Catalytic cyclopropanation of polybutadienes

Abstract

Catalytic cyclopropanation of commercial 1,2- or 1,4- cis -polybutadiene, respectively, with ethyl diazoacetate catalyzed by [Tp Br3 Cu(NCMe)] (Tp Br3 ¼ hydrotris(3,4,5-tribromo-1-pyrazo- lyl)borate) at room temperature afforded high molecular weight ( M n > 10 5 mol

1 ) side-chain or main-chain, respectively, carbox- yethyl cyclopropyl-substituted polymers with variable and con- trolled degrees of functionalization. Complete functionalization of 1,4- cis -polybutadiene afforded poly[ethylene-alt-(3-ethoxycar- bonyl-cyclopropene)]. Catalytic hydrogenation of residual dou- ble bonds of partially cyclopropanated polybutadienes provided access to the corresponding saturated polyolefins. Thermal properties are reported.