Catalyst- and Additive-Free Approach to Constructing Benzo-oxazine, Benzo-oxazepine, and Benzo-oxazocine: O Atom Transfer and C═O, C–N, and C–O Bond Formation at Room Temperature

Abstract

An exclusive synthesis of benzo-oxazine, benzo-oxazepine, and benzo-oxazocine from aryl propanal and 2-(hydroxyamino)­phenyl alcohol under metal-free conditions is described. O atom transfer and formation of new CO, C–N, and C–O bonds occur at room temperature to form six-, seven-, and eight-membered heterocycles under one-pot reaction conditions without using an external oxidant and base. The photophysical properties are studied using ultraviolet–visible absorption and photoluminescence. The mechanistic elucidation is well supported by control experiment and literature precedents.

A sustainable approach for nickel nanoparticles synthesis: expeditious access to N-heterocycles under heterogeneous condition and photophysical studies

“…The prominent optical properties were found with functionalized heterocycles due to their π -conjugated systems (see ESI†). 23 For instance, parent compounds 5a and 7a exhibited absorption at 348 and 353 nm with moderate molar extinction coefficient (29.18 × 10 5 M −1 m −1 ) and (16.18 × 10 5 M −1 m −1 ) and maximum emission at 420 and 422 nm, respectively. Moreover, they exhibited very strong blue fluorescence when excited at 348 and 353 nm in N , N -dimethylformamide.…”

Room-Temperature Synthesis of Biogenic δ-MnO2 NPs for the Dehydrogenative Coupling of Diamines with Alcohols for Benzimidazole and Quinoxaline Synthesis: An Efficient Catalyst for Electrochemical Applications

“…On the basis of control experiments and literature precedents, ,− a possible mechanism is proposed for 2-phenylbenzimidazole synthesis (Scheme , right). Initially, oxidation of benzyl alcohol in the presence of δ-MnO 2 NPs leads to the formation of benzaldehyde which upon reaction with 1,2-diamine furnishes monoamine A .…”

Synthesis of N-, O-, and S-heterocycles from aryl/alkyl alkynyl aldehydes

“…Very recently, the synthesis of a series of six, seven, and eight-membered N , O -heterocyclic compounds, including benzo-oxazine 61b, benzo-oxazepine 61c and benzo-oxazocine 61d from easily available ynals 1a and 2-(hydroxyamino)phenyl alcohols 61a was explained by Dateer and co-workers ( Scheme 84 ). 97 Synthetic utility of benzo-oxazine was demonstrated by gram-scale synthesis and further conversion into the pyrazole derivative. A mechanism for this catalyst and additive-free method is illustrated in Scheme 85 .…”

“…Very Very recently, the synthesis of a series of six, seven, and eightmembered N,O-heterocyclic compounds, including benzooxazine 61b, benzo-oxazepine 61c and benzo-oxazocine 61d from easily available ynals 1a and 2-(hydroxyamino)phenyl alcohols 61a was explained by Dateer and co-workers (Scheme 84). 97 Wu et al (Scheme 86). 98 For this purpose, they examined phosphorus decasulde and Lawesson's reagent as the sulfurtransferring reagents.…”