A Facile Synthesis of 3-Substituted-2-aminothiophenes and 1,3-Disubstituted-2-methylthiopyrroles

Abstract

Electron-rich 3-functionalized-2-aminothiophenes 6 and 1,3-disubstituted-2-methylthiopyrroles 10 were synthesized from substituted allyl benzotriazoles 2 and isothiocyanates 3 via condensation and subsequent heterocyclization.

A General and Mild Copper(I)‐Catalyzed Three‐Component Reaction of Cyanamides, Amines, and Diaryl­iodonium Triflates

“…For example, arylphenyliodoniums with tert ‐butyl, amido, iodo, and nitro groups all generated the corresponding guanidines in yields of 96, 89, 80, and 88 %, respectively (Table 3, entries 7–10). Guanidylthiophene 5d , which is unstable relative to 2‐aminothiophene,9 could not be obtained in the oxidative three‐component reaction of cyanamides, amines, and boronic acids;8f however, the reaction of phenyl(thienyl)iodonium triflate produced desired guanidylthiophene 5d in moderate yield (Table 3, entry 11). Clearly, the regioselectivities for unsymmetric arylphenyliodoniums with aryl groups with different electronics were dependent on the substrates without certain regulation (Table 3, entries 7–11); this is somewhat different from previous transition‐metal‐catalyzed reactions of diaryliodonium, for which more electron‐rich aryl groups are generally the preferred transfer groups 10.…”

Benzotriazole-Mediated Synthesis of Nitrogen-Containing Heterocycles

“…Treatment of 118 with a Lewis acid resulted in cyclization to 2-(methylthio)pyrroles 119. The low stability contributed to the low yields of the electron-rich pyrroles during purification (Scheme 41) [107].…”

1,2,3-Triazoles

“…Addition of lithiated allylbenzotriazoles 453 to the C N bond of isothiocyanates leads to thioamides 470 . Catalyzed by ZnBr 2 , thioamides 470 undergo cyclization to aminothiophenes 469 <2001JOC2850> . When the nucleophilic attack of the sulfur atom on the allylic system is blocked by methylation as in compound 471 , the nitrogen atom takes the leading role and 2-(methylthio)pyrroles 472 are formed instead.…”