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Please login or sign up for a free trial to access the full content. Variation 2: Reactions with Carbon Nucleophiles

DOI: 10.1055/sos-SD-018-00070

Braverman, S.; Cherkinsky, M.; Birsa, M. L.Science of Synthesis, (200518150.

Usually, reactions of isocyanates with carbon nucleophiles follow the general route presented in Scheme 135, and amide derivatives are formed when isocyanates are allowed to react with active methyl and methylene compounds, Grignard reagents, or lithiated compounds. A large number of such reactions have been carried out on compounds having a R1CH2CO group in which R1 is preferentially, but not necessarily, an electron-withdrawing substituent. Thus, dialkyl malonates react with phenyl and methyl isocyanate at room temperature in the presence of triethylamine or alkali to give dialkyl carbamoylmalonates 244 (Scheme 136). Heating the reaction mixture leads to consumption of two moles of isocyanate and formation of 1,3-disubstituted barbituric acid 5-carboxylates 245.[‌552‌] With 1-naphthyl isocyanate, the cyclization occurs without heating.

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