Vinyltin/aryl bromide coupling

An interesting one-pot two-step cyclization was described by Finch et al. [200], who first used PdCl2(PPh3) to cany out the hydrostannation of a triple bond and then by adding Pd(PPh3)4 closed a seven-membered ring via a vinyltin/aryl bromide coupling (Scheme 4-51). 

Vinyllithiums cf. 13, 142).10 An improved route to vinyllithiums involves coupling of vinyl and aryl triflates with tributyl- or trimethylstannylcuprates of the formula (R3Sn)2Cu(CN)Li2, prepared from LDA, R,SnH, and CuCN in THF at -50° to -60°. The higher-order cuprates couple with vinyl and aryl triflates at -20° to provide a vinyltin intermediate. Work-up of the intermediate with AgOAc provides a vinyltin, with bromine a vinyl bromide, or with CF,COOH an aryltin. 

Stille cross-coupling of aryl iodides and bromides with macroporous polymer-supported vinyltins also gave good yields and very low levels of contamination. The worst example gave 16 ppm of tin contamination after simple filtration of the product, but subsequent purification by flash chromatography reduced the tin contamination to < 1 ppm. ... 

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