Kinetics of the acid catalyzed hydrolysis of hydroxamic acids

The acid catalyzed hydrolysis of some alkylhydroxamic acids has been studied spectrophotometrically in perchloric, hydrochloric and sulfuric acids. Plots of the first order rate constant, k_obs against H⁺ show maxima, which are caused by protonation of the substrate. The mechanism of hydrolysis is found to be similar to that of amides. The variation of reaction rate with acid concentration can be described by a two-parameter equation.

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, , , . k_obs [H⁺] , . . .

     

An efficient synthesis of 1-H indazoles

The reaction of substituted salicyaldehydes with hydrazine hydrochloride under different conditions gave the corresponding 1-H indazoles. However, the reaction of benzaldehydes with hydrazine hydrate under the same conditions yielded only hydrazones.     

Pd-catalyzed sequential C-C bond formation and cleavage: evidence for an unexpected generation of arylpalladium(II) species

A Pd(II)-catalyzed reaction engaging alkenyl β-keto esters is reported that leads to the formation of 1-naphthols and an unexpected generation of arylpalladium(II) species. Interception of the in situ generated arylpalladium(II) species in a Mizoroki-Heck reaction, together with additional mechanistic studies, provided strong evidence in support of the first aromatization-driven β-carbon elimination process. A single Pd catalyst served to promote a series of both C-C bond forming and cleavage events in an unprecedented manner.     

A concise enantioselective synthesis of 1-[(S)-3-(dimethylamino)-3,4-dihydro-6,7-dimethoxyquinolin-1(2H)-yl]propan-1-one, (S)-903

A concise enantioselective synthesis of (S)-903, an inotropic agent, is described in nine linear steps and 95% ee based on asymmetric dihydroxylation of cinnamate ester and Co-catalyzed multifunctional reduction of several functional groups leading to the construction of core tetrahydroquinolin-3-ol, as the key steps.     

Synthesis and Cation Recognition Study of Novel Benzo Crown Ether Functionalized Enamine Derivatives

A novel series of benzo crown ether (dibenzo 18-crown-6 ether, benzo 18-crown-6 ether, and benzo 15-crown-5 ether) functionalized enamines derivatives from amino benzo crown ether (4-amino dibenzo 18-crown-6 ether, 4-amino benzo 18-crown-6 ether, 4-amino benzo 15-crown-5 ether) and substituted 3-(dimethylamino)-1-phenylprop-2-en-1-one compounds have been synthesized. All the synthesized compounds were characterized by infrared, ¹H NMR, ¹³C NMR, distortionless enhancement polarization transfer, and mass and elemental analysis techniques. The cation recognition property for benzo crown ether enamine 8a was studied by absorption and fluorescence spectroscopy.     

Co-catalyzed mild and chemoselective reduction of phenyl esters with NaBH4: a practical synthesis of (R)-tolterodine

CoCl₂ catalyzes effectively the chemoselective reduction of phenyl carboxylic esters to the corresponding saturated alcohols in high yields using NaBH₄ at ambient conditions. By employing this methodology, the synthesis of (R)-tolterodine, a muscarinic receptor antagonist, has been achieved in high yield and optical purity.     

On the intersection of electrochemistry and mass spectrometry

The application of nanopipettes, developed first as a tool for electrochemistry and electrophysiology, as tools for mass spectrometry is considered. Recent examples of advances in electrospray ionization and sampling for mass spectrometry with nanopipettes is discussed. These examples show a scientific intersection that is ripe for further development.     

Synthesis of Phenacyl Esters by Using PTC and Dibenzo-[18]-crown-6

In view of the importance of phenacyl esters as a protecting groups, a simple and efficient method is now reported here for synthesis of phenacyl esters in quantitative yield and high purity under mild reaction condition by using phase transfer catalyst and dibenzo-[18]-crown-6. It has been demonstrated that the spatial coordination of ion and ligand cavity plays important role in using crown ethers.