Rearrangements organoaluminum compounds

Organoaluminum compounds, reaction with imino carbocations, 66, 189 Orthoester Claisen rearrangement, 66, 22 Orthoformic acid, triethyl ester, 65, 146 Oxalic acid, diethyl ester, 65, 146... 

Rearrangements of Organoaluminum Compounds and Their Group III Analogs, 16,111... 

The presence of jr-electron-donating substituents at the 2-position of the vinyl portion of the ether allows for significant acceleration of the Claisen rearrangement.314-318 Aliphatic Claisen rearrangements can proceed in the presence of organoaluminum compounds,286-319-320 although other Lewis acids have failed to show reactivity.286,321 324 Useful levels of (Z)-stereoselection and asymmetric induction have been obtained by use of bulky chiral organoaluminum Lewis acids.325 327... 

CLAISEN REARRANGEMENT Lithium hex-amethyldisilylazide. Lithium methylsulfi-nylmethylide. Organoaluminum compounds. Sodium melhylsulllnylmethylide. 

An organoaluminum compound in hydrocarbon solvent caused rearrangement of an acid-sensitive diene monoepoxide, but a change to ether solvent mediated this (undesired) reaction. 

The intermediate iminocarbocation or alkylidyneammonium ion generated by an organoaluminum compound can be trapped intramolecularly by means of ole-fmic groups [186]. This interesting rearrangement-cyclization sequence was extended to an efBcient synthesis of muscone or muscopyridine (Scheme 6.147)... 

Unlike bis(4-bromo-2,6-di-/ert-butyl-phenoxy)methylaluniinum. the Z selectivity of other bulky organoaluminum compounds (e g., Table 5, entries 7 and 8) is lower. (4-Bromo-2,6-di-fselective rearrangements with bis(2,6-diphenylphenoxy)methylaluminum were obtained with toluene as solvent at — 20 CC. Though the reason for the high E selectivity in this case is not clear, steric as well as electronic factors may account for the result123. 

Abstract The use of organoaluminum-based Lewis acids (A1R X3 R = alkyl, alkynyl, X = halide or pseudohalide) in the period 2000 to mid-2011 is overviewed with a focus on (1) stoichiometric reactions in which one of the organoaluminum substituents is transferred to the substrate (e.g., the opening of epoxides, 1,2-additions to carbonyl compounds, coupling with C-X, and Reissert chemistry) and (2) asymmetric, often catalytic, reactions promoted by Lewis acid catalysts derived from organoaluminum species (e.g., use of auxiliaries with alanes, Diels-Alder, and related cycloaddition reactions, additions to aldehydes and ketones, and skeletal rearrangement reactions). 

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