Tunable Phosphoramidite Ligands for Asymmetric Hydrovinylation: Ligands par excellence for Generation of All-Carbon Quaternary Centers.
1-Alkylstyrenes undergo efficient hydrovinylation (addition of ethylene) in the presence of a Ni-catalyst prepared from [(allyl)NiBr](2), Na(+) [BAr(4)](-) (Ar = 3,5-bis-trifluromethylphenyl), and a phosphoramidite ligand giving products in excellent yields and enantioselectivities. In many cases phosphoramidites derived from achiral 2,2'-biphenol are almost as good as ligands derived from the more expensive enantiopure 2,2'-binaphthols. The hydrovinylation products, which carry two versatile latent functionalities, an aryl and a vinyl group, are potentially useful for the synthesis of several important natural products containing benzylic all-carbon quaternary centers.
Smith
Craig R
CR
Department of Chemistry, The Ohio State University, 100 W. 18 Ave, Columbus, OHIO 43210, USA.
Lim
Hwan Jung
HJ
Zhang
Aibin
A
Rajanbabu
T V
TV