Brønsted acid catalyzed mechanochemical domino multicomponent reactions by employing liquid assisted grindstone chemistry

Abstract

Here, we have demonstrated a metal-free energy-efficient mechanochemical approach for expedient access to a diverse set of 2-amino-3-cyano-aryl/heteroaryl-4H-chromenes, tetrahydrospiro[chromene-3,4′-indoline], 2,2′-aryl/heteroarylmethylene-bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) as well as tetrahydro-1H-xanthen-1-one by employing the reactivity of 5,5-dimethylcyclohexane-1,3-dione/cyclohexane-1,3-dione with TsOH⋅H2O as Brønsted acid catalyst under water-assisted grinding conditions at ambient temperature. The ability to accomplish multiple C–C, C=C, C–O, and C–N bonds from readily available starting materials via a domino multicomponent strategy in the absence of metal-catalyst as well as volatile organic solvents with an immediate reduction in the cost of the transformation without necessitates complex operational procedures, features the significant highlights of this approach. The excellent yield of the products, broad functional group tolerances, easy set-up, column-free, scalable synthesis with ultralow catalyst loading, short reaction time, waste-free, ligand-free, and toxic-free, are other notable advantages of this approach. The greenness and sustainability of the protocol were also established by demonstrating several green metrics parameters.

Visible‐Light‐Mediated Direct Expeditious Photochemical Construction of Spirocyclic‐Oxindoles

“…Multi-component reaction, a promising and effective approach for environmentally benign synthesis, is characterized by the capability to achieve the required compounds in "one-pot" utilizing a synthetically straightforward workup process without the use of sophisticated purification methods and without isolating reaction intermediates. [50,[86][87][88] Because of these features, Wu, Zhang, and co-workers developed an efficient, cost-effective three-component strategy for constructing spirooxindole-pyran derivatives by employing visible-light-initiated catalyst-free conditions (Scheme 4). [89] With the help of 18 W white LED irradiations, the one-pot reaction of substituted isatins 8, malononitrile 9, and CÀ H activated acids such as 4-hydroxycoumarin 10, dimedone 12, and 2-hydroxynaphthalene-1,4-dione 14 in aqueous ethyl lactate spirooxindoles of type 17 (Scheme 6).…”

“…Multi‐component reactions (MCRs) have been considered a promising approach in synthetic organic chemistry for the easy synthesis of various structural scaffolds from readily available, basic, and inexpensive raw materials via the formation of multiple bonds in a single synthetic operation. Multi‐component reaction, a promising and effective approach for environmentally benign synthesis, is characterized by the capability to achieve the required compounds in “one‐pot” utilizing a synthetically straightforward workup process without the use of sophisticated purification methods and without isolating reaction intermediates [50,86–88] …”

Functionalized graphene oxide by 4-amino-3-hydroxy-1-naphthalenesulfonic acid as a heterogeneous nanocatalyst for the one-pot synthesis of tetraketone and tetrahydrobenzo[b]pyran derivatives under green conditions

“…MCRs are very attractive processes for the synthesis of a variety of polymers, heterocyclic compounds, and materials with biological properties and provide a wide range of products often having complex molecular structures in rapid and simple procedures. [48][49][50][51] One of the most important parameters in the synthesis of organic compounds through MCRs and complying with the principles of green chemistry is choosing an eco-friendly solvent. In this Please do not adjust margins Please do not adjust margins context, performing the reactions for the synthesis of pharmaceutical precursors or final active pharmaceutical ingredients (APIs) in EtOH, as a green solvent, is one of the best strategies.…”