Crystal and molecular structure and absolute configuration of maytansine (3-bromopropyl) ether

Abstract

The molecular structure and absolute configuration of maytansine (Ia) have been found from a three-dimensional single-crystal X-ray analysis of its (3-bromopropyl) ether (Ib). Crystals are orthorhombic, space group P2₁2₁2₁ with a= 24·239(4), b= 16·044(4), c= 10·415(2)Å, and Z= 4. The structure was solved by the heavy-atom method and refined by Fourier and least-squares methods to R 0·101 for 927 independent reflections measured by counter diffractometry. The absolute configuration was established by the anomalous dispersion method.

The molecule contains a 19-membered ring with the nitrogen-containing aliphatic portion bridging a substituted phenyl group in a 1,3-ansa-fashion. The structure shows similarities to those of the ansamycin antibiotics, but has novel epoxide, carbinolamine ether, and aryl halide functions.