Terminal olefins are transformed by bromination and subsequent dehydrobromination at room temperature with a solution of sodamide or sodium hydride in DMSO to pure terminal acetylenes. trans Dehydrobromination of vinylic bromides proceeds faster than the cis. Conditions were found, where the 1-alkynes are converted into 2-alkynes.
Facile one-pot synthesis of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent
作者:Rajendra D. Patil、Girdhar Joshi、Subbarayappa Adimurthy、Brindaban C. Ranu
DOI:10.1016/j.tetlet.2009.03.047
日期:2009.5
A new method for the preparation of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent has been developed. Several α-bromoketones were successfully prepared from a variety of olefins by this method. This procedure is an alternative to conventional molecular bromine.
yields. These [3,3]-sigmatropic rearrangements are diastereoselective giving trans-configured double bonds, exclusively. Corresponding esters derived from (Z)-2-fluorocyclododec-2-enol (22), did rearrange to yield mixtures of diastereomers much less selectively. Also 2-fluorodec-2-enol (6), which was prepared by rearrangement of 2-fluoro-2-octyloxirane (5) with TMSOTf and triethylamine, was successfully
A convenient route to alkynes via phase transfer catalysis
作者:Eckehard V. Dehmlow、Manfred Lissel
DOI:10.1016/s0040-4020(01)98925-2
日期:1981.1
High yield, rapid formations of alkynes from vicdibromides are possible using powered potassium hydroxide and catalytic amounts of lipophilic phasetransfer catalysts. Reasons are given why molar amounts of expensive catalysts were necessary in earlier procedures.
Catalytic Debromination of Vicinal Dibromides<i>via</i>Phase Transfer of Diaryltellurium Compounds
作者:Hitomi Suzuki、Akiko Kondo、Atsuhiro Osuka
DOI:10.1246/bcsj.58.1335
日期:1985.4
Several vicinal dibromides were debrominated to olefins by potassium disulfite in the presence of catalytic amounts of bis(4-methoxyphenyl) telluride in a two-phase system.