Aluminum compounds alkenyl-aryl reactions

Several of the trialkylaluminum and alkylaluminum halides and hydrides mentioned above are commercially available. Alkynyl, alkenyl, cyclopentadienyl, and aryl derivatives are, in general, not commercially available and must be synthesized for laboratory use. Alkynyl derivatives can be prepared by salt metathesis, as in the reaction of Et2AlCl with NaC=CEt to give Et2AlC=CEt. The acidity of terminal alkynes is sufficient for preparation of alkynyl aluminum compounds by alkane or hydrogen elimination upon reaction with a trialkylaluminum or an aluminum hydride (equation 17), respectively. TriaUcynyl aluminum compounds are typically isolated as Lewis base adducts to stabilize them against otherwise facile polymerization. Alkenyl compounds of aluminnm have similarly been prepared. 

The substitution of aluminum by oxygen can be effected by various peroxide derivatives, such as di-r-butyl peroxide, benzoyl peroxide and r-butyl perbenzoate. The main reaction is accompanied by telltale free-radical side reactions, such as the formation of RR from R3AI, which become major pathways with aryl and vinyl compounds. Oxidation of alkenyl derivative (56) with r-butyl perbenzoate yields 45% of a mixture of cis and trans ethers (57 equation 44). As of yet there is no generally applicable, highly efficient method for oxidizing vinylaluminum compounds. 

---