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Visible-light-mediated phosphonylation reaction: formation of phosphonates from alkyl/arylhydrazines and trialkylphosphites using zinc phthalocyanine
In this work, we developed a ligand- and base-free visible-light-mediated protocol for the photoredox syntheses of arylphosphonates and, for the first time, alkyl phosphonates. Zinc phthalocyanine-photocatalyzed Csp2-P and Csp3-P bond formations were efficiently achieved by reacting aryl/alkylhydrazines with trialkylphosphites in the presence of air serving as an abundant oxidant. The reaction conditions tolerated a wide variety of functional groups.
Hosseini-Sarvari, Mona,Koohgard, Mehdi
supporting information
p. 5905 - 5911
(2021/07/12)

Chemoselective and Site-Selective Reductions Catalyzed by a Supramolecular Host and a Pyridine-Borane Cofactor
Supramolecular catalysts emulate the mechanism of enzymes to achieve large rate accelerations and precise selectivity under mild and aqueous conditions. While significant strides have been made in the supramolecular host-promoted synthesis of small molecules, applications of this reactivity to chemoselective and site-selective modification of complex biomolecules remain virtually unexplored. We report here a supramolecular system where coencapsulation of pyridine-borane with a variety of molecules including enones, ketones, aldehydes, oximes, hydrazones, and imines effects efficient reductions under basic aqueous conditions. Upon subjecting unprotected lysine to the host-mediated reductive amination conditions, we observed excellent ?-selectivity, indicating that differential guest binding within the same molecule is possible without sacrificing reactivity. Inspired by the post-translational modification of complex biomolecules by enzymatic systems, we then applied this supramolecular reaction to the site-selective labeling of a single lysine residue in an 11-amino acid peptide chain and human insulin.
Morimoto, Mariko,Cao, Wendy,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
supporting information
p. 2108 - 2114
(2021/02/06)

N-Amino-1,8-Naphthalimide is a Regenerated Protecting Group for Selective Synthesis of Mono-N-Substituted Hydrazines and Hydrazides
A new route to synthesis of various mono-N-substituted hydrazines and hydrazides by involving in a new C?N bond formation by using N-amino-1,8-naphthalimide as a regenerated precursor was invented. Aniline and phenylhydrazines are reproduced upon reacting these individually with 1,8-naphthalic anhydride followed by hydrazinolysis. The practicality and simplicity of this C?N dihalo alkanes; developed a synthon for bond formation protocol was exemplified to various hydrazines and hydrazides. N-amino-1,8-naphthalimide is suitable synthon for transformation for selective formation of mono-substituted hydrazine and hydrazide derivatives. Those are selective mono-amidation of hydrazine with acid halides; mono-N-substituted hydrazones from aldehydes; synthesis of N-aminoazacycloalkanes from acetohydrazide scaffold and inserted to hydroxy derivatives; distinct synthesis of N,N-dibenzylhydrazines and N-benzylhydrazines from benzyl halides; synthesis of N-amino-amino acids from α-halo esters. Ecofriendly reagent N-amino-1,8-naphthalimide was regenerated with good yields by the hydrazinolysis in all procedures.
Manoj Kumar, Mesram,Venkataramana, Parikibanda,Yadagiri Swamy, Parikibanda,Chityala, Yadaiah
supporting information
p. 17713 - 17721
(2021/11/10)

Discovery, synthesis and characterization of a series of (1-alkyl-3-methyl-1H-pyrazol-5-yl)-2-(5-aryl-2H-tetrazol-2-yl)acetamides as novel GIRK1/2 potassium channel activators
The present study describes the discovery and characterization of a series of 5-aryl-2H-tetrazol-3-ylacetamides as G protein-gated inwardly-rectifying potassium (GIRK) channels activators. Working from an initial hit discovered during a high-throughput screening campaign, we identified a tetrazole scaffold that shifts away from the previously reported urea-based scaffolds while remaining effective GIRK1/2 channel activators. In addition, we evaluated the compounds in Tier 1 DMPK assays and have identified a (3-methyl-1H-pyrazol-1-yl)tetrahydrothiophene-1,1-dioxide head group that imparts interesting and unexpected microsomal stability compared to previously-reported pyrazole head groups.
Sharma, Swagat,Kozek, Krystian A.,Abney, Kristopher K.,Kumar, Sushil,Gautam, Nagsen,Alnouti, Yazen,David Weaver,Hopkins, Corey R.
p. 791 - 796
(2019/02/06)

