Stereoselective reactions. 26. Solution structures of chiral bidentate lithium amide in relation to the solvent-dependent enantioselectivities in deprotonation reaction

✍ Scribed by Daisaku Sato; Hisashi Kawasaki; Ichio Shimada; Yoji Arata; Kimio Okamura; Tadamasa Date; Kenji Koga

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 516 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)00422-5

✦ Synopsis

6Li-and 15N-NMR spectroscopic analyses of a labeled chiral bidentate lithium amide ([6Li, 15N2]-(R)-I) have shown that it exists as a chelated monomer (5) in THF and in DME, as a chelated dimer (6) in toluene and in ether, while as a chelated monomer (5) in any of these solvents in the presence of 2 equivalents of HMPA.

Solvent-dependent enantioselectivities in deprotonation of 4-tert-butylcyclohexanone (2) by (R)-I appear to be correlated to these solution structures.