Ketones alkenes, samarium iodide

Addition of Vinylsamarium to Aldehydes. Treatment of (Z)-a-chloro-a,)3-unsaturatedketones with samarium iodide leads to the vinylsamarium reagent that can be trapped with aldehydes or ketones to produce Baylis-HUlman type adducts with inversion of stereochemistry at the alkene (eq 55). ... 

Intermolecular coupling of ketones and alkenes, promoted by SmH, occurs with excellent stereochemical control. In one such reaction, samarium(II) iodide has been used to prepare cyclobutanones and cyclobutanols from chiral, 6-oxohex-2-enoates (equation 137)520. The reaction is performed in THF in the presence of HMPT and occurs in good yield with excellent stereocontrol. If appropriately located carbonyl and alkene moieties are present in a molecule, then Sml2-HMPT can be used to form cyclooctanols by a radical cyclization process in some cases there is a reasonable degree of diastereoselectivity (equation 138)521,522. 

Samarium(ir) iodide in the presence of HMPA effectively promotes the intramolecular coupling of unactivated alkenic ketones by a reductive ketyl-alkene radical cyclization process (eq 25). This protocol provides a means to generate rather elaborate carbocycles through a sequencing process in which the resulting organosamarium species is trapped with various electrophiles to afford the cyclized product in high yield. ... 

The reagent prepared from a gem-dibromoalkane, samarium metal, and samar-ium(II) iodide in the presence of a catalytic amount of chromium(III) chloride was found to transform ketones into alkenes via a Wittig-type reaction. This method allows the alkylidenation of easily enolizable ketones, such as yS-tetralone (Scheme 5.26) [37]. 

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