Lewis Acid Catalyzed Annulation of Cyclopropane Carbaldehydes and Aryl Hydrazines: Construction of Tetrahydropyridazines and Application Toward a One-Pot Synthesis of Hexahydropyrrolo[1,2- b]pyridazines
In this report, a facile synthesis of tetrahydropyridazines via a Lewis acid catalyzed annulation reaction of cyclopropane carbaldehydes and aryl hydrazines has been demonstrated. Moreover, the generated tetrahydropyridazine further participated in a cycloaddition reaction with donor-acceptor cyclopropanes to furnish hexahydropyrrolo[1,2-b]pyridazines. We also performed these two steps in one pot in a consecutive manner. In addition, a monodecarboxylation reaction of hexahydropyrrolo[1,2-b]pyridazine was achieved with a good yield.
Dey, Raghunath,Kumar, Pankaj,Banerjee, Prabal
p. 5438 - 5449
(2018/05/28)

Metal-Free Synthesis of 1,3,4-Oxadiazoles from N′-(Arylmethyl)hydrazides or 1-(Arylmethyl)-2-(arylmethylene)hydrazines
An efficient and versatile metal-free synthesis of 1,3,4-oxadiazoles from N′-(arylmethyl)hydrazides or 1-(arylmethyl)-2-(arylmethylene)hydrazines through oxidative dehydrogenation is reported. A range of 2,5-disubstituted 1,3,4-oxadiazoles were prepared by treating N′-(arylmethyl)hydrazides with (diacetoxyiodo)benzene in acetonitrile or by treating 1-(arylmethyl)-2-(arylmethylene)hydrazines with [bis(trifluoroacetoxy)iodo]benzene in methyl tert-butyl ether. Aldehyde N-acylhydrazones and aldazines were initially generated in situ as intermediates.
Shang, Zhenhua,Chu, Qianqian,Tan, Sheng
supporting information
p. 1032 - 1040
(2015/03/30)

Synthesis and bioactivity study of 2-acylamino-substituted N'-benzylbenzohydrazide derivatives
The discovery of new safe and effective pesticides is one of the main means of providing eco-friendly agricultural agents for modern crop protection. To identify new biological molecules based of the anthranilic diamide skeleton of the novel pesticide chlorantraniliprole, which acts on the ryanodine receptor and functional groups in acyl hydrazine insect growth regulators, more than 40 new compounds of 2-acylamino-substituted N'-benzylbenzohydrazide derivatives were designed and synthesized. The structures of the new compounds were characterized using 1H nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), or electron impact mass spectrometry (EI-MS), and their biological activities at a concentration of 600 mg L -1 were determined against cotton aphid (Aphis gossypii Glover), carmine spider mite (Tetranychus cinnabarinus), and diamondback moth (Plutella xylostella). The results of a preliminary assay showed that compounds 6a-I-2 and 6d-III-4 maintained the lethal activity of anthranilic diamide against P. xylostella; compounds 6c-II-4, 6d-I-7, 6d-II-1, and 6d-III-5 exhibited good lethal activity against A. gossypii; and compounds 6a-II-1, 6a-III-1, 6b-I-7, 6c-I-1, and 6c-III-5 retained promising larvicidal activities against T. cinnabarinus. In subsequent further tests against T. cinnabarinus, compounds 6a-II-1, 6a-III-1, 6c-I-1, and 6c-III-5 showed an LC50 value of -1; especially, the LC50 of compound 6a-III-1 was only 27.9 mg L-1. In conclusion, the introduction of the functional fragment-substituted acyl hydrazine improved the acaricidal activity of the anthranilic diamide skeleton, and the halogen atom at X position and the methyl group at R1 play crucial roles in the biological activities of the compounds.
Ou, Junjun,Zhu, Xiaokun,Wang, Lei,Xu, Chuan,Liu, Feng,Ren, Long,Xu, Xibao,Wang, Yi,Rui, Changhui,Liu, Shangzhong
p. 10942 - 10951
(2013/01/15)

