- Palladium-catalyzed insertion of N-tosylhydrazones and trapping with carbon nucleophiles
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A Pd-catalyzed three-component cross-coupling reaction of vinyl iodide, N-tosylhydrazone, and carbon nucleophiles is reported, and a one-pot procedure is also developed. The cross-coupling is proposed to proceed through a palladium-carbene migratory inser
- Zhou, Ping-Xin,Ye, Yu-Ying,Liang, Yong-Min
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- Synthesis of Densely Substituted Conjugated Dienes by Transition-Metal-Free Reductive Coupling of Allenylboronic Acids and Tosylhydrazones
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Tosylhydrazones and allenylboronic acids underwent a transition-metal-free reductive coupling reaction. This process is suitable for synthesis of tetra- and pentasubstituted conjugated dienes. The corresponding allenyl-Bpin substrate showed a very poor re
- Wang, Dong,De Wit, Martin J. M.,Szabó, Kálmán J.
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- Green-light induced cycloadditions
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We introduce a red-shifted tetrazole that is able to undergo efficient nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) under blue and green light irradiation. We provide a detailed wavelength-dependent reactivity map, and employ a number of LEDs for high-conversion small molecule and polymer end-group modification.
- Kamm, Philipp W.,Blinco, James P.,Unterreiner, Andreas-Neil,Barner-Kowollik, Christopher
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- Potassium tert -Butoxide Promoted Synthesis of 4,5-Diaryl-2 H -1,2,3-triazoles from Tosylhydrazones and Nitriles
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Intermolecular cycloaddition of tosylhydrazones with nitriles was investigated. t -BuOK was shown to be an excellent base for increasing the effectiveness of the reaction in this protocol, and homocoupling of the tosylhydrazones was significantly inhibited by using xylene as a solvent. Through this transformation, a variety of 4,5-diaryl-2 H -1,2,3-triazoles were prepared in good to excellent yields and with high purities. The process is azide-free and transition-metal-free.
- Qiu, Shanguang,Chen, Yuxue,Song, Xinming,Liu, Li,Liu, Xi,Wu, Luyong
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supporting information
p. 86 - 90
(2020/11/02)
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- Pd-Catalyzed Cascade Metallo-Ene Cyclization/Metallo-Carbene Coupling of Allenamides
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A highly efficient palladium-catalyzed cascade metallo-ene/metallo-carbene coupling reaction was developed to produce 2,3-dihydropyrrole derivatives in high yields. In this transformation, two new Csp3?Csp2 and Csp2?Cspsu
- Cao, Chengqiang,Yang, Yi,Li, Xin,Liu, Yunxia,Liu, Hui,Zhao, Zengdian,Chen, Lei
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supporting information
p. 1538 - 1542
(2021/03/01)
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- Mn(III)-mediated phosphinoylation of aldehyde hydrazones: Direct “one-pot” synthesis of α-iminophosphine oxides from aldehydes
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A “one-pot” strategy for the straightforward Mn(III)-mediated phosphinoylation of aldehyde hydrazones with diphenylphosphine oxide to furnish α-iminophosphine oxides is described. This mild and practical method allows the direct use of aldehydes as substrates in one pot to generate the hydrazones, which are then engaged “in situ” by the phosphorus reagent in the presence of Mn(OAc)3 oxidant. Thus, the requisite isolation of the hydrazones is not needed in this operation. Conducted mechanistic experiments implicate a pathway involving phosphorus-centered radicals.
- Bian, Xue-Wei,Zhang, Ling,Shoberu, Adedamola,Zou, Jian-Ping
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supporting information
(2021/04/02)
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- Copper-Catalyzed Regioselective Coupling of Tosylhydrazones and 2-Pyridones: A Strategy for the Production of N-Alkylated Compounds
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The highly regioselective N-alkylation reaction of 2-pyridones was achieved through hydrazone chemistry, especially for substrates with bulky secondary alkyl groups. Described herein is a copper-catalyzed coupling reaction of pyridone derivatives with tosylhydrazones.
- Wu, Ye-Bin,Wu, You-Zhi,Wu, Jian,Xu, Dan,Jiang, Hui,Chang, Wen-Wu,Ma, Chang-You
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p. 6918 - 6926
(2021/05/06)
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- Diversity-Oriented Synthesis of 1,2,4-Triazols, 1,3,4-Thiadiazols, and 1,3,4-Selenadiazoles from N-Tosylhydrazones
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The diversity-oriented synthesis of 1,2,4-triazols, 1,3,4-thiadiazols, and 1,3,4-selenadiazoles from N-tosylhydrazones was developed, and the reactions were general for a wide range of substrates, in which NH2CN, KOCN, KSCN, and KSeCN were used as odorless sources. Two different pathways were proposed, and N-tosylhydrazonoyl chlorides were formed in situ in the presence of NCS.
