1-Propene, 1,1-diethoxy- → methyl trans-4-acetylamino-2,2-diethoxy-3,6-dimethyl-3,4-dihydro-2H-pyran-5-carboxylate

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Reaction Steps

1,1-Diethoxyprop-1-ene (5.0 ml) was added in one portion to a stirred solution of methyl-2-acetylaminomethylene-3-oxobutanoate (5.2 g) in toluene (15 ml) at 20°-25° C. An exothermic reaction ensued and a crystalline solid precipitated out. The reaction mixture was stirred for 2 further hours at ambient temperature and the solid was then filtered off to give methyl trans-4-acetylamino-2,2-diethoxy-3,6-dimethyl-3,4-dihydro-2H-pyran-5-carboxylate (4.0 g), m.p. 152°-154° C. The structure of this ester was ascertained using X-ray analysis. The n.m.r. spectrum in deuterochloroform showed a signal for the --CH(N)--proton at 4.85 ppm (doublet of doublets of quartets, J3,4 =1.5, J4,NH =9.8, J4,7 =0.9 Hz, C6Me=C7).

Provenance & Evidence