Studies On The Phosphites-mediated Reaction Of ?-keto Imidates And Nitrosoarenes For The Synthesis Of Ketonitrones

Brook rearrangement is an important reaction in organic synthesis.[1,2]-Phospha-Brook rearrangement,as a typical Brook rearrangements,is usually initiated by nucleophilic addition of phosphite to the carbonyl group of ?-ketoesters,followed by the [1,2]?migration of phosphite from carbonyl carbon atom to carbonyl oxygen atom.The intermediate formed by rearrangement reaction can further participate in nucleophilic addition transformations.As a result,umpolung of carbonyl carbon atoms of ?-ketoester compounds is successfully realized,which can react with the electrophilic reagents,thus expanding the bonding mode of carbonyl in the reaction.This thesis describes a novel synthetic method for construction of functionalized ketonitrones via the use of nitrosoarenes as electrophilic reagents to intercept [1,2]-phospha-Brook rearrangement intermediates that derived from ?-keto imidates.The reaction of ?-keto N-tert-butanesulfinyl imidates with nitrosoarenes triggered by phosphites was investigated.Under alkaline condition,nucleophilic addition of phosphites to ?-keto N-tert-butanesulfinyl imidates initiated [1,2]-phospha-Brook rearrangement to generate ?-phosphonyloxy enolates which could be intercepted by electrophilic of nitrosoarenes.Subsequent intramolecular transformation led to formation of ?-methoxyimidoyl ketonitrones accompaning with extrusion of phosphonyloxy group.The newly formed C=N bond for the nitrone group adopted Z configuration.The manipulations of ketonitrone products were conducted,including reaction with lithium reagents and intramolecular redox reaction.Besides,we were able to prepare the ketonitrones with E-configuration through acidic treatment of their Z isomers.The phosphate-triggered ketonitrones formation reaction can be extended to isatin derivatives,the corresponding ketonitrones with E configuration were prepared.The reaction of nitrosoarenes with polarity-reversed carbonyl compounds provided a useful method to construct the ?-methoxyimidoyl ketonitrones derived from N-tert-butanesulfinyl imidates that are not accessible by the conventional condensation reaction.Attmpts to condense steric-hindered ?-keto N-tert-butanesulfinyl imidates with PhNHOH under a range of known reaction conditions were fruitless.