[-] · C19H36CuLiSn · Lithium (1-Pentynyl)(2-tri-n-butylstannylvinyl)cuprate · (MW 453.75)
(mixed organocuprate; introduces angular acetylene equivalent to enones via vinylstannanes)
Preparative Method: prepared in situ by first monolithiating trans-1,2-Bis(tributylstannyl)ethylene with n-Butyllithium in THF at -78 °C, then transferring the anionic solution via cannula to a mixture of 1-Pentynylcopper(I) and Hexamethylphosphorous Triamide at -40 °C.1
Handling, Storage, and Precautions: air- and moisture-sensitive. Use in a fume hood.
Lithium (1-pentynyl)(2-tri-n-butylstannylvinyl)cuprate (1) undergoes 1,4-addition to a,b-enones in high yields.1 The resulting addition products can then be readily transformed into terminal alkynes with Lead(IV) Acetate in acetonitrile. This sequence provides a two-step method for the introduction of angular acetylenes (eqs 1 and 2).
Matthew E. Voss
The Du Pont Merck Pharmaceutical Company, Wilmington, DE, USA