Syntheses and Properties of a New Type of Lewis Acids Incorporating Linked Bisphenoxide Moiety

Abstract

Several ligands for a new type of Lewis acid, which incorporates two linked phenols, were synthesized and the reaction of these ligands with trimethylaluminum quantitatively gave Lewis acids. These Lewis acids were found to be an efficient promoter for the rearrangement of epoxides to carbonyl compounds as well as a useful protector of acetophenone against hydride-reduction. The VT-NMR spectrum and NOESY spectrum of a 1 : 1 complex of Lewis acid 2a (methyl[2,2′-(m-xylene-α,α′-diyl)bis(4,6-di-t-butylphenoxido)aluminum and acetophenone provided data on the structure of a complex of acetophenone and 2a.

Synthesis, structural characterisation of new oligomeric alkyl aluminium (2,2′-methylene-p-chloro-bisphenoxides) and application as catalysts in polymerisation reactions involving cyclohexene oxide

“…Bulky 2,2 0 -methylene- bisphenols constitute a versatile and easy-to-handle toolbox for the coordination chemist. The synthesis on a larger scale of these chelating ligands from formaldehyde and the corresponding bulky phenols is relatively easy and allows the rapid development of a ligand library [10]. Aluminium 2,2 0 -methylene-bisphenoxides were already extensively studied by the groups of Okuda [11], Lin [12], Chisholm [13] and newly Lewinski [14] in ring opening polymerisation of lactones, in Diels-Alder coupling reactions, and in the Meerwein-Ponndorf-Verley reduction.…”

Synthesis of Mono- And Polysulfur-Bridged Bisphenols and Their Application to New Type Lewis Acids

“…The bulky oxygenophilic organoaluminum reagents have been recognized as a highly useful Lewis acid and usually they are the methylaluminum bisphenoxide type molecules (2). We reported a new type of Lewis acids that contain carbon chain-bridged bisphenol moiety (3). We found out that sulfur-bridge of acyclic and cyclic phenol-formaldehyde oligomers improved inclusion properties of these compounds (4).…”