Substrate-directable electron transfer reactions. Dramatic rate enhancement in the chemoselective reduction of cyclic esters using SmI2-H2O: mechanism, scope, and synthetic utility.
Substrate-directable reactions play a pivotal role in organic synthesis, but are uncommon in reactions proceeding via radical mechanisms. Herein, we provide experimental evidence showing dramatic rate acceleration in the Sm(II)-mediated reduction of cyclic esters that is enabled by transient chelation between a directing group and the lanthanide center. This process allows unprecedented chemoselectivity in the reduction of cyclic esters using SmI2-H2O and for the first time proceeds with a broad substrate scope. Initial studies on the origin of selectivity and synthetic application to form carbon-carbon bonds are also disclosed.
School of Chemistry, University of Manchester , Oxford Road, Manchester, M13 9PL, United Kingdom.
Michal
M
Szostak
Malcolm
M
Spain
Kimberly A
KA
Choquette
Robert A
RA
Flowers
David J
DJ
Procter
D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D004583:Electrons; D004952:Esters / Q000737:chemistry*; D007454:Iodides / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012493:Samarium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D000438:Alcohols; D004952:Esters; D007454:Iodides; D014867:Water; D012493:Samarium; C409809:samarium diiodide