- Probing the nuclear susceptibility of mesoionic compounds using two-beam coupling with chirp-controlled pulses
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The third-order non-linear optical response of mesoionic compounds (MIC) in dimethylsulfoxide (DMSO) and methanol solutions was investigated by use of collinear pump and probe technique with chirp-controlled femtosecond pulses. The experiments allowed the investigation of non-instantaneous nuclear processes and thermal effects induced by two-photon absorption (TPA). We found that the nuclear non-linearity of MIC in DMSO is ~1/5 the benzene, which was used as a reference material. This result is attributed to the large inertia of MIC to rotation, compared to benzene. The results for MIC in methanol indicate the influence of thermal effects due to TPA.
- Bosco, Carlos A.C.,Maciel, Glauco S.,Rakov, Nikifor,de Araújo, Cid B.,Acioli, Lúcio H.,Simas, Alfredo M.,Athayde-Filho, Petr?nio F.,Miller, Joseph
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Read Online
- Substituted Pyrimidine and Triazine Compounds
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Substituted pyrimidine and triazine compounds corresponding to formula I wherein R1, R2, R3, R4a, R4b, R5a, R5b, R7, R8, R9a, R9b, R10, R11, A, a, b, s, t, V, W1, W2 and W3 have defined meanings, pharmaceutical compositions comprising such compounds, a process for preparing such compounds, and the use of such compounds and compositions to treat or inhibit pain and/or other disorders or disease states.
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Page/Page column 33
(2010/07/10)
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- Phosphinamide-directed benzylic lithiation. application to the synthesis of peptide building blocks
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N-Benzyldiphenylphosphinamides are deprotonated at the NCα position diastereospecifically upon treatment with f-BuLi in diethyl ether at low temperature. The reaction of the anions with alkyl, acyl, and tin halides, aliphatic and aromatic aldehydes, and Michael acceptors allowed installation of a variety of functional groups into the benzylic arm in excellent yields. Cleavage of the P-N linkage affords 1,2-amino alcohols and α-, β-, and γ-amino acids.
- Burgos, Pascual Ona,Fernandez, Ignacio,Iglesias, Maria Jose,Garcia-Granda, Santiago,Ortiz, Fernando Lopez
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p. 537 - 540
(2008/04/05)
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- Synthesis, characterization and crystallographic studies of three 2-aryl-3-methyl-4-aryl-1,3-thiazolium-5-thiolates
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Mesoionic 2,4-diphenyl-3-methyl-1,3-thiazolium-5-thiolate, 2-(4′-chlorophenyl)-3-methyl-4-phenyl-1,3-thiazolium-5-thiolate and 2-(4′-chlorophenyl)-3-methyl-4-(4′-isopropyl-phenyl)-1,3- thiazolium-5-thiolate were synthesized via N-methyl-C-aryl-glycines, i
- De Athayde-Filho, Petronio Filgueiras,Miller, Joseph,Simas, Alfredo Mayall,Lira, Bruno Freitas,De Souza Luis, José Alixandre,Zuckerman-Schpector, Júlio
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p. 685 - 690
(2007/10/03)
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- Synthesis and utilization of a novel glycine derived chiral precursor, based on a recyclable L-prolinol auxiliary, for the enantioselective preparation of α-amino acids and their N-methyl derivatives
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α-Amino acids and their N-methyl derivatives are synthesized in fairly high optical purity employing a new glycine derived template based on a recyclable L-prolinol chiral auxiliary.
- Pandey,Reddy,Das
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p. 3175 - 3178
(2007/10/03)
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- Optical Resolution and Asymmetric Transformation of (RS)-N-Alkyl- and (RS)-N,N-Dialkyl-2-phenylglycines
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Optical resolution of (RS)-N-methyl-2-phenylglycine and (RS)-N-ethyl-2-phenylglycine was carried out by using (1S)-10-camphorsulfonic acid as resolving agents, and that of (RS)-N-ethyl-N-methyl-2-phenylglycine by (R)- and (S)-1-phenylethylamine.Racemization rates of optically active Mpg, Epg, Emp, N,N-dimethyl-2-phenylglycine , and six α-amino acids were measured by heating in carboxylic acids.The electron-donating amino acid side chain and N-substituted alkyl group decreased therate to inhibit the formation of intermediary carbanions, whereas the electron-withdrawing side chain increased it.Asymmetric transformation of (RS)-Mpg, (RS)-Epg, and (RS)-Dmp was carried out on the basis of the results of optical resolution and racemization to give the corresponding enantiomers of approximately 100percent optical purities in over 70percent yield based on the sterting racemates.
- Shiraiwa, Tadashi,Baba, Yoshihisa,Miyazaki, Hideya,Sakata, Shinji,Kawamura, Seiko,et al.
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p. 1430 - 1437
(2007/10/02)
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- Synthesis and Antineoplastic Activity of Bisoxy>methyl>-Substituted 3-Pyrrolines as Prodrugs of Tumor Inhibitory Pyrrole Bis(carbamates)
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A series of bispyrrolines 2-4 were synthesized from either the appropriate α-silylated iminium salt, or an aziridine, or a 2H-azirine in a sequence involving 1,3-dipolar cycloaddition reactions.The antineoplastic activities of the pyrrolines were compared to the corresponding pyrroles.The C-2 gem-dimethyl-substituted pyrroline, 4, which cannot be converted to the pyrrole in vivo, was inactive.The activity of the 2-phenyl-substituted pyrrolines 3 was markedly dependent on the nature of the phenyl substituent, although the correspondingphenylpyrroles all showed comparable activity.The differences in the activities of the pyrrolines 3 may be due to the rate of metabolic conversion of the pyrroline to the pyrrole.Electron-withdrawing substituents on the phenyl ring appear to retard this process.
- Anderson, Wayne K.,Milowsky, Arnold S.
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p. 2241 - 2249
(2007/10/02)
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- NITROGEN ALKYLATION OF SCHIFF BASES AND AMIDINES AS A ROUTE TO N-ALKYL AMINO ACIDS
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Schiff base and amidine esters 3 are alkylated and then hydrolyzed to yield N-alkyl amino acids 4 in 41-75percent yield with hight to complete retention of optical activity.
- O'Donnell, Martin J.,Bruder, William A.,Daugherty, Byron W.,Liu, Deshan,Wojciechowski, Krzisztof
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p. 3651 - 3654
(2007/10/02)
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