Synthesis of Exogonic Acid and Related Compounds

Article abstract of DOI:10.1021/jo00270a031

Hydroxymercuration, cyclization, and reduction of appropriate hydroxy ketones or enones carrying a suitably located α,β-unsaturated ester function is an efficient route to exogonic acid (2-(carboxymethyl)-7-methyl-1,6-dioxaspiro<4.4>nonane), a resin constituent of the Brazilian tree Ipomoea operculata (Martin), and related <4.5> and <5.5> spiroketal systems.Procedures incorporating stereocontrol at C-2 and C-7 of exogonic acid are also reported and involve sequential alkylation with epoxypropane and 1,2-epoxy-4-(tetrahydropyranyloxy)butane of anions (or dianions) derived from methyl acetoacetate or acetone dimethylhydrazone.