A general and efficient route to the marasmane skeleton is described. Total syntheses of two simple marasmanes (35 and 37) in racemic form were achieved using a MgI2-catalyzed rearrangement-cyclopropanation reaction of trimethylsilyl enol ether 31 derived from naphthalenone 30. The reaction proceeds in high yield with complete diastereoselectivity and does not require the use of special cyclopropanation reagents. Application of this novel route to the marasmane framework was extended to the synthesis of naturally occurring (+)-isovelleral (41).

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The synthesis of cyclopropane derivatives via a MIRC reaction of azidirinyl-methylenemalonates is described. In this way it is possible to introduce a hydrogen, a phenylthio, a tributylstannyl and an olefinic function at the cyclopropane ring, that further contains an alkylamino substituent, Addition of CuCN catalyzed Grignard reagents gave the most promising results. The diastereoselectivity was dependent on the aziridine nitrogen substituent and the bulkiness of the reagent.

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It is observed that mesylate 1 on exposure to Li(Ot-Bu)(3)AlH in refluxing toluene rearranges selectively to the 11-oxatricyclo[5.3.1.0(2,6)]undecane derivative 3. A similar rearrangement, leading to a bridged tricyclic ether (14 --> 5), has been used as the key to the total synthesis of furanether B (4), a naturally occurring lactarane sesquiterpene, with the readily available ketone 8 as the starting material. Completion of the synthesis of the natural product is accomplished by an annulation method based on a Pummerer-induced cyclization reaction.