HPO promoted reactions of thioamides with 2-substituted benzyl alcohols.

In this study, we have investigated the reactivity of thioamides with alcohols by utilizing HPO as a low-toxicity, cost-effective Brønsted acid catalyst. This report includes a methodology for the synthesis of thioesters from thioamides and 2-hydroxyaryl alcohols. Thioesters are emerging as a notable class of organic molecules due to their biological relevance, extensive use in drug discovery, and industrial applications.

Regioselective Ring Opening of Aziridines by Oximes via C-C Bond Cleavage: Access to a Library of Oxime-Ethers.

A series of sulfonamido-substituted oxime-ethers have been synthesized by the reaction of donor-acceptor aziridines with aldo- and keto-oximes through C-C bond cleavage. Nucleophilic attack by an oxime hydroxyl group on the -generated azomethine ylide rather than the routine cycloaddition reaction draws the novelty of the developed methodology. Selective protection of the oxime hydroxyl group is observed in the presence of phenolic -OH, which made the protocol enriched.

Solvent- and Catalyst-Controlled Regioselective - and -Alkylation of 2-Pyridones by 2-Azirines.

The synthesis of -substituted 2-hydroxypyridines and -substituted 2-pyridones, crucial for many bioactive compounds and drugs, faces challenges due to the tautomeric nature of 2-pyridones, which complicates selective alkylation. Here we developed an efficient method for regioselective - and -alkylation of 2-pyridones using Bro̷nsted acid-catalyzed ring opening of 2-azirines. The process involves triflic acid for -alkylation and -toluenesulfonic acid for alkylation, achieving high yields under optimized conditions.

Bi(III)-Catalyzed Michael Addition of Tautomerizable Heterocycles with α,β-Unsaturated Carbonyl Compounds: Regioselective Construction of C-N Bonds.

A Bi(III)-catalyzed synthetic strategy for regioselective construction of C-N bonds via a simple Michael addition reaction is reported. A wide range of tautomerizable heterocycles such as benzoxazolones, benzothiazolones, benzimidazolinones, indolinones, and 2-pyridones along with α,β-unsaturated carbonyls (ketones and esters) are employed to create a library of corresponding -alkylated derivatives exclusively. High regioselectivity, high atom economy, and the participation of a range of tautomerizable heterocycles highlight the uniqueness and generality of the developed methodology.

Regioselective Brønsted acid catalyzed ring opening of aziridines by phenols and thiophenols; a gateway to access functionalized indolines, indoles, benzothiazines, dihydrobenzo-thiazines, benzo-oxazines and benzochromenes.

Brønsted acid catalyzed regioselective ring opening of aziridines by phenols and thiophenols have been reported. Involvement of a series of aziridines with a range of phenols and thiophenols offer the generality of the reported protocol. Completion of the reaction at room temperature within very short time brings the uniqueness of the developed technique.

Brønsted acid-catalyzed regioselective ring opening of 2-azirines by 2-mercaptopyridines and related heterocycles; one pot access to imidazo[1,2-]pyridines and imidazo[2,1-]thiazoles.

A catalytic and versatile synthetic method for the synthesis of imidazo[1,2-]pyridines has been developed. Brønsted acid-catalysis plays a major role in the regioselective ring opening of 2-azirines. Nucleophilic attack the -centre of mercaptopyridines and their analogues, followed by cyclisation by cleaving the C-S bond, allowed a library of imidazo[1,2-]pyridines and related heterocycles to be built.

Methyltrifluoromethanesulfonate Catalyst in Direct Nucleophilic Substitution of Alcohols; One-Pot Synthesis of 4-Chromene Derivatives.

