Alkylmagnesium compounds, reactions with

Reactions of Enamine Salts with OrganometalUc Compounds Organolithium and organomagnesium compounds react with enamine salts to give amines substituted on the ix-carbon atoms. The treatment of. -dehydroquinolizidinium perchlorate (163) with alkylmagnesium halides gives 9-alkylated quinolizidines (164) (252,256). Formation of... 

Metallation of alkynylcyclopropanes at the acetylenic end is accomplished either by deprotonation or via metal-halide exchange reaction with strong bases. Metallation of ethynylcyclopropane may be affected by KOH in DMF, ethereal EtMgBr or preferably BuLi in THF (equation 151)231. All three metal acetyl ides react with methyl ketones to give the corresponding alcohols. However, the instability of cyclopropyl ketones towards bases, especially at the reaction conditions required by KOH (20 °C, 6h), and the sensitivity of cyclopropenyl double bonds in cyclopropenyl ketone derivatives towards addition reactions of alkylmagnesium compounds, make the alkyllithium (-78 °C, instant reaction) superior to the other reagents. 

Iron(m) salts are effective catalysts for sp -sp2 coupling, which catalyze the reaction of alkylmagnesium compounds with aryl chlorides, triflates and tosylates as well as hetaryl chlorides in THF-NMP at 0°C (Scheme 49, 50).139 139a-i39d... 

Whereas the reactions of aromatic and unsaturated organomagnesium compounds with thiocarbonyl compounds are analogous to their reactions with carbonyl compounds (see Chapter 7), saturated alkylmagnesium compounds (apart from methyl) tend to react by thiophilic addition [1] ... 

Solvent effects were studied in the fate 1950s for reactions of alkylmagnesium compounds with 1-hexyne in diethyl ether. These reactions have already been discussed several times in this and in Chapter 11 (see Scheme 10) [22a], When 1.0 molEq triethylamine was added to the reaction mixture, the relative reactivity of methylmagnesium iodide toward 1-hexyne, which is 7 (the reactivity of ethylmagnesium bromide was arbitrarily set... 

Alkyl metals are not suitable for the metallation of tiiese compounds. For example, BuaU reacts at -78 C on the seletuum atom of selenonium salts and produces a novel organolithium in which the carb-aruonic center is more stabilized (Scheme 50, a and b), whereas alkylmagnesium bronudes and chlmides unexpectedly lead to decyl bromide and chloride respectively on reaction with decyl phenyl selenrme (Scheme 50, c). 

The reaction of [WCI2CP2] with excess of MgBr(/-Pr) affords [WHcp2(C3H6)]PF6. The olefins are formed from alkylaluminum or alkylmagnesium compounds. Cationic complexes are reversibly deprotonated by means of 1 M KOH solution ... 

Many other kinds of organometallic compounds can be prepared in a manner similar to that of Grignard reagents. For instance, alkyllithium reagents, RLi, can be prepared by the reaction of an alkyl halide with lithium metal. Alkyllithiums are both nucleophiles and strong bases, and their chemistry is similar in many respects to that of alkylmagnesium halides. 

Reactions of aryl- and alkylmagnesium halides with sulfur tetrafluoride do not result in fluori-nation of the organic part of the organometallic compound diaryl- or dialkyl sulfides and aryl or alkyl halides are the sole products.233... 

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