Synthesis of Furofuran Lignans

ABSTRACT This review covers synthetic routes to lignans belonging to the 2,6-disubstituted dioxabicyclo[3.3.0]octane subclass (also known as furofurans). The different approaches have been loosely categorised according to the synthetic strategies applied. The routes discussed range from the classical biomimetic oxidative coupling of cinnamyl derivatives to more recent asymmetric syntheses. 1 Introduction 2 Synthetic Routes to Furofurans 2.1 Oxidative Dimerisation of Cinnamyl Alcohols and Cinnamic Acids and Enolate Anions 2.2 Approaches Based on Conjugate Addition of Acyl Anion Equivalents 2.3 Approaches Based on Aldol Chemistry 2.4 Approaches Based on Cycloaddition/Rearrangement 2.5 Radical and Photochemical Strategies 2.6 Transition Metal Mediated Strategies 3 Concluding Remarks