Studies On Metal-free Catalytic Decarboxylation Coupling Reaction-based Guiding Propargyl Amine

Petasis reaction has been used to form new carbon-carbon bonds,so it can be used to build some important organic structure fragment such as allyl amine,chiral amino alcohols,chiral amino acid,2-substituted phenol derivatives.Decarboxylation coupling reaction has been recognized as an important tool for functional transformation,construction of carbon-carbon bonds,and then forming the important organic intermediates.This paper developed a novel and more efficient approaches of Petasis/Decarboxylative Domino Reaction for the preparation of various tertiary propargylamines compounds.Compared with the traditional methods,this method provided a mild reaction condition,simple operation,high yield,no metal catalyst,environmental friendliness,widely applicability of the substrate etc.This paper is mainly focused on propargyl tertiary amine oriented metal-free catalytic decarboxylation coupling reaction which included three parts:Part 1: Mild and catalyst-free Petasis/Decarboxylative Domino reaction:chemoselective synthesis of N-benzyl propargylamines.Multicomponent domino reactions are attractive for assembling functionalized compounds.To this end,a one-pot catalyst-free chemoselective synthesis of N-benzyl propargylamines is adopted with good functional group compatibility.This mild process involves in situ formation of an active amine through Petasis reaction of primary amines,formaldehyde solution,and boronic acids,which reacts with propiolic acids to give product in up to 94% yield via decarboxylative coupling reaction.Part 2: Decarboxylative dipropargylation of primary amines with propiolic acids and formaldehyde via metal-free couplingBased on the part 1,a metal-free decarboxylative coupling reaction,which produced important and useful dipropargylic amines,was developed under mild conditions.This novel methodology showed a broad range of functional group compatibility for primary amines and propiolic acids,and gave the corresponding products in up to 97% yields.Part 3: Multicomponent domino reactions of hydrazinecarbodithioates: concise access to 3-substituted 5-thiol-1,3,4-thiadiazolinesTwo classes of addition/cycloaddition cascade reactions of hydrazinecarbodithioate have been developed under mild reaction conditions.Reaction of hydrazinecarbodithioate with formaldehyde solution and propiolic acid gives 3-propargyl-5-thiol-2,3-dihydro-1,3,4-thiadiazoles via a decarboxylative coupling/cycloaddition domino sequence.When propiolic acid is switched to phenyl boronic acid,a petasis/ cycloaddition domino reaction is instead observed,in which 3-benzyl-5-thiol-2,3-dihydro-1,3,4-thiadiazoles are obtained.Both these reactions show a wide range of functional-group compatibility for propiolic acids and aryl boronic acids,and give the corresponding products in moderate to good yields.This method provides a high efficient,quick and simple route access to3-substituted 5-thiol-1,3,4-thiadiazolines.