Abstract Coumarin and its nitrogen analogue 1-aza coumarin are a class of lactones lactams, respectively, which indispensable heterocyclic units to both chemists biochemists. 1-Aza derivatives, ultimately metabolize as the corresponding 8-hydroxy coumarins in biological system therefore found be very good anti-inflammatory, anti-cancer, analgesic agents. A series hybrid substituted azacoumarin-...

The reactivity of radical cation carboxylic acids is investigated on the basis of mass spectrometry, infrared-vacuum ultraviolet (IR-VUV) photoionization spectroscopy, and high level correlated ab initio calculations. Their reactivity is found to be highly conformation specific and is governed by their initial charge distribution following ionization. In the present work, the radical cations of...

[1,4]Diazepino[2,3-h]quinolone carboxylic acid 3 and its benzo-homolog tetrahydroquino[7,8-b]benzodiazepine-3-carboxylic acid 5 were prepared via PPAcatalyzed thermal lactamization of the respective 8-amino-7-substituted-1,4-dihydroquinoline-3-carboxylic acid derivatives 8, 10. The latter compounds were obtained by reduction of their 8-nitro-7-substituted-1,4-dihydroquinoline-3-carboxylic acid ...

Reactions of 3-bromo-4-phenylisothiazole-5-carboxamide and 3-bromoisothiazole-5-carboxamide with NaNO2 (4 equiv.), in TFA, at ca. 0 °C gave the carboxylic acid products 99% 95% yields, respectively. The two compounds were fully characterized.

In the title compound, C(5)H(5)NO(2), the pyrrole ring and its carboxyl substituent are close to coplanar, with a dihedral angle of 11.7 (3)° between the planes. In the crystal structure, adjacent mol-ecules are linked by pairs of O-H⋯O hydrogen bonds to form inversion dimers. Additional N-H⋯O hydrogen bonds link these dimers into chains extending along the a axis.

The carboxylic acid residue in the title compound, C(6)H(4)BrNO(2), is twisted out of the plane of the other atoms, as indicated by the (Br)C-C-C-O(carbon-yl) torsion angle of -20.1 (9)°. In the crystal, supra-molecular chains mediated by O-H⋯N hydrogen bonds are formed with base vector [201] and C-H⋯O inter-actions reinforce the packing.

In the title compound, C(5)H(5)NO(3), the mol-ecule lies on a crystallographic mirror plane with one half-mol-ecule in the asymmetric unit. An intramolecular C-H⋯O inter-action is present. In the crystal, strong inter-molecular O-H⋯N hydrogen bonds result in the formation of a linear chain structure along [100], and there are also weak C-H⋯O hydrogen bonds between the chains which help to stabi...

The promiscuous regio- and stereoselective hydration of 4-hydroxystyrenes catalyzed by ferulic acid decarboxylase from Enterobacter sp. (FDC_Es) depends on bicarbonate bound in the active site, which serves as a proton relay activating a water molecule for nucleophilic attack on a quinone methide electrophile. This "cofactor" is crucial for achieving improved conversions and high stereoselectiv...

A chiral metal-organic framework, MOF-520, was used to coordinatively bind and align molecules of varying size, complexity, and functionality. The reduced motional degrees of freedom obtained with this coordinative alignment method allowed the structures of molecules to be determined by single-crystal x-ray diffraction techniques. The chirality of the MOF backbone also served as a reference in ...

Esterification of naturally occurring hemins and porphyrins is often a prerequisite for structural studies of these compounds. Porphyrins and hemins are in general more easily purified as their esters than as the free carboxylic acids. In addition, esterification is the most feasible procedure for preparing derivatives of tetrapyrroles for studies by mass spectrometry. The most convenient and f...