The first enantioselective hydrophosphonylation of ketimines with phosphine oxides was developed. The reaction of unprotected ketimines with phosphine oxides using a bis(imidazoline)-phosphoric acid catalyst gave chiral α-quaternary aminophosphorous compounds having a primary amino group in excellent yields and enantioselectivities. Based on experimental results and DFT calculation, transition states
Unprecedented Catalytic Asymmetric Reduction of N−H Imines
作者:Francis Gosselin、Paul D. O'Shea、Stéphanie Roy、Robert A. Reamer、Cheng-yi Chen、Ralph P. Volante
DOI:10.1021/ol047431x
日期:2005.1.1
Addition of lithium bis(trimethylsilyl)amide to perfluorinated ketones 1a-j affords (E)-N-TMS-ketimines 2a-j that are reduced in situ to afford racemic perfluoromethylated amine hydrochloride salts 3a-j in 54-97% yields. Solvolysis of the N-Si bond in MeOH leads to formation of bench-stable, isolable N-H imine Z/E isomer mixtures along with a methanol adduct. Enantioselective reduction of these three-component mixtures provides the first catalytic asymmetric synthesis of trifluoromethylated amines in 72-95% yields and 75-98% ee.
Enantioselective Rhodium‐Catalyzed Addition of Arylboroxines to N‐Unprotected Ketimines: Efficient Synthesis of Cipargamin
N-unprotected ketimines is realized for the first time by employing chiral BIBOP-type ligands with a Rh loading as low as 1 mol %. A range of chiral α-trifluoromethyl-α,α-diaryl α-tertiary amines or 3-amino-3-aryloxindoles were formed with excellent ee values and yields by employing either WingPhos or PFBO-BIBOP as the ligand. The method has enabled an efficient enantioselective synthesis of cipargamin
enantioselective Friedel–Crafts alkylation reaction of pyrroles and indoles with N‐unprotected trifluoromethyl ketimines by use of chiral phosphoric acid provided α‐trifluoromethylated primary amines bearing chiral tetrasubstituted carbon centers in high yields and with high to excellent enantioselectivities. The present reaction is unique to N‐unprotected trifluoromethyl ketimines. No reaction took place