6542-60-5Relevant articles and documents
Conformational studies of cyanomethylcyclopropane from temperature-dependent FT-IR spectra of xenon solutions and ab initio calculations
Wurrey,Shen,Zhu,Zhen,Durig
, p. 203 - 217 (1998)
Variable temperature (- 55 to -100°C) studies of the infrared spectra (3500 to 400 cm-1) of cyanomethylcyclopropane, c-C3H5CH2CN, dissolved in liquid xenon have been carried out. Utilizing the conformer bands 791 cm-1 (gauche), 802 cm-1 (cis), 823 cm-1 (gauche), and 849 cm-1 (cis), an enthalpy difference of 54 ± 4 cm-1 (0.65 ± 0.05 kJ mol-1) was obtained with the more stable gauche form conformer. The gauche conformer also remains in the infrared and Raman spectra of the solid. At ambient temperature there is approximately 28% of the cis conformer present. The optimized geometries, conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios, and vibrational frequencies are reported for both conformers from ab initio calculations. These calculations were carried out at the restricted Hartree-Fock (RHF) level and/or with electron correlation to second order (MP2), utilizing the basis sets 3-21G, 6-31G(d), 6-311G(d,p). 6-311++G(d,p) and 6-311+G(2d,2p), with the latter having 225 basis functions. From the RHF calculations the gauche form was predicted to be the more stable form by 275 cm-1 (3.29 kJ mol-1) to 207 cm-1 (2.48 kJ mol-1), but from MP2 calculations the cis form is predicted to be the more stable rotamer from 178 cm-1 (2.13 kJ mol-1) to 102 cm-1 (1.22 kJ mol-1). At the highest level of calculation, MP2/6-311+G(2d,2p), the cis conformer is predicted to be more stable by 134 cm-1 (1.60 kJ mol-1), which disagrees with the experimental results. The coefficients from the potential function governing the conformational interchange have been obtained from the far infrared data and the results are compared with the ab initio predicted values. The other calculated quantities are compared with the experimentally determined values where applicable, as well as with some corresponding results for some similar molecules.
TRISUBSTITUTED PYRAZOLO [1,5-A] PYRIMIDINE COMPOUNDS AS CDK7 INHIBITORS
-
Page/Page column 66; 67, (2020/09/27)
Compounds having activity as cancer agents are provided. The compounds have the following structure (I) or a pharmaceutically acceptable salts, stereoisomers, tautomers, thereof, wherein R1, R2, R3 and L are as defined herein. This disclosure provides methods associated with preparation and use of such compounds, pharmaceutical compositions comprising such compounds, and methods for treating a CDK7-dependent disease (e.g., cancer).
Free Radical Rearrangements in Uracil Derivatives
Fenick, David J.,Falvey, Daniel E.
, p. 4791 - 4799 (2007/10/02)
As part of an effort to develop general probes for radical reactions involving DNA bases, several uracil derivatives were synthesized.The rates of the cyclopropyl carbinyl rearrangement in these systems were evaluated by means of competition experiments.The results indicate that when a cyclopropyl group is substituted in the 5-position of uracil, the rearrangement occurs very slowly - with a rate constant of -1.On the other hand, the analog of the 5-hexenyl radical cyclization onto the 5,6-double bond of uracil derivatives occurs with rates which were similar to the parent process: (4.0-8.9)E4 s-1.The experimental results along with semiempirical calculations show that radicals 23 and 25 are unusually stable species.These results explain why no rearrangements are observed when a cyclopropyl-substituted thymine dimer is cleaved by reductive single electron transfer.
