30169-45-0Relevant academic research and scientific papers
Additivity of the Electronic Meta-Substituent Effect in 3,5-Disubstituted Cumyl Radicals Assessed by the EPR D Parameter of 1,3-Arylcyclopentane-1,3-diyl Triplet Diradicals
Adam, Waldemar,Harrer, Heinrich M.,Maas, Wiebke
, p. 7263 - 7265 (2007/10/03)
The D parameter (EPR zero-field splitting) of the 3,3′,5,5′-tetrasubstituted triplet diradicals 6 (X = X′ = H, NO2, CH3, OAc, OCH3, NH2, and OH) were determined in a MTHF matrix at 77 K and serves as a spectrosc
Diastereo- and regioselective synthesis of diquinanes and related systems from tricyclo[3.3.0.02,4]octanes by chemical electron transfer (CET)
Adam,Heidenfelder,Sahin
, p. 1163 - 1170 (2007/10/02)
A new synthetic methodology for diquinanes by one-electron oxidation of tricyclo[3.3.0.02,4]octanes and subsequent stereocontrolled rearrangement is provided. The latter compounds are conveniently accessible through acid-catalyzed isopyrazole cycloaddition, followed by hydrogenation and photoextrusion of molecular nitrogen. The oxidative rearrangement of the tricyclooctanes proceeds catalytically and cleanly to afford regio- and diastereoselectively the corresponding diquinanes.
Electronic Substituent Effects on the Acid-Catalyzed + + 2> Cycloaddition of Isopyrazoles with Cyclopentadiene and the Photochemical and Thermal Denitrogenation of the Resulting 1,4-Diaryl-7,7-dimethyl-2,3-diazabicyclohept-2-ene Azoalk
Adam, Waldemar,Harrer, Heinrich M.,Nau, Werner M.,Peters, Karl
, p. 3786 - 3797 (2007/10/02)
Eight symmetrically disubstituted 3,5-diaryl-4,4-dimethylisopyrazoles 6 with para and meta substituents (OMe, Me, H, F, Cl, Br, CN, NO2) and two unsymmetrically para-substituted derivatives (OMe and NO2; Me and CO2Me) were synthesized from the correspondi
Synthesis of 4,4-Dimethyl-3,4-dihydro-3,3,5-trisubstituted-2H-pyrazoles and N-Benzoyl Derivatives: Method for "Hydrolysis" of Unreactive Amides and Carbamates
Baumstark, Alfons L.,Choudhary, Anil,Vasquez, Pedro C.,Dotrong, My
, p. 291 - 294 (2007/10/02)
Addition of organolithium reagents to 4,4-dimethyl-3,5-disubstituted-4H-pyrazoles produced a series of 4,4-dimethyl-3,4-dihydro-3,3,5-trisubstituted-2H-pyrazoles, 2-6, in good yield.The reaction was stereoselective: addition of organolithium compounds occurred only to carbon-3 of 4,4-dimethyl-3-alkyl-5-aryl-4H-pyrazoles.The 3,4-dihydro-2H-pyrazoles were found to be of high sensitivity to oxygen.For long term storage and ease of handling, N-benzoyl derivatives were synthesized.Removal of protecting group could not be accomplished by use of many standard sets of conditions.Deprotection was accomplished in high yield by reaction of the N-benzoyl-4,4-dimethyl-3,4-dihydro-3,3,5-trisubstituted-2H-pyrazoles with anhydrous potassium t-butoxide in toluene in the presence of a phase transfer catalyst (18-Crown-6).Cleavage of a N-carbamate derivative was also achieved by this phase transfer approach.This methodology should be applicable to the hydrolysis of unreactive amides and carbamates in general.
OXYGEN-ATOM TRANSFER REAGENTS: NEW, REACTIVE α-AZOHYDROPEROXIDES
Baumstark, A. L.,Dotrong, M.,Vasquez, P. C.
, p. 1963 - 1966 (2007/10/02)
3,4,4-Trimethyl-4,5-dihydro-5-hydroperoxy-3,5-diaryl-3H-pyrazoles, synthesized by autoxidation of the corresponding 3,4-dihydro-2H-pyrazoles, are a new type of cyclic α-azohydroperoxide which is of high reactivity in oxygen-atom transfer chemistry.
Azo Bridges from Azines, VI. - Substituted Isopyrazoles as Electron-deficient Dienes for the Synthesis of 2,3-Diazabicycloheptenes and their Photochemistry
Beck, Karin,Huenig, Siegfried
, p. 477 - 484 (2007/10/02)
The ++2> cycloaddition of isopyrazoles (4H-pyrazoles) 3c-e and cyclopentadiene, norbornene, and norbornadiene leads to the azo-bridged products 5, 8, 11, and 12c-e.Irradiation of 5e, 8e, and 11e expectedly produces the tricycles 13, 15, and 17 by loss of nitrogen.In contrast, as a result of the parallel arrangement of the C=C/N=N bonds, the isomers 12c-e are transformed nearly quantitatively into diazetidines 14, 16, and 18; despite the pronounced photolability of the diazabicycloheptene moiety in 12, cycloaddition is preferred over nitrogen elimination.
