Methanesulfon amide

N-melhyl-1 H-indale-5-methanesulfon-amide (V) oxolyl chloride... 

Finally, we tried to deprotect the amide nitrogen of the obtained pyridi-nones upon reflirx in neat trifluoroacetic acid (TFA) for 18 h [ 116]. Products were isolated in 73% and 79% yield, respectively. In contrast, upon microwave irradiation at 120 °C for only 20 min, a (1 2) TFA/DCM mixture sufficed to deprotect the pyridinones (isolated yields 75% and 73% respectively). Surprisingly, deprotection with either refluxing neat TFA (18 h) or microwave irradiation in neat TFA with a catalytic amount of methanesulfonic acid (20 min) did not work for dihydrofuropyridinone. 

Cyclization of the Weinreb amide 356 under reductive conditions using lithium aluminium hydride (LAH) led to formation of the carbinolamine 357 which underwent elimination on treatment with methanesulfonic acid to give 358 in 72% yield as shown in Scheme 27 <2005TL249>. 

Secondary and tertiary (3-hydroxy amides can be cyclized to oxazolines in the presence of strong acids such as methanesulfonic acid or p-toluenesulfonic acid. For tertiary (3-hydroxy amides, elimination to the enamide can often be a competing... 

Reduction of amides is an important preparative method for the synthesis of primary amines. Reducing agents used for this purpose include lithium aluminum hydride, sodium borohydride, triphenyl-phosphine (Staudinger reduction), and thiols. In the present case it is important to consider the compatibility of the reduction system with the carboxylic and methanesulfonic acid functions. Platinum and palladium arc often used for catalytic reduction. 

Reduction of amides. Sodium borohydride combined with methanesulfonic acid in DMSO reduces amides to the corresponding amines in 60-90% isolated yield. I he system also reduces acids and esters to primary alcohols. These reductions have been conducted with lithium aluminum hydride and with borane-tetrahydrofurane (5,48),2 hut with somewhat different selectivities. This new reagent, however, appears to be less hazardous than the latter reagent. 

An analogous result was first observed by Thomas <1993S767> and has also been reported elsewhere <2000JME488>. However, in the latter study, the secondary amide was converted into a tetrazole using trifluoro-methanesulfonic anhydride (Tf20) and sodium azide. 

As mentioned above, the bis-amides 9a are used as precursors in the synthesis of Af-acylenamines. The conditions used for this reaction depend on the purpose of the synthesis and are described in numerous works, and reviewed in a series of articles35-37. The acid catalyst is usually concentrated sulfuric acid, but a successful application of 85% phosphoric, chlorosulfonic, methanesulfonic and formic acids was reported, and reactions were also conducted in the presence of anhydrous hydrogen chloride35. The solvents used are usually glacial acetic acid and chlorinated hydrocarbons. It is believed that the water necessary for the formation of the bis-amides under anhydrous conditions is obtained from conversion of the carboxylic acid to the anhydride, or even the sulfuric acid35. 

The cyclization of 3-methyl-4-pentenamide (7) proceeds with 1,2-asymmetric induction when phenylselenenyl triflate22, easily prepared from phenylselenenyl chloride and silver trifluoro-methanesulfonate in dichloromethane or toluene, is employed as the electrophile. By in situ addition of the amide at 0 3C an 83 17 mixture of the trans- and cw-lactones 8 is obtained in 49% yield. 

Sharghi, H., Niknam, K. Conversion of alcohols to amides using alumina-methanesulfonic acid (AMA) in nitrile solvents. Iranian Journal of Chemistry Chemical Engineering 1999,18, 36-39. 

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