- Wei, Zeyang,Zhang, Qi,Tang, Meng,Zhang, Siyu,Zhang, Qian
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supporting information
p. 4436 - 4440
(2021/05/26)
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- Selective hydrolysis of phosphorus(v) compounds to form organophosphorus monoacids
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An azide and transition metal-free method for the synthesis of elusive phosphonic, phosphinic, and phosphoric monoacids has been developed. Inert pentavalent P(v)-compounds (phosphonate, phosphinate, and phosphate) are activated by triflate anhydride (Tf2O)/pyridine system to form a highly reactive phosphoryl pyridinium intermediate that undergoes nucleophilic substitution with H2O to selectively deprotect one alkoxy group and form organophosphorus monoacids.
- Ash, Jeffrey,Cordero, Paula,Huang, Hai,Kang, Jun Yong
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p. 6007 - 6014
(2021/07/21)
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- Visible-Light-Catalyzed in Situ Denitrogenative Sulfonylation of Sulfonylhydrazones
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A photocatalyzed in situ denitrogenative sulfonylation of N-arylsulfonyl hydrazones has been developed. This transformation provides a low-carbon strategy to assemble arylalkyl sulfones in a stepwise denitrogenation/sulfonylation manner.
- Huang, Xiang,Chen, Xing,Xie, Haisheng,Tan, Zheng,Jiang, Huanfeng,Zeng, Wei
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supporting information
p. 6784 - 6788
(2021/09/08)
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- Photomechanical response of sulfonylhydrazone molecular crystals
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Sulfonylhydrazones are a novel hydrazone-based organic molecular photoswitch. The four derivatives with unsubstituted ando-,m- andp-nitro substituted sulfonylhydrazone (SH-1,SH-2,SH-3, andSH-4, respectively) derived fromp-toluenesulfonyl hydrazide and corresponding benzaldehydes were examined with respect to their solution state photoswitching and photomechanical response in the crystalline state. All the compounds displayed UV-inducedE→Zisomerization in the solution state, whereas the back conversion was slow. Single crystals ofSH-3displayed rapid and large photomechanical bending, whereasSH-1andSH-4crystals underwent slow bending to a comparatively lesser extent. On the contrary,SH-2crystals did not show any photomechanical effects. The photomechanical deflection of the crystal tip ofSH-1increased linearly; forSH-3, the deflection increased in a sub-linear manner for few seconds, after which it started to revert towards the light source. ForSH-4crystals, the photo-induced tip deflection initially increased in a sub-linear fashion, after which no motion was observed even after continuous exposure to UV light irradiation. The photomechanical behavior of the crystals was also inspected with the aid of velocity-time and acceleration-time plots that unravelled the instantaneous photomechanical motion at various time intervals.
- Allu, Suryanarayana,Gunnam, Anilkumar,Gupta, Poonam,Hazarika, Pragyan J.,Nangia, Ashwini K.,Nath, Naba K.
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p. 4910 - 4916
(2021/07/25)
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- Direct Access for the Regio- And Stereoselective Synthesis of N-Alkenylpyrazoles and Chromenopyrazoles
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A highly regio- and stereoselective method was developed for the preparation of N-alkenylpyrazoles and chromenopyrazoles by the reaction of N-tosylhydrazones and salicyl N-tosylhydrazones with alkynes under neat conditions in the presence of La(OTf)3. The present study was found to be efficient and convenient for direct access to N-alkenylpyrazoles and chromenopyrazoles through C-C, C-N, and C-O bond forming reactions. Structure assignment of N-alkenylpyrazole compound 5c was confirmed by X-ray analysis.
- Kurma, Siva Hariprasad,Sridhar, Balasubramanian,Bhimapaka, China Raju
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supporting information
p. 2271 - 2282
(2021/02/06)
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- Iron Hydride Radical Reductive Alkylation of Unactivated Alkenes
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Iron-catalyzed hydrogen atom transfer-mediated intermolecular C-C coupling reactions between alkenes and tosylhydrazones, followed by in situ cleavage of the tosylhydrazine intermediates using Et3N, are described. The process involves a new strategic bond disconnection resulting in the reductive alkylation of nonactivated alkenes. The reaction is operationally simple, proceeds under mild conditions, and has a wide substrate scope.
- Saladrigas, Mar,Bonjoch, Josep,Bradshaw, Ben
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supporting information
p. 684 - 688
(2020/01/31)
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- Palladium-Catalyzed Three-Component Coupling Reaction of o-Bromobenzaldehyde, N-Tosylhydrazone, and Methanol
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A ligand-controlled palladium-catalyzed three-component reaction of o-bromobenzaldehyde, N-tosylhydrazone, and methanol is described. This reaction uses readily available compounds as starting materials while displaying a broad substrate scope and good functional group compatibility.
