- Larvicidal activity and click synthesis of 2-alkoxyl-2-(1,2,3-triazole-1- yl)acetamide library
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Heterogeneous copper-in-charcoal-catalyzed click synthesis in 96-well polypropylene filter plates is an efficient method for the rapid generation of sufficient pure 2-alkoxyl-2-(1,2,3-triazole-1-yl) acetamide derivatives library by simple filtration, which directly assay the products for larvicidal activity against mosquitoes. In this procedure, copper nanoparticles on charcoal were arrayed into each well on a 96-well plate, reagents were delivered using a pipette gun, and a constant temperature shaker bath was used to complete the click reaction in 24-72 hours under temperature-controlled conditions. The results of bioassays indicated that the target compounds possessed excellent larvacidal activities against mosquitoes. In particular, the larvacidal activities against mosquitoes of compounds 8[2,3] and 8[7,1] at 2g.mL-1 were 100% and 73%, respectively.
- Su, Na-Na,Xiong, Li-Xia,Yu, Shu-Jing,Zhang, Xiao,Cui, Can,Li, Zheng-Ming,Zhao, Wei-Guang
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p. 484 - 493
(2013/07/28)
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- Reaction of methyl diazoacetate with aldehydes, amines, thiols, alcohols and acids over transition metal-exchanged clays
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Metal-exchanged clays (M = Rh and Cu) catalyze effectively the reaction of methyl diazoacetate with various aldehydes, affording the corresponding β-keto esters in high yields. They have also been effective in the decomposition of methyl diazoacetate to form metallocarbenes which, in turn, successfully insert into X-H (X = N, O, S, CO2) bonds of a variety of amines, aldehydes, thiols and acids, thereby producing the corresponding esters. The Royal Society of Chemistry 1999.
- Phukan, Prodeep,Mohan, Jakkam Madan,Sudalai, Arumugam
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p. 3685 - 3689
(2007/10/03)
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- Reactions of Carbenes with Oxetane and with Oxetane/ Methanol Mixtures
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Ethoxycarbonylcarbene, bis(methoxycarbonyl)carbene, phenylcarbene (17a), diphenylcarbene (17b), fluorenylidene (17c), 2-furylcarbene (31a), 2-furyl(phenyl)carbene (31b), 4-oxo-2,5-cyclohexadienylidene (40), and 4,4-dimethyl-2,5-cyclohexadienylidene (53) were generated by photolysis of the appropriate diazo compounds.With neat oxetane, most of these carbenes react by competitive C-H insertion (B -> A, Scheme 1) and ylide formation (B -> C). 31a and 40 do not insert into C-H bonds; 31b does not attack oxetane but rearranges exclusively with formation of 26.The ylides undergo Stevens rearrangement to give tetrahydrofurans (C -> D) and α',β-elimination, leading to allyl ethers (C -> E).With oxetane/ methanol mixtures, the intervention of oxonium ions (H) is indicated by the formation of 1,3-dialkoxypropanes (I).The oxonium ions arise either by protonation of the ylides (C -> H) or by protonation of the carbenes (B -> G), followed by electrophilic attack of the carbocations (G) at oxetane (G -> H).The former route is followed by the alkoxycarbonylcarbenes and by 40; the ylides derived from the remaining carbenes do not react with methanol, owing to their rapid Stevens rearrangements.Protonation of the carbenes 17b, 31, and 53 is clearly indicated by their product ratios and, for 31, by the formation of isomeric ethers (33, 36).The more electrophilic carbenes discriminate but slightly between oxetane and methanol while the more nucleophilic carbenes (17b, 31, 53) prefer the protic methanol strongly over the aprotic oxetane. Key Words: Carbenes/ Oxygen ylides/ Stevens rearrangement/ Oxonium ions/ Insertion, O-H/ Ylides
- Kirmse, Wolfgang,Lelgemann, Rudolf,Friedrich, Klaus
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p. 1853 - 1863
(2007/10/02)
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- OXYGEN YLIDES-I. REACTIONS OF CARBENES WITH OXETANE
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The ylides generated from carbenes (:CH2, :CHCO2Et, :CHPh) and oxetane in the presence of methanol undergo Stevens rearrangement and protonation competitively, yielding tetrahydrofurans and 1,3-dialkoxycyclopropanes as major products.
- Friedrich, Klaus,Jansen, Ulrich,Kirmse, Wolfgang
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p. 193 - 196
(2007/10/02)
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- 163. Reactions of Alkenediazonium Salts. Part 1. 2,2-Diethoxyethenediazonium Hexachloroantimonate: A Diazonium, a Carbenium or an Oxonium Salt?
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Reactions of the title compound 1 with various nucleophiles have been studied.The salt behaves like an alkylating agent towards ethers, alcohols and water forming ethyl diazoacetate (2), which reacts further with excess of the nucleophile.A solvent cage mechanism accounting for the observed products is proposed.Thermal decomposition in inert solvents leads to the alkylation of the counter-ion, i.e. formation of chloroethane, and in anisole, alkylation and chlorination of the solvent are also observed.With a standard coupling component, 2-naphtholate ion, no azo coupling reaction of 1 is observed, but instead 14-methyl-14H-dibenzoxanthene (17) is formed.The products of the reaction with diethylamine are diethylcyanoformamide (18) and ethyl diethylcarbamate (19).None of the chemistry of salt 1 is explained by the intervention of vinyl cations expected to be formed in a heterolytic dediazoniation.The predominant pathways seems to involve reactions of an oxonium salt (alkylating properties) or, in the case of diethylamine, a carbenium salt (primary nucleophilic attack on the β-C-atom of 1).The free energy barrier to C=C rotation in 1 is estimated to be 75 to 77 kJ/mol (18.0 to 18.5 kcal/mol), a value which falls between those expected for a double and a single bond.
- Szele, Ivanka,Tencer, Michal,Zollinger, Heinrich
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p. 1691 - 1703
(2007/10/02)
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- The Reactivity of Carbenes from Photolysis of Diazo-Compounds towards Carbon-Hydrogen Bonds. Effects of Structure, Temperature, and Matrix on the Insertion Selectivity
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Direct and/or sensitized photolyses of diazo-acetate (1a) and -malonate (1b) in hydrocarbons and ether were investigated at various temperatures in order to learn more about the nature of the C-H insertion process and the structural factors governing positional selectivity within the matrix.Photolysis of the diazo-compounds in a rigid matrix resulted in a marked decrease in the insertion selectivity, which may be interpreted as indicating that the matrix imposes severe steric demand especially on the direct C-H insertion process of the singlet carbene.The addition of a sensitizer in matrix photolysis causes a marked increase in the selectivity in the case of (1a), as is observed in the comparable liquid-phase experiment, but it causes a decrease in the case of (1b).This is interpreted as suggesting that the excited triplet (1b) itself is involved in C-H insertion under these conditions.More extensive temperature studies show that, as the temperature decreases, the C-H insertion selectivity of :CHCO2R decreases regularly regardless of the reaction phase, whereas that of :C(CO2R)2 increases in the liquid phase but decreases in the solid phase.This difference in the temperature dependence is explained by assuming that the singlet carbene is responsible for the C-H insertion of :CHCO2R throughout the temperature range studied, while both singlet and triplet are involved in the insertion of :C(CO2R)2.
- Tomioka, Hideo,Itoh, Masami,Yamakawa, Shyoji,Izawa, Yasuji
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p. 603 - 609
(2007/10/02)
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