Transition metal promoted reactions. 38. NiCl2(dppe)-catalyzed geminal dialkylation of dithioacetals and trimethylation of ortho thioesters
摘要:
NiCl2(dppe)-catalyzed cross-coupling of cinnamaldehyde dithioacetals gave the corresponding geminal dimethylation products in excellent yields. Allylic ortho thioesters afforded regioselectively the corresponding trimethylation products. The reaction may occur via an 18-electron pi-allyl intermediate, which undergoes facile reductive elimination to afford the geminal dimethylation product. Benzylic dithioacetals having an ortho amino group gave 2-isopropylanilines exclusively. The reaction of benzylic dithioacetals with EtMgBr under the same conditions yielded geminal diethylation products.