Heterocycles. XXV. Sodium Borohydride Reduction of Flavanonols
Solvent effects on the stereochemistry in the sodium borohydride reduction of (+/-)-flavanonols have been examined.The effects observed for the (+/-)-flavanonols with 5-OMe in 2-propanol, dioxane and methanol are explainable by the differences between the steric interactions inherent in the product-like transition states A and B.It has been also found that 5-OAc peculiarly affects the stereochemistry in the reduction to produce the (+/-)-catechin-type compounds in a one-pot process.The solvent and temperature effects are examined using a model analogous to the above.
