39781-96-9

Upstream product

• 105787-00-6 (1α,4α,4aα,7aα)-4,4a,7,7a-Tetrahydro-8,8-dimethyl-1,4-diphenyl-1,4-methano-1H-cyclopenta[d]pyridazin 
• 151993-89-4 C₂₂H₂₂ 
• 34783-15-8 (1R,2S,4R,5S)-3,3-Dimethyl-2,4-diphenyl-tricyclo[3.2.0.0^2,4]hept-6-ene 
• 41169-42-0 2,2-dimethyl-1,3-diphenylpropane-1,3-dione 
• 30169-45-0 4,4-dimethyl-3,5-diphenyl-4H-pyrazole 

Relevant academic research and scientific papers

1,3-Cyclopentanediyl diradicals: Substituent and temperature dependence of triplet - Singlet intersystem crossing

The lifetimes of 33 1,3-diaryl-1,3-cyclopentanediyl triplet diradicals were determined by laser flash photolysis of the corresponding azoalkane precursors. The first-order decay rate constants range from 0.8 to 16.7 × 105 s-1 in degassed solution at 294 K and exhibit a systematic, but nonlinear dependence on Brown's σ+ substituent constants. Analysis of spin-orbit coupling in terms of the two-electrons-in-two-orbitals model indicates that the electronic effect on the rates of intersystem crossing operates by influencing the weight of ionic contributions in the lowest singlet state wave functions of the diradicals. Counter to intuition, but in agreement with the prediction by the model, push-pull substitution does not enhance the ionic contribution. Arrhenius parameters, Ea = 2-6 kcal mol-1 and A = 107-1010 s-1, were determined from the temperature dependences of the decay rate constants. A sensitive statistical test is used to establish that the Arrhenius parameters exhibit enthalpy-entropy compensation, that is, an approximate isokinetic relationship.

Stereochemical memory in the temperature-dependent photodenitrogenation of bridgehead-substituted DBH-type azoalkanes: Inhibition of inverted-housane formation in the diazenyl diradical through the mass effect (inertia) and steric hindrance

The photochemical denitrogenation of the cyclopentene-annelated DBH-type azoalkanes 1 has been examined in solution as a function of bridgehead substitution and temperature. For all derivatives, namely, the unsubstituted 1a(H/H), monomethyl 1b(Me/H) dimet

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

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

Radical stabilization and ground state polar substituent effects in the thermal decomposition of azoalkanes

The thermolysis rates of a series of the 1,4-diaryl-2,3-diaza[2.2.1]bicyclohept-2-ene derivatives 1 with a large variety of aryl substituents (p-NH2, p-OMe, p-Me, H, p-F, p-Cl, p-Br, m-I, p-I, m-CN, p-CN, m-NO2, p-NO2, and

Azo Bridges from Azines, VI. - Substituted Isopyrazoles as Electron-deficient Dienes for the Synthesis of 2,3-Diazabicycloheptenes and their Photochemistry

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.