N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
Romanov-Michailidis, Fedor,Besnard, Celine,Alexakis, Alexandre
supporting information
p. 4906 - 4909,4
(2012/12/12)

N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
Romanov-Michailidis, Fedor,Besnard, Céline,Alexakis, Alexandre
supporting information
p. 4906 - 4909
(2013/01/15)

Liquid ammonia as a dipolar aprotic solvent for aliphatic nucleophilic substitution reactions
The rate constants for the reactions of a variety of nucleophiles reacting with substituted benzyl chlorides in liquid ammonia (LNH3) have been determined. To fully interpret the associated linear free-energy relationships, the ionization constants of phenols ions in liquid ammonia were obtained using UV spectra. These equilibrium constants are the product of those for ion-pair formation and dissociation to the free ions, which can be separated by evaluating the effect of added ammonium ions. There is a linear relationship between the pKa of phenols in liquid ammonia and those in water of slope 1.68. Aminium ions exist in their unprotonated free base form in liquid ammonia and their ionization constants could not be determined by NMR. The rates of solvolysis of substituted benzyl chlorides in liquid ammonia at 25 °C show a Hammett ρ of zero, having little or no dependence upon ring substituents, which is in stark contrast with the hydrolysis rates of substituted benzyl halides in water, which vary 107 fold. The rate of substitution of benzyl chloride by substituted phenoxide ions is first order in the concentration of the nucleophile indicative of a SN2 process, and the dependence of the rate constants on the pKa of the phenol in liquid ammonia generates a Bronsted βnuc = 0.40. Contrary to the solvolysis reaction, the reaction of phenoxide ion with 4-substituted benzyl chlorides gives a Hammett ρ = 1.1, excluding the 4-methoxy derivative, which shows the normal positive deviation. The second order rate constants for the substitution of benzyl chlorides by neutral and anionic amines show a single Bronsted βnuc = 0.21 (based on the aqueous pKa of amine), but their dependence on the substituent in substituted benzyl chlorides varies with a Hammett ρ of 0 for neutral amines, similar to that seen for solvolysis, whereas that for amine anions is 0.93, similar to that seen for phenoxide ion.(Figure Presented)
Ji, Pengju,Atherton, John,Page, Michael I.
scheme or table
p. 1425 - 1435
(2011/04/23)

Structure-activity relationship and improved hydrolytic stability of pyrazole derivatives that are allosteric inhibitors of West Nile Virus NS2B-NS3 proteinase
West Nile Virus (WNV) is a potentially deadly mosquito-borne flavivirus which has spread rapidly throughout the world. Currently there is no effective vaccine against flaviviral infections. We previously reported the identification of pyrazole ester derivatives as allosteric inhibitors of WNV NS2B-NS3 proteinase. These compounds degrade rapidly in pH 8 buffer with a half life of 1-2 h. We now report the design, synthesis and in vitro evaluation of pyrazole derivatives that are inhibitors of WNV NS2B-NS3 proteinase with greatly improved stability in the assay medium.
Sidique, Shyama,Shiryaev, Sergey A.,Ratnikov, Boris I.,Herath, Ananda,Su, Ying,Strongin, Alex Y.,Cosford, Nicholas D.P.
scheme or table
p. 5773 - 5777
(2010/04/30)

COMPOUNDS AND METHODS FOR TREATING ZINC MATRIX METALLOPROTEASE DEPENDENT DISEASES
The present invention provides compounds and methods for treating zinc matrix metalloprotease dependent diseases. In certain embodiments, the compounds of the present invention have the following formulas:
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Page/Page column 64

(2009/05/29)

Pyrazolones as inhibitors of 11B-hydroxysteroid dehydrogenase
Provided herein are compounds of the formula (I): as well as pharmaceutically acceptable salts thereof, wherein the substituents are as those disclosed in the specification. These compounds, and the pharmaceutical compositions containing them, are useful for the treatment of diseases such as, for example, type II diabetes mellitus and metabolic syndrome.
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Page/Page column 25

(2008/06/13)

