SYNTHESIS OF 2'-HYDROXYCHALCONE EPOXIDES

Various preparations of some 2'-tetrahydropyran-2-yloxychalcone epoxides and removal of their tetrahydropyranyl (THP) protective groups in slightly aqueous acidic dioxane are described. So synthesised were 2'-hydroxy-6'-isopropoxy- and 2'-hydroxy-6'-methoxychalcone epoxide, as well as the 2-CF3, 4-Cl and 4-NO2 analogues of the latter. 2',4'-dihydroxy-6'-methoxychalcone epoxide was similarly prepared. In some other 6'-methoxy cases protective group removal was accompanied by epoxide solvolysis and the corresponding alpha,beta-dihydroxydihydrochalcone was the only isolable product [2-OMe, 4-OMe, 3,4,5-(OMe)3 cases] or a byproduct [4-Me case]. Similarly prepared by THP removal were 2'-hydroxy-4'-methoxychalcone epoxide and 2',4'-dihydroxychalcone epoxide, whereas an attempt to convert 2',6'-ditetrahydropyranyloxychalcone epoxide into 2',6'-dihydroxychalcone epoxide gave the product of cyclisation of the latter, 3,5-dihydroxyflavanone.