Wijdeven MA (Wijdeven, Marloes A.), Wijtmans R (Wijtmans, Roel), van den Berg RJF (van den Berg, Rutger J. F.), Noorduin W (Noorduin, Wim), Schoemaker HE (Schoemaker, Hans E.), Sonke T (Sonke, Theo), van Delft FL (van Delft, Floris L.), Blaauw RH (Blaauw, Richard H.), Fitch RW (Fitch, Richard W.), Spande TF (Spande, Thomas F.), Daly JW (Daly, John W.), Rutjes FPJT (Rutjes, Floris P. J. T.)
N,N-Acetals as N-acyliminium ion precursors: Synthesis and absolute stereochemistry of epiquinamide
ORGANIC LETTERS    Volume: 10    Issue: 18    Pages: 4001-4003    Published: SEP 18 2008  

Abstract: A stereoselective synthesis of (+)-epiquinamide is presented in combination with determination of the absolute configuration of the natural product. Key steps in the sequence involved chemoenzymatic formation of an enantiomerically pure cyanohydrin, reductive cyclization to the corresponding cyclic N,N-acetal, and subsequent conversion into a suitable N-acyliminium ion precursor to enable construction of the second ring.