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Nagaraju Molleti, Jun Yong Kang
A highly efficient phospha-aldol reaction for the synthesis of α(1)-oxindole-α-hydroxyphosphonates is developed utilizing N-heterocyclic phosphine (NHP)-thiourea as a phosphonylation reagent under catalyst, additive free conditions. This methodology encompasses a variety of isatin derivatives to provide α(1)-oxindole- α-hydroxyphosphonates up to 99% yield.
September 26, 2016: Organic & Biomolecular Chemistry
Yunsheng Xue, Yuhui Wang, Zhongyan Cao, Jian Zhou, Zhao-Xu Chen
Density functional theory (DFT) calculations were performed to elucidate the mechanism and the origin of the high enantioselectivity of the aza-Henry reaction of isatin-derived N-Boc ketimine catalyzed by a quinine-derived catalyst (QN). The C-C bond formation step is found to be both the rate-determining and the stereo-controlled step. The results revealed the important role of the phenolic OH group in pre-organizing the complex of nitromethane and QN and stabilizing the in situ-generated nitronate and protonated QN...
October 12, 2016: Organic & Biomolecular Chemistry
Juanjuan Wang, Danfeng Huang, Ke-Hu Wang, Xiansha Peng, Yingpeng Su, Yulai Hu, Ying Fu
A convenient and efficient method for the constructions of 3-spirooxindole derivatives or 3,3'-disubstituted oxindoles has been developed from one-pot reactions of isatins, hydrazides or aromatic amines, 2-(bromomethyl)acrylic ester and tin powder in the presence of a catalytic amount of Brønsted or Lewis acid. The method avoids the use of toxic stannanes and allows easy operation. It is also proved that hydrazides are more favorable for intramolecular cyclization than amines.
October 12, 2016: Organic & Biomolecular Chemistry
James T Fleming, Corinne Wills, Paul G Waddell, Ross W Harrington, Lee J Higham
Six chiral MOP-phosphonites have been synthesised and compared via experimental and computational methods in an effort to quantify their differing structural and electronic profiles. They were found to be electron-poor ligands in comparison to their arylphosphine analogues and have a larger trans influence in square planar Pt(ii) complexes. Four [Rh(L(P))(η(2):η(2)-cod)Cl] complexes were synthesised and characterised by NMR, HRMS and X-ray crystallography. Two [Rh(L(P))2]BF4 complexes were prepared where one ligand acts as a chelating P,C-π-donor; detailed NMR studies demonstrated a hemilabile η(6)-coordination mode, which in one case was confirmed by X-ray crystallography...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Andrea Nitti, Marco Signorile, Massimo Boiocchi, Gabriele Bianchi, Riccardo Po, Dario Pasini
We report on the design, synthesis and properties of innovative, planar, pi-conjugated compounds in which a thiophene ring is fused with the skeleton of the naturally-occurring dye isatin. The synthesis is achieved in high yields making use of an intramolecular Direct Arylation reaction as the key step, making the overall process potentially scalable. The synthetic sequence has been demonstrated also for an isatin bearing fluorine substituents on the aromatic ring. NMR and X-ray studies demonstrate the crosstalk occurring between the fused, coplanar and conjugated moieties, making these novel dyes with a Donor-Acceptor character...
October 6, 2016: Journal of Organic Chemistry
Jianfeng Xu, Shiru Yuan, Maozhong Miao, Zhengkai Chen
A 1-hydroxybenzotriazole (HOBt) assisted, N-heterocyclic carbene (NHC) catalyzed direct beta-functionalization of saturated carboxylic esters is disclosed. This formal [3+2] annulation reaction of carboxylic esters with isatins affords optically pure spirooxindole lactones (on gram scale) bearing two vicinal stereogenic centers. A dual role of HOBt is proposed based on controlled experiments to rationalize the enhancement of diastereoselectivity and enantioselectivity.
October 6, 2016: Journal of Organic Chemistry
Dinesh Kumar, Sandeep R Vemula, Narayanaganesh Balasubramanian, Gregory R Cook
Stereoselective indium-mediated organic reactions have enjoyed tremendous growth in the last 25 years. This is in part due to the insensitivity of allylindium to moisture, affording facile and practical reaction conditions coupled with outstanding functional group tolerance and minimal side reactions. Despite the plethora of articles about allylindium, there is much yet to be discovered and exploited for efficient and sustainable synthesis. In this Account, we describe indium-mediated synthetic methods for the preparation of chiral amines with the aim to present a balance of practical method development, novel asymmetric chemistry, and mechanistic understanding that impact multiple chemical and materials science disciplines...
