Synthesis of the fusicoccin H aglycone. Construction of the carbon framework

Abstract

The symmetrical cyclo-octanedione (4) has been synthesized and its stereochemistry determined; cyclisation of the derived triketone (5) led to the functionalised becyclo[6.3.0]undecene (12) which embodies the B/C ring system of the fusicoccin structure, and regiospecific alkylation of (4) with 4-iodobutyl benzoate to give (13) was followed by appropriate transformations to yield the A/B fragment (16).