Asymmetric 13-dipolar cycloaddition of nitrones with ketene acetals catalyzed by chiral oxazaborolidines

✍ Scribed by Jean-Paul G. Seerden; Anita W.A. Schotte op Reimer; Hans W. Scheeren

• Book ID: 104214591
• Publisher: Elsevier Science
• Year: 1994
• Tongue: French
• Weight: 357 KB
• Volume: 35
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)73373-9

✦ Synopsis

Asymmetric 1.3-dipolar cycioad@ion of n&ones with ketenc acetals is strongly catalyzed by chiral oxazaborolidines d&ived from N-tosyl-L-a-amino acids. The 5,5dialkoxyisoxuzolidines are obtained regioselectively in high yield wish high stereoselectivity and moderate enantioselectivity up to 62% ee. Mild hydrogenoiysis of the N-O bond yields

quantitatively the corresponding &amino-ester.