Diastereo- and enantioselective tandem Michael addition and lactonization between silyl enolates and α,β-unsaturated ketones catalyzed by a chiral quaternary ammonium phenoxide

Chemistry Letters

Volumn 35, Issue 4, 2006, Pages 360-361

  Tozawa, Takashi ^a   Yamane, Yoshinobu ^a   Mukaiyama, Teruaki ^a  

^a NONE

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EID: 33745856227     PISSN: 03667022     EISSN: None     Source Type: Journal    
DOI: 10.1246/cl.2006.360     Document Type: Article

References (5)

1. T. Tozawa, Y. Yamane, T. Mukaiyama, Chem. Lett. 2006, 35, 56.
2. 1H NMR analysis and elemental analysis (see Ref. 1).
3. 1H NMR chemical shift of the characteristic vinyl proton, which resonates at a lower magnetic field in the cis-isomer than in the trans-isomer. See: T. Tozawa, Y. Yamane, T. Mukaiyama, Chem. Lett. 2005, 34, 514.
4. 3) δ 168.9, 149.8, 141.3, 132.0, 129.0, 128.9, 128.4, 127.2, 127.0, 124.5, 101.9, 54.3, 41.2, 29.1, 21.1, 20.1. The enantiomeric excess was determined by HPLC analysis using a DAICEL Chiralpak AD-H, hexane/2-propanol = 50/1, λ = 254 nm, flow rate = 1.0 mL/min, retention time = 15.0 min (major) and 16.7 min (minor).
5. -3, T = 298 K. X-ray intensities were measured on a Rigaku AFC7R diffractometer with CuKα radiation (λ = 1.54178 Å), R = 0.030.