The catalytic activity of methyltrifluoromethanesulfonate (MeOTf) has been explored toward direct nucleophilic substitution of the hydroxyl group of nonmanipulated alcohols such as benzylic, allylic, propargylic, and tertiary alcohols with a wide range of uncharged nucleophiles such as 1,3-dicarbonyl compounds, amides, alkynes, and indoles to generate functionalized 1,3-dicarbonyl compounds, amides, alkynes, and indoles, respectively. Thus, the present protocol defines an alternate pathway to construct new C-C, C-N, and C-O bonds with the formation of water as the byproduct under mild conditions without any acids or metals. A completely different mechanism was established through several control experiments to explain the reaction methodology.

Regioselective Transition Metal-Free Catalytic Ring Opening of 2-Azirines by Phenols and Naphthols; One-Pot Access to Benzo- and Naphthofurans.

Benzofuran and naphthofuran derivatives are synthesized from readily available phenols and naphthols. Regioselective ring openings of 2-azirine followed by in situ aromatization using a catalytic amount of Brønsted acid have established the novelty of the methodology. The involvement of a series of 2-azirines with a variety of phenols, 1-naphthols, and 2-naphthols showed the generality of the protocol.

The eco-friendly treatment of rubber industry effluent by using adsorbent derived from Moringa oleifera bark and Pseudomonas sp, cultured from effluent.

Rubber processing generates a large volume of wastewater containing rubber latex residues and chemicals. Remediation of the wastewater needs a cost-effective and environment-friendly treatment method. For this study, Moringa oleifera stem bark and Pseudomonas sp.

(3 + 2) cycloaddition of 2-alkoxynaphthalenes with azaoxyallyl cations: access to benzo[]indolones.

A reaction between 2-alkoxynaphthalene and an formed azaoxyallyl cation has been reported under ambient reaction conditions. The (3 + 2) cycloaddition reaction followed by aryl C-OMe/C-OEt bond cleavage produces a variety of benzo[]indolone derivatives. Based on the isolated intermediate from the control experiment and previous results, a possible mechanism has been drawn.

Potential activity of Linezolid against SARS-CoV-2 using electronic and molecular docking study.

The crescent evolution of a global pandemic COVID-19 and its respiratory syndrome (SARS-Cov-2) has been a constant concern (Ghosh 2021; Khan et al. 2021; Alazmi and Motwalli 2020; Vargas et al. 2020).

Intramolecular substitutions of secondary and tertiary alcohols with chirality transfer by an iron(III) catalyst.

Optically pure alcohols are abundant in nature and attractive as feedstock for organic synthesis but challenging for further transformation using atom efficient and sustainable methodologies, particularly when there is a desire to conserve the chirality. Usually, substitution of the OH group of stereogenic alcohols with conservation of chirality requires derivatization as part of a complex, stoichiometric procedure. We herein demonstrate that a simple, inexpensive, and environmentally benign iron(III) catalyst promotes the direct intramolecular substitution of enantiomerically enriched secondary and tertiary alcohols with O-, N-, and S-centered nucleophiles to generate valuable 5-membered, 6-membered and aryl-fused 6-membered heterocyclic compounds with chirality transfer and water as the only byproduct.

Nucleophilic ipso-Substitution of Aryl Methyl Ethers through Aryl C-OMe Bond Cleavage; Access to Functionalized Bisthiophenes.

A metal and solvent free strategy to functionalize aryl methyl ethers through direct nucleophilic substitution of aryl C-OMe bond has been described. A wide range of O, S, N, and C-centered uncharged nucleophiles has been successfully employed. Using this protocol, functional derivatives of bisthiophene have been synthesized in a straightforward way.

Brønsted Acid Catalyzed Functionalization of Aromatic Alcohols through Nucleophilic Substitution of Hydroxyl Group.

The hydroxyl groups of naphthol and tautomerizable phenol derivatives have been substituted by O-, S-, N-, and C-centered nucleophiles under solvent-free reaction conditions. The products are generated in good to excellent yields. para-Toluenesulfonic acid exhibits the best catalytic activity compared to other Brønsted acids.

Brønsted acid-catalyzed intramolecular nucleophilic substitution of the hydroxyl group in stereogenic alcohols with chirality transfer.

