Site- and stereoselective synthesis of bridgehead tetrahydropyrrolo [2,3-c]pyridines from ketoximes and acetylene gas in two synthetic operations

摘要

3H-Pyrroles, synthesized in one-pot from ketoximes and acetylene gas in a KOH/DMSO system, undergo [4 + 2] cyclodimerization in the presence of t-BuOH (closed vessel, autogenic pressure, 140 degrees C, 8 h) to site- and stereoselectively afford partially hydrogenated bridgehead pyrrolo[2,3-c]pyridines in 15-60% yield. An essential feature of this synthesis is the activating effect of t-BuOH which is attributed to reversible H-bonding of the 3H-pyrroles. (C) 2019 Elsevier Ltd. All rights reserved.