- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
-
The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
-
-
- Synthesis, Characterization, and Catalytic Reactivity of {CoNO}8PCP Pincer Complexes
-
The reaction of coordinatively unsaturated Co(II) PCP pincer complexes with nitric oxide leads to the formation of new, air-stable, diamagnetic mono nitrosyl compounds. The synthesis and characterization of five- and four-coordinate Co(III) and Co(I) nitrosyl pincer complexes based on three different ligand scaffolds is described. Passing NO through a solution of [Co(PCPNMe-iPr)Cl], [Co(PCPO-iPr)Cl] or [Co(PCPCH2-iPr)Br] led to the formation of the low-spin complex [Co(PCP-iPr)(NO)X] with a strongly bent NO ligand. Treatment of the latter species with (X = Cl, Br) AgBF4 led to chloride abstraction and formation of cationic square-planar Co(I) complexes of the type [Co(PCP-iPr)(NO)]+ featuring a linear NO group. This reaction could be viewed as a formal two electron reduction of the metal center by the NO radical from Co(III) to Co(I), if NO is counted as NO+. Hence, these systems can be described as {CoNO}8 according to the Enemark-Feltham convention. X-ray structures, spectroscopic and electrochemical data of all nitrosyl complexes are presented. Preliminary studies show that [Co(PCPNMe-iPr)(NO)]+ catalyzes efficiently the reductive hydroboration of nitriles with pinacolborane (HBpin) forming an intermediate {CoNO}8 hydride species.
- Pecak, Jan,Eder, Wolfgang,St?ger, Berthold,Realista, Sara,Martinho, Paulo N.,Calhorda, Maria José,Linert, Wolfgang,Kirchner, Karl
-
p. 2594 - 2601
(2020/06/22)
-
- Catalytic Staudinger Reduction at Room Temperature
-
We report an efficient catalytic Staudinger reduction at room temperature that enables the preparation of a structurally diverse set of amines from azides in excellent yields. The reaction is based on the use of catalytic amounts of triphenylphosphine as a phosphine source and diphenyldisiloxane as a reducing agent. Our catalytic Staudinger reduction exhibits a high chemoselectivity, as exemplified by reduction of azides over other common functionalities, including nitriles, alkenes, alkynes, esters, and ketones.
- Lenstra, Danny C.,Wolf, Joris J.,Mecinovi?, Jasmin
-
p. 6536 - 6545
(2019/05/24)
-
- Reversible capture and release of aromatic amines by vicinal tricarbonyl compound
-
In this paper, we report reversible capture and release of aromatic amines by diphenylpropanetrione (DPPT). Addition of aromatic amines to the central carbonyl group occurred readily at ambient temperature to provide the aromatic amine adducts of DPPT (DPPT-aromatic amines), which has a hemiaminal structure. On the other hand, washing a solution of DPPT-aromatic amine with diluted hydrochloric acid (HCl) enabled successful recovery of DPPT to demonstrate the reversible nature of this system.
- Yuki, Tatsuya,Yonekawa, Morio,Furusho, Yoshio,Sei, Yoshihisa,Tomita, Ikuyoshi,Endo, Takeshi
-
p. 2868 - 2873
(2016/05/19)
-
- High graphite N content in nitrogen-doped graphene as an efficient metal-free catalyst for reduction of nitroarenes in water
-
Four kinds of nitrogen-doped graphene (NG) as metal-free catalysts are synthesized by a one-step hydrothermal reaction and thermal treatment using graphene oxide and urea as precursors. It is found that the reduction of nitroarenes can be catalyzed by using a low NG loading and a small amount of NaBH4 in water with high yield. The type of nitrogen species in NG has an important effect on the reduction reaction. The NG catalyst containing the most graphite N shows the highest catalytic activity during reduction of nitroarenes, which demonstrates that the graphite N of NG plays a key role in impelling this reaction. The reaction mechanism is proven by GC-MS experiments, and DFT calculations reveal the reasons for the graphite N showing better catalytic activity. It is worth noting that no dehalogenation phenomenon occurs during the reduction process for halogen-substituted nitroarenes in contrast to conventional metal catalysts. In addition, the NG catalyst can be simply recycled and efficiently used for eight consecutive runs with no significant decrease in activity.
