Abstract:
The structural core of flavene (2-phenyl-2H-chromene) is commonly found in plant flavonoids, which exhibit a wide range of
biological activities and diverse pharmacological profiles (e.g., antioxidant and anticancer activities). Flavonoids have attracted
significant interest inmedicinal and synthetic chemistry. Substituted flav-3-ene 13 was exclusively synthesized by the stereoselective
elimination of the O-mesyl moiety on C-3 of 5,7,3,4-tetramethoxyflavan-3-mesylate 12 with 1,8-diazabicyclo[5.4.0]undec-7-ene.
The reaction of 5,7,3,4-tetramethoxyflavan-3-one 15 with ytterbium trifluoromethanesulfonate in methanol afforded a novel 3-Osubstituted
flav-3-ene derivative (3,5,7,3,4-pentamethoxyflav-3-ene) 17. The reduction of 4-(1,3,5-trihydroxybenzene)-5,7,3,4-
tetra-O-benzylflavan-3-one 19b with hydrogen afforded a new compound: 3-hydroxy-4-(1,3,5-trihydroxybenzene)-5,7,3,4-
tetrahydroxyflavan-3-en-3-ol 21 in good yield (95%), while the acetylation of 19a and 21 afforded the expected novel flav-3-en-
3-acetoxy derivatives 20 (92%) and 22 (90%), respectively.
