Infrared Absorption Spectra of Aldonitrones. I. Infrared Spectra of Benzaldehyde N-Methyl and N-Phenyl Nitrones.

Facile one-pot synthesis of novel N-benzimidazolyl-α-arylnitrones catalyzed by salts of transition metals

“…In general, in the IR spectrum for a nitrone system, it is expected that there will be ve characteristic vibrational frequencies, including C]N, N-O, and C-N stretching and C-H in-plane and out-of-plane bending frequencies. 31 A red shi at the C]NO-vibrational frequency in the N-benzimidazolyl nitrones (1535 to 1581 cm À1 ) relative to the corresponding Schiff bases (1601 to 1621 cm À1 ) as well as the appearance of a relatively strong band for N-O stretching in nitrones (1012 to 1103 cm À1 ) conrms the formation of these products. Other signals were revealed in the expected regions which are consistent with their structures.…”

“…2 ) in two steps, but with lower yields (42% to 70%), longer reaction times (1.5 to 6 hours) and more complex and tight separation of the pure product ( Scheme 4 ). The reason for the rapid formation and stability of these nitrones (compared to the formation of the oxaziridine ring or amide) may be the presence of intermolecular hydrogen bonds between the hydrogen of the imidazole 30 and the nitrone oxygen 31–33 ( Scheme 4 ). On the other hand, the intense resonance between nitrone, aryl and the benzimidazole ring accelerates this process.…”

“…In order to investigate the different probable molecular structures of the nitrones and oxaziridine, a theoretical approach was applied. 31,35 The optimized structures and relative energy comparison of these molecules are shown in Fig. 3.…”

OxaD: A Versatile Indolic Nitrone Synthase from the Marine-Derived Fungus Penicillium oxalicum F30

“…Additionally, previous infrared analysis of N -phenyl nitrones shows a very strong band between 1000–1100 cm −1 corresponding to the N-O stretch. 72 This band disappears upon isomerization of N -phenyl nitrones to the corresponding oxaziridines. Following the oxidation of roquefortine C by OxaD, an intense band was observed at 1014 cm −1 in the IR spectrum of 7 , as additional support for the presence of a nitrone functionality instead of an oxaziridine.…”

“…Analysis of the 13 C NMR spectrum of 7 was further indicative of the nitrone formation as the chemical shift of the C6 peak shifted from δ 78 ppm to δ 150 ppm. Additionally, previous infrared analysis of N -phenyl nitrones shows a very strong band between 1000 and 1100 cm –1 corresponding to the N–O stretch . This band disappears upon isomerization of N -phenyl nitrones to the corresponding oxaziridines.…”