Diastereodivergent Synthesis of Syn‐ and Anti‐9‐Hydroxyhomoisoflavanone and its Application to the Total Syntheses of (±)‐Homoferrugenone and (±)‐Portulacanone F

The diastereodivergent synthesis of syn‐ and anti‐9‐hydroxyhomoisoflavanone from various chromones and carbaldehydes is described. The synthetic approaches involving the reductive aldol reaction or the Morita‐Baylis‐Hillman reaction followed by syn‐selective 1,4‐reduction provide both diastereomers of β‐hydroxy chroman‐4‐ones in 51–98% yield with anti (2 : 1–16 : 1 anti/syn) or 22–80% yield with syn (5 : 1–48 : 1 syn/anti) diastereoselectivity. The ambiguity surrounding the stereochemistry of two 9‐hydroxyhomoisoflavanones, homoferrugenone and portulacanone F was elucidated via the first total syntheses.