Reaction of 1-Nitroso-2-naphthols with α-Functionalized Ketones and Related Compounds: The Unexpected Formation of Decarbonylated 2-Substituted Naphtho[1,2-d][1,3]oxazoles

Abstract

Reactions between 1-nitroso-2-naphthols and α-functionalized ketones such as α-bromo-, α-chloro-, α-mesyloxy-, α-tosyloxy-, and α-hydroxy ketones under basic conditions delivered 2-substituted naphtho[1,2-d][1,3]oxazoles in a single synthetic operation. The product formation was accompanied by the unexpected loss of the C═O group from the α-functionalized ketones. With aryl bromides, allyl bromides, α-bromo diketones, α-bromo cyanides, α-bromoesters, and α-bromo ketoesters as substrates the formation of naphtho[1,2-d][1,3]oxazoles was also observed. The transformations were performed in 1,2-dichloroethane or acetonitrile under reflux and gave the corresponding naphthoxazoles with yields ranging between 52% and 85%.

BF3·Et2O-Promoted Cleavage of the Csp–Csp2 Bond of 2-Propynolphenols/Anilines: Route to C2-Alkenylated Benzoxazoles and Benzimidazoles

“…Over the past few decades, some general methods for the synthesis of functionalized benz-fused azoles have been developed. These methods include: (a) the reactions of 2-aminophenol and 2-aminoanlines with either aldehyde or carboxylic acid derivatives, (b) the reactions of 2-aminophenols and 2-aminoanlines with ketone derivatives, (c) the reactions of o -hydroxy nitroso aryls with alkyl halides and benzyl halides, (d) the transition metal-catalyzed cyclization of 2-haloanilides/analogues or 2-aminophenols, and others . Despite these pioneering methodologies for the synthesis of benzoxazoles and benzimidazoles, some of them suffered one or more shortcomings, such as complicated catalyst, transition metal catalyst, use of oxidant, and/or harsh conditions (high temperature, microwave radiation).…”

Iodine and DMSO as Surrogate of Hazardous Metal and Non‐Metal Reagents in Organic Synthesis

“…[442][443][444][445] There are reports for the concerned synthesis using intermolecular cyclization. [446][447][448] But those with the intramolecular cyclization, most of the transformations include the use of metal catalysts such as copper and palladium (Scheme 48 (a), (b), and (d)). [449][450][451] The transformations, which occurs without metals include the use of high equivalence of iodosobenzene diacetate (Scheme 48 (c)).…”

“…The oxazole, especially when is substituted exhibits various appealing bioactive properties [442–445] . There are reports for the concerned synthesis using intermolecular cyclization [446–448] . But those with the intramolecular cyclization, most of the transformations include the use of metal catalysts such as copper and palladium (Scheme 48 (a), (b), and (d)) [449–451] .…”

Biomedical applications of selective metal complexes of indole, benzimidazole, benzothiazole and benzoxazole: A review (From 2015 to 2022)

“…( Al-Saidi and Khan, 2022a , Al-Saidi and Khan, 2022b , Aljaar et al, 2019 , Alrooqi et al, 2022 , Gemili et al, 2019 , Gul et al, 2022 , Kabi et al, 2022b , Khan et al, 2020 , Khan et al, 2022a , Khan et al, 2022b , Mohammad Abu-Taweel et al, 2022 , Muhammad et al, 2022 ). These compounds have excellent biological applications such as anti-ulcerogenic, anti-cancer, antihypertensive, antifungal, anti-inflammatory, antitubercular, antiparasitic, anti-obesity, antimalarial, antiglycation, antiviral potency, antineuropathic, analgesic antioxidant, antihistaminic, and antibacterial potentials ( Aljaar et al, 2023 , Aljaar et al, 2015 , Aljaar et al, 2013 , Gujjarappa et al, 2022 , Gujjarappa et al, 2020 , Kabi et al, 2022a , Kaldhi et al, 2019 , Shafiei et al, 2020 , Vodnala et al, 2018 ). Indole nucleus ( Fig.…”