Acetylene derivs halides, synthesis

Synthesis of acetylene derivatives from halides and acetylenealcohols... 

Silyl, germanyl and stannyl alk-l-ynyl ketones have been prepared from 2-lithio-2-(trimethylsilylethynyl)-l,3-dioxolane 448. The deprotonation of the dioxane 447 with n-BuLi at — 65 °C afforded the acyl anion 448 which, after reaction with trimethylsilyl, trimethylgermanyl and trimethylstannyl chloride, gave the expected derivatives (Scheme 117)658. Hydrolysis of these products with 0.01 M sulfuric acid at room temperature in aqueous acetone gave the corresponding acyl derivatives 449. On the other hand, the reaction of the intermediate 448 with alkyl halides allows the synthesis of acetylenic ketones659. 

THF is useful in the malonic ester synthesis since it dissolves many sodio derivatives. Use of aqueous THF facilitates diazotization of salts of aminopolyphenyls which are sparingly soluble in water and is recommended also for the Schiemann reaction. It is superior to ether as solvent for coupling of an acetylenic Grignard reagent with a propargylic halide. Cremlyn and Chisholm found THF superior to dioxane or Cellosolve as solvent for the hydrogenation of cholesterol at ordinary temperature and pressure with perchloric acid as catalyst. 

Substituted-3-acylindoles have been prepared through the palladium-catalyzed carbonylative cyclization of 2 -alkynyltrifluoroacetanylides with vinyl triflates [102,106]. Analogously, the palladium-catalyzed cyclocarbonylation of bis(o-trifluoroacetamido-phenyl)acetylene 59 with vinyl halides and triflates afforded 12-acyUndolo[l,2-c] quinazoline derivatives in high yields. The palladium-catalyzed reaction of 59 with the vinyl triflates 60 at 50 ° C under 5 bar of carbon monoxide allowed the synthesis of the corresponding quinazoline derivative 61 in 98% yield (Scheme 9.29) [107]. 

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