Asymmetric double-bond isomerization of cyclic allyl acetals by using diop and chiraphos modified nickel complexes
摘要:
Diop or chiraphos modified dibromo- and dichloronickel complexes proved to be readily available catalyst precursors, which upon activation with lithium triethylborohydride (Super-Hydride(R)) gave enantioselectivities up to 92% ee for the asymmetric isomerization of 5-methylene-1,3-dioxanes 3 and up to 67% ee for the asymmetric isomerization of 4,7-dihydro-1,3-dioxepins 1. (C) 1998 Elsevier Science Ltd. All rights reserved.