An unusual reaction of azide with nitroolefins

The reaction of sodium azide in DMSO with 9-dinitromethylenefluorene (DNF) and 9-bromonitromethylenefluorene (BNF) results in the formation of N-cyano-9-iminofluorene ($\text{2}$). The overall reaction time is two minutes at room temperature.     

An efficient electrochemical method for the synthesis of methylene blue

An efficient and one-pot electrochemical method for the synthesis of methylene blue based on the Michael-type reaction of electrochemically generated quinone-diimine derived from oxidation of N,N-dimethyl-p-phenylenediamine in the presence of sodium sulfide as nucleophile in aqueous solution via EC-ECECC mechanism is reported.     

Gas-phase reaction of NO3 radicals with isoprene: a kinetic and mechanistic study

The gas-phase reaction of NO₃ radicals with isoprene was investigated under flow conditions at 298 K in the pressure range 6.8<P(mbar)<100 using GC-MS/FID, direct MS, and long-path FT–IR spectroscopy as detection techniques. By means of a relative rate method, the rate constant for the primary attack of NO₃ radicals toward isoprene was determined to be (6.86±2.60)×10⁻¹³ cm³ molecule⁻¹ s⁻¹. The formation of the possible oxiranes, 2-methyl-2-vinyl-oxirane and 2-(1-methyl-vinyl)-oxirane, was observed in dependence on total pressure. In the presence of O₂ in the carrier gas, the product distribution was found to be strongly dependent on the reaction pathways of formed peroxy radicals. If the peroxy radicals mainly reacted in a self-reaction, the formation of organic nitrates was detected and 4-nitroxy-3-methyl-but-2-enal was identified as a main product. On the other hand, when NO was added to the gas mixture and the peroxy radicals were converted via RO₂+NO→RO+NO₂, the formation of methyl vinyl ketone as the main product as well as 3-methylfuran and meth-acrolein was observed. From the ratio of the product yields if NO was added to the gas mixture it was concluded that the attack of NO₃ radicals predominantly takes place in the 1-position. A reaction mechanism is proposed and the application of these results to the troposphere are discussed. © 1997 John Wiley & Sons, Inc.     

An electrochiroptical molecular switch: mechanistic and kinetic studies

Previously, we reported the synthesis and preliminary characterization of Cu(I/II) complexes of N,N-bis(2-quinilylmethyl)-(l)-methionine (Zahn, S.; Canary, J. W. Science 2000, 288, 1404-7). The chemically oxidized and reduced forms of the complexes gave nearly mirror image circular dichroism (CD) spectra as a result of reorganization of the inner coordination sphere of the copper atom. The reorganization involved exchange of oxygen for sulfur in proceeding from the Cu(II) to Cu(I) oxidation state and corresponding ligand conformational changes required to accommodate this exchange. In this paper, we demonstrate that the complex can be triggered by electrochemical means. The electrochemical and stereochemical details of the redox-induced ligand reorganization were probed by independent synthesis of alternative chemical intermediates, CD spectroelectrochemistry, curve fitting of cyclic voltammograms, CD titration, and scanning electrochemical microscopy (SECM). A square-type mechanism was most consistent with the data: the Cu(II) complex is reduced followed by a ligand reorganization step to give the stable reduced form of the complex. The Cu(I) complex is then oxidized in a fast step followed by another ligand reorganization. A millisecond time scale rate was found by SECM for one of the key conformational conversion steps.     

An efficient synthesis of chalcones based on the Suzuki reaction

A general method for the synthesis of chalcones based on the Suzuki reaction either between cinnamoyl chlorides and phenylboronic acids or between benzoyl chlorides and phenylvinylboronic acids is described.     

Zn nanosheets:An earth-abundant metallic catalyst for efficient electrochemical ammonia synthesis

Ammonia(NH₃),a critical raw material for various industrial chemicals,is also recognized as a clean and efficient energy carrier for the future energy economy[1].However,the industrial-scale production of NH₃ strongly relies on the Haber-Bosch process,which involves massive fuel consumption and enormous greenhouse gas emissions[2].Therefore,there is an urgent need to develop sustainable and energy-saving alternative routes for artificial NH3 production.     

An efficient and improved procedure for preparation of triflyl azide and application in catalytic diazotransfer reaction

An efficient and improved procedure for preparation of triflyl azide and application in catalytic diazotransfer reaction are described. The amount of highly toxic reagents NaN₃ and Tf₂O, is significantly reduced comparing with the previous protocol.     

An efficient synthesis of dihydro- and tetrahydropyrans via oxonium-ene cyclization reaction

An efficient method has been developed for the synthesis of 2,3-dihydropyrans and 4-methylenetetrahydropyrans from aldehydes and substituted homoallyl alcohols in benzene mediated by boron trifluoride etherate in good yields. The reaction proceeds via oxonium-ene reaction.     

