36438-99-0Relevant articles and documents
Synthesis of 1-amino-[1,2,3]oxadiazolo[4,3-a]phthalazin-4-ium chloride and substituted dihydro derivatives. New annelated sydnonimines
Ruxer,Mauger,Benard,Lachoux
, p. 643 - 654 (1995)
The sydnonimine 5 has been prepared by an original one-pot nitrosation and cyclisation procedure of the carbonyl chloride Reissert adduct 14 of phthalazine. This synthetic method could be extended to the preparation of dihydro derivatives 7a to 7f and represents a new access to annelated sydnonimines. The para anisoyl and ethoxycarbonyl derivatives of these sydnonimines were also prepared with analogy to molsidomine 1 or pirsidomine 2.
Aqueous N-heterocyclization of primary amines and hydrazines with dihalides: Microwave-assisted syntheses of N-azacycloalkanes, isoindole, pyrazole, pyrazolidine, and phthalazine derivatives
Ju, Yuhong,Varma, Rajender S.
, p. 135 - 141 (2007/10/03)
The synthesis of nitrogen-containing heterocycles from alkyl dihalides (ditosylates) and primary amines and hydrazines via a simple and efficient cyclocondensation in an alkaline aqueous medium that occurs under microwave irradiation is described. This improved greener synthetic methodology provides a simple and straightforward one-pot approach to the synthesis of a variety of heterocycles, such as substituted azetidines, pyrrolidines, piperidines, azepanes, N-substituted 2,3-dihydro-1H-isoindoles, 4,5-dihydropyrazoles, pyrazolidines, and 1,2-dihydrophthalazines.
Microwave-assisted cyclocondensation of hydrazine derivatives with alkyl dihalides or ditosylates in aqueous media: Syntheses of pyrazole, pyrazolidine and phthalazine derivatives
Ju, Yuhong,Varma, Rajender S.
, p. 6011 - 6014 (2007/10/03)
Direct syntheses of 4,5-dihydro-pyrazole, pyrazolidine, and 1,2-dihydro-phthalazine derivatives via double-alkylation of hydrazines by alkyl dihalides or ditosylates were accomplished in aqueous media under microwave irradiation conditions; the environmen
Elimination Reactions of Hydrazonium Salts: Experimental and Theoretical Evidence for a Large Stereoelectronic Effect of Nitrogen
Nguyen, Minh Tho,Clarke, Leo F.,Hegarty, Anthony F.
, p. 6177 - 6183 (2007/10/02)
Elimination of trimethylamine from hydrazonium salts (8, R = Me) is promoted by base (methoxide ion in methanol).The mechanism is characterized as E2 as shown by substituent effects (ρ = +2.57), Broensted coefficients, a primary kinetic isotope effect (kH/kD = 2.10), and solvent effects.Variation in the leaving group (8, R = arylmethyl) shows that N-N bond cleavage is less well advanced in the transition state than C-H bond breaking.The elimination to give the nitrile is syn-periplanar and, using the phthalazinium salt 4 as a model for the anti elimination, an anti/syn ratio of ca. 102 is found.The reactions have been modelled using ab initio methods with the transition structures located at the HF/3-21G level and relative energies computed using the MP2/6-31G* method.Using both H2O and NH3 as model bases to induce elimination on +, the calculated energy for anti elimination is lower (in the range 11-13 kcal mol-1) than that for syn elimination.The implications of the results for the ease of formation of nitriles from aldehydes via the hydrazonium salt route are discussed.
Kinetics of the Reduction of Isoquinolinium Cations by 1,4-Dihydronicotinamides
Bunting, John W.,Chew, Vivian S. F.,Chu, Gary
, p. 2303 - 2307 (2007/10/02)
The kinetics of the reduction of a series of 2-methyl-4-X-isoquinolinium cations and 2-methyl-5-X-phthalazinium cations by 1-benzyl-1,4-dihydronicotinamide (5) have been measured in 20percent CH3CN-80percent H2O (v/v) at pH 7, 25 deg C, and an ionic strength of 1.0.Pseudo-first-order rate constants (kobsd) show kinetic saturation at high concentrations of 4 (X = H and Br), and association constants of 2.1 and 1.5 M-1, respectively, have been evaluated for 1:1 complex formation.Interpretation of these data and earlier data for the reduction of the 2-methyl-5-nitroisoquinolinium cation (3) in terms of nonproductive complex formation leads to a linear free-energy relationship between the second-order rate constant (k2) for reduction and pKR+ for pseudobase formation by these cations: log k2 = -0.50pKR+ + 4.9.Substituent effects upon k2 for the reduction of 3 and 4 (X = CONH2, CN) by 1-benzyl-3-W-1,4-dihydropyridines (W = CN, CONH2, CONHCH3, CON(CH3)2) are similar to the substituent effects for cyanide ion dissociation from the corresponding 1-benzyl-4-cyano-3-W-1,4-dihydropyridines.The current study indicates that the relatively strong 1:1 complexes observed in the reduction of 5-nitroisoquinolinium cations by 1,4-dihydronicotinamides are nonproductive and also provides further evidence in support of a one-step hydride-transfer mechanism for these reactions.
