- The first 4,4′-imidazolium-tagged C2-symmetric bis(oxazolines): Application in the asymmetric Henry reaction
-
Highly efficient and recyclable imidazolium-tagged bis(oxazolines), with an imidazolium tagged onto the 4,4′-position of the box, have been designed and prepared for the first time. They have been synthesized from dimethylmalonic acid and used as chiral l
- Tang, Li-Wei,Dong, Xiao,Zhou, Zhi-Ming,Liu, Ying-Qiang,Dai, Li,Zhang, Man
-
-
Read Online
- Nickel-Catalyzed Enantioselective Hydroboration of Vinylarenes
-
The enantioselective hydroboration of vinylarenes catalyzed by a chiral, nonracemic nickel catalyst is presented as a facile method for generating chiral benzylic boronate esters. Various vinylarenes react with bis(pinacolato)diboron (B2pin2) in the presence of MeOH as a hydride source to form chiral boronate esters in up to 92% yield with up to 94% ee. The use of anhydrous Me4NF to activate B2pin2 is crucial for ensuring fast transmetalation to achieve high enantioselectivities.
- Tran, Hai N.,Stanley, Levi M.
-
supporting information
p. 395 - 399
(2021/12/27)
-
- Nickel-Catalyzed Asymmetric Hydroarylation of Vinylarenes: Direct Enantioselective Synthesis of Chiral 1,1-Diarylethanes
-
The enantioselective hydroarylation of vinylarenes catalyzed by a chiral, non-racemic nickel catalyst is presented as a facile method to generate chiral 1,1-diarylethanes. These reactions proceed via formation of a chiral, non-racemic nickel benzyl intermediate. Transmetalation with arylboron nucleophiles and subsequent reductive elimination enable the formation of a variety of chiral 1,1-diarylethanes. The 1,1-diarylethane products from reactions of arylboronic acids containing electron-donating substituents are formed with typically greater than 90% ee, while the 1,1-diarylethanes generated from reactions of arylboronic acids containing electron-withdrawing groups are generated with typically less than 80% ee. These results are consistent with the rate of transmetalation with an arylboron nucleophile playing a key role in the enantioselectivity of these hydroarylation reactions. This mechanistic insight has led to the development of reactions of neo-pentylglycolate esters of arylboronic acids with vinylarenes that occur with higher enantioselectivities based on increased rates of transmetalation.
- Tran, Hai N.,Burgett, Russell W.,Stanley, Levi M.
-
p. 3836 - 3849
(2021/03/01)
-
- Synthesis of bis(benzoxazole) frameworks chiralized by planar chiral [2.2]Paracyclophane
-
In this study, a new class of chiral bis(benzoxazole) has been synthesized. The bis(benzoxazole) framework, which has an achiral structure was chiralized by a planar chiral [2.2]paracyclophane moiety. Both enantiomeric forms of the bis(benzoxazole) deriva
- Polat, Emrah,Turbedaroglu, Ozge,Cakici, Murat
-
-
- Formamide catalyzed activation of carboxylic acids-versatile and cost-efficient amidation and esterification
-
A novel, broadly applicable method for amide C-N and ester C-O bond formation is presented based on formylpyrrolidine (FPyr) as a Lewis base catalyst. Herein, trichlorotriazine (TCT), which is the most cost-efficient reagent for OH-group activation, was employed in amounts of ≤40 mol% with respect to the starting material (100 mol%). The new approach is distinguished by excellent cost-efficiency, waste-balance (E-factor down to 3) and scalability (up to >80 g). Moreover, high levels of functional group compatibility, which includes acid-labile acetals and silyl ethers, are demonstrated and even peptide C-N bonds can be formed. In comparison to reported amidation procedures using TCT, yields are considerably improved (for instance from 26 to 91%) and esterification is facilitated for the first time in synthetically useful yields. These significant enhancements are rationalized by activation by means of acid chlorides instead of less electrophilic acid anhydride intermediates.
