Pigments of fungi. XLIV* synthesis of differentially protected chiral pentane-1,3,5-triol derivatives; confirmation of the absolute configuration of naturally occurring 3-acetoxy-2,3-dihydropiptoporic acid

Abstract

(R)-1-t-Butyldimethylsilyloxy-5-phenylmethoxypentan-3-ol (25), prepared in 68% yield and >99·9% enantiomeric excess over six steps from commercially available but-3-yn-1-ol by Katsuki-Sharpless epoxidation, was converted by way of its 3-methoxymethyl ether (30) into both enantiomers (6) and (11) of methyl 3,5-diacetoxypentanoate. Direct comparison of these substances with the ester derived by oxidative degradation of the fungus pigment 3-acetoxy-2,3-dihydropiptoporic acid (1) confirmed the (R) absolute configuration of the natural product. Some new chemistry of the differentially protected chiral triols (12) and (30) is described.