536753-70-5Relevant academic research and scientific papers
Alkylzinc complexes with achiral and chiral monoanionic N,N,O heteroscorpionate ligands
Hegelmann, Ina,Beck, Alexander,Eichhorn, Christian,Weibert, Bernhard,Burzlaff, Nicolai
, p. 339 - 347 (2003)
The synthesis of the new chiral ligand (3,5-di-tertbutylpyrazol-1-yl) (3′,5′-dimethylpyrazol-1-yl) acetic acid (bpaHtBu2,Me2) (4) has been achieved. Two different synthetic routes to its precursor 3,5-di-tert-butyl-1-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-1H-pyrazole (bpmtBu2,Me2) (3) are reported. Deprotonation at the methylene group, followed by reaction with carbon dioxide, yielded a racemic mixture of 4. The chemical behaviour of bis(3,5-di-tert-butylpyrazol-1-yl)acetic acid (bdtbpzaH) (2) and the new chiral N,N,O scorpionate ligand 4 involving their coordination to zinc ions was studied. [Zn(bpatBu2,Me2)Cl] (5) was formed from a mixture of ZnCl2, 4 and base. Reaction of bis(3,5-di-tert-butylpyrazol-1-yl)acetic acid (bdtbpzaH) (2) with Zn(CH3)2 or Zn(CH2CH3)2 gave the alkylzinc complexes Zn(bdtbpza)(CH3)] (6) and [Zn(bdtbpza)(CH2CH3)] (7). [Zn(bpatBu2,Me2)(CH3)] (8) was obtained from a synthesis analogous to that of 6 with 4. The further reactions of 6 and 8 with acetic acid resulted in the acetato complexes [Zn(OAc)(bdtbpza)] (9) and [Zn(OAc)(bpatBu2,Me2)] (10). The chiral methyl complex 8 may serve as a precursor for structural model complexes of the active sites of zinc enzymes, such as thermolysin or carboxypeptidase A. [Zn(bpatBu2,Me2)2] (11) was formed from a side reaction. Crystal structures of 4, 5, 8 and 11 were obtained; 5 crystallised as the dimer [Zn(bpatBu2,Me2) Cl]2; 11 presents an unusual zinc binding geometry. Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003.
