Triflate displacement

Rapid internal triflate displacements by neighboring acetyl or benzoyl groups have been mentioned above when the ester group and the leaving group have tranx-diaxial relationships. This leads to products where the configuration is retained, thus excluding... 

Binkley, R. W., Inversion of Configuration in 2,6-Dideoxy Sugars - Triflate Displacement by Benzoate and Nitrite Anions. J. Org. Chem. 1991, 56, 3892-3896. 

E. Triflate displacement by bromide, chloride, and iodide ions... 

IL INTRODUCING AZIDO AND HALOQENO GROUPS BY TRIFLATE DISPLACEMENT... 

D. Triflate Displacement by Bromide, Chloride, and iodide Ions [41]... 

Except for this particular example, quantitative deprotections were observed for other sugar nitrates without modification of the sugar moiety. Some other Al-deriva-tives such as diphenyl hydrazino substituents introduced by triflate displacement at the C-6 position of galactose residues were photolyzed but in low yields [112]. This group remains of limited interest for any further use in synthesis. 

Halogenoalkyl and Related Acids. Fluorinated phosphonates are often designed as a new class of biological phosphate mimics. They are used as enzyme inhibitors and metabolite probes. Therefore, these compounds have attracted much attention. During the period of this review a number of new methods of synthesis, including the preparation of novel fluorinated phosphonates, have been reported. A complementary triflate displacement approach to (a-mono-fluoroalkyl) phosphonates (219) has been elaborated. Treatment of alkyl triflates or iodides with the potassium salt of (a-fluoro-a-phenylsulfonylmethyl) phosphonate (220) yields (a-fluoro-a-phenylsulfonylalkyl) phosphonates (221), which can be cleanly desulfonated affording (219) (Scheme 58). 

Introducing Azido and Halogeno Groups by Triflate Displacement 90... 

Sulfonate displacement has been well established as a common method for introducing halogen atoms into carbohydrates. The high reactivity and easy preparation of sulfonic esters contribute to their use in carbohydrate chemistry. Triflate displacements are popular for the preparation of secondary halogenated carbohydrates and often give satisfactory results when mesylates and tosylates fail to give products. 

Sugar nitrates have been prepared by triflate displacements with nitrate ion acetals and epoxides were unaffected, enabling nitrates (70) - (72) to be obtained. 

A six step conversion of 2-acetamido-2-deoxy-D-glucose into 2-acetamido-2-deoxy-D-galactose involved as key steps a selective 6-O-deacetylation with yeast esterase, acid-catalysed acetate migration from 0-6 to 0-4 under acidic catalytic, and inversion at C-4 via triflate displacement. 2-Acetamido-2-deoxy-3-[ H]-E>-galactose was obtained via boiodeuteride reduction of benzyl 2-acetamido-4,6-C)-benzylidene-a-D-glucopyranosid-3-ulose, a reaction in which only a trace of the C-3 epimeric D-gw/o-derivative was formed. ... 

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