Stannylcopper reagents

Trialkyl- or triarylallenyltin compounds can also be prepared by Sn2 displacement of propargylic mesylates with various stannylcopper reagents in THF (Eq. 9.82) [71]. This reaction is postulated to proceed by an anti Sn2 pathway based on the stereochemical relationship between the enantioenriched mesylate and the allenic product (Eq. 9.83). The allene obtained from the reaction of the mesylate of (R)-3-phenyl-l-propyn-3-ol with Ph3SnCu was assigned the (P) configuration from a consideration of the observed optical rotation and an application of Brewster s rules [71]. 

Scheme 2.20. Stannylation of terminal alkynes with stannylcopper reagents derived from stannylated aluminium compounds.

Eor reviews on stannylcopper reagents see reference 6 and (a) trimethyl-stannylcopper-dimethyl sulfide E. Piers, C. Rogers, in Encyclopedia of Reagents for Organic Synthesis,... 

Stannylcopper reagents convert optically active propargylic substrates 13 into chiral al-lenylstannanes 14 via an SN2 substitution18. 

The initial reports in 1982-83 by Westmijze et. al. [25a] and Piers [25b] on the addition of stannylcopper and cuprate reagents to simple alkynes were followed by full studies [76] and reports from several laboratories [14b, 16b-e, 25c, 77-78]. In the earlier studies, the vinylcopper species could only be trapped with a proton. Marino achieved success in the addition to cyclohexenone of the vinyl cuprate generated by addition of BusSnCuCNLi to acetylene [79a-b], and Fleming [79c]... 

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