Alternating Copolymers of Functional Alkenes with Carbon Monoxide

Abstract

The alternating copolymerization of functional alkenes, CH2CH(CH2)xOH (x = 2, 3, 4, 9), CH2CH(CH2)xCOOH (x = 1, 2, 4, 8), and 4-allylanisole, with carbon monoxide was achieved by using [Pd(Me-DUPHOS)(MeCN)2](BF4)2 [Me-DUPHOS = 1,2-bis(2,5-dimethylphospholano)benzene] as the catalyst. The resultant polymers were optically active with isotactic sequences in the backbone. With most alkenes, the polymers had poly(1,4-ketone) and/or “regular” poly(spiroketal) (i.e., 1,6-dioxaspiro[4.4]nonane) enchainments. However, with 4-penten-1-ol and 3-buten-1-ol, the participation of the pendant hydroxyl group in intrachain reactions led to the formation of unusual polycyclic repeating units in the backbone. A comparison of [Pd(Me-DUPHOS)(MeCN)2](BF4)2 with [Pd(DPPP)(MeCN)2](BF4)2 [DPPP = 1,3-bis(diphenylphosphino)propane] indicated that the former was a significantly better catalyst for the alternating copolymerization of alkenols and alkenoic acids with carbon monoxide.