Synthesis of Sterically Hindered Chiral 1,4-Diols from Different Lignan-Based Backbones

Methods for synthetic modifications of the natural dibenzylbutyrolactone lignan hydroxymatairesinol into chiral 1,4-diols with different lignan-derived backbones have been developed. A stepwise procedure, involving alkylation and oxidation, was shown to be successful and several highly substituted 1,4-diols were prepared. Some substituted butyrolactones resisted alkylation and led to the formation unusually stable hemiketals (butyrolactols). The formation of stable hemiketals was investigated in detail, showing that different backbone structures influence the formation and reactivity of the hemiketals.