Synthesis and structure of aluminium amine-phenolate complexes

Abstract

Reaction of Al(OiPr)3 with the tris-phenol amine ligand L1H3 in toluene at ambient temperature results in the formation of the iso-propanol adduct [HOiPr.Al(L1)]. Single crystal X-ray diffraction analysis reveals the structure to be a hydrogen bonded dimer. Reaction of Al(OiPr)3 (or AlMe3) with L1H3 in THF affords the related, and structurally characterised THF adduct, [THF.Al(L1)]. Similar reaction of Al(OiPr)3 (or AlMe3) with the bis-phenol amine and tetra-phenol diamine ligands, L2H3 and L3H4, results in the formation and isolation of the complexes [Al(L2)]2 and [Al(L3)H] respectively, both of which have been structurally characterised via single crystal X-ray diffraction studies. Reaction of the alkoxide bridged dimer [Al(L2)]2 with the strong Lewis base HMPA results in the formation of the monomeric HMPA adduct [HMPA.Al(L2)] which was also structurally characterised. The adduct [HOiPr.Al(L1)] and the dimer [Al(L2)]2 were tested for their activity in the ring-opening polymerisation (ROP) of rac-lactide under solvent-free conditions (130 degrees C). Under the conditions employed [Al(L2)]2 failed to produce polymer after 48 h, in stark contrast to [HOiPr.Al(L1)] which after 24 h and 48 h produced narrow molecular weight polymer (24 h: yield=25%, Mn=14500 and PDI=1.05; 48 h: yield=65%, Mn=47700 and PDI=1.06).

Dimeric alumatranes as catalysts for trimethylsilylcyanation reaction

“…As shown in Chart 1, alumatranes with tricyclic ve- [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] and six-membered 17,18,[34][35][36][37][38] rings are well known. Like other atranes, [39][40][41] all alumatranes with tricyclic veor six-membered ring systems also have a transannular N / Al interaction from the bridgehead N atom in the tetradentate ligand to the Al atom.…”

“…Even though some examples of structurally characterized alumatranes with tricyclic six-membered rings have been reported, 17,[34][35][36][37][38] few examples of ve-membered alumatranes and their derivatives 20,[31][32][33] have been identied.…”

Facile synthesis of zwitterionic organoaluminum complexes containing formally dianionic homoscorpionate ligands

“…In contrast, a similar reaction conducted in toluene led to intractable materials. Interestingly, [(2‐HOC 6 H 4 ) 3 N] (H 3 [O 3 N]) and [(2‐HO‐3,5‐Me 2 C 6 H 2 CH 2 ) 3 N] (H 3 [O 3 N*]) that are both pnictogen analogs of H 3 [O 3 P] react with AlCl 3 and AlMe 3 , respectively, to afford {Al[O 3 N]} 2 and {Al[O 3 N*]} 2 after thorough deprotonation. These divergent results highlight the significant roles that the pnictogen atoms of these closely related tris(phenolate) ligands play in protonolysis reactions.…”

Synthesis and tautomerization of hydroxylated isoflavones bearing heterocyclic hemi-aminals

“…The Mannich reaction affects the aminomethylation of carbonyl and activated aromatic compounds 6,7 and accommodates a range of amines including amino alcohols, N-benzylamino alcohols, 8,9 N,N-dibenzylamino alcohols, 10–12 3,4-dihydro-2H-1,3-benzoxazines, 13–15 (1,3-oxazolidin-3-yl)methylphenols and (1,3-morpholin-3-yl)methyl phenols. 15,16 Despite this precedent and our understanding of the Mannich reaction, we could not predict the outcome and preference for tautomeric forms in Mannich reactions using isoflavones and various ω-amino-1-alcohols.…”