Alkynyl Grignard reagents chloride

Coupling of terminal acetylenes [top of 1, 169, after the formulation]. Miller173 has described a procedure for the cuprous chloride-catalyzed coupling of an alkynyl Grignard reagent (1) with propargyl bromide to produce a skipped 1,4-diyne (2) and its isomerization under mild conditions to a conjugated 1,3-diyne (3). 

Although alkyl Grignard reagents undergo 1,2- and 1,4-addition to N-methoxycarbonylpyridinium chloride in variable ratio, alkenyl and alkynyl Grignard reagents give 1,2-adducts exclusively. 

The preparation of alkyl, alkenyl, and aryl derivatives of cyanoacetylene (1) poses no particular problems. In most cases a terminal acetylene is metalated or converted into an alkynyl Grignard reagent, and these intermediates are subsequently intercepted by a cyano source , which in most cases is either cyanogen chloride or bromide and sometimes cuprous cyanide or phenyl cyanate. Of course, dehydration of an acetylenic amide as described for the parent molecules is also possible and has occasionally been employed. 

The action of alkynyl Grignard reagents on the pyridinium salt 67 affords solely 1,2-dihydropyridine derivative 68, whereas alkyl Grignard reagents yield mixtures of 1,2- and 1,4-dihydropyridines (equation 10). The contrasting behaviour of the two nucleophiles was explained by means of the Principle of Hard and Soft Acids and Bases". Application of the reaction to the action of the acetylenic Grignard compound 69 on l-methoxycarbonyl-2-methylpyridinium chloride gave the dihydropyridine derivative 70, which was transformed into ( ) -monomorine 71, a train pheromone of the pharao ant. ... 

The use of cobalt species to catalyze cross-coupling reactions of activated or unactivated alkyl halides with alkynyl Grignard reagents in order to form C(sp)-G(sp ) bonds is also of interest. Cobalt compleres promote the crossbenzyl chlorides and bromides react with 2-trimethylsilylethynyl- and 1-octyn-l-ylmagnesium halides to provide l-aryl-2-alkynes in the presence of a catalytic amount of a cobalt complex [100,101]. 

Grignard reagents convert aromatic sulfonyl chlorides or aromatic sulfonates to sulfones. Aromatic sulfonates have also been converted to sulfones with organolithium compounds.1745 Vinylic and allylic sulfones have been prepared by treatment of sulfonyl chlorides with a vinylic or allylic stannane and a palladium-complex catalyst.1746 Alkynyl sulfones can be prepared by treatment of sulfonyl chlorides with trimethylsilylalkynes, with an AICL catalyst.1747... 

Acetylenic ketones can be prepared in moderate yield by the reaction of acetylenic Grignard reagents with acid chlorides or anhydrides [Eq. (41) 75-78]. Alkynyl magnesium chloride reacts with acetic anhydride to give acetylenic ketones in good yield (see Table 4, entry 17). 

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