SYNTHESIS OF NOVEL (2,3-DIHYDRO-1,4-THIASELENIN-2-YL)SULFANYL-SUBSTITUTED PHARMACOPHORIC NITROGEN HETEROCYCLES BASED ON 2-(BROMOMETHYL)-1,3-THIASELENOLE

Abstract

A new method for regioselective nucleophilic substitution at one of the three possible reaction centers of seleniranium cation, generated from 2-(bromomethyl)-1,3-thiaselenole, with mono- and bicyclic nitrogen-containing heteroaromatic thiols was developed. The reaction was directed at the carbon atom attached to sulfur atom of the intermediate seleniranium cation and was accompanied by rearrangement with ring expansion to afford in high yields new (2,3-dihydro-1,4-thiaselenin-2-yl)sulfanyl-substituted pharmacophoric heterocycles with one to four nitrogen atoms. The reaction of 2-(bromomethyl)-1,3-thiaselenole and quinoxaline-2,3-dithiol provided the corresponding 2,3-bis[(2,3-dihydro-1,4-thiaselenin-2-yl)sulfanyl] derivative. In the case of 5-methyl-1,3,4-thiadiazole-2-thiol, the reaction in MeCN led to 2-methyl-5-{[(1,3-thiaselenol-2-yl)methyl]sulfanyl}-1,3,4-thiadiazole at the expense of rearrangement of the intermediate (2,3-dihydro-1,4-thiaselenin-2-yl)sulfanyl derivative in a form of hydrobromide salt with the ring contraction proceeding via seleniranium cation. The synthesized novel sulfur- and selenium-containing functionalized unsaturated heterocycles can be considered as potential scaffolds for medicinal chemistry.