Diastereoselective [2+2]-Cycloaddition Reactions of Unsymmetrical Cyclic Ketenes with Imines: Synthesis of Modified Prolines and Theoretical Study of the Reaction Mechanism
作者:Alberto Macías、Eduardo Alonso、Carlos del Pozo、Alessandro Venturini、Javier González
DOI:10.1021/jo040163w
日期:2004.10.1
The synthesis of enantiomerically pure modified proline derivatives was achieved by using spiro β-lactams as starting material that were prepared in turn by the [2+2]-cycloaddition of unsymmetrical cyclic ketenes with optically active imines. A theoretical study of the [2+2]-cycloaddition reaction, using density-functional methods, gave insights on the origin of the observed stereoselectivity of the
对映体纯的修饰脯氨酸衍生物的合成是通过使用螺状β-内酰胺作为起始原料而完成的,该原料依次通过不对称环状烯酮与光学活性亚胺的[2 + 2]-环加成而制得。[2 + 2]-环加成反应的理论研究,使用密度泛函方法,对所观察到的Staudinger反应的立体选择性的起源提供了见解。将螺β-内酰胺转化为N- Boc衍生物,并进行亲核开环,得到相应的对映体纯的修饰脯氨酸衍生物,其被分离为正交保护的化合物。