarbonyl) compounds bearing diazoacetate and diazoacetamide units

Abstract

The potential of diazoacetamides as a class of monomers for Pd-initiated C1 polymerization was investigated. Copolymerization of a series of diazoacetamides with ethyl diazoacetate (EDA) proceeded to afford relatively high M_n copolymers with a diazoacetamide composition of ca. 10 mol% (e.g., M_n = 9800; diazoacetamide composition = 11 mol%), indicating that the presence of certain diazoacetamides did not prevent the progress of the C1 polymerization. Hetero-bis(diazocarbonyl) compounds with diazoacetate and diazoacetamide groups incorporated in one molecule were designed and prepared for cyclocopolymerization for the first time. The Pd-initiated cyclocopolymerization of the monomers proceeded to yield cyclopolymers with ester and amide linkages in a repeating cyclic framework and M_n values of a few thousand, demonstrating that 1 : 1 alternating copolymerization of diazoacetate and diazoacetamide is indeed possible with a suitable design of the monomer structure and an appropriate choice of the Pd-based initiating system. The chain end analysis of the cyclopolymer using MALDI-TOF-MS measurements suggested that chain transfer through β-H elimination of the acetamide propagating species prevented the formation of high M_n polymers.