A New Synthesis of (+/-)-Dihydrorecifeiolide

Article abstract of DOI:10.1002/hlca.19860690605

Ethyl 1-(2'-formylethyl)-2-oxocyclooctane-1-carboxylate (2) prepared by Michael reaction of ethyl 2-oxocyclooctane-1-carboxylate (1) was regioselectively methylated at the aldehyde group with (CH3)2Ti2 to give 3 (Scheme 1).The alcohol 3 was treated with Bu4NF to give the deethoxycarbonylated product 4 which by distillation gave the bicyclic enol ether 5.Oxidation (m-chloroperbenzoic acid) of 5 and reduction of the resulting oxolacton 6 yielded the title compound (+/-)-dihydrorecifeiolide (7) in an overall yield of nearly 50 percent.Methylation of the aldehyde 2 with MeLi gave the ring-enlarged lacton 9 in poor yield (13 percent).The deethoxycarbonylation reaction 3 -> 4 was studied in more detail (Scheme 3).