Biomedical subjects
Publications and source records attributed to Lidia S Konstantinova.
Fused aromatic and heterocyclic 1,2,3,4,5-pentathiepins react with triphenylphosphine and alkynes bearing electron-withdrawing groups to give the corresponding 1,4-dithiins in high yields. Unsymmetrical alkynes add regioselectively to afford products in agreement with the electron distribution in a proposed reaction intermediate. A mechanism for these reactions is proposed.
[chemical reaction: see text]. Treatment of N-substituted 2,5-dimethylpyrroles 2 with an equilibrated mixture of disulfur dichloride and DABCO in chloroform at 0 degrees C gives pentathiepinopyrroles 3 in moderate yields; further reaction of 3 with the same mixture at room temperature leads, in an extensive reaction cascade, to bis(dithiolo)pyrroles 4 in high yield; 2 can be converted into 4 in a one-pot operation under unusually mild conditions.
Treatment of nucleophilic heterocycles like pyrroles and thiophenes, and their tetrahydro derivatives, with S2Cl2 and DABCO in chloroform at room temperature provides a simple one-pot synthesis of fused mono and bispentathiepins. N-Methylpyrrole and its 2-chloro and 2,5-dichloro derivatives and N-methylpyrrolidine all give the same dichloropentathiepin 1a. N-Ethyl, isopropyl and tert-butylpyrrolidine behave similarly; the isopropylpyrrolidine also gives the bispentathiepin 6which undergoes an intriguing rearrangement to the symmetrical monopentathiepin 1c. N-Methyl and ethyl indole give either 2,3-dichloro derivatives 8 or the pentathiepinoindoles 9, depending upon the reaction conditions. Thiophene and tetrahydrothiophene give the pentathiepin 10. X-Ray crystal structures are provided for the pentathiepins 1a and 1d, and possible reaction pathways are suggested for the extensive cascade reactions reported.
[reaction: see text] In a remarkable cascade reaction, triethylamine is converted into the thienopentathiepin 2a and the heptathiocane 3a by a preequilibrated solution of disulfur dichloride and DABCO in chloroform.
Treatment of nucleophilic heterocycles like pyrroles and thiophene, and their tetrahydro derivatives, with S2Cl2 and a base in chloroform at room temperature provides a simple one-pot synthesis of heterocyclic fused mono and bis pentathiepins such as 2, 3, 4, 5, 9, and 11.