Cyclopropanation using dicarbonyl diazomethane

With a range of methods available for the formation of 1,3-dicarbonyl compounds, the dicarbonyl diazomethanes can be readily prepared via a simple diazo transfer reaction with sulfonyl azide. This has made a vast array of dicarbonyl diazomethanes available, which enhances the versatility in organic synthesis. A selection of examples from recent literature to illustrate the versatility of the cyclopropanation using dicarbonyl diazomethane in the construction of natural products as well as other biologically active compounds is described below. 

A few natural products which contain the cyclopropyl ring have been synthesized through metal catalysed cyclopropanation using dicarbonyl diazomethanes. ( )-Cycloeudesmol 63, isolated from marine alga Chondria oppositiclada, was synthesized via a sequence involving a copper catalysed cyclopropanation of a-diazo-/8-ketoester 61 to give the key intermediate 62 (equation 73)1 7,108. Similarly, the bicyclo[3.1.0]hexane derivative 65 was synthesized from the corresponding a-diazo-/8-ketoester 64 via the catalytic method and was converted into ( )-trinoranastreptene 66 (equation 74)109. Intramolecular cyclopropanation of -diazo-/i-ketoesters 67 results in lactones 68 which are precursors to 1-aminocyclopropane-l-carboxylic acids 69 (equation 75)110. 

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