- Zhu, Lei,Ren, Xiaojian,Yu, Yinghua,Ou, Pengcheng,Wang, Zhi-Xiang,Huang, Xueliang
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supporting information
p. 2087 - 2092
(2020/03/04)
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- Divergent Synthesis of Vinyl-, Benzyl-, and Borylsilanes: Aryl to Alkyl 1,5-Palladium Migration/Coupling Sequences
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Organosilicon compounds have been extensively utilized both in industry and academia. Studies on the syntheses of diverse organosilanes is highly appealing. Through-space metal/hydrogen shifts allow functionalization of C?H bonds at a remote site, which are otherwise difficult to achieve. However, until now, an aryl to alkyl 1,5-palladium migration process seems to have not been presented. Reported herein is the remote olefination, arylation, and borylation of a methyl group on silicon to access diverse vinyl-, benzyl-, and borylsilanes, constituting a unique C(sp3)?H transformation based on a 1,5-palladium migration process.
- Han, Jie-Lian,Ju, Cheng-Wei,Qin, Ying,Zhao, Dongbing
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supporting information
p. 6555 - 6560
(2020/03/03)
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- Copper(I)/Bpy-Catalyzed C-2-H Benzylation of Quinazolin-4(3H)-ones with N-Tosylhydrazones
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A general and efficient copper-catalyzed C–H benzylation reaction of quinazolin-4(3H)-ones with N-tosylhydrazones is reported. The formation of new C(sp3)–C(sp2) bonds through cross-coupling occurs at the electron-poor C-2 position of quinazolin-4(3H)-one and represents an exceedingly practical method to afford 2-benzylated quinazolin-4(3H)-ones in moderate to good yields under mild reaction conditions. A possible reaction mechanism for this transformation was proposed. This catalytic transformation has the potential to be an important synthetic application for the late-stage functionalization of advanced synthetic intermediates.
- Li, Fei,Gu, Xiao-Juan,Zeng, Chang-E.,Li, Xia,Liu, Bo,Huang, Guo-Li
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supporting information
p. 2923 - 2928
(2020/05/16)
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- Acid-Promoted [3 + 1 + 1] Cyclization of N-Tosylhydrazones and Isocyanides: A Method for the Preparation of 4,5-Diaminopyrazoles
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A facile method for the preparation of 4,5-diaminopyrazoles from N-tosylhydrazones and isocyanides was developed. The reaction was general for a wide range of substrates, and it demonstrated excellent tolerance to a variety of substituents. More important
- Zhang, Qian,Tang, Meng,Zhang, Siyu,Wei, Zeyang
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supporting information
p. 5182 - 5186
(2020/07/04)
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- Umpolung Difunctionalization of Carbonyls via Visible-Light Photoredox Catalytic Radical-Carbanion Relay
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The combination of photoredox catalysis with the Wolff-Kishner (WK) reaction allows the difunctionalization of carbonyl groups by a radical-carbanion relay sequence (photo-Wolff-Kishner reaction). Photoredox initiated radical addition to N-sulfonylhydrazones yields α-functionalized carbanions following the WK-type mechanism. With sulfur-centered radicals, the carbanions are further functionalized by reaction with electrophiles including CO2 and aldehydes, whereas CF3 radical addition furnishes a wide range of gem-difluoroalkenes through β-fluoride elimination of the generated α-CF3 carbanions. More than 80 substrate examples demonstrate the broad applicability of this reaction sequence. A series of investigations including radical inhibition, deuterium labeling, fluorescence quenching, cyclic voltammetry, and control experiments support the proposed radical-carbanion relay mechanism.
