Chondria oppositiclada cycloeudesmol from

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. 

A very neat intramolecular Diels-Alder route has been developed for the synthesis of the ketone (466) which can be converted into selina-3,7(ll)-diene (467) (Scheme 58). Attempts to synthesize the cycloeudesmol obtained from the marine alga Chondria oppositiclada Dawson have so far not been successful. 

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