Organometallics 2010, 29, 3357–3361 3357
DOI: 10.1021/om100296m
Zirconium Complexes Supported by Imidazolones: Synthesis,
Characterization, and Application of Precatalysts for the
Hydroamination of Aminoalkenes
Yu-Cheng Hu,† Cheng-Feng Liang,† Jie-Hong Tsai,† Glenn P. A. Yap,‡ Ya-Ting Chang,†,§
and Tiow-Gan Ong*,†
†Institute of Chemistry, Academia Sinica, Nangang, Taipei, Taiwan, Republic of China, §Graduate Institute
of Engineering, National Taiwan University of Science Technology, Taipei, Taiwan, Republic of China, and
‡Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
Received April 13, 2010
Dimeric zirconium benzyl and amide complexes supported by an imidazolone framework have
been successfully synthesized and fully characterized. The amide complexes were found to be effective
catalysts for intramolecular hydroamination of primary and secondary amines.
Hydroamination has emerged as an atom-economical and
one-step strategy for constructing nitrogen-containing mo-
lecules via functionalization of an N-H bond across a
carbon-carbon unsaturation.1 Eliciting significant interest
among chemists over the years, the advantages of hydro-
amination have led to exploitation of much of the periodic
table in an effort to improve the effectiveness and complexity
of this process.2-4 Over the past decade, the application of
group 4 transition metal to intramolecular hydroamination
of C-C multiple bonds with primary amines has arisen as
one such alternative, with the additional benefit of commer-
cial availability, low cost, and low toxicity.5
Previously, we reported the isolation of a zirconium complex
bearing a unique η2(N,C) imidazolyl carbene moiety resulting
from the C-N cleavage of an amino-linked nitrogen hetero-
cyclic carbene.6 Interestingly, such imidazolyl carbene moieties
have been implicated as intermediate species for scandium-,
yttrium-, and uranium-mediated ring opening of imidazole
rings.7 Unfortunately, having a highly reactive imidazolyl car-
bene moiety in a metal complex may circumvent the stability of
the complex that is important to the catalytic application. To
eliminate the chemical promiscuity of the imidazolyl carbene
group, while maintaining the desired imidazole scaffold, we
have turned our attention to imidazolones, which are easily
assembled five-membered heterocyclic molecules contain-
ing N and O binding sites. The imidazolones are known to
*To whom correspondence should be addressed. E-mail: tgong@
chem.sinica.edu.tw.
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2010 American Chemical Society
Published on Web 07/02/2010
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