- Wang, Shun,Cheng, Bei-Yi,Sr?en, Matea,K?nig, Burkhard
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supporting information
p. 7524 - 7531
(2020/08/05)
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- Base-Promoted Direct Synthesis of Sulfinates from N -Sulfonyl-hydrazones under Metal-Free Conditions
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A base-promoted direct synthesis of sulfinates from N -sulfonylhydrazones is described. Various N -sulfonylhydrazones, derived from aldehydes and ketones, are converted into the corresponding sulfinates in moderate to good yields. This protocol possesses
- Ji, Yuan-Zhao,Li, Hui-Jing,Luo, Dong-Hui,Wu, Qin-Xi,Wu, Yan-Chao
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p. 755 - 762
(2020/02/25)
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- Copper-catalyzed cross-coupling and sequential allene-mediated cyclization for the synthesis of 1,2,3-triazolo[1,5-a]quinolines
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In this paper, a tandem reaction involving copper-catalyzed cross-coupling and allene-mediated cyclization of 1-(2-ethynylaryl)-1,4-disubstituted-1,2,3-triazole withN-tosylhydrazone has been developed. This method features operational simplicity, excellen
- Jiang, Yubo,Ren, Yongsheng,Xiao, Tiebo,Xiong, Shaoqi,Yang, Jianhua
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supporting information
p. 7174 - 7182
(2020/10/02)
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- Discovery of a new fungicide by screening triazole sulfonylhydrazone derivatives and its downy mildew inhibition in cucumber
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Downy mildew is a very important detrimental disease that lead reduced to fruits and vegetables. Due to the continuous growth of drug resistance, finding novel fungicides with dissimilar modes of function from present fungicides for controlling downy mildew are imminent. This work is an extension of our preceding research on the original triazole sulfonamide derivatives lead compound. Triazole sulfonamide as a remarkable nitrogen-containing heterocyclic compound opposed cucumber downy mildew (CDM) develops a quite vital part in the sphere of the study of new farm chemicals. The existing report designs a certain amount of 1,2,4-triazole-1,3-disulfonamide derivatives. Hydrazones have obtained extensive attention in the field of pharmaceutical due to its unique chemical structure and remarkable activity (insecticidal, antibacterial, antifungal and herbicidal). By means of coupling numerous hydrazone with triazole sulfonyl chloride groups, 24 novel derivatives were synthesized. Spectrum analysis of LC-MS, 1H NMR and 13C NMR were used for characterizing these new compounds. Compared with commercial Cyazofamid using bioassays, most of these compounds displayed preferable fungicidal activities. Moreover, compounds 8q illustrated the greatest CDM resistance (EC50 = 7.776 mg/L). Field efficacy trials revealed that compound 8q fungicidal activity was higher than the purchased agrochemical Cyazofamid and Amisulbrom. Thus, the research declared that 8q displayed a great potential for the application of fungicide against CDM.
- Gao, Guoliang,Jing, Dewang,Li, Yitao,Lin, Jian,Wu, Yang,Yao, Wenqiang
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- I2 Promoted Synthesis of 2-Aminothiadiazoles Employing KSCN as a Sulfur Source Under Metal-Free Conditions
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A new three-component strategy from aldehyde, p-toluenesulfonyl hydrazide and potassium thiocyanate for the synthesis of 2-aminothiadiazoles promoted by I2 under metal-free conditions has been described. Potassium thiocyanate was used as an odo
- Zhu, Fuyuan,Yan, Zhaohua,Ai, Chengmei,Wang, Yanmei,Lin, Sen
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supporting information
p. 6561 - 6565
(2019/10/22)
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- One-Pot Reaction between N-Tosylhydrazones and 2-Nitrobenzyl Bromide: Route to NH-Free C2-Arylindoles
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A one-pot Barluenga coupling between N-tosylhydrazones and nitro-benzyl bromide, followed by deoxygenation of ortho-nitrostyrenes, and subsequent cyclization has been developed, providing a new way to synthesize various C2-arylindoles. This method exhibits a good substrate scope and functional group tolerance, and it allows an access to NH-free indoles, which can present a potential utility in medicinal chemistry applications.
- Bzeih, Tourin,Zhang, Kena,Khalaf, Ali,Hachem, Ali,Alami, Mouad,Hamze, Abdallah
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p. 228 - 238
(2019/01/04)
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- Copper(i)-catalyzed benzylation of triazolopyridine through direct C-H functionalization
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A general and efficient copper-catalyzed benzylation reaction of triazolopyridine with N-tosylhydrazones was developed. This reaction forms a C(sp2)-C(sp3) bond through cross-coupling, and represents an exceedingly practical method t
- Reddy Lonka, Madhava,Zhang, Jinquan,Gogula, Thirupathi,Zou, Hongbin
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p. 7455 - 7460
(2019/08/20)
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- Lewis Acid Catalyzed [4 + 2] Cycloaddition of N-Tosylhydrazones with ortho-Quinone Methides
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A formal [4 + 2] cycloaddition of N-tosylhydrazones with ortho-quinone methides was developed, affording the facile synthesis of diverse 1,3-oxazine derivatives under mild conditions. In this transformation, N-tosylhydrazones are used as a 1,2-dipole synt
- Wang, Chun-Ying,Han, Jia-Bin,Wang, Long,Tang, Xiang-Ying
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p. 14258 - 14269
(2019/11/11)
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- Trifluoromethylation of Allenes: An Expedient Access to α-Trifluoromethylated Enones at Room Temperature
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A silver(I) catalyzed regioselective trifluoromethylation of allenes using Langlois's salt (NaOSOCF3) is demonstrated. This transformation enables direct expedient access to α-trifluoromethylated acroleins, which are valuable synthons for a number of pharmaceuticals and agrochemicals containing vinyl-CF3 moieties. Versatility of this trifluoromethylation method has been established with good yield and excellent regioselectivity. Preliminary experiments and computational studies were carried out to elucidate the mechanistic insight of this protocol.
