Control of Regio-, Diastereo-, and Enantioselectivity in the [Ti(OTs)2(TADDOLato)]-catalyzed 1,3-dipolar cycloaddition reaction between 3-acryloyloxazolidin-2-one and nitrones

✍ Scribed by Kim B. Jensen; Kurt V. Gothelf; Karl Anker Jørgensen

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: German
• Weight: 529 KB
• Volume: 80
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19970800704

✦ Synopsis

Catalytic control of regio-, diastereo-, and enantioselectivity in the 1,3-dipolar cycloaddition of 3-acryloyloxazolidin-2-one (4) with different nitrones 2 by the application of a [TiX,(TADDOLato)] complex as the catalyst was developed (TADDOL = a,ru,a',a'-tetraary1-1,3-dioxolane-4,5-dimethanol). In the absence of a catalyst, the I,3-dipolar cycloaddition of 4 with 2 proceeded to give a mixture of regioisomers, whereas, in the presence of a catalyst, the regioselectivity of the reaction could be controlled. Three asymmetric [TiX,(TADDOLato)] catalysts were tested, and it was found that use of the [Ti(OTs),(TADDOLato)] complex gave complete regioselectivity, high 'endo'-selectivities (r 90% d.e.), and enantioselectivities corresponding to 48-70 % e.e.