Vinylation of Betulin with Calcium Carbide

A method for the synthesis of betulin vinyl ether using calcium carbide as a source of acetylene has been proposed. Optimal conditions for synthesis of betulin mono- and divinyl ether have been selected. It has been found that the addition of alkali metal fluorides in an excess of calcium carbide promotes the formation of a divinylated product. Two-dimensional NMR spectroscopy proves the formation of monovinyl ether at the primary alcohol group.