- Yang, Fan,Chi, Cheng,Wang, Chunxia,Wang, Ying,Li, Yongfeng
-
supporting information
p. 4254 - 4262
(2016/08/02)
-
- Development and evaluation of ST-1829 based on 5-benzylidene-2-phenylthiazolones as promising agent for anti-leukotriene therapy
-
Different inflammatory diseases and allergic reactions are mediated by leukotrienes, which arise from the oxygenation of arachidonic acid catalyzed by 5-lipoxygenase (5-LO). One promising approach for an effective anti-leukotriene therapy is the inhibition of this key enzyme. This study presents the synthesis and development of a potent and direct 5-LO inhibitor based on the well characterized 5-benzylidene-2-phenylthiazolone C06, whose further pharmacological investigation was precluded due to its low solubility. Through optimization of C06, evaluation of structure-activity relationships including profound assessment of the thiazolone core and consideration of the solubility, the 5-benzyl-2-phenyl-4-hydroxythiazoles represented by 46 (ST-1829, 5-(4-chlorobenzyl)-2-p-tolylthiazol-4-ol) were developed. Compound 46 showed an improved 5-LO inhibitory activity in cell-based (ICinf50/inf values 0.141/4M) and cell-free assays (ICinf50/inf values 0.03 1/4M) as well as a prominent enhanced solubility. Furthermore, it kept its promising inhibitory potency in the presence of blood serum, excluding excessive binding to serum proteins. These facts combined with the non-cytotoxic profile mark a major step towards an effective anti-inflammatory therapy.
- Lill, Andreas P.,R?dl, Carmen B.,Steinhilber, Dieter,Stark, Holger,Hofmann, Bettina
-
p. 503 - 523
(2014/12/11)
-
- The ortho effect on the acidic and alkaline hydrolysis of substituted formanilides
-
The kinetics of formanilides hydrolysis were determined under first-order conditions in hydrochloric acid (0.01-8 M, 20-60°C) and in hydroxide solutions (0.01-3 M, 25 and 40°C). Under acidic conditions, second-order specific acid catalytic constants were used to construct Hammett plots. The ortho effect was analyzed using the Fujita-Nishioka method. In alkaline solutions, hydrolysis displayed both first- and second-order dependence in the hydroxide concentration. The specific base catalytic constants were used to construct Hammett plots. Ortho effects were evaluated for the first-order dependence on the hydroxide concentration. Formanilide hydrolyzes in acidic solutions by specific acid catalysis, and the kinetic study results were consistent with the AAC2 mechanism. Ortho substitution led to a decrease in the rates of reaction due to steric inhibition of resonance, retardation due to steric bulk, and through space interactions. The primary hydrolytic pathway in alkaline solutions was consistent with a modified BAC2 mechanism. The Hammett plots for hydrolysis of meta- and para-substituted formanilides in 0.10 M sodium hydroxide solutions did not show substituent effects; however, ortho substitution led to a decrease in rate constants proportional to the steric bulk of the substituent.
- Desai, Salil Dileep,Kirsch, Lee E.
-
p. 471 - 488
(2015/06/30)
-
- Synthesis, cytotoxic evaluation, and in silico studies of substituted N-alkylbromo-benzothiazoles
-
In efforts to develop a new class of anticancer agents with improved efficacy and selective action, a series of N-alkylbromo-benzothiazoles were synthesized and evaluated for in vitro cytotoxic activity against various human cancer cell lines such as lung (A-549), prostate (PC-3), leukemia (THP-1), and colon (Caco-2). They were found to be highly active against prostate (PC-3) and leukemia (THP-1) cancer cells, moderately active against colon (Caco-2) cancer cells and less active against lung (A-549) cancer cells. Of the 12 compounds, two (11d, 11j) exhibit IC50 values of ≤ 1 μM against leukemia (THP-1) cancer cell lines. Compound 11l showed significant cytotoxic activity against the PC-3 (IC50 = 0.6 μM), THP-1 (IC50 = 3 μM) and Caco-2 cell lines (IC50 = 9.9 μM), respectively. Docking study of the synthesized ligand was done on epidermal growth factor receptor using ArgusLab flexible docking, to determine their observed activity. Further QSAR investigations with stepwise multiple linear regression analysis were applied to find correlation between various physicochemical parameters and anticancer activity. The QSAR results showed that anticancer activity could be modeled with descriptors. The predictive ability of models was cross-validated by observation of the low residual activity values and adjusted coefficient of variation (radj2) obtained by leave-one-out technique.
