Mechanistic studies on the hydrolysis of a dimeric alkylzinc bis(2-pyridylmethyl)amide
摘要:
Bis(2-pyridylmethyl) amine 7 reacts with selected dialkylzinc compounds to give dimeric alkylzinc bis(2-pyridylmethyl) amides 8. Regardless of the steric bulk of the alkyl substituent, dimers with central Zn2N2 rings are formed. Compounds 8 undergo spontaneous hydrolysis reactions upon exposure to air/moisture which can be partially controlled if the alkyl substituent R is bulky enough [R=CH(SiMe3)(2)]. A dimeric compound 9 containing both zinc-alkyl substituents and a l-OH functionality results. In the course of this reaction, an amide instead of the expected RH is eliminated. Extensive DFT calculations show that the facile formation of a three-centered Zn[mu(HO center dot center dot center dot H center dot center dot center dot NHR)] Zn functionality is a crucial step. Further evidence for the importance of Zn[mu-(X center dot center dot center dot H center dot center dot center dot Y)]Zn intermediates (X, Y = O and now N) in the general mechanism of hydrolysis catalyzed by binuclear zinc compounds is thus provided. (C) 2007 Elsevier B. V. All rights reserved.
Mechanistic studies on the hydrolysis of a dimeric alkylzinc bis(2-pyridylmethyl)amide
摘要:
Bis(2-pyridylmethyl) amine 7 reacts with selected dialkylzinc compounds to give dimeric alkylzinc bis(2-pyridylmethyl) amides 8. Regardless of the steric bulk of the alkyl substituent, dimers with central Zn2N2 rings are formed. Compounds 8 undergo spontaneous hydrolysis reactions upon exposure to air/moisture which can be partially controlled if the alkyl substituent R is bulky enough [R=CH(SiMe3)(2)]. A dimeric compound 9 containing both zinc-alkyl substituents and a l-OH functionality results. In the course of this reaction, an amide instead of the expected RH is eliminated. Extensive DFT calculations show that the facile formation of a three-centered Zn[mu(HO center dot center dot center dot H center dot center dot center dot NHR)] Zn functionality is a crucial step. Further evidence for the importance of Zn[mu-(X center dot center dot center dot H center dot center dot center dot Y)]Zn intermediates (X, Y = O and now N) in the general mechanism of hydrolysis catalyzed by binuclear zinc compounds is thus provided. (C) 2007 Elsevier B. V. All rights reserved.