Radical-mediated desulfonylation reactions with group 14 metallo hydrides : synthesis of (a-fluoro)phosphonates and (a-fluoro)vinyl silanes

Document Type



Master of Science (MS)



First Advisor's Name

Stanislaw F. Wnuk

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Kathleen Rein

Third Advisor's Name

Fenfei Leng

Date of Defense



The sulfone group is a well-established activating moiety important in many organic transformations. Standard procedures for desulfonylation [Al(Hg), or Na(Hg)] were ineffective for the removal of the pyridin-2-ylsulfonyl group from the α-carbon of phosphonic esters. Prompted by these results, we undertook a study for the synthesis of α-(arylsulfonyl)phosphonates, and their fluorination with Selectfluor to produce α-fluoro-α-(arylsulfonyl)phosphonates, Radical mediated hydrogenolysis of α-fluoro-α-(arylsulfonyl)phosphonates using BujSnH gave (α-fluoro)phosphonates. We observed that the yield for the desulfonylation reaction depends on the n-deficiency effect and increase in the order pyrimidinyl > pyridinyl > phenyl sulfonyl.

The (α-fluoro)phosphonates were employed as convenient precursors in the Homer-Wadsworth-Emmons (HWE) reaction to provide (α-fluoro)vinyl sulfones. The vinyl and (α-fluoro)vinyl sulfones underwent substitutive silyl and germyl- desulfonylation to yield vinyl and (α-fluoro)vinyl silanes and germanes via an addition-elimination mechanism. The vinyl tris(trimethylsilyl)silanes were employed as nucleophiles (under oxidative conditions) in palladium-catalyzed cross coupling reactions with iodobenzene and bromobenzene.



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