- Brochetta, Massimo,Borsari, Tania,Gandini, Andrea,Porey, Sandip,Deb, Arghya,Casali, Emanuele,Chakraborty, Arka,Zanoni, Giuseppe,Maiti, Debabrata
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supporting information
p. 750 - 753
(2019/01/04)
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- Rh(III)-Catalyzed [3 + 2] Annulation via C-H Activation: Direct Access to Trifluoromethyl-Substituted Indenamines and Aminoindanes
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The rhodium(III)-catalyzed direct C-H addition and annulation of benzimidates and aldimines with β-(trifluoromethyl)-α,β-unsaturated ketones is described. This protocol provides the facile and efficient formation of various trifluoromethyl-containing inde
- Chaudhary, Bharatkumar,Auti, Prashant,Shinde, Suchita Dattatray,Yakkala, Prasanna Anjaneyulu,Giri, Deepesh,Sharma, Satyasheel
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supporting information
p. 2763 - 2767
(2019/04/30)
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- Rhodium(III)-Catalyzed Directed C-H Dienylation of Anilides with Allenes Leads to Highly Conjugated Systems
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Allenes are unique coupling partners in transition-metal-catalyzed C-H functionalization leading to a variety of products via alkenylation, allenylation, allylation, and annulation reactions. The outcome is governed by both the reactivity of the allene and the formation and stability of the organometallic intermediate. An efficient Rh(III)-catalyzed, weakly coordinating group-directed dienylation of electronically unbiased allenes is developed using an N-acyl amino acid as a ligand. Further elaboration of the dienylated products to construct polycyclic compounds is also described.
- Ghosh, Chiranjit,Nagtilak, Prajyot Jayadev,Kapur, Manmohan
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supporting information
(2019/05/08)
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- Substituent-Oriented Synthesis of Substituted Pyrazoles/Chromeno[3,2- c]pyrazoles via Sequential Reactions of Chromones/3-Chlorochromones and Tosylhydrazones
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A facile and efficient synthetic strategy for the chemoselective synthesis of monocyclic/tricyclic-fused pyrazoles was developed, and it was oriented by different 3-position substituents (H or Cl) on the chromones. The reaction proceeded in a one-pot sequential way with a broad substrate scope and moderate to excellent yields.
- Dai, Tianzi,Li, Qunyi,Zhang, Xiaofei,Yang, Chunhao
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p. 5913 - 5921
(2019/05/10)
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- Selective C?C Coupling of Vinyl Epoxides with Diborylmethide Lithium Salts
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Vinyl epoxides and styrene oxide can react with diborylmethide lithium salts through an exclusive SN2 borylmethylation/ring opening in a regio- and diastereoselective way, depending on the nature of the substrate. The ring-opening protocol prov
- Gava, Riccardo,Fernández, Elena
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supporting information
p. 8013 - 8017
(2019/05/29)
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- Copper-catalyzed one-pot coupling reactions of aldehydes (ketones), tosylhydrazide and 2-amino(benzo)thiazoles: An efficient strategy for the synthesis of N-alkylated (benzo)thiazoles
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An efficient and practical C–N bond formation methodology for the synthesis of N-alkylated (benzo)thiazoles was developed, via the copper-catalyzed one-pot two-step reactions of 2-amino(benzo)thiazoles and aldehydes (ketones) with tosylhydrazide. This cross-coupling reaction proceeded smoothly and tolerated a broad range of functional groups (46 examples). A variety of functionalized N-alkylated (benzo)thiazoles were obtained in moderate to high yields. Notably, gram-scale synthesis of fanetizole (anti-inflammatory drug) was also realized through this protocol.
