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Syntheses of Zinc Complexes with Multidentate Nitrogen Ligands: New Catalysts for Aldol Reactions
Author(s) -
Darbre Tamis,
Dubs Christian,
Rusanov Eduard,
StoeckliEvans Helen
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200212)2002:12<3284::aid-ejic3284>3.0.co;2-6
Subject(s) - chemistry , zinc , pyridine , denticity , benzaldehyde , catalysis , medicinal chemistry , methanol , aldol reaction , nitrogen , chloride , polymer chemistry , crystal structure , organic chemistry
The ligands 2,6‐bis{[(pyrid‐2‐ylmethyl)amino]methyl}pyridine with an N 5 pattern and (6‐{[(pyrid‐2‐ylmethyl)amino]methyl}pyrid‐2‐yl)methanol with an N 3 O pattern were synthesized. Zn II complexes of the two ligands could be obtained, and the single‐crystal X‐ray structure of (2,6‐bis{[(pyrid‐2‐ylmethyl)amino]methyl}pyridine)zinc chloride showed Zn coordination to all five nitrogen atoms. The strong complexation of 2,6‐bis{[(pyrid‐2‐ylmethyl)amino]methyl}pyridine and (6‐{[(pyrid‐2‐ylmethyl)amino]methyl}pyrid‐2‐yl)methanol with Zn II were demonstrated by 1 H NMR spectroscopic studies and electrospray mass spectrometry. The coupling of 2‐hydroxyacetophenone and benzaldehyde was studied in the presence of the prepared Zn complexes, and it was shown that the coupling product was obtained at room temperature in up to 60% yield with 7.5 mol % of the zinc catalyst. The present complexes mimic the active site of the zinc‐dependent class II aldolases, where Zn II is coordinated to three nitrogen atoms. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)