Direct synthesis of fused 1,2,3,4,5-pentathiepins

Abstract

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.

Regioselective synthesis of pentathiepines fused with pyrrole, thiophene, or indole rings

“…These reactions with N alkylpyrrolidines gave dichloropentathiepines 4 in slightly lower yields along with pentathiepine 3a, chloro pentathiepine 8, and bispentathiepine 5 (Scheme 7). 6 It has also been demonstrated that pentathiepines 3, 5, and 8 are intermediates in the synthesis of final dichloro pentathiepines 4.…”

“…6 Thus, the reaction with reagent 2 we synthesized is more selective than the reaction with a mixture of S 2 Cl 2 and DABCO.…”

Synthesis of 1,2,5,6-tetrathiocines from fused 1,2,3,4,5-pentathiepines

“…1 We have recently developed the methods for syntheses of 1,2,3,4,5 pentathiepines fused with such heterocycles as pyrrole, indole, thiophene, and furan. 2 These syn theses are based on the reaction of these nucleophilic heterocycles with sulfur monochloride and 1,4 diazabi cyclo[2.2.2]octane (DABCO) or their complexes. 3 The chemistry of pentathiepines has previously been studied mainly for the benzofused analogs.…”

Novel fused tetrathiocines as antivirals that target the nucleocapsid zinc finger containing protein of the feline immunodeficiency virus (FIV) as a model of HIV infection

“…40,41 The DABCO activated approach used a two-step procedure, involving production of 1,2,3,4,5-pentathiepins, which underwent reduction to form fused 1,2,5,6-tetrathiocines. 42,43 This was achieved by dropwise addition of sulfur monochloride to a solution of DABCO in chloroform at -35 o C to form a 1:2 complex after 1 hour, which was followed by the addition of various heterocycles 12a-f and the reaction allowed to stir at room temperature for 48 hours yielding the corresponding pentathiepino-fused heterocycles 13a-f. [44][45][46] 13a-f were suspended in acetonitrile and treated with sodium cyanide for 1 hour after which the fused 1,2,5,6-tetrathiocines (14a-f) formed in good yield (54-74%). 47,48 When the same method was applied with compound 15 to form the asymmetric indolopentathiepine 16 two regioisomers -17, were formed as a 1:1 inseparable mixture as shown (Sch.…”