Synthesis 2017; 49(17): 3905-3915
DOI: 10.1055/s-0036-1590502
special topic
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Additions of Stabilized Carbanions to Imines Generated from α-Amido Sulfones By Using Lipophilic Salts of Chiral Tris(1,2-diphenylethylenediamine) Cobalt(III) Trications as Hydrogen Bond Donor Catalysts

Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, USA   Email: gladysz@chem.tamu.edu
,
Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, USA   Email: gladysz@chem.tamu.edu
,
Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, USA   Email: gladysz@chem.tamu.edu
› Author Affiliations
We thank the Welch Foundation (Grant A-1656) for support.
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Publication History

Received: 10 April 2017

Accepted after revision: 04 May 2017

Publication Date:
13 June 2017 (online)


Published as part of the Special Topic Cobalt in Organic Synthesis

Abstract

The enantiopure salt ∆-[Co((S,S)-dpen)3]3+ 2ClBArf [BArf = B(3,5-C6H3(CF3)2)4] is an effective hydrogen bond donor catalyst (10 mol%, r.t., CH2Cl2) for enantioselective additions of dialkyl malonates to Boc-derivatized aryl imines generated from sulfones [ArCH(SO2Ph)NHBoc] in the presence of K2CO3 (ten examples, 91–97% isolated yields, 87–99% ee). The diastereomeric salt Λ-[Co((S,S)-dpen)3]3+ 2ClBArf20 [BArf20  = B(C6F5)4 ] is similarly applied to additions of nitroalkanes (four examples, 89–93% isolated yields, 79–91% ee). Precautions to exclude air or moisture are unnecessary.

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