Radical-mediated desulfonylation reactions with group 14 metallo hydrides : synthesis of (a-fluoro)phosphonates and (a-fluoro)vinyl silanes
Document Type
Thesis
Degree
Master of Science (MS)
Major/Program
Chemistry
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
7-21-2004
Abstract
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.
Identifier
FI15101514
Recommended Citation
Garica, Pedro Israel Jr., "Radical-mediated desulfonylation reactions with group 14 metallo hydrides : synthesis of (a-fluoro)phosphonates and (a-fluoro)vinyl silanes" (2004). FIU Electronic Theses and Dissertations. 3524.
https://digitalcommons.fiu.edu/etd/3524
Rights Statement
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).