- Nucleophilic Reactivities of Thiophenolates
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The nucleophilic reactivities of substituted thiophenolates were determined by following the kinetics of their reactions with a series of quinone methides (reference electrophiles) in DMSO at 20 °C. The experimentally determined second-order rate constants were analyzed according to the Mayr-Patz equation log k = sN(N + E) to derive the nucleophile-specific reactivity parameters N and sN for ten thiophenolate ions.
- Jüstel, Patrick M.,Pignot, Cedric D.,Ofial, Armin R.
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supporting information
p. 5965 - 5972
(2021/05/04)
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- Inherent Reactivity of Spiro-Activated Electrophilic Cyclopropanes
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The kinetics of the ring-opening reactions of thiophenolates with geminal bis(acceptor)-substituted cyclopropanes in DMSO at 20 °C was monitored by photometric methods. The determined second-order rate constants of the SN2 reactions followed linear relationships with Mayr nucleophilicity parameters (N/sN) and Br?nsted basicities (pKaH) of the thiophenolates as well as with Hammett substituent parameters (σ) for groups attached to the thiophenolates. Phenyl-substituted cyclopropanes reacted by up to a factor of 15 faster than their unsubstituted analogues, in accord with the known activating effect of adjacent π-systems in SN2 reactions. Variation of the electronic properties of substituents at the phenyl groups of the cyclopropanes gave rise to parabolic Hammett relationships. Thus, the inherent SN2 reactivity of electrophilic cyclopropanes is activated by electron-rich π-systems because of the more advanced C1?C2 bond polarization in the transition state. On the other hand, electron-poor π-systems also lower the energetic barriers for the attack of anionic nucleophiles owing to attractive electrostatic interactions.
- Jüstel, Patrick M.,Ofial, Armin R.,Pignot, Cedric D.,Stan, Alexandra
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supporting information
p. 15928 - 15935
(2021/10/25)
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- NOVEL HETEROCYCLIC COMPOUNDS USEFUL FOR THE TREATMENT OF INFLAMMATORY AND ALLERGIC DISORDERS: PROCESS FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM
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The present invention relates to novel Phosphodiesterase type 4 (PDE4) inhibitors of the formula (1) and analogs, tautomers, enantiomers, a diasteromers, regioisomers, stereoisomers, polymorphs, pharmaceutically acceptable salts, appropriate N-oxides, pharmaceutically acceptable solvates thereof and the pharmaceutical compositions containing them which are useful in the treatment of allergic and inflammatory diseases including asthma, chronic bronchitis, atopic dermatitis, urticaria, allergic rhinitis, allergic conjunctivitis, vernal conjunctivitis, eosinophilic granuloma, psoriasis, rheumatoid arthritis, septic shock, ulcerative colitis, Crohn's disease, reperfusion injury of the myocardium and reperfusion injury of the brain, chronic glomerulonephritis, endotoxic shock and adult respiratory distress syndrome.
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Page/Page column 42
(2009/12/24)
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- PROCESS FOR THE SYNTHESIS OF N9-(3,5-DICHLORO-4-PYRIDYL)-6- DIFLUOROMETHOXYBENZO(4,5)FURO(3,2-C)PYRIDINE-9-CARBOXAMIDE AND SALTS THEREOF
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The present invention relates to a process for the synthesis of N9-(3,5- dichloro-4-pyridyl)-6-difluoromethoxybenzo[4,5]furo[3,2-c]pyridine-9-carboxamide and salts thereof which are useful as a PDE4 inhibitor. The invention also relates to a process for the synthesis of methyl-2-formyl-7-cyclopentyloxybenzo[b]furan-4-carboxylate and salts thereof, which are useful as intermediates in preparing compounds with PDE4 inhibitory activity.
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Page/Page column 28
(2008/12/07)
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- Nucleophilic Attacks on Carbon-Carbon Double Bonds. 34. Intramolecular Element Effect in Competitive Expulsion of Two Halide Nucleofuges as a Tool for Investigating the Rapid Step of Nucleophilic Vinylic Substitution
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The substitution of 9-(bromochloromethylene)fluorene (8) and β,β-bis(p-nitrophenyl)-α-bromo-α-chloroethylene (9) by p-toluenethiolate and p-cresolate ions gives the monobromo, the monochloro, and the disubstitution products.The / substitution product ratios were determined in CD3CN, DMSO-d6, and DMSO-d6-CD3OD under conditions where the disubstitution was negligible.The ratios were 2.0-3.2, were slightly higher for 8 than for 9, and showed no discernible solvent dependence.The ratios did not change in the presence of radical traps although an ESR spectrum was observed with 8 and p-MeC6H4S-.The "intermolecular element effects" kBr/kCl derived from competitive substitution of 8 or 9 with their dibromo or dichloro analogues were 1.2-1.76.The results were interpreted in terms of a multistep nucleophilic vinylic substitution proceeding via an intermediate carbanion, which may be formed either directly or by an initial single-electron transfer followed by combination of the anion radical and the radical.The ratios of the products were hence identified as the ratios of the rate constants for expulsion of Br- and Cl- (kel(Br)/kel(Cl)-the "intramolecular element effect") from the carbanion.The low ratios and their relative insensitivity to the solvent and to the delocalizing ability of negative charge of the β-substituents were ascribed to an early transition state for the expulsion of halide ions from the carbanion.Generalizations concerning the expulsion of poor and good nucleofuges from carbanions substituted by poor and good electron-withdrawing groups are discussed.
