Conformational Control in the Rebeccamycin Class of Indolocarbazole Glycosides

J Org Chem. 1999 Jul 23;64(15):5670-5676. doi: 10.1021/jo990296v.

Abstract

Indolocarbazole glycosides are balanced between two conformations: a "closed" conformation containing a cyclic hydrogen bond between the indolocarbazole NH and the pyranose oxygen and an "open" conformation in which the indolocarbazole NH is hydrogen bonded to solvent. The open conformation never has a commanding advantage, even in DMSO, but in nonpolar environments the cyclic conformation predominates.