A New Diastereoselective Synthesis of Enantiomerically Pure 1,2-Oxazine Derivatives by Addition of Lithiated Methoxyallene to Chiral Nitrones

All articles of this category Addition of lithiated methoxyallene 2 to nitrones provided hydroxylamine derivatives which usually undergo very fast cyclization to 3,6-dihydro-2 H -1,2-oxazines. Chiral nitrones 5 , 8 , or 10 which furnished 1,2-oxazines 6 , 9 , and 11 with excellent syn diastereoselectivities are of particular interest. By precomplexation of nitrone 5b with diethylaluminum chloride 1,2-oxazine 6b was produced with excellent anti selectivity. The resulting 3,5-dihydro-2 H -1,2-oxazines are versatile starting materials for stereoselective syntheses of polyfunctional compounds. methoxyallene - nitrone - allenyl hydroxylamine - 1,2-oxazine