Me2AlCl

Dihydropyrans [71] and 4-dihydropyranones [72] have been prepared by BF3 or Me2AlCl catalyzed Diels-Alder reactions of alkyl and aryl aldehydes with dienes 72 and 73 (Equations 3.20 and 3.21). Allylic bis-silanes are useful building blocks for synthesizing molecules of biological interest [73], 4-Pyra-nones have been obtained by cerium ammonium nitrate (CAN) oxidation of the cycloadducts. 

Dehydrosilylation reaction. While the dehalosilylation reaction is very powerful for the synthesis of Ga—Sb and In—Sb heterocycles, this reaction type completely failed for the synthesis of the corresponding stibinoalanes. Only the reaction of Me2AlCl with Sb(Tms)3, leading to the formation of [Me(Gl)AlSb(Tms)2]3 38, yielded an Al—Sb heterocycle [36a]. However, 38 obviously was not formed by dehalosilylation but by tetramethylsilane elimination reaction (Scheme 9). 

The bis(3-t-butylpyrazolyl)hydroborato complex, [BpBut]AlMe2, has been synthesized by the reactions of either Me3Al or Me2AlCl with K[BpBut] (Scheme 14). Similarly, [Et2Bp]AlEt2 has been prepared by the reaction of Et2AlCl with K[Et2Bp] (108). 

Another photochemically induced domino process consisting of three steps was employed for the formation of 1,2-disubstituted cyclopentanes 5-39, as described by Tietze and coworkers. Irradiation of a mixture of 5-36, dimethyl malonate and catalytic amounts of the Lewis acid Me2AlCl in a Pyrex flask caused a Norish Type I cleavage of 5-36, followed by an intramolecular hydrogen shift to give the acyclic... 

TABLE 5-7. Me2AlCl-Promoted Intramolecular Diels-Alder Reactions of Trienimides 138 and 141... 

In addition to neutral five-coordinate aluminum alkyls, rare examples of five-coordinate cationic compounds have also been reported.101 The cationic compound [(PMDETA)AlMe2][Me2AlCl2] (PMDETA = pentamethyldiethylene triamine) (Figure 10(a)) was prepared by the reaction of Me2AlCl with PMDETA in toluene. The NMR showed... 

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