- Xie, Zengyang,Chen, Ruijiao,Ma, Mingfang,Kong, Lingdong,Liu, Jun,Wang, Cunde
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- Palladium-catalyzed cascade reactions of alkene-tethered carbamoyl chlorides with: N-tosyl hydrazones: Synthesis of alkene-functionalized oxindoles
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A palladium-catalyzed cascade reaction of alkene-tethered carbamoyl chlorides with N-tosyl hydrazones is described. It provided a new way to synthesize various alkene-functionalized oxindoles bearing an all-carbon quaternary center. The olefin moieties co
- Sun, Wan,Chen, Chen,Qi, Yuan,Zhao, Jinghui,Bao, Yinwei,Zhu, Bolin
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supporting information
p. 8358 - 8363
(2019/09/30)
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- Phototriggered Active Alkyne Generation from Cyclopropenones with Visible Light-Responsive Photocatalysts
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A photocatalytic active alkyne generation reaction was developed using cyclopropenone as a starting reagent. Visible light-responsive photocatalysts induced cyclopropenone decarbonylation. The resulting highly reactive alkyne could be used directly, witho
- Mishiro, Kenji,Kimura, Takeshi,Furuyama, Taniyuki,Kunishima, Munetaka
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supporting information
p. 4101 - 4105
(2019/06/17)
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- Rapid Synthesis of N-Tosylhydrazones under Solvent-Free Conditions and Their Potential Application Against Human Triple-Negative Breast Cancer
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Some N-tosylhydrazone derivatives were effectively synthesized under solvent-free conditions by using a grinding method at room temperature. The short reaction time, clean and mild process with simple workup and easy purification of the target compounds w
- Xie, Zengyang,Song, Yuying,Xu, Lujia,Guo, Yukun,Zhang, Min,Li, Limei,Chen, Kai,Liu, Xue
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p. 977 - 983
(2018/11/27)
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- Wittig Ylide Mediated Decomposition of N -Sulfonylhydrazones to Sulfinates
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N-Sulfonylhydrazones generate sulfinates selectively when treated with a stabilized Wittig ylide in a polar aprotic solvent at elevated temperature. The transition metal and base free decomposition method is applicable to N-sulfonylhydrazones generated from a number of aromatic and heteroaromatic aldehydes and ketones. In the case of N-tosylhydrazones derived from O-allyl and O-propargyl salicylaldehydes, selective formation of sulfinate occurs over intramolecular [3 + 2]-cycloaddition reaction.
- Choudhary, Deepika,Khatri, Vineeta,Basak, Ashok K.
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supporting information
p. 1703 - 1706
(2018/04/14)
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- Phosphine-Free and Reusable Palladium Nanoparticles-Catalyzed Domino Strategy: Synthesis of Indanone Derivatives
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The carbene migratory insertion involving a domino reaction by highly stable, reusable, and binaphthyl-stabilized Pd-nanoparticles (Pd-BNP) is disclosed. The reaction was catalyzed by 2 mol % of a heterogeneous Pd-BNP catalyst under external ligand-free c
- Saha, Rajib,Arunprasath, Dhanarajan,Sekar, Govindasamy
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p. 4692 - 4702
(2018/04/26)
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- Synthesis of 1,2-diarylethylenes by Pd-catalyzed one-pot reaction of benzyl halides, tosylhydrazide, and aryl aldehydes
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Background: Substituted olefins are versatile functional groups and intermediates in chemistry, medicine, electronics, and optics and materials science fields because of their unique properties. One important class of substituted olefins 1,2-diarylethylenes have attracted considerable attention due to their presence in both natural products and pharmacologically active substances. Methods: In this paper, we developed a one-pot two-step coupling reaction of aryl aldehydes, tosylhydrazide with benzyl halides by using inexpensive Pd(PPh3)4 as catalyst, leading to a variety of 1,2- diphenylethenes derivatives with moderate to good yields. Results: The desired 1,2-diarylethylenes were obtained in 46-96% yields via Pd(0)-catalyzed one-pot reaction of benzyl halides, tosylhydrazide, and aryl aldehydes. Conclusion: The catalytic system presented here enables the use of easily accessible starting materials and good functional group tolerance.
- Shen, Xu,Liu, Ping,Liu, Yan,Dai, Bin
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supporting information
p. 709 - 715
(2018/07/14)
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- Rhodium-Catalyzed B-H Bond Insertion Reactions of Unstabilized Diazo Compounds Generated in Situ from Tosylhydrazones
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Although transition-metal-catalyzed B-H bond insertion of carbenes into stable borane adducts has emerged as a promising method for organoborane synthesis, all the diazo compounds used to date as carbene precursors have had an electron-withdrawing group to stabilize them. Herein, we report a protocol for rhodium-catalyzed B-H bond insertion reactions of unstabilized diazo compounds generated in situ from tosylhydrazones. In addition, by using chiral dirhodium catalysts, we also achieved an asymmetric version of the reaction with good to excellent enantioselectivities (up to 98:2 e.r.). This is the first enantioselective heteroatom-hydrogen bond insertion reaction to use unstabilized diazo compounds as carbene precursors. The protocol exhibited good functional group tolerance and could be carried out on a gram scale. It also enabled one-pot transformation of a carbonyl group to a boryl group enantioselectively. The B-H bond insertion products could be easily transformed into chiral alcohols and other widely used organoboron reagents with enantiomeric fidelity.
