Reactions of Metallated Acetylenes and Allenes with Alkylating Agents

摘要: The alkylation of metallated acetylenes and allenes involves the reaction with alkyl halides in usual organic solvents Et 2 O THF liquid ammonia. As compared to several other types synthetic intermediates, 1-alkynylides, RC≡CM (M═Li, Na, K), show a moderate reactivity towards halides. In absence dipolar aprotic co-solvents for example, Dimethyl sulfoxide (DMSO) or Hexamethylphosphorous triamide (HMPT), lithium alkynylides, RC≡CLi, react sluggishly tetrahydrofuran (THF) most ammonia, alkali alkynylides lower (up C-5) primary bromides iodides proceeds at satisfactory rate. A certain amount DMSO added mixture increases solubility longer carbon chain. gradually over range from –33°C (bp NH 3 ) room temperature. Dimethylformamide (DMF) is used as solvent alkylations higher sodium acetylide prepared Selective on acetylenic takes place if an equivalent halide dilithiated propargyl alcohol, LiC≡CCH OLi, more strongly basic metal compounds structure systems MC═C═C C≡C–CM, obtained by metallation non-terminal allenes, are much reactive toward alkylating agents. Successful reactions acetylides restricted agents general XCH CH R, which X ═ Br Cl R Alkyl, OAlkyl . chapter also discusses oxiranes oxetanes, α-haloethers, orthoesters.