Preparation from other organomagnesium compounds

Dzhemilev, A. G. Ibragimov, E. V. Gribanova and L. M. Khalilov, Izvest. Akad. Nauk SSSR, 428 (1988) Engl, transl., 347. 

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Miscellaneous preparations from other organomagnesium compounds... 

Although the isolated yield from the above preparation was modest, the true yield was higher, and the work-up procedure should be capable of improvement, and the method should be applicable to other organomagnesium compounds [6]. 

More attractive copper-catalyzed (mediated) transformations of allenes into alkynes were reported by Caporusso and co-workers [27f, 73-75], Allenes 142 were converted into alkynes 143 by treatment with stoichiometric amounts of a cuprate species, as exemplified in Scheme 14.35. The problem of regioselective formation of either alkyne 143 or allene 144 was solved by the proper choice of the organometallic species. Preferential formation of alkynes 143 could be achieved employing cuprates such as R3Cu(CN)ZnCl-LiCl, which are prepared from organozinc compounds. On the other hand, reactions of organomagnesium derived cuprates (R3CuBr)Mg-LiBr mostly provided allenes 144 as major components. 

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