[EN] SYNTHESIS OF TETRAHYDRO-1,2-OXAZINES BY THE CYCLOADDITION OF NITRONES WITH CYCLOPROPANES [FR] SYNTHESE DE TETRAHYDRO-1,2-OXAZINES PAR CYCLOADDITION DE NITRONES ET DE CYCLOPROPANES
Highly Enantioselective and Diastereoselective Cycloaddition of Cyclopropanes with Nitrones and Its Application in the Kinetic Resolution of 2-Substituted Cyclopropane-1,1-dicarboxylates
作者:Yan-Biao Kang、Xiu-Li Sun、Yong Tang
DOI:10.1002/anie.200604645
日期:2007.5.18
Enantioselective Addition of Nitrones to Activated Cyclopropanes
作者:Mukund P. Sibi、Zhihua Ma、Craig P. Jasperse
DOI:10.1021/ja0421497
日期:2005.4.1
In this paper, we demonstrate the first examples of chiral Lewis acid catalysis in the formation of tetrahydro-1,2-oxazines with very high enantioselectivity starting with diactivated cyclopropanes and nitrones (>90% yields and ee). Reactions with racemic substituted cyclopropanes provide approximately 1:1 diastereomeric tetrahydro-1,2-oxazine products with high enantioselectivity. Mechanistic information for the formation of the tetrahydro-1,2-oxazines is also detailed.