2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → Dimethyl 4-ethyl-6-methoxy-3-(4-methoxyphenyl)pyrrolo[2,1,5-cd]indolizine-1,2-dicarboxylate

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Reaction Steps

A solution of 1-ethyl-7-methoxy-2-(4-methoxyphenyl)indolizine (25.0 g, 0.089 mol) in 800 ml of toluene was stirred in an ice bath, while dimethyl acetylenedicarboxylate (12.6 ml, 0.103 mol) was added dropwise. When the starting material had been consumed according to TLC, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (21.18 g, 0.093 mol) was added in portions. When the addition was complete, the mixture was refluxed for one hour. The resulting hydroquinone was filtered off, and the filtrate was concentrated to dryness. The residue was triturated with petroleum ether (40-60) and isolated to afford 33.8 g (92%) of the title compound. M.p. 153-5° C. 1H-NMR (DMSO-d6, 200 MHz) δ: 1.36 (t, 3H), 3.07 (q, 2H), 3.76 (s, 3H), 3.86 (s, 3H), 3.89 (s, 3H), 4.10 (s, 3H), 7.15 (d, 2H), 7.53 (d, 2H), 7.84 (d, 1H), 8.00 (d, 1H). (Compound 1).

Provenance & Evidence