NEW PROCESS FOR PRODUCING CATHARANTHINE AND ALLOCATHARANTHINE DERIVATIVES

Racemic or optically active katarantin of formula (Ia) or allo-katarantin of formula (Ib) derivs. are prepd. initially from 3-ethyl-pyridine and chloro-formic-acid-benzyl-ester below 0 deg.C, in the presence of sodium-borohydride in protic, pref. 1-4C alcohol, solvent. - A mixt. of N-(benzyl-oxy-carbonyl)-5 -ethyl-1,2-dihydroxy -pyridine and of N-benzyl-oxy-carbonyl) -3-ethyl-di:hydroxy -pyridine obtd. reacting in inert solvents with acrylates and by adding an alcohol, corresp. alkyl-esters are formed. The protective benzyl-oxy-carbonyl gp. is removed by acid treatment from the nitrogen atom, and the base is liberated from the acid adduct salt obtd. by addn. of an alkali. The sec. amine produced is acylated with indolyl-3-acetic-acid. Opt. the prod. and 5-oxo-derivs. also present are isolated and reduced to katarantin (Ia) and allo-katarantin (Ib) derivs. to be sep Opt. all racemic cpds. are resolved at any synthesis stage.