Dimetalated tertiary succinamides. Synthesis of several classes of lignans including the mammalian urinary lignas enterolactone and enterodiol

Reaction of dimetalated succinamides with benzyl halides and aromatic aldehydes provides short routes to diverse lignan natural products $\text{2}$, $\text{3}$, and $\text{4a}$, including the human urinary metabolites ($\text{3d}$) and ($\text{2e}$).