Reactions between organoaluminium compounds and N-substituted acid amides

Abstract

Reactions between R13AI and R2NH*C0.R3 (R1 = Me or Et; R3 = Me or Ph) leading to materials ( R1,AI*NR2*CO*R3), are described. 1.r.. mass, and lH n.m.r. spectroscopic details of the products are given. Cyclic 8-membered ring structures (n = 2) are proposed for these compounds in the solution phase. Cryoscopic studies support dimeric structuresfor the compounds (Me,AI.NPh*CO*Me), and (Me,AI.NBut.CO.Me), in benzene, although an X-ray crystallographic study of the former, which can also be prepared from Me3Al and PhNCO, shows a trimeric structure to be more likely in the crystal. The related sulphur compound Me,Al*NPh.CS*Me, from Me,AI and PhNCS, probably also has a similar cyclic structure in solution. Durham R2 = Me, Et, But, or Ph; IN common with many other organonietallic compoiinds,l organoaluminium compounds R1,Al t react with isocyanates R2NC0 to give products which on hydrolysis afford N-substituted acid amides R1CO-NHR2.203 The reaction could in principle involve addition of R1-A1 across either the C=N or C=O bond, giving materials (I) or (11), respectively, both of which would afford the same amide R1CO-NHR2 on hydrolysis. Largely on the [R1,AI*NR2*CO*R1] R1CO*NHR2 t (1) H2O [R1,A1O*CR1:NR2] _ + R1C(OH):NR2 I: (11) R ',A 1 R2NC0basis of the i.r. spectra of the products, Reinheckel, Jahnke, and Kretzschmar concluded that addition to the C=N bond normally occurs, giving intermediates of type (I) which were believed to exist as chain oligomers or polymers (111). They reported no molecular weight R1,Al(*NR2*CR1:O+AlR12)~*NRz*CO*R1 (111) measurements, however. Horder and Lappert $ recently showed that the products of insertion of isot Aluminium trialkyls are referred to throughout this paper by their empirical formulae R,Al, although when R is Me or Et they are dimeric in non-donor solvents.

An Unusual N‐Bridged (Amido)(hydrido)(phenoxido)aluminium Dinuclear Compound – The Role of Nitrogen Substituents in Determining Nuclearity: A Combined Experimental and Theoretical Study

“…[37,51] Examples are known with both O and N atoms bridging in hydroxypyridine ligands (in an isolobal disposition to carboxylatebridged ligands) [25] or with an amidate group [52][53][54][55] between two aluminium atoms.…”

Reactions of group 13 metal trialkyls with oxamides

“…First results on reactions between organoaluminum compounds and N-substituted acid amides were reported in 1966 by Tani et al [1]. In 1968, Wade et al [2], Lappert et al [3] and Tani et al [4] published [Me 2 Al(RNC(O)R 0 )] 2 compounds as the dimeric molecules composed of a centrosymmetrical eight-membered ring with aluminum atoms bridged by OCN groups. The alkylaluminum amidates have been of considerable interest for their activity in acetaldehyde polymerization [4] and transamidation of secondary carboxamides [5].…”

“…Although oxamidate ligands deserve a particular attention in the supramolecular chemistry [10], group 13 oxamidates are rather poorly described. It was demonstrated in 1975, that trialkyl derivatives of gallium and indium reacted with N,N 0 -dimethyloxamide to yield products of the general formula (R 2 M) 2 (CONMe) 2 [11]. On the basis of the NMR spectroscopy and X-ray diffraction studies, Fischer and Stezowski [12] found that the gallium compounds can exist in the form of two configurational isomers, A and B (Scheme 1).…”

“…Similarly, literature data concerning reactions of alkyl compounds of group 13 metals with acid multi-amides are poor. Recently, mononuclear aluminum complexes supported by the tripodal tris(amidate) ligands and a reaction product of Me 3 Al with 1,2-C 6 H 4 [NHC( t Bu)O] 2 have been described [9]. Although oxamidate ligands deserve a particular attention in the supramolecular chemistry [10], group 13 oxamidates are rather poorly described.…”

Synthesis, Characterization, and Catalytic Activity of a Series of Aluminium–Amidate Complexes

“…Amidate ligand complexes have been shown to support a variety of transition [19][20][21][22][23] and rare-earth metals [24][25][26][27][28] that has resulted in a family of useful reagents for metalmediated transformations. The synthesis of Al-amidate complexes was originally reported by Lappert and Horder [29] and Wade et al, [30] and was expanded on by the Lin group to include various substituents in the amidate ligand. [31,32] The MacBeth group has more recently reported the preparation of a tris(amidate)aluminium complex implementing a tripodal ligand.…”