- Synthesis and characterization of the titanium complexes bearing two regioisomeric trifluoromethyl-containing enaminoketonato ligands and their behavior in ethylene polymerization
-
A series of new titanium complexes bearing two regioisomeric trifluoromethyl-containing enaminoketonato ligands (3a-h and 6a-h), [PhNCRCHC(CF3)O]2TiCl2 (3a, R = Me; 3b, R = n-C5H11; 3c, R = i-Pr; 3d, R = Cy; 3e, R = t-Bu; 3f, R = CHCHPh; 3g, R = Et; 3h, R = n-C11H23) and [PhNC(CF 3)CHC(R)O]2TiCl2 (6a, R = Ph; 6b, R = n-C 5H11; 6c, R = i-Pr; 6d, R = Cy; 6e, R = t-Bu; 6f, R = CHCHPh; 6g, R = CHPh2; 6h, R = CF3) have been synthesized and characterized. X-ray crystal structures analyses suggest that complexes 3c-e and 6c-d all adopt a distorted octahedral geometry around the titanium center. Complexes 3c, 3d and 6c display a cis-configuration of the two chlorine atoms around the titanium center, while complex 6d shows a trans-configuration of the two chlorine atoms. Especially, the configurational isomers (cis and trans) of complex 3e were identified both in solution and in the solid state by NMR and X-ray analyses. With modified methylaluminoxane as a cocatalyst, all the complexes are active towards ethylene polymerization, and produce high molecular weight polymers. With the variation of the relative position of the imino group and the trifluoromethyl group of the β-enaminoketonato ligands, the polymerization behavior of the catalysts changed remarkably. It is observed that the substituent directly joined to the carbonyl in the ligands plays an important role for both the catalytic activities and the properties of the polymers produced. The Royal Society of Chemistry 2009.
- Ye, Wei-Ping,Mu, Hong-Liang,Shi, Xin-Cui,Cheng, Yan-Xiang,Li, Yue-Sheng
-
scheme or table
p. 9452 - 9465
(2010/03/04)
-
- Synthesis and evaluation of indenopyrazoles as cyclin-dependent kinase inhibitors. 3. Structure activity relationships at C3
-
The identification of indeno[1,2-c]pyrazol-4-ones as inhibitors of cyclin-dependent kinases (CDKs) has led to the discovery of a series of novel and potent compounds. Herein, we report the effects of substitutions at C3 of the indeno[1,2-c]pyrazol-4-one core with alkyls, heterocycles, and substituted phenyls. Substitutions at the para position of the phenyl ring at C3 were generally well-tolerated; however, larger groups were generally inactive. For alkyls directly attached to C3, longer chain substituents were not tolerated; however, shorter alkyl groups and cyclic alkyls were acceptable. In general, the heterocycles at C3 gave the most potent analogues. One such heterocycle, 24j, was examined in detail and was determined to have a biological profile consistent with CDK inhibition. An X-ray crystal structure of one of the alkyl compounds, 13q, complexed with CDK2 was determined and showed the inhibitor residing in the adenosine 5′-triphosphate pocket of the enzyme.
- Yue, Eddy W.,Higley, C. Anne,DiMeo, Susan V.,Carini, David J.,Nugiel, David A.,Benware, Carrie,Benfield, Pamela A.,Burton, Catherine R.,Cox, Sarah,Grafstrom, Robert H.,Sharp, Diane M.,Sisk, Lisa M.,Boylan, John F.,Muckelbauer, Jodi K.,Smallwood, Angela M.,Chen, Haiying,Chang, Chong-Hwan,Seitz, Steven P.,Trainor, George L.
-
p. 5233 - 5248
(2007/10/03)
-