A photochemical ring expansion of 6- to 8-membered nitrogen heterocycles by [1,3]-sigmatropic rearrangement

Regioselectivity and tautomerism of novel five-membered ring nitrogen heterocycles formed via cyclocondensation of acylthiosemicarbazides.

A series of 1-acyl-4-phenyl/(acridin-9-yl)thiosemicarbazides 3, including four new compounds, were prepared in order to study substituent effects on cyclization reactions with oxalyl chloride (producing imidazolidine-4,5-diones 4), dimethyl acetylenedicarboxylate (to give thiazolidin-4-ones 7 and 8) and autocondensation under alkaline conditions (to yield 1,2,4-triazoles 9). A positional isomer...

Cross sections for electron collision with five-membered ring heterocycles

The absolute total cross-section (TCS) for electron scattering from isoxasole, (CH)3NO, molecule has been measured using the linear transmission technique for impact energies ranging from 1 to 400 eV. The measured TCS energy dependence appears typical for highly polar targets; over whole energy range applied, the magnitude of TCS generally decreases as the energy increases. Some narrow features...

RhI-catalyzed C-C bond activation: seven-membered ring synthesis by a [6+1] carbonylative ring-expansion reaction of allenylcyclobutanes.

Stereospecific photochemical ring expansion of lithiated benzamides.

Treatment of N-benzyl benzamides with a strong base (LDA or t-BuLi) followed by irradiation with a 500 W tungsten lamp provides, according to the substitution pattern of the starting amides, either norcaradienes or cycloheptadienones by overall insertion of the N-benzyl group into the benzamide's aromatic ring system. Chiral benzamides undergo the ring expansion with high (sometimes complete) s...

Syntheses and antimicrobial activities of five-membered ring heterocycles coupled to indole moieties.

Indole-substituted oxazolidinones, oxazolones, pyrrolidinone, imidazolidinone and imidazolones were synthesized. Their inhibitory potencies towards protein kinase C and protein kinase A were determined and their in vitro activities against Streptomyces chartreusis, Streptomyces griseus, Bacillus cereus, Candida albicans and Escherichia coli were examined. The inhibition of Streptomyces sporulat...