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Various hydrazone derivatives of α-keto esters were prepared. The carbonyl group was readily regenerated in high yield from phenylhydrazones through oxidative hydrolysis using hypervalent organoiodine(III) reagents—either bis(trifluoroacetoxy)-iodobenzene (BTIB) in aqueous acetonitrile or hydroxy(tosyloxy)iodobenzene (HTIB) in chloroform. α-Acetoxy phenyl- or methylazo compounds were readily synthesized by oxidation of the corresponding hydrazones with iodobenzene diacetate (IBDA) in dichloromethane or acetic acid. α-Methoxy phenyl- or methylazo compounds were also prepared by oxidation of the hydrazones in methanol. The mechanisms of the oxidation reactions are discussed.

Denitration of various important intermediates in the synthesis of sorgolactone and its analogs using radical chemistry on nitroketones or on the derived isocyanides is described. The nitro group is needed for the first step of the annellation process, the Michael addition of substituted nitroalkanes to cyclopentenones. Then it can be removed directly or after reduction to the amine or via the ketone obtained by the Nef-reaction.

An application of the Barton ester based radical reactions in carbohydrate chemistry is described. The chain-elongation reaction with ethyl α-trifluoroacetoxy acrylate 2 , followed by treatment with phenylhydrazine provided 3-deoxy-α-hydrazono-octulosonates 8a,b , derivatives of KDO and its gluco -isomer in good yield.

Carboxylic acids can be transformed into the homologous α-keto acids by Barton-ester based radical chemistry. This method was especially successful when ethyl α-trifluoroacetoxy acrylate was used as a radical trap.

A new synthesis of thiols in high yield utilizing carbon radicals and elemental sulfur is demonstrated. The procedure is applicable to 1°, 2° and 3° carboxylic acids.

Thionothiocarbonates as well as the corresponding selenium compounds are good radicophilic starting materials for the efficient radical chain reactions of alcohols.

The addition of Se-phenyl p -tolueneselenosulfonate 1 to electron rich olefins 4a–4e upon visible light photolysis with a catalytic amount of tris(2,2′-bipyridine)ruthenium(II) gives adducts 5 in high yield.

Nitroalkanes can be transformed into olefins in high yielding reactions via nitroolefins and β-nitro trithiocarbonates in radical olefination reactions.

α-Ketoacids and ketones can easily be regenerated in high yield from their phenylhydrazones via hydroxy azo compounds upon oxidation with hupervalent iodine reagents.

Reagents, containing a P-H bond, such as dimethyl phosphite, diethyl phosphite, hypophosphorous acid and various salts of hypophosphorous acid are effective radical reducing agents for organic amides, thionoesters, and isocyanides affording high yields of the corresponding hydrocarbons. Reduction of tertiary phenyl selenides and tertiary nitro compounds are not efficient under these conditions. Oleamination of 1,2-diols is also accomplished via the corresponding thiocarbonyl derivatives using hypophosphorous acid and triethylamine in the presence of a suitable «sacrificial olefin» in moderate to good yields

The reaction of α-trifluoroacetoxy acrylates and acrylonitriles with carbon radicals formed from carboxylic acids gives adducts that can be transformed into vic-diols, esters, amides, and homoaldehydes in good to high yield. Aldoses can be smoothly degraded to the corresponding nor- or bis-nor compounds using radical chemistry.

A number of diazirines were synthesized for the purpose of exploring the addition of a carbon radical to the nitrogen-nitrogen double bond. Carbon radicals, generated from the photolysis of the 0-acyl derivatives of N-hydroxy- 2-thiopyridone or via radical exchange from the corresponding organotellurides, were shown to add smoothly to the diazirines leading to imines 34. When 3-(trifluoromethyl)-3-phenyldiazirine (13) is used as the trap, the thus formed imines can be easily hydrolyzed to amines. A mechanism that involves dimerization of the diaziridinyl radicals 32 to produce tetraazo intermediates 33 is suggested in accord with variable temperature NMR data for the reaction. Proof for this mechanistic scheme was furthermore obtained by isolation and X-ray structure determination of 33d. The first X-ray structure of a 3-(trifluoromethyl)-3-aryldiazirine is also reported.

Various thionocarbonates and xanthates of alcohols and bis -xanthates of vic -diols are readily deoxygenated to the corresponding hydrocarbons or olefins, while bromides and iodides are dehalogenated with diphenylphenylsilane in good yield.

O -Acyl derivatives of N -hydroxy-2-thiopyridone can be photolysed with suitable commercial visible-light lamps to give reactions with very short half-lives (down to 20 s) at 0° C or room temperature.

