- Conformational studies of cyanomethylcyclopropane from temperature-dependent FT-IR spectra of xenon solutions and ab initio calculations
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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.
- Wurrey,Shen,Zhu,Zhen,Durig
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- Reactivity of an α-Acyl-α-cyclopropyl-carbenium Ion: a Highly Stereoselective Cyclopropylmethyl-Cyclopropylmethyl Rearrangement
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The complete stereoselectivity in a cyclopropylmethyl-cyclopropylmethyl rearrangement which has been investigated is rationalized in terms of a highly preferred conformation of the transient α-acyl-α-cyclopropyl-carbenium ion.
- Pardo, Claude,Charpentier-Morize, Micheline
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- TRISUBSTITUTED PYRAZOLO [1,5-A] PYRIMIDINE COMPOUNDS AS CDK7 INHIBITORS
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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).
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Page/Page column 66; 67
(2020/09/27)
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- PROCESSES FOR PREPARATION OF CYCLOPROPYLETHANOL, CYCLO-PROPYLACETONITRILE AND INTERMEDIATES OF BOTH
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A process for preparation of cyclopropylethanol, which comprises subjecting a 3-cyclopropyl-2,3-epoxypropionic acid ester to solvolysis, treating the product of the solvolysis with an acid to obtain cyclopropylacetaldehyde, and reducing the obtained cyclopropylacetaldehyde; and a process for preparation of cyclopropylacetonitrile, which comprises subjecting a 3-cyclopropyl-2,3-epoxypropionic acid ester to solvolysis in the presence of a base, treating the product of the solvolysis with an acid to obtain cyclopropylacetaldehyde, reacting the obtained cyclopropylacetaldehyde with hydroxylamine or salts thereof to obtain cyclopropaneacetaldehyde oxime, and reacting the obtained cyclopropaneacetaldehyde oxime with acetic anhydride. According to the present invention, cyclopropylethanol and cyclopropylacetonitrile can be prepared at low costs and industrially advantageously.
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- Free Radical Rearrangements in Uracil Derivatives
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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.
- Fenick, David J.,Falvey, Daniel E.
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p. 4791 - 4799
(2007/10/02)
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- The synthesis of methyl cyclopropylacetate by palladium(II) acetate catalysed reaction of diazomethane with vinyl group
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The methyl cyclopropylacetate was prepared in high yield by Palladium(II) acetate catalysed reaction of vinyl acetic acid with an excess of diazomethane. The cyclopropylacetonitrile was prepared from allyl cyanide by the same method.
- Basnak,Jurkovic,Basnakova
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p. 773 - 782
(2007/10/02)
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- All ring compounds-XXIX. Thermal decomposition of t-butyl per (trans-2-substituted cyclopropyl) acetates
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Three kinds of t-butyl per (trans-2-substituted cyclopropyl) acetates (RH, CH3, C6H5) were synthesized from the corresponding acyl chlorides and thermally decomposed in cyclohexane to investigate the chemical stability and behaviour of the cyclopropylcarbinyl radical. Clean first-order kinetics were obtained in all of the thermal decomposition reactions. The experimental fact that the decompositoin rates and activation parameters of these three t-butyl peresters are similar to each other may indicate the absence of the ionic character in the transition state suggesting the almost complete homolytic decomposition of these peresters. Although the typical concerted decomposition might be invalid for these peresters in view of the activation parameters, it would be suggested from the product studies that the decomposition of these peresters was characterized by a considerable loss of their acyl-alky] bonds at the time of the fission of their OO bonds. The products yielded from the thermal decomposition of t-butyl per (trans-2-phenylcyclopropyl) acetate in various hydrogen donating solvents consisted of three hydrocarbons and two t-butyl ethers. The formation of these t-butyl ethers, possibly cage products, was significant.
- Shono,Nishiguchi
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p. 2173 - 2181
(2007/10/12)
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