Transition-Metal-Catalyzed Ylide Formation

Diazo compounds are one of the most important compounds in organic chemistry,and they are usually used as metal carbene precursors in transition metal catalyzed reactions.In most cases,transition metal catalyzed diazo compounds to generate highly active metal carbene species,which underwent a variety of metal carbene conversions,such as C-H insertions,X-H insertions?X=O,N,S,Si,etc.?,cyclopropanations and ylide formations.The interaction of the metal carbene with a Lewis base generates a ylide commonly with high reactivity,which further undergo intramolecular or intermolecular reactions to give stable products.In these tandem transformations,complex organic compounds can be quickly and easily obtained from simple raw materials.Therefore,chemists have shown great interest and conducted extensive research on ylide formations from transitional metal-catalyzed diazo compounds.This paper mainly focuses on various ylide formation reactions,and develops an array of novel ylide interception reagents.The research consists of the following five parts:Part one:we have successfully achieved the interception of nitrile ylides with carboxylic acids as nucleophiles.A Cu-catalyzed cascade reaction,encompassing diazo compounds,carboxylic acids and nitriles,was well developed for the synthesis of unsymmetrical diacylglycine esters.Mechanistic studies indicated that nitrile ylides,in situ generated from Cu-carbene and nitrile,could be intercepted by carboxylic acid to afford imidate intermediate,which is then underwent Mumm rearrangement.This reaction provides new ideas for the reaction of nitrile ylide and helps to develop a new multi-component reaction of nitrile ylide.In addition,this reaction involves two nucleophiles and a diazo compound,we achieved selectivity by controlling the feed ratio of two nucleophiles.Part two:we have successfully achieved the interception of azomethine ylides with sulfonamides as nucleophiles.A Cu-catalyzed cascade reaction,encompassing diazo compounds,nitriles and sulfonamides,was well developed for the synthesis of fully substituted amidines.Mechanistic studies indicated that 5-alkoxyoxazole,in situ generated from diazo compound and nitrile,as imine source,reacts with a second equivalent of diazo compound to afford azomethine ylide,which is then intercepted by sulfonamide.This reaction is the selectivity reaction of double diazo compounds and is the first cascade reaction of nitrile ylide and azomethine ylide.In addition,this reaction involves two nucleophiles and a diazo compound,we achieved selectivity by controlling the feed ratio of two nucleophiles.Part three:we have successfully achieved the interception of tertiary amide ylides with sulfonamides as nucleophiles.A Zn-catalyzed cascade reaction,encompassing diazo compounds,tertiary amides and sulfonamides,was well developed for the synthesis of N-sulfonyl amidines.Mechanistic studies indicated that tertiary amide ylides,in situ generated from Zn-carbene and tertiary amide,could be intercepted by sulfonamides.This reaction provides new ideas for the reaction of tertiary amide ylide and helps to develop new reaction of tertiary amide ylide.In addition,this reaction involves two nucleophiles and a diazo compound,we achieved selectivity by controlling the reactivity of the two nucleophiles.Part four:we have successfully achieved the interception of secondary amide ylides with sulfonamides as nucleophiles.We also developed a novel catalyst control selective tandem reactions.In this reaction,diazo compounds,sulfonamides,and secondary amides were chosen as the substrates.When manganese was used as the catalyst,N-sulfonyl amidines containing N-H bonds were selectively obtained.When zinc was used as the catalyst,N-sulfonyl amidines containing erters were selectively obtained.Mechanistic studies indicated that Mn-carbene selectively react with carbonyl group of secondary amide.Zn-carbene reacts with both carbonyl group and N-H bond of secondary amide.This reaction breaks through using special substrates for the activation of secondary amides,and achieves the conversion of an array of common secondary amides.this reaction involves two nucleophiles and a diazo compound,we achieved selectivity by controlling the reactivity of the two nucleophiles.Part five:based on the concept of selectivity reaction of two nucleophiles,we have successfully achieved site-selectivity reaction of two nucleophiles with olefin.A cascade reaction,encompassing 2-vinylphenols and carboxylic acids,was well developed for the synthesis of 3-acyloxybenzodihydrofuran by using Bu₄NI as catalyst and t-BuOOH as oxidant.Mechanistic studies indicated that Bu₄NOI,in situ generated from Bu₄NI and t-BuOOH,reacts with 2-vinylphenol to afford iodonium ion,which is then undergo intramolecular cyclization and subsequent intermolecular nucleophilic substitution.This reaction is notable due to the ability to complete it under metal-free conditions,with easily available precursors,resulting in product with high atom economy and high functional group tolerance.In addition,this reaction breaks through previous studies on the addition of carboxylic acids with olefins.We successfully achieved the addition of phenols with olefins by the formation of five-membered rings.