A novel, C2-symmetric, chiral bis-cyclosulfinamide-olefin tridentate ligand in Rh-catalyzed asymmetric 1, 4-additions. Issue 29 (18th July 2018)

• Record Type: Journal Article
• Authors: Zhang, Li; Tan, Mingchao; Zhou, Lihong; Zeng, Qingle
• Is Part Of: Tetrahedron letters. Volume 59:Issue 29(2018)
• Page Start: 2778
• Page End: 2783
• Publication Date: 2018-07-18
• Subjects: Asymmetric catalysis -- Chiral tridentate ligand -- Bis-cyclosulfinamide -- 1-Oxo-2, 3-dihydro-1, 2-benzisothiazole -- Asymmetric 1, 4-addition; OIIBYKBJPMVAST-PESMWXFUSA-N -- CKDBPHXKIGVKRP-ZEQRLZLVSA-N -- OKKIKRICMVKKHG-ZFTMLNQLSA-N; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2018.06.008
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: A novel chiral bis-cyclosulfinamide-olefin tridentate ligand (DICSO) achieved extremely high enantioselectivities (>99%ee). The DICSO is more superior to its structure-similar bidentate ligands. The DICSO ligand has two rigid (S)-1-oxo-2, 3-dihydro-1, 2-benzisothiazole skeletons and a flexible butenylene chain. HRMS and NMR analyses verify that the DICSO as a tridentate ligand coordinates to rhodium(I) to form a complex. Abstract: A C2 -symmetric, chiral bis-cyclosulfinamide-olefin ligand composed of two 1-oxo-2, 3-dihydro-1, 2-benzisothiazole moieties with rigid skeletons and a conformationally flexible butenylene chain is disclosed for the first time. HRMS and 1 H NMR analyses verify that the in situ-generated complex of the ligand and [Rh(C2 H4 )2 Cl]2 possesses a rhodium (I) center coordinated to the tridentate ligand via two sulfinyl moieties and a CdbndC bond. The chiral ligand provided extremely high enantioselectivity (up to >99%ee) in the Rh-catalyzed asymmetric 1, 4-additions of arylboronic acids to cyclohexenone and cyclopentenone. The tridentate ligand gave much higher enantioselectivity than the analogous chiral bidentate ligands.