Neue Synthese von Vinblastinderivaten; 20′‐Deethyl‐20′‐deoxyvinblastin und 20′‐Deethyl‐20′‐deoxy‐C′‐homovinblastin Vorläufige Mitteilung

A New Synthesis of the Vinblastine Derivatives 20′‐Deethyl‐20‐deoxyvinblastine and 20′‐Deethyl‐20′‐deoxy‐C′‐homovinblastine A new synthesis of vinblastine derivatives is described. In the key step, the chloroindolenine derivative 14 was reacted with vindoline ( 2 ) to give, after cyclization, stereospecifically 17/I and 20′‐deethyl‐20′‐deoxyvinblastine ( 17/II ). In an analogous manner, the epimeric C′‐homovinblastine derivatives 21/I‐21/IV were synthesized.