Synthesis of bromodifluoromethyl substituted pyrazoles and isoxazoles was written by Yang, Xueyan;Shui, Shengxia;Chen, Xi;He, Haiou;Wu, Fanhong. And the article was included in Journal of Fluorine Chemistry in 2010.Reference of 17355-75-8 The following contents are mentioned in the article:
Bromodifluoromethyl substituted pyrazoles I (R1 = Ph, 4-MeC6H4, etc.; R2 = Ph, 4-O2NC6H4, etc.) were prepared regioselectively by the reaction of the corresponding ketones with Et bromodifluoroacetate in the presence of sodium methoxide followed by cyclocondensation of the intermediate β-diketones R1C(O)CH2C(O)CF2Br with aryl hydrazines R2NHNH2. The reaction of R1C(O)CH2C(O)CF2Br with hydroxylamine hydrochloride gave dihydroisoxazoles, which afforded bromodifluoromethyl substituted isoxazoles II by dehydration with PPA or concentrated sulfuric acid. This study involved multiple reactions and reactants, such as Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate (cas: 17355-75-8Reference of 17355-75-8).
Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate (cas: 17355-75-8) belongs to pyrazole derivatives. The 1H-pyrazole provides an excellent means by which to provide the requisite hydrogen bond acceptor–donor motifs, whether as a monocyclic ring or as a fused indazole ring. Protonation of pyrazole in strong acid leads to pyrazolium cations, which undergo electrophilic substitution preferentially at C3 rather than C4. The pyrazole anion is not reactive toward nucleophiles but is mostly reactive to electrophiles.Reference of 17355-75-8
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics