A New Diastereoselective Synthesis of Enantiomerically Pure 1,2-Oxazine Derivatives by Addition of Lithiated Methoxyallene to Chiral Nitrones
作者:Wolfgang Schade、Hans-Ulrich Reissig
DOI:10.1055/s-1999-2662
日期:1999.5
Addition of lithiated methoxyallene 2 to nitrones provided hydroxylamine derivatives which usually undergo very fast cyclization to 3,6-dihydro-2H-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
将锂化的甲氧基丙二烯 2 加成到硝酮提供了羟胺衍生物,其通常会非常快速地环化为 3,6-二氢-2H-1,2-恶嗪。提供具有优异顺式非对映选择性的 1,2-恶嗪 6、9 和 11 的手性硝酮 5、8 或 10 尤其令人感兴趣。通过硝酮 5b 与二乙基氯化铝的预络合,1,2-恶嗪 6b 具有优异的抗选择性。所得的 3,5-二氢-2H-1,2-恶嗪是用于立体选择性合成多官能化合物的通用起始材料。