24789-49-9Relevant articles and documents
Preparation method of crisaborole
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Paragraph 0114-0118, (2021/09/04)
The invention discloses a preparation method of crisaborole. The preparation method comprises the following steps: by taking m-methylphenol as a raw material, firstly coupling the m-methylphenol with 4-halogenated-cyanophenyl, and then under the action of a halogenating reagent, increasing the yield of an intermediate product 4-(4-halogen-3-methylphenoxy) cyanophenyl; and carrying out halogen-metal exchange, halogenation, ring closing and other reactions to prepare the crisaborole. Compared with the prior art, the method has advantages that the raw materials are cheap and easy to obtain, and expensive reagents and raw materials in the prior art are not used; the reaction is mild, and ultralow-temperature reaction in the prior art can be avoided; the method is short in reaction time, free of column chromatography purification, simple in process, convenient to operate and suitable for industrial production.
Heterogeneous O -arylation of nitroarenes with substituted phenols over a copper immobilized mesoporous silica catalyst
Maity, Tanmoy,Bhunia, Susmita,Das, Soma,Koner, Subratanath
, p. 33380 - 33386 (2016/05/09)
Highly porous and robust mesoporous silica, SBA-15 has been subjected to post-synthesis modification for the anchoring of copper through Schiff base moiety formation using the silicon alkoxide route. The hybrid porous material has been fully characterized by powder-XRD, electronic spectra, EPR, thermogravimetric analysis, N2 sorption measurements, and TEM and SEM/EDS studies. The efficiency of the catalyst has been assessed in the O-arylation reaction using various substituted phenols and nitroarenes in heterogeneous conditions. The catalytic coupling reaction efficiently produces unsymmetrical diaryl ethers. The impressive capability to activate substrates having electron-donating or electron-withdrawing substituents and to have a high turnover frequency in the catalytic reactions made the catalyst highly desirable.
A family of ligand and anion dependent structurally diverse Cu(II) Schiff-base complexes and their catalytic efficacy in an O-arylation reaction in ethanolic media
Maity, Tanmoy,Saha, Debraj,Bhunia, Susmita,Brand?o, Paula,Das, Soma,Koner, Subratanath
, p. 82179 - 82191 (2015/10/12)
Two nitrato bridged dinuclear systems [Cu2(L1)2(NO3)3]NO3·H2O (1) and [Cu2(L2)2(NO3)3]NO3·MeOH (2), five monomeric complexes viz. [Cu(L3)(NO3)]NO3 (3), [Cu(L4)(NO3)]NO3 (4), [Cu(L5)(NO3)]NO3 (5), [Cu(L6)(NO3)NO3] (7), [Cu(L7)(NO3)]NO3 (8) and one hetero bi-bridged (phenoxido and water) dinuclear complex [Cu2(L2)2(H2O)2](ClO4)4·4H2O (6) have been synthesized and characterized using several physicochemical methods (L1 = 1-(N-3-methoxysalicylideneimino)-ethane-2-piperazine, L2 = 1-(N-3-ethoxysalicylideneimino)-ethane-2-piperazine, L3 = 1-(N-4′-ethoxy-α-methylasalicylideneimino)-ethane-2-piperazine, L4 = 1-(N-5′-chloro-α-methylasalicylideneimino)-ethane-2-piperazine, L5 = 1-(N-5-chlorosalicylideneimino)-ethane-2-piperazine, L6 = 1-(N-4-methoxysalicylideneimino)-ethane-2-piperazine and L7 = 1-(N-4′-methoxy-α-methylasalicylideneimino)-ethane-2-piperazine). X-ray structural analysis showed that complexes 1 and 2 are discrete dinuclear species where the pentacoordinated metal centers are bridged through a nitrate ion. In 3, 4, 5 and 8 the monomeric copper center displays a square pyramidal geometry with a weak axial Cu-O bond. In 7, the monomeric copper center shows a distorted octahedral geometry with two coordinated nitrate anions. However, in 6 the two copper centers coordinate in different manners (one is square-pyramidal and the other is distorted octahedral) and are bridged through a phenoxido group and a water molecule. All complexes efficiently catalyze the C-O coupling reaction under homogeneous conditions at 80 °C to afford unsymmetrical diaryl ethers using nitroarenes to act as an excellent electrophile. Notably, the reaction is carried out in ethanol media which facilitates the avoidance of toxic wastes. Structurally diverse copper(ii) Schiff-base complexes have rarely been used systematically in catalytic C-O coupling reactions.
