Synthesis and Bioactivity of Isosteviol Derivatives: A Facile Method for Preparation of Ent-16α-hydroxy-15β-hydroxymethylbeyeran-19-oic Acid

In this paper, two new compounds, ent-l6α-hydroxy-15β-hydroxymethylbeyeran-19-oic acid 4 and its ethyl ester 5 were synthesized in good yield with a facile method that has never been reported. The mechanism of this reaction was discussed and the mono-hydroxymethylation of carbonyl compound with two α-hydrogens via Tollens' reaction was firstly achieved. Compounds 2-5 were tested for activity of inhibition against glycosidases, among which 5 displays good inhibition of β-glucosidase and α-mannase, respectively.