- Huy, Peter H.,Mbouhom, Christelle
-
p. 7399 - 7406
(2019/08/20)
-
- Preparation and Characterisation of a Bis-μ-Hydroxo-NiIII 2 Complex
-
Hydroxide-bridged high-valent oxidants have been implicated as the active oxidants in methane monooxygenases and other oxidases that employ bimetallic clusters in their active site. To understand the properties of such species, bis-μ-hydroxo-NiII 2 complex (1) supported by a new dicarboxamidate ligand (N,N′-bis(2,6-dimethyl-phenyl)-2,2-dimethylmalonamide) was prepared. Complex 1 contained a diamond core made up of two NiII ions and two bridging hydroxide ligands. Titration of the 1 e? oxidant (NH4)2[CeIV(NO3)6] with 1 at ?45 °C showed the formation of the high-valent species 2 and 3, containing NiIINiIII and NiIII 2 diamond cores, respectively, maintaining the bis-μ-hydroxide core. Both complexes were characterised using electron paramagnetic resonance, X-ray absorption, and electronic absorption spectroscopies. Density functional theory computations supported the spectroscopic assignments. Oxidation reactivity studies showed that bis-μ-hydroxide-NiIII 2 3 was capable of oxidizing substrates at ?45 °C at rates greater than that of the most reactive bis-μ-oxo-NiIII complexes reported to date.
- Spedalotto, Giuseppe,Gericke, Robert,Lovisari, Marta,Farquhar, Erik R.,Twamley, Brendan,McDonald, Aidan R.
-
supporting information
p. 11983 - 11990
(2019/08/26)
-
- Electrochemical Formation of 3,5-Diimido-1,2-dithiolanes by Dehydrogenative Coupling
-
A synthetic approach to the cyclic disulfide moiety of 3,5-diimido-1,2-dithiolane derivatives starting with readily available precursors including the electrochemical coupling of dithioanilides is developed. The electrochemical key step provides sustainab
- Breising, Valentina M.,Gieshoff, Tile,Kehl, Anton,Kilian, Vincent,Schollmeyer, Dieter,Waldvogel, Siegfried R.
-
supporting information
p. 6785 - 6788
(2018/10/25)
-
- Synthesis and characterization of ferrocenyl esters: Their anti-oxidant activity and DNA-binding ability
-
In continuation to our work on biologically active material, some new ferrocenyl esters were prepared by condensation of 4-ferrocenyl phenol (ROH) with ferrocenyl dicarboxylic acid chlorides (DCC) at low temperature. The synthesized compounds (E1-E9) were characterized by analyzing their physical properties, FT-IR, 1H-NMR, UV-visible spectroscopic and cyclic voltammetric studies. The DPPH free radical scavenging assay was performed to explore their potential as antioxidant which showed that the E1 had maximum scavenging ability (77.11%) whereas E3 showed minimum (52%) compared with the standard. Cyclic voltammetric studies indicated that these compounds were electroactive in potential window of 2.0-0.0V. Binding mode found in these esters was an electrostatic interaction which is considered as strongest amongst all. Therefore, these compounds are considered to have DNA-binding capability and are potential DNA binders.
- Bukhari, Syeda Anam,Gul, Asghari,Akhter, Zareen,Bashir, Amna
-
p. 375 - 382
(2018/06/06)
-
- Amide-ligand-controlled highly para-selective arylation of monosubstituted simple arenes with arylboronic acids
-
Pd-catalyzed highly para-selective arylations of monosubstituted simple arenes with arylboronic acids to widely existed biaryls have been developed. Inspired by requisite amide-directing groups in reported selective oxidative couplings, amide ligands, especially DMF, are designed and found to be critical for the selectivity control in current arylations.
- Luan, Yu-Xin,Zhang, Tao,Yao, Wei-Wei,Lu, Ke,Kong, Lu-Yao,Lin, Yu-Tong,Ye, Mengchun
-
supporting information
p. 1786 - 1789
(2017/02/15)
-
- Access to Pyrazolidin-3,5-diones through Anodic N–N Bond Formation
-
Pyrazolidin-3,5-diones are important motifs in heterocyclic chemistry and are of high interest for pharmaceutical applications. In classic organic synthesis, the hydrazinic moiety is installed through condensation using the corresponding hydrazine building blocks. However, most N,N′-diaryl hydrazines are toxic and require upstream preparation owing to their low commercial availability. We present an alternative and sustainable synthetic approach to pyrazolidin-3,5-diones that employs readily accessible dianilides as precursors, which are anodically converted to furnish the N?N bond. The electroconversion is conducted in a simple undivided cell under constant-current conditions.
- Gieshoff, Tile,Schollmeyer, Dieter,Waldvogel, Siegfried R.
