Rate acceleration of the Baylis-Hillman reaction in polar solvents (water and formamide). Dominant role of hydrogen bonding, not hydrophobic effects, is implicated.

摘要: A substantial acceleration of the Baylis-Hillman reaction between cyclohexenone and benzaldehyde has been observed when is conducted in water. Several different amine catalysts were tested, as with reactions absence solvent, 3-hydroxyquinuclidine was found to be optimum catalyst terms rate. The extended other aldehyde electrophiles including pivaldehyde. Attempts extend this work acrylates only partially successful rapid hydrolysis methyl ethyl occurred under base-catalyzed water-promoted conditions. However, tert-butyl sufficiently stable couple relatively reactive electrophiles. Further studies on use polar solvents revealed that formamide also provided significant 5 equiv (optimum amount) gave faster rates than Using formamide, further achieved presence Yb(OTf)(3) (5 mol %). scope new conditions tested a range Michael acceptors acrylate. origin rate discussed.