Chiral Calcium–BINOL Phosphate Catalyzed Diastereo‐ and Enantioselective Synthesis of syn‐1, 2‐Disubstituted 1, 2‐Diamines: Scope and Mechanistic Studies1. Issue 4 (21st November 2014)

• Record Type: Journal Article
• Authors: Lalli, Claudia; Dumoulin, Audrey; Lebée, Clément; Drouet, Fleur; Guérineau, Vincent; Touboul, David; Gandon, Vincent; Zhu, Jieping; Masson, Géraldine
• Is Part Of: Chemistry. Volume 21:Issue 4(2015)
• Page Start: 1704
• Page End: 1712
• Publication Date: 2014-11-21
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201405286
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A highly enantioselective, chiral, Lewis acid calcium–bis(phosphate) complex, Ca[<bold>3 a</bold>]_{<italic>n</italic>}, which catalyzes the electrophilic amination of enamides with azodicarboxylate derivatives <bold>2</bold> to provide versatile chiral 1, 2‐hydrazinoimines <bold>4</bold> is disclosed. The reaction gives an easy entry to optically active <italic>syn</italic>‐1, 2‐disubstituted 1, 2‐diamines <bold>6</bold> in high yields with excellent enantioselectivities, after a one‐pot reduction of the intermediate 1, 2‐hydrazinoimines <bold>4</bold>. The geometry and nature of the N‐substituent of the enamide affect dramatically both the reactivity and the enantioselectivity. Although the calcium–bis(phosphate) complex was a uniquely effective catalyst, the exact nature of the active catalytic species remains unclear. NMR spectroscopy and MS analysis of the various calcium complexes Ca[<bold>3</bold>]_{<italic>n</italic>} reveals that the catalysts exist in various oligomer forms. The present mechanistic study, which includes nonlinear effects and kinetic measurements, constitutes a first step in understanding these calcium–bis(phosphate) complex catalysts. DFT calculations were carried out to explore the mechanism and the origin of the enantioselectivity with the Ca[<bold>3</bold>]_{<italic>n</italic>} catalysts.</p> </abstract>