- Pang, Yue,He, Qiao,Li, Zi-Qi,Yang, Ji-Min,Yu, Jin-Han,Zhu, Shou-Fei,Zhou, Qi-Lin
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supporting information
p. 10663 - 10668
(2018/09/06)
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- Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1 H-Pyrazoles Using Lewis Acid
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An unusual transformation of indoles to pyrazoles via an aromatic ring-opening strategy has been developed. The salient feature of this strategy involves the C2-N1 bond opening and concomitant cyclization reaction of the C2=C3 bond of the indole moiety with the tosylhydrazone, which proceeds under transition-metal and ligand free conditions. This ring-opening functionalization of indoles provides a wide scope of differently substituted pyrazoles.
- Panda, Subhankar,Pradhan, Nirmalya,Manna, Debasis
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supporting information
p. 573 - 578
(2018/09/25)
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- Palladium-catalyzed heck-type cascade cyclization of (Z)-1-iodo-1,6-dienes with N-tosyl hydrazones
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A palladium-catalyzed heck-type cascade cyclization of (Z)-1-iodo-1,6-dienes with N-tosyl hydrazones is reported. The alkylpalladium intermediate coupled with the diazo compound, generating the second alkylpalladium species bearing two β-H, which generate
- Li, Jun,Chi, Xiaochen,Meng, Long,Jiao, Luyang,Shang, Wenhui,Wang, Ping,Zhang, Daopeng,Dong, Yunhui,Liu, Qing,Liu, Hui
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supporting information
p. 7356 - 7360
(2018/10/24)
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- Regioselective Ring Expansion of Isatins with in Situ Generated α-Aryldiazomethanes: Direct Access to Viridicatin Alkaloids
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A novel efficient one-pot regioselective ring-expansion reaction of isatins with in situ generated α-aryl/heteroaryldiazomethanes for the construction of viridicatin alkaloids has been described under metal-free conditions. The utility of this protocol is further demonstrated in the synthesis of naturally occurring viridicatin, viridicatol, and substituted 3-O-methyl viridicatin and their scale up.
- Tangella, Yellaiah,Manasa, Kesari Lakshmi,Krishna, Namballa Hari,Sridhar,Kamal, Ahmed,Nagendra Babu, Bathini
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supporting information
p. 3639 - 3642
(2018/06/26)
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- Base-Promoted Denitrogenative/Deoxygenative/Deformylative Benzannulation of N-Tosylhydrazones with 3-Formylchromones for Diverse and Polyfunctionalized Xanthones
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A simple and efficient base-promoted denitrogenative/deoxygenative/deformylative benzannulation is developed for the construction of biologically interesting polyfunctionalized xanthones starting from N-tosylhydrazones and two molecules of 3-formylchromon
- Shrestha, Rajeev,Lee, Yong Rok
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supporting information
p. 7167 - 7171
(2018/11/23)
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- Asymmetric radical cyclopropanation of alkenes with in situ-generated donor-substituted diazo reagents via Co(II)-based metalloradical catalysis
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Donor-substituted diazo reagents, generated in situ from sulfonyl hydrazones in the presence of base, can serve as suitable radical precursors for Co(II)-based metalloradical catalysis (MRC). The cobalt(II) complex of D2-symmetric chiral porphyrin [Co(3,5-DuBu-Xu(2'-Naph)Phyrin)] is an efficient metalloradical catalyst that is capable of activating different N-arylsulfonyl hydrazones for asymmetric radical cyclopropanation of a broad range of alkenes, affording the corresponding cyclopropanes in high yields with effective control of both diastereo- and enantioselectivity. This Co(II)-based metalloradical system represents the first catalytic protocol that can effectively utilize donor-type diazo reagents for asymmetric olefin cyclopropanation.
- Wang, Yong,Wen, Xin,Cui, Xin,Wojtas, Lukasz,Zhang, X. Peter
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supporting information
p. 1049 - 1052
(2017/05/15)
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- One-Pot Acid-Catalyzed Ring-Opening/Cyclization/Oxidation of Aziridines with N-Tosylhydrazones: Access to 1,2,4-Triazines
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A new, three-step, telescoped reaction sequence for the regioselective conversion of N-tosyl hydrazones and aziridines to 3,6-disubstituted and 3,5,6-trisubstituted 1,2,4-triazines is described. The process involves an efficient nucleophilic ring opening of the aziridine, giving access to a wide range of aminohydrazones, isolated with excellent yields. A “one-pot” procedure, combining the ring opening with a cyclization and an oxidation step, allows the preparation of diversified triazines in good yields.
