Lewis Acid Or Bronsted Acid-catalyzed Cascade Reaction Of Propargylic Alcohols

This thesis mainly aims at the studies on the Lewis acid or Bronsted acid-catalyzed propargylic alcohols for the synthesis of acyclic,carbocycle,heterocycle,bridged-ring and condensed ring compounds,which chiefly involves the following eight chapters.Chapter ?:First,we introduced the importance and practicability of propargylic alcohol compounds.Propargylic alcohols have extensively used as synthons in the field of organic synthesis due to it possess alkynyl and hydroxyl functional groups.Lewis acid or Bronsted acid-catalyzed propargylic alcohols has enabled efficient access to a series of complex acyclic,carbocycle,heterocycle,bridged-ring and condensed ring compounds.Furthermore,the direct acid-catalyzed nucleophilic substitution reaction of propargylic alcohols accord with the concept of green sustainable development,which reduced the pollution to the environment and generated water as the only by-product.Here,we introduced the type reactions of propargyl alcohols catalyzed by Lewis acid or Bronsted acid,such as nucleophilic substitution reactions,rearrangement reactions,cascade cyclization reactions,and miscellaneous reactions.Chapter?:An high-efficiency Lewis acid catalyzed for the synthesis of valuable?,?-unsaturated amides and alkenyl nitriles from readily available propargylic alcohols and hydroxylamine hydrochloride is described.This protocol,which used inexpensive NH₂OH·HCl as the nitrogen source,extended the application of NH₂OH·HCl to the chemistry of propargylic alcohols.In addition,secondary propargylic alcohols,tertiary propargylic alcohols,and terminal propargylic alcohols were well tolerated in the transformation and generated anticipated products in moderate to excellent yields under the standard reaction conditions.Chapter ?:We have developed a Lewis acid catalyzed[4+3]cascade annulation of readily available internal tertiary propargylic alcohols with azides for the synthesis of seven-membered N-heterocycles containing an imine-based indole azepine scaffold.This annulation protocol offers a straightforward,efficient,and atom-economical access to a series of polycyclic products containing an imine-based scaffold,which highlights the latent applicability in the construction of seven-membered N-heterocycles.Chapter ?:We have developed a Lewis acid catalyzed cascade annulation for the formation of valuable 3,4-dihydro-2H-2,4-methanochromans from propargylic alcohols and2-vinylphenol.This annulation protocol,which tolerates a broad variety of functional groups,provides a practical,versatile,and atom-economical access to a new class of valuable bridged-ring products in satisfactory yields.Compared with the traditional reaction conditions for the synthesis of bridged-ring compounds,our reaction conditions are mild,neutral,and without any oxidizing agent.Chapter ?:An high-efficiency Lewis acid catalyzed for the synthesis of valuable2-?quinolin-2-yl?prop-2-en-1-ones through dehydrogenative coupling of readily available internal propargylic alcohols and quinoline N-oxides is described.This protocol,which tolerates a wide variety of functional groups,offers a straightforward access to the products 2-?quinolin-2-yl?prop-2-en-1-one scaffolds in good yields.Furthermore,this method could be scaled up to the gram scale efficiently,which highlights the latent applicability of this methodology.Chapter ?:We have developed a copper?II?trifluoromethanesulfonate-catalyzed[4+2]cascade annulation for the construction of valuable quinoline derivatives from propargylic alcohols and benzo[d]isoxazoles.The cycloaddition protocol,which tolerates a wide variety of functional groups,proceeds through a sequential ring opening/Meyer–Schuster rearrangement/intermolecular cyclization.In addition,this transformation provides a straightforward and atom-economical access to a new class of quinoline derivatives in good yields under mild conditions.Chapter ?:We have developed a Bronsted acid-mediated formal[3+3]cascade annulation of propargylic alcohols and 1,3-diketones for the formation of valuable chromenone derivatives in good yields under mild conditions.The cycloaddition protocol,which tolerates a broad variety of functional groups,proceeds through a sequential Meyer-Schuster rearrangement/1,2-addition.Furthermore,this transformation could be scaled up to a gram scale efficiently,which has shown a latent application of this method.Chapter ?:An unprecedented Lewis acid-catalyzed formal[3+3]cascade annulation of propargylic alcohols with 4-hydroxy-2H-chromen-2-ones for the synthesis of valuable diversetricycliccompoundspossessingfunctionalized pyrano[3,2-c]chromen-5?2H?-one scaffolds is described.The cycloaddition protocol,which has a wide scope,enables efficient and straightforward access to a broad range of important chromenone derivatives in excellent yields under mild conditions.