Thionocarbonates and xanthates of primary and secondary alcohols, as well as bis-xanthates of vic-diols are readily deoxygenated to the corresponding hydrocarbons or olefins with phenylsilane, triphenylsilane, and triethylsilane in good yield.

Oxygen centered radicals, formed by the photolysis of derivatives of N -hydroxy-2-thiopyridone, have been trapped by vinyl ethers. In the case of the benzoyloxy radical, smooth deoxygenation is effected by III P compounds. Evidence for the formation of the dimethyl t butylsilyloxy and of the hydroxy radical is also presented.

Dixanthanes, formed from vic-diols, can easily be transformed to the corresponding olefins with diphenylsilane in a new, high-yielding radical reaction.

The reaction of various olefins with carbon radicals generated by photolysis of Barton-esters finishes adducts suitable for transformation into the corresponding malonic acids.

Thionocarbonates and xanthates of alcohols, bromides, iodides and isonitriles can be transfromed to the corresponding hydrocarbons with hypophosphorous acid or its salts in radical chain reactions.

O -Acyl derivatives of N -hydroxy-2-thiopyridone can be photolysed with suitable commercial visible-light lamps to give reactions with very short half-lives (down to 20 s) at 0° C or room temperature.

α-Ketoacids and ketones can easily be regenerated in high yield from their phenylhydrazones via hydroxy azo compounds upon oxidation with hupervalent iodine reagents.

d -glucono 1,5-lactone was converted to O-protected d -gluconic acids. The latter were transformed to gluco-KDO derivatives using Barton ester-based radical chemistry with high diastereoselectivity.

The reaction of various olefins with carbon radicals generated by photolysis of Barton-esters finishes adducts suitable for transformation into the corresponding malonic acids.

The 2,4-bis-thinocarbonate 3 of 1,6-anyhydro-D-glucose 1 can be transformed to the corresponding dideoxy compound 5 with diphenylsilane 7 as well as with tris(trimethylsilyl)silane 4 in a radical chain reaction.

Thionocarbonates and xanthates of alcohols, bromides, iodides and isonitriles can be transfromed to the corresponding hydrocarbons with hypophosphorous acid or its salts in radical chain reactions.

Secondary alcohols were transformed into various thiocarbonyl derivatives. Reduction of these compounds using tributyltin hydride and an initiator afforded the corresponding deoxy-compounds. Half-life and competitive measurements showed that all these reactions were fast and could be run to completion.

Reaction of olefins containing a three carbon atom chain with carbon radicals generated from carboxylic acids furnishes adducts that are precursors of the corresponding two carbon atom longer α-keto-acids. The keto-acids are furnished in high overall yield.

Reaction of substituted terminal olefins with carbon radicals generated carboxylic acids gives adducts that can be transformed to one carbon atom longer homo-acids in high overall yield. With 6b yields are very good and the conditions of hydrolysis exceptionally mild.

Thionocarbonates and xanthates of alcohols, and various halides and phenylselenides can be transformed to the corresponding hydrocarbons with alkyl phosphites and benzoyl peroxide in most cases in high-yielding radical reactions.

Reaction of p-toluenesulphonyl cyanide or methanesulfonyl cyanide with carbon radicals, generated from the corresponding O-acyl-N-hydroxy-2-thiopyridone derivatives by visible light photolysis gives nitriles in good yield. The homolysis products of these sulfonyl nitriles can also be trapped by electron rich olefins. We have also found that carbon radicals react easily with mesyl or tosyl isothiocyanate producing thiocyanates.

A new thiohydroxamic acid was synthesized and found to be an excellent generator of carbon radicals via its O-acyl derivatives.

Hypervalent iodine compounds react with organolithium reagents instantaneously even at −80°C resulting in the formation of hydrocarbons. Our findings indicate that the carboncarbon bond formation is the result of ligand exchange and second displacement on the carbon bonded to iodine.

D-Ribose was transformed to its protected tosylate 15 , followed by a Wittig-reaction to give 16 as a 3:1 mixture of the corresponding Z and E isomers. This mixture was then transformed to the aniseltelluride 17 and the latter cyclized in a radical exchange reaction to a mixutre of the carbocycles 18a and 18b (in a 17:2 ratio). The major product 18a was then transformed to various chiral cyclopentane derivatives including the cyclopentenone-derivative 23 . Various other carbohydrate-based approaches have also been explored.

Thionocarbonates and xanthates of primary and secondary alcohols, as well as dixanthates of vic-diols can easily be deoxygenated to the corresponding hydrocarbons or olefins with triethylsilane and benzoyl peroxide in high-yielding radical reactions.