Preferential Reactivity of Pyridylmagnesiumchloride with N,N-Dialkyl Arylamides over Carbonitriles: Synthesis of 2-(Aroyl) Pyridines

Reaction of 2-pyridylmagnesium chlorides with N,N-dialkyl arylamides afford exclusively 2-(aroyl) pyridines in high yields and purity without the formation of any tertiary alcohol. This method employs easily available raw materials and avoids the use of hazardous lithium reagents and cryogenic conditions. Further, preferential reactivity of this Grignard reagent with N,N-dialkyl arylamides over its carbonitrile counterparts offers a variety of 2-(aroyl) pyridines including the ones containing carbonitrile groups on the aryl ring.     

Structural characterization of monomeric and oligomeric arylamides by solution and solid‐state NMR spectroscopy

An extensive study of both liquid‐ and solid‐state NMR spectroscopy was undertaken in order to elucidate the structural features of a phenyleneterephthalamide oligomer (OPTA) and of some related diarylamides. 1D‐ and 2D‐COSY measurements allowed us to assign completely the proton signals of the title compounds in solution, while 1D‐, 2D‐HETCOR and 2D‐COLOC measurements were used to assign ¹³C resonances. Solid‐state ¹³C NMR experiments, by conventional cross‐polarization (CP) at different contact times and with the dipolar dephased CP technique, were used to characterize these molecules in the solid state. Such techniques allowed us to differentiate among different carbon atoms; in the resulting spectra it was then possible to observe the selective appearance of signals from protonated and quaternary carbon atoms. It was also ascertained that the limited structural mobility of the insoluble OPTA, existing as a single monophasic species, can be explained in terms of hydrogen‐type bonds present in the solid state. Copyright © 2002 John Wiley & Sons, Ltd.     

Acylation and Cyclodehydration of Benzofuran-, Benzothiophene-, and Indolyl-3-acetic Acid Arylamides. Synthesis of Novel Benzofuro[2,3-c]-, Benzothieno[2,3-c], and Indolo[2,3-c]pyrilium and Pyridine Derivatives

The acylation of benzo[b]furan-, benzo[b]thiophene, and indolyl-3-acetic acid arylamides using acetic anhydride in the presence of 70% perchloric acid occurs at the -position of the heterocycle to give 2-acetylbenzo[b]furan-, 2-acetylbenzo[b]thiophene, and 2-acetylindolyl-3-acetic acid arylamides. Depending on the amount of perchloric used in the reaction they undergo cyclodehydration to 3-arylamino-1-methylhetero[2,3-c]pyrilium salts and to N-aryl-1-methyl-3(2H)hetero[2,3-c]pyridones.