Reductive cyclisation cascades of lactones using SmI2-H2O

Abstract

It was over 30 years ago when Kagan[1] and co-workers turned their attention to the field of divalent lanthanide reducing agents. Of the reductants initially chosen for investigation, samarium diiodide (SmI2) emerged as one of the most promising and has since become one of the most important reducing agents available to the synthetic organic chemist. Samarium diiodide demonstrates great versatility, promoting a multitude of synthetic organic transformations, with its inclusion in over 100 publications per year being a testament to its synthetic importance.Until recently, the reduction of unfunctionalised esters with the reagent SmI2 was thought to be impossible. I have employed the unusual radical-anion intermediates in cyclisations to form cycloheptandiols and in cascade reactions in which 7- and 5-membered rings are formed, with good diastereocontrol in a single step, using a single reagent.In the Procter group, it was found that 6-membered lactones can be reduced using SmI2-H2O. These are the first examples of the reduction of simple, aliphatic ester carbonyl groups with SmI2. Furthermore, the radical-anions generated have been used for the first time in cyclisations with alkenes. My work has attempted to exploit the previously unexplored reaction space by accessing unique radical-anion species. It was proposed that new reaction pathways and selectivity would result from our studies.

Date of Award	1 Aug 2011
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Procter (Supervisor)