Enantio- and diastereoselective michael reactions of silyl enol ethers and chalcones by catalysis using a chiral quaternary ammonium salt

Organic Letters

Volumn 3, Issue 4, 2001, Pages 639-641

  Zhang, Fu Yao ^a   Corey, E J ^a  

^a HARVARD UNIVERSITY   (United States)

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EID: 0001667250     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol015592k     Document Type: Article

References (7)

1. Zhang, F.-Y.; Corey, E. J. Org. Lett. 2000, 2, 1097.
2. + 347.1447, found 347.1448. The ee value was determined by HPLC analysis at 23°C with a Chiralcel OD column, 5% isopropyl alcohol in hexanes, 1.0 mL/min, λ = 254 nm; retention times, minor 26.7 min; major 36.9 min.
3. 3OD) δ 149.9, 147.6, 146.7, 133.6, 132.5, 131.8, 130.1, 130.0, 129.9, 129.2, 128.7, 128.1, 128.0, 127.9, 125.4, 125.3, 125.2, 125.1, 124.6, 123.9. 123.3, 120.4, 118.2, 68.6, 66.0, 64.4, 55.5, 52.2, 36.5, 26.3, 25.6, 23.8, 21.6, 10.4 ppm.
4. 4, can be obtained, on request, from the Director, Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, U.K.
5. (a) Corey, E. J.; Noe, M. C.; Xu, F. Tetrahedron Lett. 1998, 39, 5347.
6. (b) Corey, E. J.; Zhang, F.-Y. Org. Lett. 1999, 1, 1247.
7. 3) δ 203.7, 198.4, 140.9, 136.9, 136.8, 133.6, 133.3, 131.8, 130.4, 129.1, 128.8, 128.6, 128.4, 120.8, 45.7, 44.0, 43.5, 16.9 ppm. The ee value was determined by HPLC analysis with a Chiralcel OD column, 10% isopropyl alcohol in hexanes, 1.0 mL/min, λ = 254 nm; retention times, minor 10.5 min, major 12.4 min. The absolute configurations of the chiral centers were determined by X-ray analysis, which demonstrated the structure shown in Figure 1.