Pyro-Borates, Spiro-Borates, and Boroxinates of BINOL-Assembly, Structures, and Reactivity

Autor: Mathew J. Vetticatt, Anil K. Gupta, Li Huang, Rui H. Huang, Xiaopeng Yin, Gang Hu, Wenjun Zhao, Joseph A. Izzo, Wynter E. G. Osminski, William D. Wulff
Rok vydání: 2017
Předmět:
Zdroj: Journal of the American Chemical Society. 139(30)
ISSN: 1520-5126
Popis: VANOL and VAPOL ligands are known to react with three equivalents of B(OPh)3 to form a catalytic species that contains a boroxinate core with three boron atoms, and these have proven to be effective catalysts for a number of reactions. However, it was not known whether the closely related BINOL ligand will likewise form a boroxinate species. It had simply been observed that mixtures of BINOL and B(OPh)3 were very poor catalysts compared to the same mixtures with VANOL or VAPOL. Borate esters of BINOL have been investigated as chiral catalysts, and these include meso-borates, spiro-borates, and diborabicyclo-borate esters. Borate esters are often in equilibrium, and their structures can be determined by stoichiometry and/or thermodynamics, especially in the presence of a base. The present study examines the structures of borate esters of BINOL that are produced with different stoichiometric combinations of BINOL with B(OPh)3 in the presence and absence of a base. Depending on conditions, pyro-borates, spir...
Databáze: OpenAIRE