Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl ester → 2-O-tert-butyl 4-O-ethyl 5-(3-ethoxy-3-oxoprop-1-enyl)-3-methyl-1H-pyrrole-2,4-dicarboxylate

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Reaction Steps

5-Formyl-3-methyl-1H-pyrrole-2,4-dicarboxylic acid 2-tert-butyl ester 4-ethyl ester 1 b (23 g, 81.7 mmol) and (ethoxycarbonylmethylene)triphenylphosphorane (34.66 g, 99.4 mmol) were dissolved in 450 ml of tetrahydrofuran, and stirred at room temperature overnight under an argon atmosphere. After thin lay chromatography showed the disappearance of starting materials, the reaction mixture was concentrated under reduced pressure to obtain a yellow oil. The residue was dissolved in the solvent mixture of n-hexane and ethyl acetate (V:V=20:1), and purified by sand funnel decompression column chromatography to obtain the title compound 5-(2-ethoxycarbonyl-vinyl)-3-methyl-1H-pyrrole-2,4-dicarboxylic acid 2-tert-butyl ester 4-ethyl ester 1c (24 g, yield 84%) as a light yellow solid.

Provenance & Evidence