Synthesis And Transformation Of 6-Aminomethyl Derivatives Of 7-Hydroxy-2 '-Fluoroisoflavones

Mannich aminomethylation of 8-methyl-7-hydroxy-2'-fluoroisoflavones applying bis-(N,N-dimethylamino)methane afforded C-6 substituted N,N-dimethylaminomethyl derivatives. Subsequent acetylation of these compounds in acetic anhydride in the presence of potassium acetate provided access to the corresponding acetoxymethyl derivatives that were converted to hydroxymethyl- and alkoxymethyl-substituted 7-hydroxyisoflavonoids. Addition of 3-(N,N-dimethylamino)-5,5dimethyl-2-cyclohexen-1-one or 1,3-dimethyl-5-aminopyrazole with thermally generated ortho-quinone methides led to hetero-Diels-Alder or Michael adducts.