Bentya A. Elecrtophilic intramolecular cyclization of 6-[alkenyl(alkinyl)thio(amino)]pyrazolo[3,4-d]pyrimidines

This work is devoted to the study of intramolecular electrophilic cyclization of a 6-alkenyl(alkinyl)thio(amino)- pyrazolo[3,4-d]pyrimidines under the action of iodine, arylsulfenyl chlorides and concentrated sulfuric acid. This study has given results, which have revealed factors that affect on regiochemistry of this cyclization. It was shown that structure of parent compound, the nature of elecrtophilic reagents and the reaction conditions have the affect on chemo- and regioselectivity of 6-alkenyl(alkinyl)thio(amino)pyrazolo[3,4 d]pyrimidines cyclization. It has been established that the direction of cyclization of 6-alkenyl(alkinyl)thio(amino)pyrazolo[3,4-d]pyrimidines depend on the strength of internal nucleophile and they steric accessibility.