- Crespin, Lorène,Biancalana, Lorenzo,Morack, Tobias,Blakemore, David C.,Ley, Steven V.
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supporting information
p. 1084 - 1087
(2017/03/15)
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- Synthesis of Di- and Triarylmethanes through Palladium-Catalyzed Reductive Coupling of N -Tosylhydrazones and Aryl Bromides
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A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)-C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.
- Xia, Yamu,Hu, Fangdong,Xia, Ying,Liu, Zhenxing,Ye, Fei,Zhang, Yan,Wang, Jianbo
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p. 1073 - 1086
(2017/02/24)
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- A Transition-Metal-Free and Base-Mediated Carbene Insertion into Sulfur-Sulfur and Selenium-Selenium Bonds: An Easy Access to Thio- and Selenoacetals
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A transition-metal-free and base-mediated carbene insertion across sulfur-sulfur and selenium-selenium bonds has been developed by employing N-tosylhydrazone as a stable and safe carbene precursor. The ylide formation from carbene followed by Stevens rearrangement are considered to be the key steps. This thiol and selenol-free protocol delivers thioacetals and selenoacetals in good to excellent yields in short reaction time with good functional group tolerance. A one-pot synthesis involving in situ generation of tosylhydrazone has also been demonstrated. (Figure presented.).
- Arunprasath, Dhanarajan,Sekar, Govindasamy
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p. 698 - 708
(2017/02/23)
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- Synthesis of Benzyltributylstannanes by the Reaction of N-Tosylhydrazones with Bu3SnH
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An efficient stannylation process with N-tosylhydrazones or directly with carbonyl compounds has been developed. A series of functionalized benzyl- and alkyltributylstannanes can be synthesized in moderate to good yields under transition-metal-free conditions. Tandem transformations involving stannylation/Stille cross-coupling reaction have been carried out without purification of the benzyltributylstannane intermediates to afford a series of diarylmethane derivatives.
- Qiu, Di,Wang, Shuai,Meng, He,Tang, Shengbo,Zhang, Yan,Wang, Jianbo
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p. 624 - 632
(2017/04/26)
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- Highly stereoselective synthesis of 1-cyanocyclopropane-carboxamides from 3-substituted-2-cyanoacrylamides with N-tosylhydrazones under metal-free conditions
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A metal-free cyclopropanation of electron-deficient olefins 3-substituted-2-cyanoacrylamides with N-tosylhydrazones has been successfully developed. This strategy provide a simple route to the synthesis of very valuable 1-cyanocyclopropanecarboxamides wit
- Nie, Xufeng,Wang, Yachuan,Yang, Lijun,Yang, Zaijun,Kang, Tairan
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supporting information
p. 3003 - 3007
(2017/07/17)
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- Hypervalent iodine (III)-mediated oxidation of aryl sulfonylhydrazones: A facile synthesis of N-aroyl-N′-acyl arylsulfonylhydrazides
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We have developed a novel and efficient method for the oxidation of aryl sulfonylhydrazones to N-aroyl-N′-acyl arylsulfonylhydrazides, using hypervalent iodine (III) reagent in good yields at room temperature.
- Ramakrishna,Dev, Kapil,Maurya, Saransh Wales,Siddiqui, Ibadur Rahman,Maurya, Rakesh
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supporting information
p. 570 - 573
(2017/01/16)
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- Directed C-C bond cleavage of a cyclopropane intermediate generated from: N -tosylhydrazones and stable enaminones: Expedient synthesis of functionalized 1,4-ketoaldehydes
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An efficient method to construct functionalized 1,4-ketoaldehydes bearing all-carbon α-quaternary centers via regioselective C-C bond activation has been described. The cyclopropanation of bench-stable enaminones with in situ generated diazo reagents from
- Ni, Meiyan,Zhang, Jianguo,Liang, Xiaoyu,Jiang, Yaojia,Loh, Teck-Peng
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supporting information
p. 12286 - 12289
(2017/11/20)
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- Transition-Metal-Free Trifluoromethylation of Aldehyde Derivatives with Sodium Trifluoromethanesulfinate
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A metal-free and cost-effective synthetic protocol for the trifluoromethylation of N,N-disubstituted hydrazones with Langlois's reagent (CF3SO2Na) to afford the corresponding functionalized trifluoromethyl ketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a trifluoroalkyl radical may be involved in the reaction. Applications of the methodology in industry will be found and the development of new methods for trifluoromethylation with Langlois's reagent will be continued in our laboratory.
- Tan, Zheng,Zhang, Shiwei,Zhang, Yan,Li, Yunpeng,Ni, Minjie,Feng, Bainian
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p. 9384 - 9399
(2017/09/23)
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