Tetrahydrothiopyrano pyrazole cannabinoid modulators
The invention relates to a CB modulator compound of Formula (I) or a pharmaceutically acceptable form thereof and a method for use in treating, ameliorating or preventing a CB receptor mediated syndrome, disorder or disease.
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Page/Page column 46

(2008/06/13)

Novel route to N-alkyl- and N,N′-dialkylhydrazines by high-pressure alkylation of azines
Reactions of alkyl halides with azines of p-nitrobenzaldehyde, benzaldehyde, and p-methoxybenzaldehyde at a high pressure (10 kbar) were studied. Hydrolysis of the reaction mixtures gives pure N-monoalkyl- or N,N′-dialkylhydrazines in high yields, depending on the structure of the starting azine and the solvent nature. It was found that non-symmetrical N,N′-dialkylhydrazines can be synthesized without isolating intermediate N-monoquaternary immonium salts. The effect of the phase transition of the solvent on the direction of the alkylation is discussed.
Agafonov,Dudin,Preobrazhenskii
p. 714 - 716
(2007/10/03)

The synthesis of azapeptidomimetic beta-lactam molecules as potential protease inhibitors.
Synthetic methods for the construction of a novel peptidomimetic structure are reported. The structure incorporates a beta-lactam and an azapeptide in a peptide backbone with the intention of generating rationally designed substrate-based protease inhibitors. The beta-lactam is formed by subjecting serine or threonine-azapeptides to Mitsunobu reaction conditions. Importantly, the azapeptidomimetic beta-lactam structure permits extended binding inhibition and the synthetic methods to create tetrapeptidomimetic structures are described.
Malachowski, William P,Tie, Chenyang,Wang, Katherine,Broadrup, Robert L
p. 8962 - 8969
(2007/10/03)

1,3-Dipolar cycloreversion of a 1,3,4-oxadiazolidine as a controlled azomethine imine surrogate for pyrazolidine synthesis
Azomethine imines were generated in a controlled manner through a thermally allowed 1,3-dipolar cycloreversion of 1,3,4-oxadiazolidines and subsequently trapped with dipolarophiles. This method results in the construction of the pyrazolidine heterocycles. A new method for the selective formation of the key semicarbazide substrate, from benzylidene hydrazone, is also disclosed.
Khau, Vien V.,Martinelli, Michael J.
p. 4323 - 4326
(2007/10/03)

Mechanisms of benzyl group transfer in the decay of (E)-arylmethanediazoates and aryldiazomethanes in aqueous solutions
Rate constants are reported for the buffer-independent decay of ten (E)-arylmethanediazoates in aqueous media at 25 °C, ionic strength 1 M (NaClO4), 4% 2-propanol, in the region of pH 4-12. The rate constants are proportional to hydrogen ion concentration at high pH and become pH independent in the low-pH region. Varying concentrations of oxyanion, amine, and hydrazine buffers over the range 0.05-0.2 M increased the pseudo-first-order rate constant for decay of the diazoates by less than 10%. The azide - water selectivities, ka/ks, for partitioning of the benzyl groups in the decay of (E)-(3,5-bis(trifluoromethyl)phenyl)methanediazoate and the (3,5-bis(trifluoromethyl)phenyl)diazomethane are determined to be 0.20 and 0.21 M-1, respectively, in phosphate buffered water and 0.27 and 0.26 M-1, respectively, in 20/80 DMSO-water. It is concluded that these two reactants decompose, in these media, via a common free diazonium ion intermediate that is formed in the case of the diazoate upon unassisted N-O bond cleavage of the diazoic acid. A common rate-limiting step is indicated for all the diazoates by the correlation line for the plot of log k1, the pH independent rate constant, against σ that has a slope q = -1.23. Product ratios for trapping of benzyl groups derived from other pairs of arylmethanediazoates and aryldiazomethanes with less electron withdrawing groups are different outside experimental error, indicating the importance of different nitrogen-separated ion pairs in these reactions. The (E)-(p-methoxy)phenyl)methane-16O-diazoate decomposes in 16O/18O water to give alcohol that has an "excess" abundance of 16O compared to solvent. Decomposition of the same compound in 50/50 trifluoroethanol-water with varying concentrations of azide indicates that azide ion appears to trap a limiting amount, ～80%, of the p-methoxybenzyl group. Quantitative analysis of the data indicates that 16% of the p-methoxybenzyl cation is trapped by solvent at the nitrogen-separated ion pair stage, in the absence of azide ion. There is a 9-fold enhancement of selectivity for trifluoroethanol at the ion pair stage that is ascribed to a proton switch initiated by the leaving hydroxide ion in the ion pair. The values of Ka/ks ～ 0.2 M-1 and kT/kH ～ 0.5-0.6 for the trifluoroethanol-water selectivity and kET/kT ～ 1 for the ethanol-trifluoroethanol selectivity are independent of substituent in the decay of arylmethanediazoates (X = H and EWG) in water, water-trifluoroethanol (50/50), and water-trifluoroethanol-ethanol (50/40/10), respectively. It is concluded from this that the productdetermining steps do not involve chemical bonding but rather rotational/translational reorientation of the nucleophiles in the first solvation sphere of the carbocation intermediates. It is concluded that the values of kH/kT = 0.5-0.6 indicate preferential solvation of the cation precursor by trifluoroethanol. It is shown that a preferential interaction for trifluoroethanol of 1 kcal/mol is required to generate the observed selectivities.
Finneman, Jari I.,Fishbein, James C.
p. 4228 - 4239
(2007/10/02)