-
supporting information
p. 9437 - 9440
(2016/08/05)
-
- Substrate scope in the copper-mediated construction of bis-oxindoles via a double C-H/Ar-H coupling process
-
Abstract The synthesis of bis-oxindoles via the copper(II)-mediated double cyclisation of linear bis-anilides is described. Cu(OAc)2·H2O was identified as an efficient and inexpensive catalyst for this process. In contrast to previous methods, which rely on the synthesis of the central core from existing oxindole building blocks, this new approach focusses on concurrent formation of both oxindole rings from a simple linear precursor, allowing the formation of bis-oxindoles containing a diverse range of cyclic and acyclic linkers using a single synthetic method.
- Drouhin, Pauline,Hurst, Timothy E.,Whitwood, Adrian C.,Taylor, Richard J.K.
-
supporting information
p. 7124 - 7136
(2015/03/30)
-
- Copper-mediated construction of spirocyclic bis-oxindoles via a double C-H, Ar-H coupling process
-
A double C-H, Ar-H coupling process for the conversion of bis-anilides into spirocyclic bis-oxindoles, enabling the concomitant formation of two all-carbon quaternary centers at oxindole 3-positions in a diastereoselective manner, is described. The optimum cyclization conditions utilize stoichiometric Cu(OAc)2·H2O/KOtBu in DMF at 110 °C and have been applied to prepare a range of structurally diverse bis-spirooxindoles in fair to good yields (28-77%); the method has also been extended to prepare bis-oxindoles linked by a functionalized acyclic carbon chain.
- Drouhin, Pauline,Hurst, Timothy E.,Whitwood, Adrian C.,Taylor, Richard J.K.
-
supporting information
p. 4900 - 4903
(2015/04/27)
-
- Design of bisquinolinyl malonamides as Zn2+ ion-selective fluoroionophores based on the substituent effect
-
A series of malonamides possessing two quinoline moieties were synthesized and characterized as fluoroionophores for the Zn2+ ion. We focused on the relationship between the substituents introduced to the C2-position of the malonamides and their Zn2+ ion-selectivity, exploiting the structural effect of the substituents in the design of the fluoroionophores with high selectivity. The substituents introduced to the malonamides were the methyl, benzyl and naphthalenylmethyl groups. In dimethyl sulfoxide solvent, all substituted bisquinolinyl malonamides showed excellent fluorescence sensing for the Zn2+ ion, while unsubstituted bisquinolinyl malonamide 1 displayed ratiometric sensing for the Co2+ ion. N,N′-Bis(8-quinolyl)-2-methyl-2-naphthalenylmethyl malonamide 4 exhibited the highest Zn2+ ion-selectivity against the Cd2+ ion. Although the substituents introduced into the C2-position are spatially distant from the quinoline recognition moiety, this study indicated that they greatly influenced the ion selectivities of the bisquinolinyl malonamides. Furthermore, it was demonstrated that visible fluorescence analyses could be performed on malonamide 4.
- Moriuchi-Kawakami, Takayo,Kawata, Keita,Nakamura, Sho,Koyama, Yoshiaki,Shibutani, Yasuhiko
-
p. 9805 - 9813
(2015/01/09)
-
- NOVEL INSECTICIDES
-
Compounds of Formula I wherein the substituents are as defined in claim 1, and the agrochemically acceptable salts and all stereoisomers and tautomeric forms of the compounds of formula I can be used as agrochemical active ingredients and can be prepared
- -
-
Page/Page column 50
(2009/04/25)
-
- Enantioselective synthesis of the C8-C20 segment of curvicollide C
-
The enantioselective synthesis of the C8-C20 fragment of curvicollide C has been accomplished. A catalytic asymmetric Claisen rearrangement (CAC), a diastereoselective methyl cupration of an alkynoate, and a Julia-Kocienski olefination served as key C/C-connecting transformations.
- Koerner, Marleen,Hiersemann, Martin
-
p. 4979 - 4982
(2008/03/28)
-
- Chiral bis(amino alcohol)oxalamides as ligands for asymmetric catalysis. Ti(IV) catalyzed enantioselective addition of diethylzinc to aldehydes
-
Several chiral bis(aminoalcohol)oxalamides with C2-symmetry have been prepared and used as ligands for the enantioselective addition of diethylzinc to aromatic and aliphatic aldehydes. The reaction proceeds in the presence of titanium isopropoxide to give the corresponding (S)-alcohols with ee up to 78%. In the absence of Ti(IV), the alcohols with the opposite configuration are obtained.
- Blay, Gonzalo,Fernandez, Isabel,Marco-Aleixandre, Alicia,Pedro, Jose R.
