Download Barton*McCombie Deoxygenation

Khitam Dyab
Contents
Objectives
Background
Reaction and Mechanism
Application and recent
literature
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Conclusion
References
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To discover a new procedure for producing hydride
which is Barton Mc-combie reaction.
Knowing the reaction application and its recent
literature.
The Barton-McCombie deoxygenation is an organic
reaction in which an hydroxy functional group in
an organic compound is replaced by a hydride to
give an alkyl group [1][2]. It is named for the British
chemists Sir Derek Harold Richard Barton (1918–
1998) and Stuart W. McCombie.
This deoxygenation reaction is a radical substitution.
In the related Barton decarboxylation the reactant
is a carboxylic acid.
The reaction mechanism consists of a catalytic radical initiation step
and a propagation step.[3] The alcohol (1) is first converted into a
xanthate (2). The other reactant tributyltin hydride 3 is decomposed
by AIBN 8 into a tributyltin radical 4. The tributyltin radical abstracts
the xanthate group from 2 leaving an alkyl radical 5 and tributyltin
xanthate (7). The sulfur tin bond in this compound is very stable and
provides the driving force for this reaction. The alkyl radical in turn
abstracts a hydrogen atom from a new molecule of tributyltin
hydride generating the desired deoxygenated product (6) and a new
radical species ready for propagation..
We have learned about Barton Mc-combie
Reaction ,its radical mechanism and we know
that its part of deoxygenation reaction in
which hydride is produced.
http://www.organic-chemistry.org/namedreactions/bartonmccombie-reaction.shtm
1.
2.
3.
^ Barton, D. H. R.; McCombie, S. W. (1975). "A new method
for the deoxygenation of secondary alcohols". J. Chem. Soc.,
Perkin Trans. 1 16: 1574–1585.
doi:10.1039/P19750001574.
^ Crich, D.; Quintero, L. (1989). "Radical chemistry
associated with the thiocarbonyl group". Chem. Rev. 89:
1413–1432. doi:10.1021/cr00097a001.
^ Forbes, J. E.; Zard, S. Z. Tetrahedron Lett. 1989, 30, 4367.