Electrophilic Aromatic Deuteration of Lignans: Mostly Reliable but Occasionally Aberrant Selectivities. 
Lignans are a ubiquitous group of natural products of plant or mammalian origin.  In the human diet, especially in fiber-rich foods, there are measurable amounts of lignans.  Lignan intake is associated with a reduced risk of a range of chronic Western diseases, and in studying these compounds and their biological activity, authentic stable isotope labeled analogues are needed.  This review summarizes the reported labeling methods and discusses the selectivity and reactivity in the electrophilic aromatic deuteration of lignans where recently a number of unexpected selectivities or nonselectivities have been encountered.