The first colchicine analogue with an eight membered B-ring. Structure, optical resolution and inhibition of microtubule assembly

Synthesis, crystal structure, enantiomeric resolution, and CD spectroscopy of the first colchicine derivative with an eight-membered B-ring lactam obtained via a Beckmann reaction, is described and only one of the stable atropisomeric enantiomers arrests microtubule assembly.