The Gold Catalyzed Synthesis Of α-haloketones And β-ketophosphonates

In recent years, gold catalysis, especially homogeneous gold catalysis has beenplaying an increasingly important role in building carbon-carbon bonds and carbon-hetero bonds, which has been a hot topic in organic chemistry. Gold catalyst has aproperty of soft Lewis acid and pi-acid. It can activate carbon-carbon double bond ortriple bond, and subsenquently nucleophilic addition occurs. In addition, goldcatalysts are not very sensitive for water and air, not easy to be oxidatived, C-Aubonds prone to leave. These properties make gold catalysis often different from thetraditional transition metal catalyzed reaction, presenting the gold catalysis uniquecatalytic properties. This thesis, mainly involves gold catalyzed intermolecularoxidation of alkynes to generate α-gold carbenes participating N-H insertion processand efficient gold-catalyzed alkynyl phosphates hydrolysis, Including the followingtwo aspects:1Gold-catalyzed intermolecular oxidation of terminal alkynes to generatealpha-carbonyl carbene intermediates simultaneously captureing the halogen fromhalogenated solvents such as1,2-dichloroethane or1,2–dibromoethane. Thecorresponding alpha-chloro-/bromomethyl ketones were prepared. The authorsinvestigated the influence of the catalyst, pyridine/quinoline N-oxides, temperature,acid, halogen sources and other factors on the reaction yield. Through a series offilters to give the optimum reaction conditions:5mol%Ph3PAuNTf2,1.3equivalentsof8-methyl-quinoline N-oxides,1.1equivalents of methylsulfonic acid,1,2-dichloroethane or1,2-dibromoethane as the solvent,. The strong electrophilicityof the gold carbene intermediates reveals that gold in general is less effective in backbonding than rhodium but perhaps similar to Ag.2In order to expand the scope of application of the gold catalyst, the authorsstudied the homogeneous gold catalysis hydrolysis of the alkynyl phosphates toprepare the corresponding β-ketophosphonates. β-ketophosphonates are a kind ofimportant phosphorus containing compounds.especially for the preparation of α,β-unsaturated carbonyl compounds via HWE reaction. They can serve as usefulprecursors in the synthesis of chrial β-amino and β-hydroxy phosphonic acids,both ofwhich exhibit a range of biological activitives.We found that in the presence of XphosAuNTf2,a series of alkynylphosphonates can be highly efficient hydrated to the corresponding β-ketophosphonates undermild conditions.