Radical Cyclisation Based Approach to Lignans. Synthesis of 4-Arylmethyldihydrofuran-2-Ones

Bromoacetalisation of the cinnamyl alcohols 7a–d, obtained from the corresponding benzaldehydes, generated the bromoacetals 10a–d. The 5-exo trig radical cyclisation of the bromoacetals 10a–d followed by one step hydrolysis-oxidation of the resulting cyclic acetals 11a–d furnished the title compounds 6a–d, respectively, well-established intermediates of a variety of lignans.