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Full-Text Articles in Physical Sciences and Mathematics
Regio- And Diastereoselective Samarium-Mediated Allylic Sulfone Reductions, Cody Schwans
Regio- And Diastereoselective Samarium-Mediated Allylic Sulfone Reductions, Cody Schwans
WWU Graduate School Collection
A series of allylic sulfones were synthesized containing a stereodirecting group and chelating element and subjected to samarium diiodide reductions in the presence of a proton donor. The resulting products could be obtained with high regioselectivity (no less than 95:5) and high diastereoselectivity (>10:1) that correlated with the size of the stereodirecting group. A mechanism is proposed that includes loss of the sulfone and formation of a chelated organosamarium intermediate followed by intramolecular protonation by a samarium-bound proton source. In this way, both the regioselectivity and absolute stereochemistry of the resulting products are explained.
Development Of Regio- And Diastereoselective Samarium (Ii) Iodide Mediated Allylic Benzoate Reductions, Trevor Stockdale
Development Of Regio- And Diastereoselective Samarium (Ii) Iodide Mediated Allylic Benzoate Reductions, Trevor Stockdale
WWU Graduate School Collection
Herein, we report a regio- and diastereoselective samarium mediated allylic benzoate reduction. The reaction can achieve high yields, regioselectivity, and diastereoselectivity, however there appear to be many factors influencing the outcome: proton sources, alkene geometry, chelating group length, relative stereocenter positioning, and stereocenter identity. These substrate parameters were looked at in-depth which ultimately led to several conclusions about optimized substrates. For instance, experiments indicate that the reaction proceeds through a bicyclic organosamarium species followed by intramolecular protonation from samarium bound water.