Samarium carbenoids cyclopropanation with

Two DFT studies (one in Chinese and one in English) of the cyclopropanation of ethene with samarium(II) carbenoids have been reported.53,54 The reaction path is likely to involve a methylene transfer rather than a carbometallation with or without coordination of up to two THF molecules to the rare earth. 

When a-halo ketones are treated with diiodomethane and samarium at 0 °C, cyclopropanols can be obtained in reasonable yields. Curiously, under the same conditions 1,2-dibenzoylethane also leads to cyclopropanol products (equations 34 and 35). Several pathways for conversion of a-halo ketones to the observed cyclopropanols can be envisioned. It has been proposed that the mechanism of this reaction involves reduction of the a-halo ketone by Sm (or Smh) to a samarium enolate. Cyclopropanation of this enolate with a samarium-based carbenoid subsequently provides the observed product. 

Zhao, C., Wang, D., Phillips David, L. Theoretical study of samarium (II) carbenoid (ISmCH2l) promoted cyclopropanation reactions with ethylene and the effect of THF solvent on the reaction pathways. J. Am. Chem. Soc. 2003, 125, 15200-15209. 

A computational study of cyclopropanation reactions of the divalent samarium carbenoid ISmCH2I with ethylene has been presented. The ISmCH2I species was found to have a samarium carbene complex character with... 

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