October 4, 2016: Accounts of Chemical Research
Rong Zeng, Peng-Hao Chen, Guangbin Dong
The first decarbonylative cycloaddition of less-strained cyclic ketones (isatins) with isocyanates is reported. Initiated by C-C activation, this distinct [5-2+2] transformation provides a rapid entry to access various benzimidazolidinone derivatives, through which a wide range of isocyanates can be efficiently coupled with broad functional group tolerance. A modified one-pot process, combining Curtius rearrangement and C-C activation, was also achieved by using acyl azides as the starting materials. Detailed mechanistic study revealed a surprising double-decarbonylative reaction pathway...
February 5, 2016: ACS Catalysis
Atulya Nagarsenkar, Lalita Guntuku, Sravanthi Devi Guggilapu, Danthi Bai K, Srinivasulu Gannoju, V G M Naidu, Nagendra Babu Bathini
In our venture towards the development of effective cytotoxic agents, a panel of triazole linked 3-benzylidene isatin hybrids were synthesized and characterized by IR, (1)H NMR, (13)C NMR and Mass spectral analysis. All the newly synthesized target compounds were assessed against DU145 (prostate), PC-3 (prostate), MDA-MB-231 (breast), BT549 (breast), A549 (lung) and HeLa (cervical) human cancer cell lines by employing MTT assay for their cytotoxic potential. Significantly, compound Z-8l was found to be most potent amongst all the tested compounds with an IC50 value of (3...
September 4, 2016: European Journal of Medicinal Chemistry
Christopher Foley, Arthur Shaw, Christopher Hulme
Two-step methodology described herein showcases the first example of an oxidation/oxidative amidation cyclization cascade of MCR products toward diverse N-functionalized isatins. Products of both the Ugi 3CR and the Ugi azide reactions are oxidatively cyclized through a postcondensation process utilizing selenium dioxide. This methodology was found to be applicable for the generation of bis-peptidomimetic-like isatins containing multiple points of diversification.
October 7, 2016: Organic Letters
Hong-Yu Wang, Chang-Wu Zheng, Zhuo Chai, Jia-Xing Zhang, Gang Zhao
Over the past few decades, enantioselective phosphine organocatalysis has evolved rapidly into a highly efficient catalytic strategy for a range of useful reactions. However, as restricted by the traditional catalytic modes, some important reactions, such as asymmetric Strecker-type reactions, have thus far been out of reach of this strategy. Reported herein is an application of enantioselective phosphine organocatalysis for asymmetric Strecker-type reactions, enabled by a dual-reagent catalyst system in which the key organophosphorus zwitterion intermediate, generated in situ by mixing a chiral dipeptide-derived multifunctional organophosphine with methyl acrylate, is used as a highly efficient chiral Lewis base catalyst...
2016: Nature Communications
Bochra Tourki, Philippe Matéo, Jessica Morand, Mohamed Elayeb, Diane Godin-Ribuot, Naziha Marrakchi, Elise Belaidi, Erij Messadi
Cardiac ischemia is one of the leading causes of death worldwide. It is now well established that natriuretic peptides can attenuate the development of irreversible ischemic injury during myocardial infarction. Lebetin 2 (L2) is a new discovered peptide isolated from Macrovipera lebetina venom with structural similarity to B-type natriuretic peptide (BNP). Our objectives were to define the acute cardioprotective actions of L2 in isolated Langendorff-perfused rat hearts after regional or global ischemia-reperfusion (IR)...
2016: PloS One
Guangcheng Wang, Jing Wang, Dianxiong He, Xin Li, Juan Li, Zhiyun Peng
This study synthesized a series of novel coumarin-isatin derivatives and evaluated them for α-glucosidase inhibitory activity. The majority of the screened compounds exhibited excellent inhibition activities with IC50 values of 2.56 ± 0.08-268.79 ± 3.04 μm, when compared to acarbose. Among the newly derivatives, compound 5p was found to be the most active compound in the library of coumarin-isatin derivatives. Furthermore, enzyme kinetic studies showed that compound 5p is a non-competitive inhibitor with a Ki of 2...
