Tnflic anhydride

A vanety of oxo-bridged dicationic Inflates with the positive charges localized on the heteroatoms can be prepared from tnflic anhydride and the corresponding substrates [90, 91, 92, 93], Treatment of hexamethylphosphonctriamide with tnflic anhydnde yields the diphosphonium inflate salt [90] (equation 42). 

The intermediate formation of covalent inflates is assumed also in the reaction of alcohols with tnflic anhydride in the presence of nitriles to give the corresponding amides [96] (equation 47),... 

A new synthesis of acetylenes using the reaction ot tnflic anhydride with acyl ylides (equation 48) was developed recently [97] Vinyl inflates, generated in situ, are proposed to be the key intermediates... 

In recent years, tnflate derivatives of bivalent iodine have found more and more applications as versatile reagents in organic synthesis [7i5, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145] p.-Oxo-bi [(trifIuoramethanesulfonyloxy) (phenyl)iodine], which is readily available from lodosobenzene and tnflic anhydride (equation 44), is especially valuable for the preparation of alkynyl lodonium Inflates from silyl- or stannylacetylenes [136] (equation 70)... 

Tnflic anhydride is a useful reagent for the preparation of covalent inflate esters from alcohols, ketones, and other organic substrates [66] In many cases, very reactive inflates can be generated in situ and subjected to subsequent transformation without isolation [94, 95, 96, 97] Typical examples are cyclization of amides into dihydroisoqumolines (equation 45) and synthesis of A/-hydroxy-a-amino acid denvatives (equation 46) via the intermediate covalent Inflates... 

Oxo-bridged diiodonium triflate [Zefirov s reagent), a useful reagent for the synthesis of triflate esters and iodonium salts, can be prepared by the treatment of lodosobenzene with triflic anhydride [92] or by the reaction of lodobenzene diacetate with tnflic acid [93] (equation 44). 

The chloride of triflic acid (trifluoromethanesulfonyl chloride) is an effective sulfonylating agent Like triflic anhydride, it usually reacts with alcohols and other nucleophiles with the formation of the corresponding derivatives of tnflic acid [69] However, in some reactions, it acts as a chlorinating reagent [98] The reactions of tnfluoromethanesulfonyl chloride with 1,3-dicarbonyl compounds or some carboxylic esters in the presence of a base result m the formation of chlonnated products in high yields (equation 49)... 

Trifluoromethanesulfonic (triflic) anhydride is commercially available or can be prepared easily by the reaction of triflic acid with phosphorus pentoxide [66] This moderately hygroscopic colorless liquid is a useful reagent for the preparation of various organic derivatives of tnflic acid A large variety of organic ionic triflates can be prepared from triflic anhydride A recent example is the preparation of unusual oxo-bndged dicatiomc salts of different types [ S, 89, 90, 91, 92, 93] (equations 38-44) Stabilized dication ether salts of the Huckel aromatic system and some other systems (equations 38 and 39) can be prepared in one step by the... 

Like the reaction of ketones, the interaction of triflic anhydride with thiourea and substituted thioureas also gives dicationic Inflates (equations 40 and 41) however, two sulfur atoms form the bndge in this case This result indicates that tnflic anhydnde is acting as an oxidizing reagent toward thiourea [59]. 

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