SYNTHESIS OF ERYTHRININ A, A NATURALLY OCCURING PYRANOISOFLAVONE

Article abstract of DOI:10.1016/S0040-4020(01)96643-8

Erythrinin A (10) has been synthesised by the oxidative rearrangement of dihydropyranochalcone 1 with thallium(III)nitrate (TTN) in trimethyl orthoformate (TMOF) to the dimethyl acetal 2, followed by cyclisation to 3, demethylation to 6 and dehydrogenation.Compound 10 could also be obtained from chalcone 4 on similar rearrangement followed by cyclisation, demethoxymethylation and dehydrogenation.In another route, chalcone 7 was oxidatively rearranged with TTN in TMOF, to 8 which on treatment with HCl yielded 10.