Useful Chiral Dirhodium(II) Complex Catalyst

Hashimoto et al. have developed chiral dirhodium(II) complexes, Rh₂(R-PTTL)₄, Rh₂(S-PTTL)₄, Rh₂(R-TCPTTL)₄, Rh₂(S-TCPTTL)₄, Rh₂(R-TFPTTL)₄ and Rh₂(S-TFPTTL)₄, and reported their usefulness. According to their results, intramolecular C-H insertion reactions, 1,3-dipolar cycloaddition of carbonyl ylides and amination of silyl enol ethers are catalyzed by these dirhodium(II) complexes to proceed highly enantioselectively and give corresponding products in high yields.

Typical Procedure: ¹⁾
A solution of diazo compound 3 (60.5 mg, 0.20 mmol) and styrene (62.5 mg, 0.60 mmol) in CF₃C₆H₅ (1.0 mL) is added via syringe pump over 1 h to a stirred solution of 1b (3.95 mg, 0.002 mmol, 1 mol%) in CF₃C₆H₅ (1.0 mL). After complete addition, the reaction mixture is concentrated in vacuo, and the residue is purified by column chromatography (silica gel, hexane:EtOAc = 6:1) to provide 4 (64.5 mg, Y. 85%) as a white solid.