Reaction of tosylmethyl isocyanide with methyl 3-substituted propiolates as acetylenic Michael acceptors.

Oligosubstituted Pyrroles Directly from Substituted Methyl Isocyanides and Acetylenes

“…Methyl 2-(ethoxycarbonyl)-1H-pyrrole-4-carboxylate (3 fp): [47] The pyrrole 3 fp (73 mg, 37 %) was obtained from methyl propiolate (2 p; 84 mg, Methyl 2-(4-toluenesulfonyl)-1H-pyrrole-4-carboxylate (3 bp): [48] The pyrrole 3 bp (83 mg, 30 %) was obtained from methyl propiolate (2 p; 84 mg, 1.0 mmol) and tosylmethyl isocyanide (1 b; 195 mg, 1.0 mmol) following GP 4, after column chromatography (hexane/ethyl acetate 2:1, R f = 0.22) as a colorless solid. M.p.…”

“…The mixture was stirred at 60 8C for 16 h, then the solvent was evaporated in vacuo, and the residue was purified by column chromatography. Methyl 2-(4-toluenesulfonyl)-1H-pyrrole-4-carboxylate (3 bp): [48] The pyrrole 3 bp (83 mg, 30 %) was obtained from methyl propiolate (2 p; 84 mg, 1.0 mmol) and tosylmethyl isocyanide (1 b; 195 mg, 1.0 mmol) following GP 4, after column chromatography (hexane/ethyl acetate 2:1, R f = 0.22) as a colorless solid. M.p.…”

Silver-catalysed reactions of alkynes: recent advances

“…However, following the initial report in 1979, 79 there was a long period of silence. However, following the initial report in 1979, 79 there was a long period of silence.…”

Versatile Direct Synthesis of Oligosubstituted Pyrroles by Cycloaddition of α‐Metalated Isocyanides to Acetylenes

“…We envisaged that formal cycloaddition of an α‐metalated isocyanide 1 across a CC triple bond in an electron‐acceptor‐substituted acetylene 2 (Scheme ) might furnish a transient 2 H ‐pyrrole 4 , which would undergo a 1,5‐hydrogen shift and protonation to give a 2,3,4‐trisubstituted pyrrole 6 . Although a number of pyrrole syntheses4 from alkenes and isocyanides via pyrrolines, which contain a leaving group appropriate for elimination, have been described,5 a direct access to pyrroles from acetylenes has been elusive so far 6…”