Synthesis Of N-Sulfonamide And N-Sulfonylamine Catalyzed By Iron And Amino Acid

N-sulfinylimides and N-sulfonylimines are important classes of organic synthesis intermediates.In this paper,we developed a novel method for the oxidation of alcohols followed by condensation with sulfinamide or sulfonamide in one pot for the synthesis of N-sulfinyl-and N-sulfonylimines compounds.In the reaction we using natural amino acids as highly effective bidentate ligands and oxygen as a green oxidant,4-OH-TEMPO as co-oxidant to oxidize benzyl alcohols,allyl alcohols to the corresponding aldehydes under mild conditions,followed by reaction of aromatic,aliphatic or aromatic sulfinamides and sulfonamides get the target product.This transformation accommodates a variety of substrates,shows high functional-group tolerance,and affords the corresponding products in good to excellent yields.Amino acids have a wide range of applications in metal-catalyzed organic synthesis reactions as a class of multidentate ligands.We chose amino acids as the bidentate ligand to react with iron catalysts to obtain complexes to increase the catalytic activity.Afterwards,the natural amino acids,functionalized amino acid,and various nitrogenous compounds are screened to determine the best ligand.The reaction of unsubstituted benzyl alcohol with 4-toluenesulfinamide was selected as the model reaction to establish the best reaction conditions.Through systematic screening of iron salts,solvents,additives,reaction temperature,reaction time and other factors on the reaction selectivity and reaction yield,,we get the best reaction conditions:0.4mmol substrate alcohol,0.2mmol sulfinamide,10 mol%FeCl₃ as catalyst,10 mol%L-proline ligand,20 mol%4-OH-TEMPO（4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy）was used as co-oxidant.Oxygen was used as oxidant and reacted in 2ml of toluene containing 700 mg 4?molecular sieve at 60°C.Under the catalytic system,the substrates can be efficiently reacted to obtain the target product,which has good functional group tolerance.Based on the iron/amino acid-catalyzed reaction conditions for the preparation of N-sulfonylimine,a variety of sulfonamides such as 4-toluenesulfonamide,tert-butanesulfonamide and 2-pyridinesulfonamide were employed successfully in this process even though the nucleophilicity of the nitrogen atom of sulfonamides is much lower than that of sulfinamides.Through the selection of factors such as amino acids,iron salts,solvents,and additives,A new method was developed for the preparation of N-sulfonylimides using L-valine as a ligand,FeCl₃ as a catalyst,4-OH-TEMPO as a co-oxidant,and oxygen as an oxidant.Under this optimal reaction system,aromatic alcohol compounds can react with a variety of aliphatic or aromatic sulfonamides to form N-sulfonylimides compounds.And all the examined substrates provided medium to good yields.