Selective Catalytic Hydrogenations and Hydrogenolyses VIII [1]: Stereoselective Synthesis of the Stereomeric Pilopyl Alcohols

Summary.  The stereoselective synthesis of pilopyl- and isopilopyl alcohol is reported. The reaction of dimethyldioxanone and diethoxyphosphoryl-butyric acid ethyl ester afforded the corresponding dioxanylidenbutyric acid ester as the key intermediate. Upon treatment with mineral acid it cyclized giving 3-ethyl-4-hydroxymethylfuran-2-one which in turn could be converted either to 3-ethyl-4-methylfuranone or pilopyl alcohol with excellent stereoselectivity and quantitative chemical yield. On the other hand, hydrogenation and subsequent cyclization of the same key compound furnished isopilopyl alcohol with good stereomeric purity and yield. Corresponding author. E-mail: ebrei@cup.uni-muenchen.de Received April 3, 2002; accepted April 9, 2002