Barton Decarboxylation

The Radical Decarboxylation Of A Barton Ester Proceeds To The Corresponding Alkane After Treatment With tributyltin Hydride or t-butylmercaptan:

An Alternative Possibility Is The Introduction Of A Substituent By Reaction With A Suitable Radical Trapping Agent:

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Mechanism Of The Barton Decarboxylation

The Initiation Of The Barton Decarboxylation ( Bu₃Sn-H -> Bu₃Sn^. ) Is Effected With A Radical Initiator, And As With The Barton-McCombie Deoxygenation, The Driving Force For The Reaction Itself Is The Formation Of The Stable S-Sn Bond.

In Addition, Barton Esters Can Also Be Cleaved Photolytically Or Thermally:

If An Excess Of A Suitable Radical Trapping Agent Is Present In The Reaction Medium, Substitution Will Occur; Otherwise, Radical Recombination Takes Place To Give The Pyridyl Sulfide:

The Barton Decarboxylation Offers Several Options For The Introduction Of Substituents - Some Examples Are Shown Below:

J. Zhu, A. J. H. Klunder, B. Zwanenburg, Tetrahedron, 1995, 51, 5099-5116.

Recent Literature

Synthesis Of 6-functionalized Tricyclodecadienones Using Barton's Radical Decarboxylation Reaction. Generation Of Tricyclo[5.2.1.0^2,6]decatrienone, A Norbornene Annulated Cyclopentadienone
J. Zhu, A. J. H. Klunder, B. Zwanenburg, Tetrahedron, 1995, 51, 5099-5116.

Synthesis Of (-)-Ilimaquinone Via A Radical Decarboxylation And Quinone Addition Reaction
T. Ling, E. Poupon, E. J. Rueden, E. A. Theadorakis, Org. Lett., 2002, 4, 819-822.