-
p. 1207 - 1213
(2007/10/03)
-
- Novel potassium channel openers. Part 4: Transformation of the 1,4- benzoxazine skeleton into 1,4-benzothiazine, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroquinoxaline, indoline, and 1,5-benzoxazepine
-
As part of a search for a new potassium channel opener, the 1,4- benzoxazine skeleton derived from the benzopyran skeleton of cromakalim, was transformed into other fused rings such as 1,4-benzothiazine, 1,2,3,4- tetrahydroquinoline, 1,2,3,4-tetrahydroqui
- Matsumoto, Yuzo,Tsuzuki, Ryuji,Matsuhisa, Akira,Yoden, Toru,Yamagiwa, Yoko,Yanagisawa, Isao,Shibanuma, Tadao,Nohira, Hiroyuki
-
p. 393 - 404
(2007/10/03)
-
- Photochemical transformation of trithiobarbiturate into thiohydantoin and imidazolinothiophene derivatives
-
Upon irradiation of trithiobarbiturate (1), ring contraction reaction occurred to give thiohydantoin (2 or 3) and imidazolinothiophene (4) derivatives. Further, on treating with iodine, the thiohydantoins (2 and 3) undergo ring closure, giving imidazolino
- Takechi, Haruko,Takahashi, Hajime,Machida, Minoru
-
p. 159 - 168
(2007/10/03)
-
- Clemmensen reduction. XII The synthesis and acidolysis of some diaryl-substituted cyclopropane-1,2-diols. The possible involvement of a cyclopropyl cation
-
The generation of a number of 1,2-diarylcyclopropane-1,2-diols is reported. Reaction of these in situ with acid gives, primarily, an α,β-unsaturated ketone in which the aryl substituent attached to the double bond is that which is best able to stabilize a benzylic cation. It is proposed that the reaction proceeds by O-protonation of the cyclopropane- 1,2-diol, followed by loss of water and opening of the resulting cyclopropyl cation and final deprotonation. Such initial O-protonation contrasts with the C-protonation normally observed in the acidolysis of cyclopropanols and other dialkyl- and alkylaryl-cyclopropane-1,2-diols.
- Davis, Brian R.,Hinds, Mark G.
-
p. 309 - 319
(2007/10/03)
-
- Total Synthesis of Marine Sesquiterpenoids Containing a Primnatriene Skeleton
-
The concise synthesis of a group of five indane-based sesquiterpenoids, isolated from a marine origin, is reported. Carvacrol methyl ether was chosen as the starting point for the syntheses, and the primnatriene skeleton was produced by electrophilic aromatic substitution reactions.
- Lewis, Mark L.,De Meijere, Armin
-
p. 261 - 262
(2007/10/03)
-
- Synthesis, Antitumor Activity, and Chemical Properties of Silaplatin and Related Platinum(II) and Platinum(IV) Complexes Derived from β-Silyl Amines
-
Platinum(II) and platinum(IV) coordination complexes derived from β-silyl-substituted amines were prepared.The solubility of selected complexes in water and physiological saline was measured, and the effect of the β-silicon on the reactivity of the complex in aqueous solution was determined by HPLC.The stabilities of selected silyl complexes were compared to the carbon analogues.The cyclic complexes 2a ("silaplatin") and its Pt(IV) analogue, 2b, were very active against L1210 leukemia in vivo.Both the platinum(II) complex 2a and the platinum(IV) complex 2b produced a significant number of cures over the dose range 10-40 mg/kg.The platinum(II) complex 2a, silaplatin, was very active in vivo against an L1210 leukemia subline that was resistant to cisplatin; 2a was also active, when given ip against ic implanted L1210.The cyclobutanedicarboxylic acid complex 3c was synthesized; this complex was active against both cisplatin sensistive and resistant L1210 leukemia but was less potent than the analogous dichloro compound 2a.The acyclic platinum(II) and platinum(IV) complexes 1a,b were synthesized and unexpectedly found to be inactive in vivo against L1210 leukemia.More lipophilic silaplatin analogues were prepared-Pt(II) complex 2c and Pt(IV) complex 2d have one additional methylene carbon compared to 2a,b, whereas Pt(II) complex 2e and Pt(IV) complex 2f have two additional methylene carbons.Cyclization of the alkyl groups attached to the silicon gave the spiro bicyclic Pt(II) complexes 10a and 11a and the Pt(IV) complexes 10 b and 11b.
