Cyclosulfenylation of 3-allylthiohydantoin

Abstract

New fused derivatives – 2-(arylsulfanylmethyl)-2,3,5,6-tetrahydroimidazo[2,1-b][1,3]thiazol-7-onium perchlorates have been synthesized by the cyclosulfenylation reaction of 3-allylthiohydantoin in highly polar nitromethane in the presence of an equimolar amount of lithium perchlorate as “doping-additive”. Their structures have been reliably proven by spectral characteristics. In particular, annelation of the tetrahydrothiazolonium cycle is confirmed by multiplet signals of diastereotopic protons of the CH2-group in position C3 at 3.87-4.04 ppm and the CH-group in position C2 at 4.67-4.77 ppm in 1H NMR-spectra. Thethiazolonium salts obtained were converted to the corresponding free bases – 2-(arylsulfanylmethyl)-2,3-dihydroimidazo[2,1-b] [1,3]thiazole-5(6H)-ones by the interaction with the aqueous solution of sodium acetate at the room temperature. According in their 1H NMR spectra, protons of CH-group in position 2 resonates in a stronger field (0.4-0.5 ppm) compared to the original substrates. Imidazothiazolonium perchlorates are labile to HN-nucleophiles, and under the action of the excess of the secondary amine (morpholine or piperidine) there is the disclosure of an amide bond in the imidazolidine cycle. It leads to formation of thiazolidine derivatives with arylsulfanyl fragments. Preservation of the thiazolidine nucleus in the process of opening the imidazole cycle has been confirmed by spectral characteristics of the compounds obtained.