The Mannich reaction has been used for decades to prepare many pharmaceutically important molecules. Here, using a "double-Mannich-β-elimination" synthetic sequence, we report the synthesis and the characterization details of a novel class of β-amino diaryldienones with prominent antiprostate cancer activity. Through these studies, we correct an erroneous structure in the current literature, present a discussion of the stereochemical outcome of a new reaction, and probe the mechanism(s) of byproduct formation through isotopic studies.