Sml2 Barbier-type cyclization

Aryl radical cyclization.10 Sml2 in HMPA/THF at 25° can effect cyclization of l-allyloxy-2-iodobenzene to a Sm(III) intermediate (a) that can be trapped by electrophiles, including aldehydes or ketones. The report suggests that a similar mechanism operates in the Barbier-type coupling generation of an alkyl radical followed by formation of RSml2, which adds to a carbonyl compound to form an adduct that is hydrolyzed to an alcohol. 

Lantanides and Sml2 specifically in carbon-carbon bond formation or for functional group transformation (cyclization, Barbier type reaction, intramolecular coupling, aldol, Evans, Tishenco). 

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