N-NITRENES. II. INVESTIGATION OF THE MECHANISM OF DISSOCIATION OF DIBENZYLAMINONITRENE BY CHEMICALLY INDUCED POLARIZATION OF 1H NUCLEI. THE SPIN STATE OF DIBENZYLAMINONITRENE
The mechanism of the dissociation of dibenzylaminonitrene and p-bromodibenzylaminonitrene into molecular nitrogen and hydrocarbon products was studied.Dibenzylaminonitrene forms dibenzyl and o- and p-benzyltoluenes.In the presence of thiophenol significant amounts of toluene are formed.During dissociation p-bromodibenzylaminonitrene gives a mixture of symmetrical and unsymmetrical dibenzyls.In the presence of octanethiol only unsymmetrical p-bromodibenzyl is formed.The dissociation of dibenzylaminonitrene takes place by synchronous cleavage of the two C-N bonds and the formation of a pair of benzyl radicals.Dibenzylaminonitrene dissociates from the singlet electronic state.
Savin, V. I.
p. 15 - 25
(2007/10/02)

N-NITRENES. I. FORMATION OF FREE RADICALS IN THE DISSOCIATION OF DIBENZYLAMINONITRENE
By ESR with spin traps it was shown that the dissociation of dibenzylaminonitrene to nitrogen and bibenzyl takes place through the formation of benzyl radicals.Various methods of generation of dibenzylaminonitrene in the presence of spin traps (2-methyl-2-nitrosopropane, nitrosodurene, phenyl-N-tert-butyl-nitrone) give spin adducts (nitroxyl radicals) stable at room temperature.The formation of two nitroxyl radicals during the dissociation of dibenzylaminonitrene labeled at one methylene group with deuterium imdicates that one molecule of dibenzylaminonitrene gives two benzyl radicals during dissociation.
Savin, V. I.,Morozov, V. I.,Kitaev, Yu. P.
p. 866 - 870
(2007/10/02)

Reactions of N-Aminophthalimide With Electrophiles. II. Preparation and Properties of Araldehyde Hydrazones
N-Aminophthalimide (I) reacted with a variety of aromatic aldehydes to give the related arylideneaminophthalimides (III-X), although typical ketones such as acetone and benzophenone did not under the specific conditions employed.Catalytic reduction of benzylideneaminophthalimide (III) led to N-benzylaminophthalimide (XI), a stable acid-free precursor of benzylhydrazine.
Hearn, Michael J.,Lucero, Elena R.
p. 1537 - 1539
(2007/10/02)

Pyrazol-4-acetic acid compounds
Pyrazol-4-acetic acid compounds, such as substituted pyrazol-4-acetic acid, its esters, amides, nitriles and their pharamaceutically acceptable salts and method for the preparation of these compounds are disclosed. The novel compounds are useful analgesics, anti-inflammatory, and antipyretics.
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(2008/06/13)