protected 3-hydrazino fragment into the corresponding primary amine was also demonstrated, to expand the synthetic flexibility of asymmetric electrophilic amination with azo-dicarboxylic esters en route to enantioenriched 3-amino-2-oxindoles. The absolute configuration of 3-amino-3-phenyl-2-oxindole was independently established by electronic circular dichroism (ECD), combined with time-dependent density
Rhodium-Catalyzed Enantioselective Addition of Arylboroxines to Isatin-Derived <i>N</i>-Boc Ketimines Using Chiral Phosphite–Olefin Ligands: Asymmetric Synthesis of 3-Aryl-3-amino-2-oxindoles
作者:Yue-Na Yu、Wei-Yi Qi、Chun-Yan Wu、Ming-Hua Xu
DOI:10.1021/acs.orglett.9b02787
日期:2019.9.20
An efficient rhodium-catalyzed enantioselective arylation of isatin-derived N-Boc ketimines with arylboroxines has been developed using H8-BINOL-derived phosphite-olefin as a chiral ligand. This method allows access to a broad variety of valuable tetrasubstituted 3-amino-2-oxindole derivatives in good yields (up to 98%) with excellent enantioselectivities (up to 98% ee).
The bifunctional quinine-derived thiourea catalyst 14 was found to catalyze the direct amination of unprotected3-aryl and aliphatic substitutedoxindoles with di-tert-butylazodicarboxylate (DBAD) to construct a tetrasubstituted stereogenic carbon center at the C-3 position of oxindoles in good to excellent yield and enantioselectivity.