C-alkylation by 3-diazopropene, and the function of diazoalkanes as nitrogen bases
Abstract
3-Diazopropene alkylates 3-cyanocoumarin, giving 4-allyl-3-cyanocoumarin. The pyrazole formed by isomerisation of 3-diazopropene slowly adds to 4-allyl-3-cyanocoumarin, giving 3-cyano-4-[2-methyl-2-(pyrazol-1-yl)-ethyl]coumarin (III), this addition being catalysed by 3-diazopropene acting as a nitrogen base.