Isopropylidene diazomalonate

Isopropylidene diazomalonate (1). Mol. wt. 170.13, m.p. 93-95°. This compound is prepared by diazo transfer from tosyl azide to Meldrum s acid. ... 

The effect of substituents on the temperature dependence of a-carbonyl-carbene reactivity has been examined using carbenes generated by low-temperature photolysis of methyl diazophenylacetate. A correction to the literature on the photoreaction of isopropylidene diazomalonate (98) with 1,3,3-trimethyl-cyclohexane (99) has been reported. The photoproduct, originally thought to be a cyclopropane derivative, has now been shown to be the cyclobutanone (100), the formation of which presumably involves a photo-Wolff rearrangement as illustrated in Scheme 11. Substituent effects observed in the product distribution of diazo-amide photochemistry have been ascribed to conformational factors the jS-lactam, oxindole, and Wolff rearrangement products appear to arise directly from the excited singlet state of the sym-Z form of the diazo-amide itself. 

---