An improved total synthesis of (±) - podocarpic acid by a cyclialkylation route

Abstract

A number of total syntheses of (±) - podocarpic acid (i) have been described King, King and Topliss first identified one of the products from nonstereo-selective cyclization of (4) with polyphosphoric acid as (±)- ethyl-O-methylpodocarpate (2) and correlated that with the corresponding acid (3), prepared in an extremly poor yield (ca 0.4%) by Bhattacharyya, and Haworth and Moore by cyclization of (5) with a mixture of sulfuric acid and acetic acid. More recently Mancini, Fringuelli and Taticchi prepared (3) (in 4.8% yield) by repeating Howorth s cyclization of (4). In continuation of our studies on cyclialky.