Asymmetric Synthesis of Palladacycles by Regioselective Oxidative Cyclization of C2-Symmetrical, Chiral Alkenes and Determination of the Configuration of All Stereocenters
摘要:
The reaction of Pd-2(dba)(3) . CHCl3 with 2 equiv of chiral, C-2-symmetrical cyclopropenes bearing lactate esters at the 1- and 2-positions provided trans-5-palladatricyclo[4.1.0.0(2,4)]heptanes (PTHs) in high diastereomeric excess. The configuration of all stereocenters in the major diastereomer was determined by X-ray structure analyses of the complexes of the PTH-with norbornadiene; the C-2 symmetry of the (+)-DIOP complex of the minor diastereomer proves that this was also a trans isomer.