| Abstract
| - The reaction of 10 carboxamides activated by two β-electron-withdrawing groups, which mostlyexist completely or partially in their enol forms, with diazomethane was investigated. The mainoutcome is the diversity of reactions observed. With the most acidic enols 3−7, activated by atleast one trifluoroethoxycarbonyl group or a cyano group, O-methylation or O,N-dimethylation takesplace. With β-dimethoxycarbonyl-activated systems 5 and 8, the C-methylation product of the amideform was one of the products. With a Meldrum's acid anilide enol 2, a cleavage took place leadingto the C-alkylated imine having a CH(CO2Me)2 group. Exchange of one 2,2,2-trifluoroethoxycarbonylby a methoxycarbonyl in the C,N-dimethylation product of Me2CHNHC(OH)C(CO2CH2CF3)24took place. The 2-anilido-1,3-cyclopentanedione 10 was methylated on a ring carbonyl while theenol of the 1,3-indanedione analogue 11 reacted with three diazomethane molecules and underwenta ring expansion and O-methylation to the 3-anilido-1,4-dimethoxynaphthalene. It is suggestedthat the reaction initiates by protonation of the diazomethane by the enol and an approximatequalitative relationship exists between the acidity of the enol and Kenol and the regioselectivity ofthe reaction.
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