September 12, 2016: Chemical Biology & Drug Design
G Rainoldi, M Faltracco, L Lo Presti, A Silvani, G Lesma
A diastereoselective, DABCO-catalyzed reaction of isatin-derived ketimines with allenoates is described. Exploiting the stereodirecting effect of the bulky tert-butanesulfinyl chiral auxiliary, the method provides an efficient access to single diastereoisomers of unprecedented spirocyclic oxindoles, bearing a 4-methyleneazetidine ring at the spiro junction. The versatility of the method is fully demonstrated by further transformations including the conversion to relevant spirocyclic oxindolo-β-lactams.
October 4, 2016: Chemical Communications: Chem Comm
Kun Zhao, Ying Zhi, Tao Shu, Arto Valkonen, Kari Rissanen, Dieter Enders
An asymmetric organocatalytic domino oxa-Michael/1,6-addition reaction of ortho-hydroxyphenyl-substituted para-quinone methides and isatin-derived enoates has been developed. In the presence of 5 mol % of a bifunctional thiourea organocatalyst, this scalable domino reaction affords 4-phenyl-substituted chromans bearing spiro-connected oxindole scaffolds and three adjacent stereogenic centers in good to excellent yields (up to 98 %) and with very high stereoselectivities (up to >20:1 d.r., >99 % ee)...
September 19, 2016: Angewandte Chemie
Bin Yu, Sai-Qi Wang, Ping-Ping Qi, Dong-Xiao Yang, Kai Tang, Hong-Min Liu
A series of new isatin/triazole conjugates were designed based on the hypothesis that the ester-linked compounds could be enzymatically hydrolyzed by cellular esterases inside the cells. These compounds showed moderate to good growth inhibition toward the tested cancer cells, exerted selective inhibition toward MGC-803 cells and were less toxic to normal cells HL-7702 and GES-1. Of these compounds, compound 5a showed the best inhibitory activity against MGC-803 cells (IC50 = 9.78 μM), induced apoptosis through multiple mechanisms, as well as inhibited migration of MGC-803 cells...
August 28, 2016: European Journal of Medicinal Chemistry
Mohammad Shahbazy, Parvaneh Pakravan, Mohsen Kompany-Zareh
Interactions of Isatin and its derivatives, Isatin-3-isonicotinylhydrazone (IINH) and Isatin-β-thiosemicarbazone (IBT), with calf thymus DNA (ctDNA) have been investigated to delineate pharmaceutical-physicochemical properties using UV-Vis/fluorescence/circular dichroism (CD) spectroscopy, viscosity measurements, and multivariate chemometrics. IINH and IBT molecules intercalate between base pairs of DNA, hypochromism in UV absorptions, increase in the CD positive band, sharp increase in specific viscosity, and the displacement of the methylene blue and Neutral Red dye in complexes with ctDNA, by the IINH and IBT molecules, respectively...
September 3, 2016: Journal of Biomolecular Structure & Dynamics
Minsu Kim, Jin-Hyung Lee, Eonmi Kim, Hyukjae Choi, Younghoon Kim, Jintae Lee
Indole is an interspecies and interkingdom signaling molecule widespread in different environmental compartment. Although multifaceted roles of indole in different biological systems have been established, little information is available on the microbial utilization of indole in the context of combating odor emissions from different types of waste. The present study was aimed at identifying novel bacteria capable of utilizing indole as the sole carbon and energy source. From the selective enrichment of swine waste and cattle feces, we identified Gram-positive and Gram-negative bacteria belonging to the genera Arthrobacter and Alcaligenes...
June 2016: Indian Journal of Microbiology
Sachin Suresh Bhojgude, Anup Bhunia, Akkattu T Biju
Arynes are highly reactive intermediates having several applications in organic synthesis for the construction of various ortho-disubstituted arenes. Traditionally, arynes are generated in solution from haloarenes under strongly basic conditions. However, the scopes of many of the aryne reactions are limited because of the harsh conditions used for their generation. The renaissance of interest in aryne chemistry is mainly due to the mild conditions for their generation by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates...
September 20, 2016: Accounts of Chemical Research
Hee Seung Jang, Yubin Kim, Dae Young Kim
Chiral binaphthyl-modified squaramide-catalyzed enantioselective addition of diphenyl phosphonate to ketimines derived from isatins has been achieved. This method affords practical and efficient access to chiral 3-amino-3-phosphonyl-substituted oxindole derivatives in high yields with excellent enantioselectivities (up to 99% ee).
2016: Beilstein Journal of Organic Chemistry
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