Cobalt(III)‐Catalyzed and Dimethyl Sulfoxide‐Involved Cross‐Coupling of Ketones and Amides for Direct Synthesis of β ‐Amino Ketones

Cu(II)-Catalyzed [3 + 1 + 1 + 1] Cyclization of 1,3-Diketones and 2-Naphthols Using N,N-Dimethylethanolamine as a Dual Carbon Synthon for the Synthesis of 2H-Chromenes

Reactions with diverse C1 synthons to realize homologation were well explored. However, homologations occurring twice with one C1 synthon in a reaction were less reported. We disclose herein a Cu(II)-catalyzed novel and efficient synthesis of 2H-chromenes from 2-naphthols, 1,3-diketones, and N,N-dimethylethanolamine (DMEA) as a dual carbon synthon. Various 2H-chromenes with different functional groups are constructed in moderate to good yields. This is the first report that DMEA acts as a dual C1 synthon.

β-Ketoallylic methylsulfones synthesis via inert C(sp3)-H bond activation by magnetic Ag-Cu MOF

Herein, the one-pot tandem synthesis of β-ketoallylic methylsulfones has been achieved from readily available dimethyl sulfoxide and acetophenones as coupling partners in one step. In this procedure, dimethyl sulfoxide serves as a triple role including solvent, dual synthon and as an oxidant agent. The use of magnetic Ag-Cu MOF as a bimetallic catalyst is the key to the progress of the reaction due to its accessible active sites. It provides facile access to various β-ketoallylic methylsulfone derivatives from direct C(sp3)-H bond activation and functionalization of aromatic methyl ketones especially acetophenones with electron-rich and electron-poor groups. Moreover, the present work offers a synthetically powerful strategy to form products in good to excellent yields (74-96%) with the atom, step, and pot economics. It has also delivered a new chromane-4-one derivative from 2-hydroxy acetophenone with intramolecular Michael-addition of related β-ketoallyl methylsulfone product. In the final step, the electronic properties of some products have been predicted with the theoretical studies.

NH4OAc/DMSO-Promoted Benzylation of Pyrrolo[2,1-a]isoquinolines

Benzylation of pyrrolo[2,1-a]isoquinoline derivatives has been realized with various phenols by the use of ammonium acetate as a promoter (20 examples, up to 84% yield). DMSO served as the source of methylene and solvent. The employment of iron chloride as a catalyst can also afford the desired benzylated products in moderate to good yields (11 examples, up to a 74% yield).

Cobalt(III)-Catalyzed and DMSO-Involved Allylation of 1,3-Dicarbonyl Compounds with Alkenes

Cobalt(III)-catalyzed allylation of 1,3-dicarbonyl compounds has been reported with in situ generated allyl reagents from alkenes and dimethyl sulfoxide (DMSO). This novel protocol enables a high regio- and stereoselective access for a broad range of allyl 1,3-dicarbonyl compounds. In the transformation, DMSO plays the role of a C1 source, and it incorporates with alkenes to form the allyl reagent allylic methyl thioether. Moreover, a multiple-step pathway has been proposed to rationalize the mechanism study, which involves silver-mediated coupling, Co(III)-catalyzed π-allylation, and intermolecular nucleophilic substitution.

Modification of Pyrrolo[2,1-a]isoquinolines and Polysubstituted Pyrroles via Methylenation with Acetyl Chloride and Dimethylsulfoxide

A convenient synthesis of methylene-bridged pyrrolo[2,1-a]isoquinolines has been developed. Treatment of pyrroloisoquinolines with acetyl chloride and dimethylsulfoxide (DMSO) at ambient temperature afforded bispyrroloisoquinolylmethanes in 17-85% yields. This reaction system can also be expanded to the synthesis of bispyrrolylmethanes (34-94% yields). Easy chemical transformation of methylene-bridged pyrroloisoquinoline provided an unsymmetric acid and amide possessing a privileged framework.

Modification of Pyrrolo[2,1-a]isoquinolines and Pyrrolo[1,2-a]quinolines with Ammonium Acetate and Dimethyl Sulfoxide via Methylthiomethylation

An efficient methylthiomethylation of pyrroloisoquinolines and pyrroloquinolines has been reached by the use of ammonium acetate and dimethyl sulfoxide. Methylthiomethylated heterocycles can be obtained in moderate to good yields in most cases, while trace amounts to good yields of methylene-bridged products can be observed. Choice of DMSO activator and its amount have a great influence on the chemoselectivity of this process. It is worth noting that this process can also be scalable. Another feature of this process is that the product can be transformed to sulfone and sulfoxide easily.

