Barton-McCombie radical

D. Crich, On the use of S-(4-alkenyI)-dithiocarbonates as mechanistic probes in the Barton-McCombie radical deoxygenation reaction, Tetrahedron Lett. 29 5805 (1988). 

This "thiophilic" mode of reaction fits well with the other ionic and radical thiophilic additions on a thiocarbonyl group (see [120], and the Barton-McCombie radical thiophilic addition [227] previously discussed in Sections 4.2.2 and 3.2). With thioaldehydes, both C-C and C-S bonds were formed, as in the following case in which 0-pinene was used to trap thiobenzaldehyde [514] ... 

The Barton-McCombie radical deoxygenation [221-223] (vide infra Section 3.2) has also been applied for transforming v/c-diols into olefins. Commercially available diphenylsilane and the easily formed dixanthates can be conveniently used for this purpose, as in the following example in the sugar series [224],... 

In the Barton-McCombie radical deoxygenation reaction the hydroxyl group of an alcohol is replaced with a hydrogen atom. Even hindered secondary and tertiary alcohols may be deoxygenated by this method. In a typical procedure the alcohol is first converted to a thioxoester derivative, which is then exposed to tri-n-butyltin hydride in refluxing toluene. 

S.J. Danishefsky and co-workers developed a synthetic route to the neurotrophic illicinones and a total synthesis of the natural product tricycloillicinone. Illicinones were found to enhance the action of choline acetyltransferase, which catalyzes the synthesis of acetylcholine from its precursors. The application of Corey-Snider oxidative cycHzation and the Barton-McCombie radical deoxygenation provided a direct route to tricycloillicinone. 

Shioiri s group also employed a 2-lithiooxazole to construct the bis-oxazolyl methanol core of 904. Here, lithiation of a silyl-protected 4-oxazolemethanol 905a/ b followed by condensation with 902 afforded a racemic bis-oxazolyl methanol 906a/b in modest yield (Scheme 1.242). Attempts to improve the yield of 906 using a Lewis acid to coordinate the oxazole nitrogen, alternate bases, or addition of cosolvents were not successful. Barton-McCombie radical deoxygenation was used... 

To the best of our knowledge, only a few groups have developed such methodologies. Lythgoe and Waterhouse, in 1977, were the first to use the Barton-McCombie radical deoxygenation approach to induce the elimination of the aryl... 

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