- Gill, Rupinder Kaur,Singh, Gagandeep,Sharma, Anuradha,Bedi,Saxena
-
p. 4211 - 4222
(2013/09/02)
-
- A facile and efficient method for the selective deacylation of N-arylacetamides and 2-chloro-Narylacetamides catalyzed by SOCl2
-
Thionyl chloride efficiently and selectively promoted the deacylation of N-arylacetamides and 2-chloro-N-arylacetamides, under anhydrous conditions, without effecting the ester group, aminosulfonyl group, or benzyloxyamide group. This method, which has been successfully applied to a variety of substrates including different N-arylacetamides and 2-chloro-N-arylacetamides, has the attractive advantages of inexpensive reagents, satisfactory selectivity, excellent yields, short reaction time, and convenient workup. This new method can probably be used to selectively deacylate between aromatic amides and alkyl amides. Springer Science+Business Media B.V. 2011.
- Wang, Gong-Bao,Wang, Lin-Fa,Li, Chao-Zhang,Sun, Jing,Zhou, Guang-Ming,Yang, Da-Cheng
-
-
- Bromination and diazo-coupling of pyridinethiones; microwave assisted synthesis of isothiazolopyridine, pyridothiazine and pyridothiazepines
-
Isothiazolopyridines, pyridothiazines and pyridothiazepines are important compounds that possess valuable biological activities. This paper reports on the synthesis of these compounds using both conventional chemical methods and modern microwave techniques. 3-Bromo-6-hydroxy-4-methyl-2-thioxo-2,3- dihydropyridine-3-carboxamide, 5-arylazo-6-hydroxy-4-methyl-2-thioxo-1,2- dihydropyridine-3-carboxamides, 3,5-bis-arylazo-6-hydroxy-4-methyl-2-thioxo-2,3- dihydropyridine-3-caboxamide, 4-methyl-2,3,6,7-tetrahydroisothiazolo[5,4-b]- pyridine-3,6-dione, 2,2'-(methylene-bis-(sulfanediyl))bis(4-methyl-6-oxo-1,6- dihydropyridine-3-carboxamide), 2-hydroxy-5-methyl-4H-pyrido[3,2-e][1,3]- thiazine-4,7(8H)-dione and 2-arylmethylene-8-hydroxy-6-methyl-2,3,4,5- tetrahydropyrido-[3,2-f][1,4]thiazepine-3,5-diones have been prepared from 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide. Some of these compounds were prepared using microwave-assisted reaction conditions, that provided higher yields in shorter times than the conventional methods.
- Youssef, Ayman M. S.,Azab, Mohamed E.,Youssef, Mohamed M.
-
experimental part
p. 6930 - 6943
(2012/09/07)
-
- Kinetics and mechanism of the anilinolysis of dicyclohexyl phosphinic chloride in acetonitrile
-
The nucleophilic substitution reactions of dicyclohexyl phosphinic chloride [3; cHex2P(=O)Cl] with substituted anilines (XC6H 4NH2) and deuterated anilines (XC6H 4ND2) are investigated kinetically in acetonitrile at 60.0 °C. The anilinolysis rate is too slow to be rationalized by the stereoelectronic effects. The rate is contrary to expectations for the electronic influence of the two ligands and exhibits exceptionally great negative deviation from the Taft's eq. The deuterium kinetic isotope effects (DKIEs) involving deuterated anilines invariably change from primary normal (kH/kD > 1; max kH/kDt = 1.10 with X = 4-MeO) with the strongly basic anilines (X = 4-MeO, 4-Me, 3-Me) to secondary inverse (kH/kDt H/k Dt = 0.673 with X = 3-Cl) with the weakly basic anilines (X = H, 4-F, 4-Cl, 3-Cl). A concerted SN2 mechanism is proposed on the basis of both secondary inverse and primary normal DKIEs. The obtained DKIEs imply that the fraction of a frontside attack increases as the aniline becomes more basic. A hydrogen-bonded, four-center-type transition state is suggested for a frontside attack, while the trigonal bipyramidal pentacoordinate transition state is suggested for a backside attack.