The structure of the ion: An ion kinetic energy spectrometry study

The kinetic energy release (T) values for the loss of CO from ions from five compounds have been obtained and are consistent with at least two different structures for the ion. This result is supported by the T value obtained for the decomposition of the molecular ions.     

Catalyst-free aromatic nucleophilic substitution of meso-bromoporphyrins with azide anion: efficient synthesis and structural analyses of meso-azidoporphyrins

meso-Mono- or diazidoporphyrins were readily obtained in high yields by the catalyst-free aromatic nucleophilic reaction of the corresponding bromoporphyrins with azide anions under mild conditions. The molecular structures of the obtained azides were unambiguously determined by X-ray crystallographic analysis.     

Reaction of allenyl esters with sodium azide: an efficient synthesis of e-vinyl azides and polysubstituted pyrroles

The nucleophilic addition of sodium azide to 1,2-allenyl esters can generate vinyl azides in excellent yields with excellent regio- and stereoselectivities. Moreover, pyrroles are synthesized using 1-allyllic 1,2-allenyl esters as substrates in t-BuOH at 65 degrees C. The sequential reaction for pyrroles is developed on the basis of a novel domino process involving nucleophilic addition, cycloaddition, denitrogenation, and aromatization.     

Gas-phase pyrolytic reaction of 3-anilino-1-propanol derivatives: kinetic and mechanistic study

3-Anilino-1-propanol derivatives 4a-c, 5a-c, 6a-c containing primary, secondary, and tertiary alcohols and PhNH, PhNMe, and (Ph)₂N were prepared and subjected to gas-phase pyrolysis in a static reaction system. The pyrolytic reactions were homogeneous and followed a first-order rate equation. Reactions took place by retro-ene process, with the exception of compounds 5a and 5b. Analysis of the pyrolysate showed the products to be N-substituted aniline and carbonyl compounds. The kinetic results and product analysis of each of the nine investigated 3-amino alcohols are rationalized in terms of a plausible transition state for the elimination pathway.     

An ultrafast study of phenyl azide: the direct observation of phenylnitrenium ion

Ultrafast photolysis (lambda(ex) = 308 nm) of phenyl azide in 100% formic acid produces a broadly absorbing transient within the instrument time resolution (300 fs), which is assigned to an excited state of the azide. The azide excited state fragments within 300 fs to form singlet phenylnitrene. The decay of the nitrene (tau = 12.0 ps) produces a new species with absorption centered at 500 nm, which is assigned to phenylnitrenium ion. The lifetime of phenylnitrenium ion is 110 ps in 100% formic acid. This is the first spectroscopic observation of phenylnitrenium ion.     

An efficient glycosylation reaction for the synthesis of asialo GM2 analogues

We investigated the coupling reaction of glycosyl donors N-trichloroethoxycarbonyl-galactosamine-O-trichloroacetimidate (2a) and N-p-nitrobenzyloxycarbonyl-galactosamine-O-trichloroacetimidate (2b) with the 4′-OH of lactose derivatives (3a-d) to synthesize key intermediates of asialo GM2 analogues, and found that the glycosylation yield with 2a was 90% or more in all investigated cases.     

An efficient synthesis of dienic nucleoside analogues via a Mitsunobu reaction

Nucleoside analogues 9 and 12 were obtained in good yields from alcohol 7 which, under Mitsunobu conditions, led to the title products after deprotection steps.     

An efficient and simple aminobenzannulation reaction: pyrrolidine as a trigger for the synthesis of 1-amino-acridines

[reaction: see text] A new aminobenzannulation methodology has been developed and applied successfully to the synthesis of 1-amino-acridines. The key and last step goes through an enamine intermediate that was detected in some cases. When pyrrolidine and powdered 4 A molecular sieves were used, the enamine synthesis and the aminobenzannulation step took place subsequently, whereas for other secondary amines, neutral Al(2)O(3) or PtCl(2) catalysis was necessary.     

An efficient one-pot reaction for the synthesis of pyrazolones bearing a phenothiazine unit

A simple one-pot approach for the synthesis of new pyrazolones containing a phenothiazine unit is reported. Compound 4b was evaluated for its antiproliferative activity on a NCI-60 cancer cell line panel and exhibited selective cytostatic activity toward CCRF-CEM, HL-60(TB), K-562, MOLT-4, and RPMI-8226 leukemia cell lines.     

An unexpected diethyl azodicarboxylate-promoted dehydrogenation of tertiaryamine and tandem reaction with sulfonyl azide

It is shown here for the first time that diethyl azodicarboxylate promotes dehydrogenation of tertiaryamines to afford enamines, which subsequently take place in tandem reactions with sulfonyl azides to give the N-sulfonyl amidine derivatives. A number of different substituted tertiaryamines and sulfonyl azides can successfully be coupled, and several functionalized groups are tolerated in this system. The reaction described here is mild, general, and efficient, thus providing an extremely preferable method for synthesis of a variety of N-sulfonyl amidine derivatives.