Stereospecific Copper(II)-Catalyzed Tandem Ring Opening/Oxidative Alkylation of Donor–Acceptor Cyclopropanes with Hydrazones: Synthesis of Tetrahydropyridazines
Aerobic copper(II)-catalyzed tandem ringopening and oxidative C–H alkylation of donor–acceptorcyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89–98% enantiomeric excess)
novel efficient tandem reaction of hydrazones and α-bromo ketones is reported for the preparation of 1,3,5-trisubstituted pyrazoles by visible light catalysis. In this system, the monosubstituted hydrazones show wonderful reaction activity with alkyl radicals, generated from α-bromo ketones. A radical addition followed by intramolecular cyclization affords the important pyrazole skeleton in good to
A novel chemoselective synthesis of 3H-spiro[isobenzofuran-1,3′-pyrazole] derivatives by oxidative cleavage of their corresponding dihydroindeno[1,2-c]pyrazoles
作者:Mohammad Reza Mohammadizadeh、Fatemeh Basti
DOI:10.1007/s13738-014-0578-4
日期:2015.7
This paper reports a new and simple procedure for the synthesis of 3H-spiro[isobenzofuran-1,3′-pyrazole] derivatives by reacting 1-benzylidene-2-phenylhydrazine derivatives with ninhydrin in acetic acid medium at room temperature followed by oxidative cleavage of their corresponding dihydroindeno[1,2-c]pyrazoles. 1-Benzylidene-2-phenylhydrazine derivatives were prepared via the reaction between phenylhydrazine and benzaldehyde derivatives. Easy procedure, mild reaction conditions, high yields in short reaction times, availability of starting materials, and no formation of by-product are the advantages of this approach.
Synthesis of a new class of pyrazole embedded spirocyclic scaffolds using magnetically separable Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>–SO<sub>3</sub>H nanoparticles as recyclable solid acid support
作者:Ashis Kundu、Sayan Mukherjee、Animesh Pramanik
DOI:10.1039/c5ra23599e
日期:——
from the acid catalyzed condensation of tetrone and arylhydrazones, leads to the formation of pyrazole embedded spirocyclic scaffolds. The significant advantages of this methodology are the use of solvent-free reaction conditions, employment of simple and easily available starting materials and reagents, good yields of the products with high atom-economy and operational simplicity of the reaction with
已经开发了一种高效,绿色和可持续的方法,用于合成新型的吡唑嵌入的螺环支架。该方法包括在无溶剂条件下,在作为固体负载酸催化剂的Fe 3 O 4 @SiO 2 -SO 3 H磁性纳米颗粒(MNP)存在下,将四氢噻酮与各种芳基hydr缩合。原位有趣的串联重排生成的加合物,源自于四氢呋喃和芳基hydr的酸催化缩合反应,导致形成吡唑包埋的螺环骨架。该方法的显着优点是:使用无溶剂的反应条件,使用简单易用的起始原料和试剂,具有高原子经济性的产物具有良好的收率以及使用可磁分离的反应操作简便和可回收的纳米催化剂。
Synthesis of 3,4-diaryl-1-phenyl-4,5-dihydro-1$H$-pyrazole-5-carbonitriles via 1,3-dipolar cycloaddition reactions
Nitrile imines generated by the oxidative dehydrogenation of aromatic aldehyde phenylhydrazones with chloramine-T as a catalytic dehydrogenating agent were trapped in situ by 4-methoxy cinnamonitrile to afford 3,4-diaryl-1-phenyl-4,5-dihydro-1H-pyrazole-5-carbonitrile in moderate to good yields. The structures of the cycloadducts were confirmed by spectral studies and elemental analysis.