Barton radical decarboxylation

Radical decarboxylation via the corresponding thiocarbonyl derivatives of the carboxylic acids. 

Barton, D. H. R. Crich, D. Motherwell, W. B. J. Chem. Soc., Chem. Commun. 1983, 939. Derek Barton (United Kingdom, 1918—1998) studied under Ian Heilbron at Imperial College in his youth. He taught in England, France and the US. Barton won the Nobel Prize in Chemistry in 1969 for development of the concept of conformation. He passed away in his office at the University of Texas at Austin. 

Radical Reactions in Organic Synthesis Oxford University Press Oxford, UK, 2003. (Book). 

Name Reactions, 4th ed., DOI 10.1007/978-3-642-01053-8 11, Springer-Verlag Berlin Heidelberg 2009 

Example 1, Tin hydride not used and elimination occurs via thioether intermediate  

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 13, Springer International Publishing Switzerland 2014 

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Attardi, M. E., Taddei, M. The Barton radical decarboxylation on solid phase. A versatile synthesis of peptides containing modified amino acids. Tetrahedron Lett. 2001, 42, 3519-3522. 

Related reactions Barton radical decarboxylation reaction ... 

This approach was later extended to an enantioselective synthesis,5415 Scheme 10. Unfortunately, some racemization occurred during preparation of substrate 94, but not during cyclization to 95, this time mediated by iodosobenzene diacetate. Reduction/closure, followed by Barton radical decarboxylation yielded the known thebaine analogue 97.56... 

Conformational memory is also observed in Barton radical decarboxylations of optically active tetrahydropyrans [31]. Photolysis of thiohydroxamate esters derived from optically pure tetrahydropyrans in the presence of various hydrogen atom... 

The last and the seventh synthesis of chaetomellic acid A was reported in 1997 by the Samadi group from CNRS, France [81]. This one step synthesis involves a Barton radical decarboxylation and gave 77% overall yield (Scheme 8). The method requires preparation of a thiohydroxamic ester of the corresponding alkyl acid followed by in-situ irradiation in the presence of citraconic anhydride and silica gel chromatography. The last intermediate in this synthesis is similar to the synthesis reported by Branchaud and Slate [75,76]. 

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