13892-46-1Relevant academic research and scientific papers
Regioselectivity of the thermal van Alphen–Hüttel rearrangement of 4- and 5-mono- and 4,5-disubstituted 3,3-diphenyl-3H-pyrazoles
Vasin,Razin,Bezrukova,Petrov
, p. 862 - 872 (2016)
Thermal van Alphen–Hüttel rearrangement of methyl 3,3-diphenyl-3H-pyrazole-4-carboxylate, 3,3-diphenyl-3H-pyrazole-4-carbonitrile, and methyl 5-methyl-3,3-diphenyl-3H-pyrazole-4-carboxylate involves completely regioselective migration of one phenyl group from the 3-position to N2with formation of aromatic 1H-pyrazole system. Thermal rearrangement of methyl 3,3-diphenyl-3H-pyrazole-5-carboxylate leads to the formation of methyl 4,5-diphenyl-1H-pyrazole-3-carboxylate as a result of migration of the 3-phenyl group exclusively to the C4atom and subsequent prototropic isomerization. Under analogous conditions, methyl 4-methyl-3,3-diphenyl-3H-pyrazole-5-carboxylate, methyl 5-(methanesulfonyl)-3,3-diphenyl-3H-pyrazole-4-carboxylate, methyl 5-(benzenesulfonyl)-3,3-diphenyl-3H-pyrazole-4-carboxylate, and dimethyl 3,3-diphenyl-3H-pyrazole-4,5-dicarboxylate have been regioselectively converted into the corresponding 4H-pyrazoles. Thermolysis of 5-(4-methylbenzenesulfonyl)-3,3-diphenyl-3H-pyrazole-4-carbonitrile gives rise to a mixture of 1H- and 4H-pyrazoles, the former considerably prevailing, whereas the corresponding 1H-pyrazoles are formed as the only product from 5-(methanesulfonyl)- and 5-(benzenesulfonyl)-3,3-diphenyl-3H-pyrazole-4-carbonitriles.
Similarity and Differences in the Regioselectivities of Thermal and Acid-Catalyzed van Alphen–Hüttel Rearrangements in the Series of 3,3-Diphenyl-3H-pyrazoles Containing Electron-Withdrawing Substituents on C4 and C5
Vasin,Razin,Bezrukova
, p. 1045 - 1054 (2018/09/11)
3,3-Diphenyl-3H-pyrazoles containing an electron-withdrawing substituent in the 5-position undergo van Alphen–Hüttel rearrangement with migration of one phenyl group to C4 on heating in an aprotic solvent (benzene, toluene), as well as on keepi
Pd(II)-catalyzed ligand controlled synthesis of pyrazole-4-carboxylates and benzo[b]thiophene-3-carboxylates
Dhage, Yogesh Daulat,Daimon, Hiroki,Peng, Cheng,Kusakabe, Taichi,Takahashi, Keisuke,Kanno, Yuichiro,Inouye, Yoshio,Kato, Keisuke
, p. 8619 - 8626 (2014/12/10)
Cyclization-carbonylation of α,β-alkynic hydrazones and (o-alkynylphenyl) (methoxymethyl) sulfides with Pd(tfa)2 in DMSO/MeOH afforded methyl pyrazole-4-carboxylates and benzo[b]thiophene-3-carboxylates, respectively, in good yields. A simple change of the ligand (solvent) allowed controlled, effective switching between cyclization-carbonylation-cyclization-coupling (CCC-coupling) reactions and cyclization-carbonylation reactions.
1,3-Dipolar Cycloadditions, 88. C-Methyl-N-phenylnitrilimine and the Regiochemistry of its Cycloadditions
Fliege, Werner,Huisgen, Rolf,Clovis, James S.,Knupfer, Hans
, p. 3039 - 3061 (2007/10/02)
The title compound, a representative of the little known C-alkylnitrilimines, is accessible by three routes: NaNO2 elimination from sodium (α-nitroethylidene)phenylhydrazine in boiling acetonitrile, photolysis of 5-methyl-2-phenyltetrazole, and the thermo