Selectfluor-Mediated Synthesis of β-Acyl Allyl Sulfones/β-Acyl Allyl Benzotriazoles from Ketones/Acetylenes, Aryl Sulfinates/Benzotriazole, and DMSO as a Dual-Carbon Synthon

A Selectfluor-mediated approach for the synthesis of β-acyl allyl sulfones/β-acyl allyl benzotriazoles with excellent atom economy from readily available acetophenones/aryl acetylenes, aryl sulfinates/benzotriazoles, and dimethyl sulfoxide (DMSO) is described. In this protocol, DMSO acts as a dual-carbon synthon, resulting in a transition-metal-free construction of two C-C and one C-S or two C-C and one C-N bonds in one pot. This approach is extended to generate chemically diverse compounds. Additionally, β-acyl allyl sulfones/β-acyl allyl benzotriazoles were prepared from acetylenes instead of acetophenones.

Recent Advance on Dimethyl Sulfoxide (DMSO) Used as a Multipurpose Reactant

Abstract:

Dimethyl sulfoxide (DMSO) is not only a common and cheap aprotic polar solvent with low toxicity, but also serves as an efficient and multipurpose reactant and has widely been used in organic synthesis. DMSO as an important precursor can effectively introducea broad range of functional fragments into organic molecules, such as -Me, -CH, -CH2, -SMe2, -CH2SMe, -CH2SOMe, -SMe, -SO2Me, -SOMe or as O substituents, and serves as a mild oxidant in organic transformations. Many significant achievements based on DMSO as a synthon in synthetic chemistry have rapidly made over the past several years. To help researchers further understand the recent advances in the field, the review summarizes the applications of DMSO as carbon, sulfur, and oxygen sources and is used as the dual synthon in synthetic transformations.

Synthesis of methylene-bridged α,β-unsaturated ketones: α-Csp3-H methylenation of aromatic ketones using Selectfluor as a mild oxidant

A three starting material four component reaction (3SM-4CR) is developed for the synthesis of α,β-unsaturated ketones and β-amino ketones in good yields. The reaction employs tetramethylethylenediamine (TMEDA) as a methylene and terminal olefin source, and Selectfluor as a mild oxidant. TMEDA worked as a dual synthon to provide two carbons in this metal-free transformation process. The scope and versatility of the methods have been demonstrated with 23 examples. A Selectfluor-promoted oxidative reaction mechanism is proposed based on the results of the experimental studies.

Synthesis of Cyclopentenes and Cyclohexenes Via Cobalt(II)-Catalyzed Oxidative Cyclization

A unique method for the synthesis of cyclopentenes and cyclohexenes has been achieved by the coupling of diketones and alkenes under cobalt(II) catalysis and dimethyl sulfoxide involvement. Under optimal conditions, the formation of five- and six-membered rings can be readily controlled by the α-position substitution of styrenes. This process is proposed to proceed through a reaction sequence of oxidative coupling (mediated by K₂S₂O₈), regioselective alkene insertion (promoted by cobalt), and intramolecular attack of the resulting allylcobalt species on the carbonyl group or methyl group in the reactive methylene process.

Formylation and Bromination of Pyrrolo[2,1-a]isoquinoline Derivatives with Bromoisobutyrate and Dimethyl Sulfoxide

We have developed an efficient formylation of pyrroloisoquinolines using bromoisobutyrate and dimethyl sulfoxide as carbonyl reagent. Various formylated pyrroloisoquinolines could be prepared in good yields (up to 94%). This formylation process can be easily scaled up to gram scale with good yield. In most cases of pyrroloisoquinolines without methoxy groups, the combination of bromoisobutyrate and dimethyl sulfoxide could act as a bromination reagent, delivering brominated pyrroloisoquinolines in acceptable to good yields (up to 82%).

Transition-metal mediated carbon-sulfur bond activation and transformations: an update

Carbon-sulfur bond cross-coupling has become more and more attractive as an alternative protocol to establish carbon-carbon and carbon-heteroatom bonds. Diverse transformations through transition-metal-catalyzed C-S bond activation and cleavage have recently been developed. This review summarizes the advances in transition-metal-catalyzed cross-coupling via carbon-sulfur bond activation and cleavage since late 2012 as an update of the critical review on the same topic published in early 2013 (Chem. Soc. Rev., 2013, 42, 599-621), which is presented by the categories of organosulfur compounds, that is, thioesters, thioethers including heteroaryl, aryl, vinyl, alkyl, and alkynyl sulfides, ketene dithioacetals, sulfoxides including DMSO, sulfones, sulfonyl chlorides, sulfinates, thiocyanates, sulfonium salts, sulfonyl hydrazides, sulfonates, thiophene-based compounds, and C[double bond, length as m-dash]S functionality-bearing compounds such as thioureas, thioamides, and carbon disulfide, as well as the mechanistic insights. An overview of C-S bond cleavage reactions with stoichiometric transition-metal reagents is briefly given. Theoretical studies on the reactivity of carbon-sulfur bonds by DFT calculations are also discussed.