Dealkylation with boron bromide chelates

Potential two-point Lewis acid compounds can be formed by combining the salen(tBu)H2 (N,N′-alkylenenebis(3,5-di-tertbutyl(2-hydroxy)benzylidenimine) class of ligands and its derivatives with boron tribromide. In the present study compounds having the formula, L(BBr2)2 (L=salen(tBu) (1), salhen(tBu) (2), L([ptolyl]BBr) (L=salen(tBu) (3), salpen(tBu) (4), salben(tBu) (5), salhen(tBu) (6), and tBu-sal(tBu)BBr2 (7) were prepared. These compounds are active towards the dealkylation of alkyl phosphates and are catalytic when stoichiometric amounts of BBr3 and trimethylphosphate are introduced to the chelate ligand. All of the compounds were characterized by Mp, elemental analysis, 1H- and 11B-NMR, IR, MS and in the case of 2 by X-ray crystallography.