Alcohol groups TFAA

Oxidation-sensitive functionalities other than alcohols are remarkably resistant to the action of the TFAA-mediated Moffatt oxidation. Functional groups resistant to this oxidation include p-methoxybenzyl ethers133 and esters,143 sulfides,143a 144 thioacetals,145 nitrogen heterocycles146 and most peculiarly even selenides,147 and p-hydroquinones.148... 

This diol possesses a high tendency to suffer a selective oxidation of the secondary alcohol, which can be performed with 84% using DMSO activated with TFAA or with a lower yield with PDC. According to the authors, who intended to make a selective oxidation of the primary alcohol, however, all attempts to selectively oxidize the primary hydroxy function in the presence of the secondary hydroxy group failed. ... 

The synthesis of a-homonojirimycin (1) has been carried ont from nojirimycin snlfite (25) (Scheme 4). Conversion of 25 to the nitrile 26, followed by benzoylation, and protection of the NH with TFAA afforded the nitrile 27. Hydrolysis of 27 in 90% TFA fnmished the corresponding amide, whose snbseqnent reaction with N2O4 gave carboxylic acid 28. Reduction of 28 afforded the alcohol 29, which nnderwent removal of the protecting groups to produce 1. 

The versatility and efficiency of the Swem conditions means that they can also be applied to various functional groups to effect different transformations other than just oxidations of alcohols. For example, primary amides have been converted to nitriles using the Swem reagents as dehydrating agents.42 Although different activators of DMSO were tested, for example, the S03-pyridine complex and TFAA, oxalyl chloride was found to be the best based on the yield of the final product. 

This group also employed the Dakin-West reaction to prepare a series of amino alcohols (not shown) by reduction of the trifluoromethyl ketones 85, resulting from treatment of Walkoxycarbonylamino acids 84 with TFAA (Fig. 4.27). 

Migration of all three primary alkyl groups from boron to the one carbon unit under the influence of TFAA is possible and results in tertiary alcohols. The synthesis of tri- -hexylmethanol is formulated. 

The Boekelheide reaction was applied by the Nicolaou groups in the synthesis of a model system of the thiopeptide antibiotic thiostrepton (302). The tetrahydroquinoline 303 was converted into the A -oxide by /w-CPBA oxidation followed by treatment with TFAA and then hydrolysis to afford key intermediate alcohol 304 as a diastereomeric mixture. 

Alcoholic functional groups in HFAs can be derivati-zed using a trifluoroacetic acid anhydride (TFAA)-pyridine mixture after esterification of the carboxylic function. Methyl iodide (CH3I) can be used for preparation of the methyl esters of HFAs. 

Treatment with the system DMSO-TFAA (trifluoroacetic anhydride) followed by treatment with base provides an effective procedure for oxidation of alcohols to carbonyl compounds, and is particularly useful for oxidation of hindered alcohols. On the other hand, tertiary alcohols react with DMSO-AC2O to give methylthiomethyl ethers, which can be used as protecting groups since they are hydrolytically cleaved under HgCl2 catalysis. ... 

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