Selenium chlorides in the domino process of the regiospecific allyl chlorination of betulin and diacetylbetulin

Abstract

ABSTRACTThe interaction of betulin and diacetylbetulin with selenium chlorides occurs regiospecific with allylic chlorination of the substrate. Selenium chlorides are obtained by chlorination of selenium with sulfuryl chloride in the form of a mixture of SeCl2 and Se2Cl2. An intermediate product of the domino process, unsaturated allylic structure chloroselenide, was detected by 77Se and 1H NMR. The rate of conversion of selenide to allyl chloride was determined. According to the results of quantum-chemical calculations, in the reactions of betulin and diacetylbetulin with both SeCl2 and Se2Cl2, intermediates of the episelenuran type are formed in the first stage. Further, these intermediates are converted to unsaturated selenium chlorides by elimination of HCl. According to the calculation results, the final stage of the domino process – the formation of allyl chlorides is realized due to the catalytic action of SeCl2 in the elimination of selenium.