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Synthesis 2003(3): 0350-0356
DOI: 10.1055/s-2003-37339
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Modified Tris(pyrazolyl)methane Ligands: Backbone Functionalization­

Daniel L. Reger*a, T. Christian Grattanb
a Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
e-Mail: Reger@mail.chem.sc.edu;
b Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, SC 29733, USA
Further Information

Publication History

Received 4 November 2002
Publication Date:
19 February 2003 (online)

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Abstract

The deprotonation of HC(pz)3 with n-butyllithium followed by reaction with methyl iodide, benzyl bromide and chloro­trimethylsilane produced the respective substituted ligands RC(pz)3 [R = CH3, C6H5CH2, (CH3)3Si] in good yield. Analogous chemistry starting with HC(3-Phpz)3 was only successful in high yield when the deprotonation step was carried out with LiN[Si(CH3)3]2, added at low temperature, and led to the syntheses of RC(3-Phpz)3 [R = CH3, (CH3)3Si, CH2=CHCH2, C6H5CH2]. In contrast, the alcohol derivatives HOCH2C(pz)3 and HOCH2C(3-Phpz)3 were prepared using potassium tert-butoxide for the deprotonation step followed by paraformaldehyde. For HC(3-t-Bupz)3, deprotonation with n-butyllithium at low temperature was most successful and led to the syntheses of RC(3-t-Bupz)3 [R = CH3, (CH3)3Si, HOCH2]. The compound HOCH2C(pz)3 was converted into t-BuPhCH2OCH2C(pz)3 by reaction with sodium hydride and (tert-butyl)benzyl bromide. These synthetic routes have made a variety of functionalized tris(pyrazolyl)methane ligands available for studies of their coordination chemistry.

Key words

tris(pyrazolyl)methane - ligands - electrophilic additions - lithiation - alcohol

11

Reger, D. L.; Little C. A. unpublished results.

12

Baker, M. V. personal communication.