<i>C</i><sub>2</sub>-Symmetric Cu(II) Complexes as Chiral Lewis Acids. Catalytic, Enantioselective Cycloadditions of Silyl Ketenes
作者:David A. Evans、Jacob M. Janey
DOI:10.1021/ol016096z
日期:2001.6.1
[reaction: see text] C(2)-Symmetric bis(oxazoline)-Cu(II) complexes (4a-g) catalyze the enantioselective [2 + 2] cycloaddition between (silyl)ketenes and chelating carbonyl substrates. A range of substituted beta-lactones can be produced in excellent yields and selectivities. It was also found that (trimethylsilyl)ketene (1) may also undergo a highly selective hetero Diels-Alder reaction with beta