Experiments on the synthesis of tetracycline. Part II. The synthesis of potential ring a and ring C–ring D components

Abstract

The preparation of 3,4-dihydro-2-phenylnaphtho[1,8-bc]furan-5-one and methyl 6-acetoxy-4-diacetoxymethyl-benzisoxazole-7-carboxylate, as precursors of the CD ring system and of ring A, respectively, is described. Their condensation to a tricyclic ACD compound and subsequent attempts to transform this into 4-de(dimethylamino)-4a, 12a-anhydrotetracycline are presented.