(Passerini-type reactions). The catalytic system of silicon tetrachloride and a chiral bisphosphoramide (R,R)-1b provided high yields and good to excellent enantioselectivities for the addition of tert-butyl isocyanide to a wide range of aldehydes (aromatic, heteroaromatic, olefinic, acetylenic, aliphatic). Aqueous workup afforded the α-hydroxy tert-butyl amides whereas a low-temperature methanol quench followed
已经证明了
异氰酸酯催化醛的对映选择性α-加成反应的普遍性(Passerini型反应)。
四氯化硅和手性双
磷酰胺(R,R)-1b的催化体系为
叔丁基异氰酸酯加成多种醛(芳族,杂芳族,烯属,炔属,脂族)提供了高收率和良好至优异的对映选择性。
水处理得到α-羟基叔胺-丁基酰胺,而低温
甲醇淬灭,然后进行碱性后处理,得到α-羟基甲基酯。该反应对于其他
异氰酸酯也成功,尽管对映选择性降低。发现反应条件,特别是
异氰酸酯的添加速率对于良好的产率和高的选择性至关重要。