Syntheses of polysubstituted pyrroles and of 2,3‐disubstituted quinoxalines and substituted benzo[g]quinoxalines

Abstract

Tetraacetylethylene (1), and cis‐diacetylethylene (4) reacted under mild conditions with 3‐amino‐2‐butenoic acid methyl ester (6), benzene‐1,2‐diamine and naphthalene‐2,3‐diamine to give polysubstituted pyrroles, 2,3‐disubstituted quinoxalines and 2,3‐disubstituted benzo[g]quinoxalines respectively. Some aspects of the reactions mechanisms are discussed.

1-[(2RS,3RS)-4-Acetyl-2-hydroxy-3-(5-methoxy-4-methyl-3-phenylpyrazol-1-ylamino)-2,5-dimethyl-2,3-dihydrofuran-3-yl]ethanone

“…3,4-Diacetylhex-3-ene-2,5-dione (0.196 g, 1 mmol; Adembri et al, 1997) and 5-methoxy-4-methyl-3-phenylpyrazol-1-ylamine (0,203 g, 1 mol; Adembri et al, 1972) were dissolved in dichloromethane (10 ml) and left at room temperature for 24 h. The solid, obtained in quantitative yield, was ®ltered off and recrystallized from diethyl ether (m.p. 387 K).…”

Synthesis ofC-vinylpyrroles

“…129 Tetraacetylethylene (304) reacted with methyl 3-aminobut-2enoate (305) under mild conditions to give a mixture of dihydropyrrole 306 and tetrasubstituted furan 307. 130 Upon refluxing in methanol, the latter underwent recyclisation to produce a mixture of N-acyl-(308) and NH-pyrroles (309). 130 Condensation of 1,3-bis(dimethylamino)-2-[dimethylamino(methoxy)methyl]-1-methoxyprop-2-ene (310) with ketones 311a ± c did not furnish the expected polyenic bis(dimethylamino) ketones 312 containing the N,O-acetal groups at the g,g H positions; instead, products of their intramolecular cyclisations, viz., di[b-(N-methylpyrrol-3-yl)vinyl] ketones 313, were isolated.…”

“…130 Upon refluxing in methanol, the latter underwent recyclisation to produce a mixture of N-acyl-(308) and NH-pyrroles (309). 130 Condensation of 1,3-bis(dimethylamino)-2-[dimethylamino(methoxy)methyl]-1-methoxyprop-2-ene (310) with ketones 311a ± c did not furnish the expected polyenic bis(dimethylamino) ketones 312 containing the N,O-acetal groups at the g,g H positions; instead, products of their intramolecular cyclisations, viz., di[b-(N-methylpyrrol-3-yl)vinyl] ketones 313, were isolated. 131 ± 133 The reactions of conjugated dimethylamino ketones 314 with the compound 310 taken in an equimolar ratio proceeded analog-ously to give unsaturated amino ketones 315 containing the pyrrole ring in one of the b positions.…”