Acid-induced rearrangements of polycyclic β-hydroxy acids and their esters

The work describes acid-catalyzed transformations of (homo)adamantane, terpenoids and related structure-derived γ-branched β-hydroxy acids and their esters, synthesized via the Reformatsky reaction using the corresponding carbonyl compounds. Under acidic conditions, these substrates can dehydrate and then undergo functional group-assisted Wagner-Meerwein-type rearrangement or other cascade transformations. The direction of the process is determined by numerous factors including the relationships of ring strain and molecular topology of substrates and possible products. This study focuses on the synthesis of fused bridged γ-lactones and explores the factors that affect the fate of different substrates under acidic conditions. The synthesized complex lactone scaffolds are relevant to medicinal chemistry as synthetic or metabolic precursors of the corresponding GABA analogues and racetams.