Investigation On The NH₄I-Promoted N-Acylation Of Amines And The Reaction Of DMSO With Acetylenic Sulfones

In this paper,the N-acylation of amines and the reaction of DMSO with acetylenic sulfones promoted by NH₄I was investigated.A series of amides and??keto thioethers were synthesized by NH₄I-promoted reactions of N,N-Dimethylformamide with amines and dimethyl sulfoxide with acetylenic sulfones.The research content of this paper include the following two parts:Firstly,NH₄I-promoted N-acylation of amines was investigated.The reaction of4-methoxyaniline?1a?and N,N-dimethylformamide was chosen as the model reaction to optimise the reaction conditions.The effects of promoter,solvent and reaction temperature were explored.The reaction of various amines with N,N-dimethylformamide were conducted under the optimized reaction conditions to evaluate the scope and generality of this protocol.The results show that the reaction is quite general,both aromatic amines and aliphatic amines can react smoothly with N,N-dimethylformamide.A series of formamides were obtained by the NH₄I-promoted transamidation reaction of N,N-dimethylformamide with amines in up to 94%yield.Furthermore,the reaction of amines with N,N-dimethylacetamide was studied and a series of acetamides was synthesized in up to52%yield.The reaction uses easily available N,N-dimethylformamide or N,N-dimethylacetamide as an acylating reagent,ammonium iodide as a promoter.The reaction has the advantages of cheap and easily available starting material and convenient operation.All the products were characterized by ¹H NMR,¹³C NMR,IR and HRMS.Secondly,the NH₄I-promoted reaction of acetylenic sulfones with dimethyl sulfoxide to afford??keto thioethers was investigated.The reaction of dimethyl sulfoxide and 1-phenyl-2-?p-tolylsulfonyl?ethylene?4a?was chosen as the model reaction to optimise the reaction conditions.The effects of promoter,solvent and reaction temperature were explored.Various substituted acetylenic sulfones and dimethyl sulfoxide were employed in the optimized reaction conditions to evaluate the scope and generality of this protocol.The results show that the reaction is compatible with differently substituted acetylenic sulfones and??keto thioethers containing different substituents were obtained in moderate to good yield.The reaction uses common organic solvents dimethyl sulfoxide as sulfur source,avoiding the use of toxic and foul thiols or sulfides as sulfur sources.The present work provides a new protocol for the synthesis of??keto thioethers from easily available starting materials.All the products were characterized by ¹H NMR,¹³C NMR,IR and HRMS.