- Ul Hoque, Md. Ehtesham,Lee, Hai Whang
-
experimental part
p. 1997 - 2002
(2012/02/01)
-
- Concurrent primary and secondary deuterium kinetic isotope effects in anilinolysis of O-aryl methyl phosphonochloridothioates
-
The nucleophilic substitution reactions of Y-O-aryl methyl phosphonochloridothioates with substituted anilines (XC6H 4NH2) and deuterated anilines (XC6H 4ND2) are investigated kinetically in acetonitrile at 55.0°C. The Hammett and Bronsted plots for substituent (X) variations in the nucleophiles are biphasic concave downwards with a break region between X = H and 4-Cl. The deuterium kinetic isotope effects (DKIEs) are primary normal (kH/kD = 1.03-1.30) for stronger nucleophiles (X = 4-MeO, 4-Me and H), and extremely large secondary inverse (kH/kD = 0.367-0.567) for weaker nucleophiles (X = 4-Cl, 3-Cl and 3-NO2). The cross-interaction constants are negative (ρXY(H) = -0.95 and ρXY(D) = -1.11) for stronger nucleophiles, while positive (ρXY(H) = +0.77 and ρXY(D) = +0.21) for weaker nucleophiles. These kinetic results indicate that the mechanism changes from a concerted process involving frontside nucleophilic attack for stronger nucleophiles to a stepwise process with a rate-limiting leaving group expulsion from the intermediate involving backside attack for weaker nucleophiles. A hydrogen-bonded, four-center-type transition state (TS) is suggested for a frontside attack, while a trigonal bipyramidal pentacoordinate TS is suggested for a backside attack. The unusually small DKIEs, as small as or equal to 0.4, for weaker nucleophiles seem to be ascribed to severe steric congestion in the TS.
- Ul Hoque, Md. Ehtesham,Guha, Arun Kanti,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang
-
experimental part
p. 2919 - 2925
(2011/02/28)
-
- Kinetics and mechanism of the aminolysis of dimethyl and methyl phenyl phosphinic chlorides with anilines
-
The reactions of dimethyl phosphinic chloride (1) and methyl phenyl phosphinic chloride (2) with X-anilines have been studied kinetically in acetonitrile at 15.0 and 55.0 °C, respectively. The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC 6H4ND2) are also reported for the same reactions. The obtained KIEs for 1 are secondary inverse (kH/k D=0.703-0.899H/kD=1.62-2.10> 1). A concerted mechanism involving predominantly backside nucleophilic attack is proposed for the anilinolysis of 1. A concerted mechanism involving predominantly frontside attack via a hydrogen-bonded four-center-type transition state is proposed for the anilinolysis of 2. The degree of steric hindrance is the major factor that determines both the reactivity of the phosphinates and the direction of the nucleophilic attack on the phosphinates. Copyright
- Dey, Nilay Kumar,Hoque, Md. Ehtesham Ul,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang
-
experimental part
p. 425 - 430
(2010/04/30)
-
- Synthesis of 3-alkoxymethylcoumarin from 3-cyanochromene via a novel intermediate 2-phenylimino-3-alkoxymethylchromene
-
(Chemical Equation Presented) In this paper a concise, efficient, and environmentally benign method for the synthesis of 3-alkoxymethylcoumarin is described. From the reaction of 3-cyanochromene with an alkoxide and arylamine in THF, (Z)-2-phenylimino-3-a
- Tsai, Jui-Chi,Li, Sie-Rong,Chiang, Michael Y.,Chen, Lian-Yeu,Chen, Po-Yuan,Lo, Yi-Fang,Wang, Chen-Hao,Lin, Chun-Nan,Wang, Eng-Chi
