Acetic Acid → 2-Butenoic acid, 3-amino-, ethyl ester, (2Z)-

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Reaction Steps

A mixture of 2-nitrobenzaldehyde (6.8009 g), methyl 4,4-dimethoxyacetoacetate (8.7204 g), acetic acid (0.5405 g) and piperidine (0.4598 g) in benzene (30 ml) was heated to reflux for 2 hours under azeptropic dehydration. The reaction mixture was diluted with benzene (100 ml), washed twice with water, and in turn with diluted aqueous sodium bicarbonate solution and water, dried over magnesium sulfate and evaporated to dryness under reduced pressure to give crude oily methyl 2-(2-nitrobenzylidene)-4,4-dimethoxyacetoacetate (15.23 g). A mixture of thus obtained crude oil (15.23 g) and ethyl 3-aminocrotonate (6.6840 g) was heated at around 65° C. for 6 hours and then at 98° to 100° C. for 5 hours. The resultant viscous brown oil was dissolved in ethyl acetate, washed three times with water, dried over magnesium sulfate and evaporated to dryness under reduced pressure to give brown oil (19.40 g). The residual oil was crystallized by trituration with methanol (10 ml) to give yellowish crystalline powder (12.77 g) of ethyl 2-methyl-4-(2-nitrophenyl)-5-methoxycarbonyl-6-dimethoxymethyl-1,4-dihydropyridine-3-carboxylate. An additional 0.53 g of crystals was recovered from the mother liquor. Recrystallization from methanol gave yellowish granules, m.p. 122°-124° C.

Provenance & Evidence