On Regioselectivity of Aldol Condensation of Aromatic Aldehydes with Borate Complex of Acetylacetone

Abstract While cinnamoyl acetone 1 is obtained in good yield by a condensation of 3 molar excess of a borate complex of acetylacetone with benzaldehyde, products of Knoevenagel condensation 2 are predominantly obtained with furfural and 5-substituted furfurals. Cinnamoyl acetone 1 can be further condensed with furfural to form unsymmetrical curcuminoid 5. Compound 2a does not produce any new products under the same conditions. Compounds 3 and 5 are good inhibitors of growth of protozoan Trichomonas vaginalis.