- Anderson, Wayne K.,Kasliwal, Ravindra,Houston, D. Michael,Wang, Yueh-sha,Narayanan, Ven L.,et al.
-
p. 3789 - 3797
(2007/10/03)
-
- Photochemistry of nonconjugated diketones: internal self-quenching and energy transfer
-
The triplet state behavior of nine α,ο-dibenzoylalkanes indicates the occurrence of a rapid quenching interaction between the two carbonyl groups.This quenching is fastest (k=3E7 s-1) in dibenzoylbutane, is slightly slower (ca.E7 s-1) in dibenzoylethane, dibenzoylpentane, and 2,2-dibenzoylpropane, but is absent in 1,3-dibenzoylpropane.It also occurs in several "mixed" 1,4-diaroylbutanes incorporating p-ethylbenzoyl or p-methoxybenzoyl chromophores.This internal self-quenching is interpreted as the intramolecular counterpart of the well-know bimolecular self-quenching of aryl ketones, although no exact mechanism can be proposed.Such internal quenching does not occur as rapidly, if at all, in three "turned around" diketones: δ-(p-acetylphenyl)valerophenone, δ-(p-acetylphenoxy)valerophenone, and γ-(p-acetylphenoxy)butyrophenone.This fact, together with the varying rates of internal self-quenching in the dibenzoylalkanes, indicates the necessity for a very specific and close orientation of the two carbonyl groups for self-quenching.In the mixed diketones containing a p-alkylbenzoyl group, triplet excitation appears to be fully equilibrated between the two chromophores.However, in those containing a p-methoxybenzoyl group, excitation does not fully equilibrate before triplet decay, as evidenced by different quenching efficiencies for products from the two carbonyls.Analysis indicates intramolecular energy transfer rate constants -1.These are sufficiently lower than in other bichromophoric systems to suggest relatively slow energy hopping in the polymers of phenyl vinyl ketone.Key words: nonconjugated diketones, dibenzoylalkanes, sefl-quenching, energy transfer, triplet ketones.
- Wagner, Peter J.,Frerking, Harlan W. Jr.
-
p. 2047 - 2061
(2007/10/03)
-
- o-Naphthoquinodimethanes and o-Phenanthroquinodimethanes. Isoindene-Related Species
-
Three isoindene-related naphthoquinodimethane and phenanthroquinodimethane species were synthesized and trapped with 4-phenyl-1,2,4-triazoline-3,5-dione.They are 2,2-dimethyl-2H-benzindene (3), 2,2-dimethyl-2H-benzindene (4), and 2,2-dimethyl-9H-cyclopentaphenanthrene (10).Compound 3 could be isolated and characterized by 1H NMR.The effect of solvent on the bisacylation of naphthalene and phenanthrene by dimethylmalonyl chloride is discussed.Also the use of the Vilsmeier reagent generated from PBr3/DMF if highly recommended as a general reagent for conversion of alcohols to alkyl bromides.
- Dolbier, William R.,Dulcere, Jean-Pierre,Sellers, Simon F.,Koroniak, Henryk,Shatkin, Blane T.,Clark, Thomas L.
-
p. 2298 - 2303
(2007/10/02)
-
- Cholestano-cobaloximes and Cholestano-rhodoximes. Synthesis, Characterisation, and Rearrangement of Model Compounds for the Active Site of Methylmalonyl-CoA Mutase
-
Cholestano-cobaloximes and cholestano-rhodoximes, three diastereoisomers of each constitution, were synthesised from cholestane-2,3-dione dioxime (3).The diastereoisomeric complexes were separated and characterised by their spectra.One of the axial ligands was invariably pyridine, the other either chlor (9), methyl (10), 2,2-bis(methoxycarbonyl)propyl (11), 2,2-bis(benzyloxycarbonyl)propyl (12), or 2,2-bis(2-naphthylmethoxycarbonyl)propyl (13 and 14).Irradiation of the complexes 11, 12, 13, and 14 in ethanol or 2-propanol afforded, apart from dimethylmalonic diester, other products among which was the corresponding methylsuccinic diester in yields of approx. 1, 20, 23, and 13percent, respectively.The methylsuccinic acid bis(2-naphthylmethyl ester) obtained from the irradiation of the diastereoisomeric cholestano-cobaloximes 13a, b and c was found to be practically racemic.
- Fountoulakis, Michael,Retey, Janos
-
p. 650 - 668
(2007/10/02)
-
