The mechanism of formation of carborane-containing oligo(carbonate methacrylates)

Under the conditions of low-temperature acceptor-catalytic telomerization, acylation of o-carboranediol can be performed by both nucleophilic and general base catalyses, the latter being more effective. As evidenced by 'H NMR spectroscopic data, high efficiency of the general base catalysis is associated with the formation of a specific reactive complex between o-carboranediol and triethylamine. The triethylamine-o-car-boranediol complex incorporates both OH groups of diol (1:1 complex), which is related to the ortho arrangement of these groups. The ortho effect determines different reactivity of the two OH groups of a symmetrical o-carborane molecule: under mild conditions, only a single OH group is involved in the reaction. The ortho effect makes it possible to synthesize oligomers of sufficiently high molecular masses from o-carboranediol via a step-by-step process.