Reductive Couplings of Imines and Their Equivalents

Representative procedure. To a stirred solution of nitrone (1 equiv) and acrylate (1 equiv) in THF (0.05 M) at —78 °C was added ferf-butanol (2 equiv) followed by 

Finally, in 2006, Ellman reported a single example of a sulfinimine-alkene coupling mediated by Sml2 in their work on the total synthesis of the anticancer agent, tubulysin D. It was found that the coupling of enantiomerically pure sulfinimine 67 with methyl methacrylate was effectively promoted by the 

The addition of sp3 or sp2 carbon-centred radicals to unsaturated carbon carbon bonds is yet another class of synthetically useful reactions promoted by the low-valent lanthanide reagent Sml2. Halides and sulfones are the most common functional groups used as precursors to radicals, although other groups have also been successfully employed. Although the intermolecular variant of this reaction has found only limited application, intramolecular variants can be highly successful. In most of these cyclisation events, the 

To date, the 5-exo-trig and 5-exo-dig radical cyclisations represent the most successful classes of Sml2-mediated radical-alkene/alkyne cyclisations and have been applied to a diverse array of substrates. The application of this approach to the generation of larger ring sizes is more challenging and success is highly dependent on the structure of the radical precursor. 

---