-
supporting information; experimental part
p. 8798 - 8801
(2010/03/01)
-
- An efficient and practical method for highly chemoselective hydrogenation of nitrobenzylamines to aminobenzylamine hydrochlorides
-
Aqueous hydrochloric acid proved to be a very reliable modulator for adjusting the reactivity of palladium on carbon. Thus an efficient and practical method for the highly chemoselective hydrogenation of N,N- dialkylnitrobenzylamines to amino-N,N-dialkylbenzylamine hydrochlorides was established. The method features convenient performance, easy work-up and high efficiency
- Cheng, Chuanjie,Wang, Xinyan,Xing, Lixin,Liu, Bo,Zhu, Rui,Hu, Yuefei
-
p. 1775 - 1780
(2008/02/11)
-
- Synthesis of primary amines by the electrophilic amination of Grignard reagents with 1,3-dioxolan-2-one O-sulfonyloxime
-
(Chemical equation presented) Primary amines are prepared by the electrophilic amination of Grignard reagents with 4,4,5,5-tetramethyl-1,3- dioxolan-2-one O-phenylsulfonyloxime and the acidic hydrolysis of the resulting imines.
- Kitamura, Mitsuru,Suga, Takahiro,Chiba, Shunsuke,Narasaka, Koichi
-
p. 4619 - 4621
(2007/10/03)
-
- NUCLEOPHILIC SUBSTITUTION REACTIONS OF CUMYL CHLORIDES IN METHANOL
-
Nucleophilic substitution reactions of cumyl chlorides with anilines in methanol have been investigated.Large negative ρY+ values in methanol and weak chloride common ion rate depression support a mechanism in which a preformed benzylic-type carbocation intermediate reacts with the solvent and the added nucleophile, aniline.All positive ρX (ρnuc) values observed and the estimated non-interactive point, ?Y+ = 0.72, strongly suggest that deprotonation of a mobile proton from the nucleophile occurs during the reaction.Fair linear correlation is exhibited for the plot of stability of carbocation, as expressed by the enthalpy of cation formation (AM1), and ?Y+, indicating that the thermodynamic driving force is nearly compensated for by the intrinsic barrier.
- Lee, Ikchoon,Koh, Han Joong,Hong, Sung Nam,Lee, Bon-Su
-
p. 347 - 352
(2007/10/02)
-
- New Methods and Reagents in Organic Synthesis. 60. A New Synthesis of Aromatic and Heteroaromatic Amines Using Diphenyl Phosphorazidate (DPPA)
-
Aromatic and heteroaromatic organometallics (Grignard and lihium compounds) reacts with diphenyl phosphorazidate (DPPA) to give labile phosphinyltriazenes.A study of the conversion of phosphinyltriazenes into amines has revealed that reductive work-up with aluminum hydride gives much better results than acidic or alkaline work-up.Sequential treatment of aromatic and heteroaromatic organometallics with DPPA, followed by aluminum hydride provides a convenient new method for the preparation of aromatic and heteroaromatic amines.Keywords - organometallic; aromatic halide; Grignard compound; organolithium compound; aromatic amine; heteroaromatic amine; phosphinyltriazene; hydride reduction; diphenyl phosphorazidate
- Mori, Shigehiro,Aoyama, Toyohiko,Shioiri, Takayuki
-
p. 1524 - 1530
(2007/10/02)
-
- Substituted-4-oxo-1,6,7,8-tetrahydro-4H-pyrido[1,2-a]pyrimidines
-
Nitrogen bridgehead compounds (pyrido-[1,2-a]-pyrimidine derivatives) which are useful intermediates in the making of known compounds of this class and which themselves possess PG-antagonist, analgesic, antiartheriosclerotic, tranquilizing and like pharmaceutical activity.
- -
-
-
