Syntheses of 2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecanols

Abstract

Synthetic approaches to ring- and side-chain hydroxy derivatives of the 2-ethyl-8-methyl-1,7-dioxaspiro-[5.5]undecane system 8 are described. Alkylation reactions of diethyl 3-oxopentanedioate, pentane-2,4-dione and acetone N,N-dimethylhydrazone have been employed. Appropriate choices of enantiomeric iodides in the alkylation sequences, sometimes followed by asymmetric dihydroxylation of derived hydroxyenones, have permitted access to key enantiomers of these alcohols, which have been fully characterised by ¹H and ¹³C NMR spectroscopy, gas chromatographic–mass spectrometric methods, and chiral gas chromatography.