SYNTHESES OF GAMMA-OXO ACIDS OR GAMMA-OXO ESTERS BY PHOTOOXYGENATION OF FURANIC COMPOUNDS AND REDUCTION UNDER ULTRASOUND - APPLICATION TO THE SYNTHESIS OF 5-AMINOLEVULINIC ACID HYDROCHLORIDE

The photooxygenation of 5-hydroxymethyl-2-furfural (1a) or derivatives 1b-g yields 4-hydroxy-Delta(2)-butenolides 2 which are the percursors of butenolides 3 or alpha,beta-unsaturated gamma-oxo esters 5. The se lective reduction of olides 2 or oxo esters 5 with zinc in acetic acid under sonication leads to gamma-oxo acids 4 or gamma-oxo esters 6. Th e photooxygenation of amino derivative 1d, followed by selective reduc tion of corresponding lactone 2d, gives 5-aminolevulinic acid hydrochl oride (7) (ALA) after hydrolysis.