Studies on the Synthesis of the Diterpenoid Mold Metabolite Sordaricin. Exploration of a Prospective Biogenetic Intramolecular Cacloaddition

Article abstract of DOI:10.1021/jo00011a027

In a model study directed toward the synthesis of the diterpenoid sordaricin 3, the main carbon skeleton was established via intramolecular <4+2> cycloaddition of the 5,5-cyclopentadienyl derivatives 24 and 30.These intermediates were prepared by two similar routes, beginning with the alkylation of either the norbornenyl ester 14 or its enantiomer with iodide 16.The oxygenated two-carbon bridge in each of the resulting adducts was then cut away by a sequence of oxidative processes to form the diene component for the cycloadditions.For 24 this began with the Bayer-Villiger oxidation (21 --> 22) and for 30, Vedejs α-hydroxylation of 27, followed by periodate cleavage.In the latter case, the benzyloxy group was introduced into the dienophile moiety by selective epoxidation of the isopropenyl group followed by amide-initiated elimination.