Water → Methyl 4-phenyl-1H-pyrrole-3-carboxylate

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A solution of 4-toluenesulphonylmethyl isocyanide (4.9 g, 25.2 mmol) and methyl trans-cinnamate (4.0 g, 24.7 mmol) in diethyl ether (40 ml) and dimethyl sulphoxide (20 ml) was added drop-wise over 30 minutes to a stirred suspension of sodium hydride (60% dispersion, 1.25 g, 31.3 mmol) in diethyl ether (100 ml) under nitrogen. After 20 minutes a further portion of dimethyl sulphoxide (25 ml) was added to the reaction vessel. The mixture was stirred for 1 hour then water (200 ml) was cautiously added. The product was extracted into dichloromethane (1×400 ml and 1×250 ml) then the combined dichloromethane layers were dried (Na2SO4) and the solvent removed in vacuo. The residue was purified by flash chromatography over silica gel eluting with a gradient of heptane:ethyl acetate:dichloromethane 2:1:0→1:1:1. Appropriate fractions were combined and the solvents removed in vacuo to leave 4-phenyl-1H-pyrrole-3-carboxylic acid methyl ester as a white solid (1.55 g, 31%). TLC (single spot, Rf=0.25, heptane:ethyl acetate 2:1), HPLC-MS (main UV peak with Rt=7.849 mins, 202.1 [M+H]+, 425.1 [2M+Na]+).

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