Experimental and Computational Study of an Unexpected Iron-Catalyzed Carboetherification by Cooperative Metal and Ligand Substrate Interaction and Proton Shuttling

Abstract

An iron-catalyzed cycloisomerization of allenols todeoxygenated pyranose glycals has been developed. Combinedexperimental and computational studies showthat the ironcomplex exhibits adual catalytic role in that the non-innocentcyclopentadienone ligand acts as proton shuttle by initialhydrogen abstraction from the alcohol and by facilitatingprotonation and deprotonation events in the isomerization anddemetalation steps.Molecular orbital analysis provides insightinto the unexpected and selective formation of the 3,4-dihydro-2H-pyran.