- Avramovitch, Bianca,Weyerstahl, Peter,Rappoport, Zvi
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p. 6687 - 6697
(2007/10/02)
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- N-(amino)alkyl)-1-pyrrolidine, 1-piperidine and 1-homopiperidinecarboxamides (and thiocarboxamides) with sulfur linked substitution in the 2, 3 or 4-positions
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Novel pyrrolidine, piperidine and homopiperidinecarboxamide and thiocarboxamide compounds having the formula: STR1 wherein X is --S--, --S(O)-- or --S(O)2 --; A is a loweralkalene chain and A1 and A2 are alkalene chains when p and d are one; R, R1 and R2 are hydrogen, loweralkyl, phenyl cycloalkyl or phenylalkyl and R1 and R2 may form a heterocyclic residue with the adjacent nitrogen atom; Q is a selected aromatic radical, and the pharmaceutically acceptable acid addition salts useful as cardiac antiarrhythmia agents are disclosed. Novel chemical intermediates, unsubstituted on pyrrolidine, piperidine and homopiperidine nitrogen but with --(A2)p --X--(A2)d --Q side chain are also disclosed.
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- N-[(amino)alkyl]-1-pyrrolidine, 1-piperidine and 1-homopiperidinecarboxamides (and thiocarboxamides) with sulfur linked substitution in the 2, 3 or 4-position
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Novel pyrrolidine, piperidine and homopiperidinecarboxamide and thiocarboxamide compounds having the formula: STR1 wherein X is --S--, --S(O)-- or --S(O)2 --; A is a loweralkalene chain and A1 and A2 are alkalene chains when p and d are one; R, R1 and R2 are hydrogen, loweralkyl, phenyl cycloalkyl or phenylalkyl and R1 and R2 may form a heterocyclic residue with the adjacent nitrogen atom; Q is a selected aromatic radical, and the pharmaceutically acceptable acid addition salts useful as cardiac antiarrhythmia agents are disclosed. Novel chemical intermediates, unsubstituted on pyrrolidine, piperidine and homopiperidine nitrogen but with --(A2)p --X--(A2)d --Q side chain are also disclosed.
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- Determination of Rate Constants for Electron Transfer from Radical Anions of Aromatic Compounds to Diaryl Disulfides
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Rate constants for electron transfer from the radical anions of aromatic compounds to diaryl disulfides (ArSSAr) have been determined in tetrahydrofuran.By the change of the reduction potentials of the aromatic compounds from -1.04 to -1.91 V (vs.SCE), the rate constants varied from 0.015 to 2.3 * 108 M-1 s-1; conventional spectrophotometry has been employed to measure the slow reaction rates, and the xenon-flash photolysis technique has been applied to the fast reaction systems.The reaction including the free ion or the loose ion pair of the thioxanthone sulfone radical anion, (TO-SO2)-/., was faster than that including the tight ion pair.In the case of the (TO-SO2)-/., Na+-PhSSPh system, temperature variation yielded the free energy of activation (ΔG* = 18.7 kcal/mol) and activation enthropy (ΔS* = -29.1 eu) at 22.4 deg C; the reduction potential of PhSSPh was estimated to be -1.80 V vs.SCE from ΔG* value.Electron-withdrawing substituents of ArSSAr increase the rates and vice versa; the Hammett reaction constants (ρ) were estimated to be ca. +1.50 and 1.40 for electron transfer from perylene radical anion and (TO-SO2)-/.,Na+ to ArSSAr, respectively.The factors controlling the rates have been examined.
- Tagaya, Hideyuki,Aruga, Tamotsu,Ito, Osamu,Matsuda, Minoru
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p. 5484 - 5489
(2007/10/02)
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- Quinones. Part 9. Side-chain Alkylthiolation of Methyl-1,4-naphthoquinones
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2-Methyl-1,4-naphthoquinones react with an excess of sodium methanethiolate to give methylthiomethyl derivatives.Corresponding products were obtained, but in lower yield, using α-toluene- and toluene-p-thiolates.With 3-chloro-2-methyl-1,4-naphthoquinone and methanethiolate, replacement of chlorine occurs before reaction with the side chain, while the minor products formed provide evidence that the side-chain alkylation proceeds by addition of thiolate to the tautomeric quinone methide form of the methylquinone.
- Thomson, Ronald H.,Worthington, Roger D.
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p. 282 - 288
(2007/10/02)
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