The hydroxyl group of enantioenriched benzyl, propargyl, allyl, and alkyl alcohols has been intramolecularly displaced by uncharged O-, N-, and S-centered nucleophiles to yield enantioenriched tetrahydrofuran, pyrrolidine, and tetrahydrothiophene derivatives with phosphinic acid catalysis. The five-membered heterocyclic products are generated in good to excellent yields, with high degree of chirality transfer, and water as the only side-product. Racemization experiments show that phosphinic acid does not promote SN1 reactivity.

One-pot synthesis of keto thioethers by palladium/gold-catalyzed click and pinacol reactions.

An atom-efficient synthesis of keto thioethers was devised via tandem gold/palladium catalysis. The reaction proceeds through a regioselective thiol attack at the β-position of the alcohol, followed by an alkyl, aryl, or benzyl 1,2-shift. Both acyclic and cyclic systems were studied, in the latter case leading to the ring expansion of cyclic substrates.

Tandem Pd/Au-catalyzed route to α-sulfenylated carbonyl compounds from terminal propargylic alcohols and thiols.

An efficient and highly atom-economical tandem Pd/Au-catalyzed route to α-sulfenylated carbonyl compounds from terminal propargylic alcohols and thiols has been developed. This one-step procedure has a wide substrate scope with respect to substituents at the α-position of the alcohol. Both aromatic and aliphatic thiols generated the α-sulfenylated carbonyl products in good to excellent yields.

Atom-efficient gold(I)-chloride-catalyzed synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols: substrate scope and experimental and theoretical mechanistic investigation.

Gold(I)-chloride-catalyzed synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols showed a wide substrate scope with respect to both propargylic alcohols and aryl thiols. Primary and secondary aromatic propargylic alcohols generated α-sulfenylated aldehydes and ketones in 60-97% yield. Secondary aliphatic propargylic alcohols generated α-sulfenylated ketones in yields of 47-71%.

The efficiency of the metal catalysts in the nucleophilic substitution of alcohols is dependent on the nucleophile and not on the electrophile.

In this study, we investigate the effect of the electrophiles and the nucleophiles for eight catalysts in the catalytic SN 1 type substitution of alcohols with different degree of activation by sulfur-, carbon-, oxygen-, and nitrogen-centered nucleophiles. The catalysts do not show any general variance in efficiency or selectivity with respect to the alcohols and follow the trend of alcohol reactivity. However, when it comes to the nucleophile, the eight catalysts show general and specific variances in the efficiency and selectivity to perform the desired substitution.

A gold(I)-catalyzed route to α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols.

A one-step atom efficient gold(I)-catalyzed route to α-sulfenylated ketones and aldehydes from propargylic alcohols and aryl thiols is described.

Iron-catalyzed synthesis of functionalized 2H-chromenes via intramolecular alkyne-carbonyl metathesis.

An iron-catalyzed intramolecular alkyne-aldehyde metathesis strategy of the alkynyl ether of salicylaldehyde derivatives has been developed which works under mild reaction conditions to produce the functionalized 2H-chromene derivatives. This protocol is compatible toward a wide range of functional groups, such as methoxy, fluoro, chloro, bromo, and phenyl groups. This method provides an atom-economical and environmentally friendly approach for the synthesis of a series of substituted 2H-chromenes.

Iron(III)-catalyzed four-component coupling reaction of 1,3-dicarbonyl compounds, amines, aldehydes, and nitroalkanes: a simple and direct synthesis of functionalized pyrroles.

A simple, convenient, and multicomponent coupling strategy for the synthesis of highly functionalized pyrroles catalyzed by iron(III) salts has been developed. This strategy demonstrated four-component coupling reactions of 1,3-dicarbonyl compounds, amines, aromatic aldehydes, and nitroalkanes without an inert atmosphere. This methodology provides an alternative approach for easy access of highly substituted pyrroles in moderate to very good yields using four simple and readily available building blocks via one-pot tandem reaction.