Organosamarium reagents

The initial products of such additions under aprotic conditions are organosamarium reagents and further (tandem) transformations are possible, including addition to ketones, anhydrides, or carbon dioxide. 

Scheme 2.68. Copper-catalyzed 1,4-addition of organosamarium reagents.

The C-linked (1 6)-disaccharides 176, 178 and 180 are all obtained in good yields (83 to 89%). The addition of the organosamarium reagents to the carbonyl group of aldehyde 175 also occurred with a high facial selectivity (diastereomeric ratio of about 95 5), exclusively controlled by the asymmetry of the C-glycosyl donor. 

Molander, G. A., McKie, J. A. Intramolecular nucleophilic acyl substitution reactions of halo-substituted esters and lactones. New applications of organosamarium reagents. J. Org. Chem. 1993, 58, 7216-7227. 

It was found that Me3SiCl accelerates the conjugate addition of in situ prepared organosamarium reagents to a,f3-unsaturated carbonyl compounds and nitriles in the presence of HMPA and catalytic amounts of Cu(l) salts (Scheme 296). HMPA is also necessary for the in situ preparation of the organosamarium species from alkyl halide and Sml2.1081... 

Addition to C =0. Organosamarium reagents, formed by treatment of r-butyl a-haloalkyl ketones with Sml2 in THF at —78°, are active toward carbonyl compounds. ... 

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