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Boland NA Casey M Hynes SJ Matthews JW Smyth MP 《The Journal of organic chemistry》2002,67(11):3919-3922
A novel procedure for the preparation of enantiopure 1,4-disubstituted 2-imidazolines is reported. Enantiopure beta-amino alcohols are converted into N-hydroxyethylamides, which are reacted with excess thionyl chloride, or with thionyl chloride followed by phosphorus pentachloride to yield N-chloroethylimidoyl chlorides. These intermediates are treated with amines and anilines to produce N-chloroethylamidines, which are converted into imidazolines upon workup with aqueous hydroxide. The method is simple and efficient and has been used to prepare a wide variety of enantiopure imidazolines, in a modular fashion, from readily available amino alcohols. 相似文献
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John B. Hynes Alenka Tomai
Arvind Kumar Veena Kumar James H. Freisheim 《Journal of heterocyclic chemistry》1991,28(8):1981-1986
A series of thirty eight 2,4-diaminoquinazolines having diverse substitution patterns on the aromatic ring was evaluated for inhibitory activity against dihydrofolate reductase (DHFR) obtained from a human lymphoblast cell line. Many of these compounds were also evaluated as inhibitors of rat liver DHFR under the same experimental conditions. In most instances the results obtained with each enzyme were comparable indicating that the rodent enzyme is a suitable model for the human DHFR as far as the determination of I50 values is concerned. The results demonstrate that relatively simple 5-substituted- or 5,6-disubstituted-2,4-diaminoquinazolines can be potent DHFR inhibitors. The presence of a nonpolar substituent at position 7 or 8 was highly detrimental to inhibitory potency. 相似文献
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Daniel BorgisJames T. Hynes 《Chemical physics》1993,170(3):315-346
A general dynamical theory is presented for the rate constant of weak coupling, nonadiabatic proton-tunneling reactions in solution. The theory incorporates the critical role of the solvent and the vibration of the separation of the heavy particles between which the proton transfers, including their dynamics. The formulation which allows the computation of the quantum rate constant k via classical molecular dynamics simulation techniques is presented, as are a number of approximate analytic results for k in a variety of different important regimes. The frequent appearance of (nearly) classical Arrhenius behavior for k — even though the intrinsic reactive event is quantum proton tunneling — is discussed, together with the solvent and vibrational contributions to the apparent activation energy. In certain weak solvation limits, however, non-Arrhenius behavior for k is found and is related to vibrational Franck-Condon features in the reaction. 相似文献
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Molecular Dynamics simulations are used to examine the title issue for the I-/HOD/D2O solution system in connection with recent ultrafast infrared spectroscopic experiments. It is argued that the long "modulation time" associated with the spectral diffusion of the OH frequency, extracted in these experiments, should be interpreted as reflecting the escape time of an HOD from the first hydration shell of the I- ion, i.e., the residence time of an HOD in this solvation shell. Shorter time features related to the oscillation of the OH ...I- hydrogen bond and the breaking and making of this bond are also discussed. 相似文献