Asymmetric Cyclopropanations by Rhodium(II) <i>N</i>-(Arylsulfonyl)prolinate Catalyzed Decomposition of Vinyldiazomethanes in the Presence of Alkenes. Practical Enantioselective Synthesis of the Four Stereoisomers of 2-Phenylcyclopropan-1-amino Acid
作者:Huw M. L. Davies、Paul R. Bruzinski、Debra H. Lake、Norman Kong、Michael J. Fall
DOI:10.1021/ja9604931
日期:1996.1.1
to]dirhodium. The carbenoid structure has a critical effect on the degree of asymmetric induction, and the combination of a small electron-withdrawing group such as a methyl ester and an electron-donating group such as vinyl or phenyl resulted in the highest levels of enantioselectivity. The use of electron neutral alkenes and pentane as solvent also enhanced the enantioselectivity of the process.
N-(芳基磺酰基)脯氨酸铑在烯烃存在下催化乙烯基重氮甲烷的分解导致以高度非对映选择性和对映选择性模式合成官能化环丙烷的非常通用的方法。进行了详细研究以确定控制该过程的对映选择性的关键因素。使用环状 N-(芳基磺酰基)氨基酸作为二铑催化剂的配体获得了最高水平的对映选择性,优化的催化剂是四[N-[(4-十二烷基苯基)磺酰基]-(L)-脯氨酰]二铑。卡宾结构对不对称诱导的程度有关键影响,小的吸电子基团(例如甲酯)和给电子基团(例如乙烯基或苯基)的组合导致最高水平的对映选择性。使用电子中性烯烃和戊烷作为溶剂也提高了该过程的对映选择性。这种化学的合成效用...