A New Pyrrole Synthesis via Silver(I)-Catalyzed Cycloaddition of Vinylogous Diazoester and Nitrile

Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N,N-diacyl-β-amino esters

An efficient multicomponent reaction of newly designed β-trifluoromethyl β-diazo esters, acetonitrile, and carboxylic acids via an interrupted esterification process under copper-catalyzed conditions has been developed, which affords various unsymmetrical β-trifluoromethyl N,N-diacyl-β-amino esters in good to excellent yields. The reaction features mild conditions, a wide scope of β-amino esters and carboxylic acids, and also applicability to large-scale synthesis, thus providing an efficient way for the synthesis of β-trifluoromethyl β-diacylamino esters. Furthermore, this reaction represents the first example of a Mumm rearrangement of β-trifluoromethyl β-diazo esters.

Rhodium-Catalyzed [3+2]-Cycloaddition of in-situ Generated Nitrile Ylides with Nitrosoarenes

Herein we report the rhodium-catalyzed one-pot three-component reaction of diazo compounds, nitriles, and nitrosoarenes to construct 2,5-dihydro-1,2,4-oxadiazole derivatives. Mechanistic studies indicate that the transformation may proceed through the formation of nitrile ylides intermediates, which then undergo [3+2]-cycloaddition with nitrosoarenes. The strategy exhibits several synthetic advantages, including operational simplicity, good functional group tolerance, and scalability.

Synthesis and Applications of π-Conjugation-Extended Vinyl Sulfoxonium Ylides

Herein, we report the synthesis of π-conjugation-extended vinyl sulfoxonium ylides from vinyl sulfoxonium ylide and electron-deficient alkynes. The new dienoate ylides are used in various transformations, such as X-H (X = S, O) insertion, halogenation, carbene-mediated transformation, and radical-mediated reductions to obtain a variety of conjugated dienoates.

Insights into the multifaceted applications of vinyl sulfoxonium ylides

Sulfoxonium ylides are important synthetic precursors in various organic transformations. Their synthetic potential was well explored in the synthesis of various bioactive natural products and pharmaceuticals. Vinyl sulfoxonium ylide is a stabilized sulfoxonium ylide containing an electron-deficient alkene at the ylidic carbon. Similar to α-keto sulfoxonium ylides, these reagents can generate vinyl carbenes in the presence of metals under suitable conditions. These vinyl carbenes can be used for various organic transformations such as X-H (X = C, N, O, S) insertions, annulations, and rearrangement reactions. Due to the dipole structure of the vinyl sulfoxonium ylide, it can undergo electrophilic addition with electrophiles at the α-position. These reagents are used as synthons for various aromatic and heteroaromatic compound syntheses. Moreover, their stability and convenient handling make them potential replacements for thermally less stable vinyl diazo compounds. Herein, we provide an overview of early efforts in this area, with particular emphasis on our own recent development of vinyl sulfoxonium ylide-mediated transformations in the presence and absence of metal catalysis, and also give personal perspectives on the challenges and future scope for improving the application of vinyl sulfoxonium ylides.

Ir(I)-Catalyzed Synthesis of Furanones from Vinyl Sulfoxonium Ylides

A method for the synthesis of allyl substituted γ-butenolides via carbonyl ylide rearrangement of vinyl sulfoxonium ylide-derived carbenes has been developed. At rt, the mechanism involves a carbonyl ylide generation/allyloxy furan formation/[3,3]-sigmatropic rearrangement/isomerization sequence for the generation of 3-allyl butenolides. At 70 °C, instead of the final isomerization step, the resulting [3,3]-sigmatropic rearrangement product undergoes further [3,3]-sigmatropic rearrangement to produce 5-allyl butenolide. In the absence of the catalyst, the reaction affords a diene via [2,3]-sigmatropic rearrangement.

The Renaissance of Organo Nitriles in Organic Synthesis

In the arena of functional group-oriented organic synthesis, the nitrile or cyano functionality is of immense importance. The presence of nucleophilic N -atom, π-coordinating ability of the triple bond, and electrophilic C-center imparts unique and interesting reactivity. Owing to the ability of the nitrile to transform into various other functional groups or intermediates, the chemistry is very rich and diverse. In particular, the involvement of nitrile in numerous organic reactions such as inter- or intramolecular alkyne insertion, [2 + 2 + 2] cycloaddition with alkynes, [3 + 2] cycloaddition with azides, [4 + 2] cycloaddition with diene allow the synthesis of many important carbocycles and heterocycles. Furthermore, the nitrile serves as a directing group in many C-H bond functionalization reactions to introduce diverse functionality and participate as a radical acceptor in radical cascade strategies to obtain a large variety of functional molecules. This review mainly focuses on the reactivity and diverse synthetic application of the nitrile including C-H bond functionalization, alkyne insertion, cycloaddition, and thermal or photochemical cascade strategy. The objective of the current review aims at bringing out the striking collection of various nitrile-triggered organic transformations.

AgI -Catalyzed Reaction of Enol Diazoacetates and Imino Ethers: Synthesis of Highly Functionalized Pyrroles

An unprecedented Ag^I -catalyzed efficient method for the coupling of imino ethers and enol diazoacetates through a [3+2]-cycloaddition/C-O bond cleavage/[1,5]-proton transfer cascade process is reported. The general class of imino ethers that includes oxazolines, benzoxazoles and benzimidates are applicable substrates for these reactions that provide direct access to fully substituted pyrroles with uniformly high chemo- and regioselectivity. High variability in substitution at the pyrrole 2-, 5- and N-positions characterizes this methodology that also presents an entry point for further pyrrole diversification via facile modification of resulting N-functional pyrroles.

Three-component reactions of aromatic amines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal to access N-(hetero)aryl-4,5-unsubstituted pyrroles

N-(Hetero)aryl-4,5-unsubstituted pyrroles were synthesized from (hetero)arylamines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal by using aluminum(III) chloride as a Lewis acid catalyst through [1 + 2 + 2] annulation. This new versatile methodology provides a wide scope for the synthesis of different functional N-(hetero)aryl-4,5-unsubstituted pyrrole scaffolds, which can be further derived to access multisubstituted pyrrole-3-carboxamides. In the presence of 1.2 equiv of KI, a polysubstituted pyrazolo[3,4-b]pyridine derivative was also successfully synthesized.

Tandem Carbenoid C-H Functionalization/Conia-ene Cyclization of N-Propargyl Indoles Generates Pyrroloindoles under Cooperative Rh(II)/Zn(II) Catalysis

The decomposition of diazodicarbonyl compounds in the presence of various metal catalysts has become a reliable method for the functionalization of indoles via carbenoid intermediates. Exploiting the nucleophilic reactivity of the in situ generated malonic ester product formed, we herein report a tandem C-H functionalization/Conia-ene cyclization of N-alkyne tethered indoles. This double functionalization of diazodicarbonyls generates a range of pyrrolo[1,2-a]-, pyrido[1,2-a]-, and azepino[1,2-a]indole products with good synthetic efficiency.

[3 + 2] Cycloaddition of Nitrile Ylides with Diazonium Salts: Copper-Catalyzed One-Pot Synthesis of Fully Substituted 1,2,4-Triazoles

A novel [3 + 2] cycloaddition between nitrile ylides and diazonium salts was well-established. This copper-catalyzed three-component reaction was distinguished by mild conditions, ready availability, and operational simplicity, thus opening access to 1,2,4-triazoles with a diverse set of substitution patterns.

Base-promoted C–C bond cleavage for the synthesis of 2,3,4-trisubstituted pyrroles from N-propargyl β-enaminones

The synthesis of 2,3,4-trisubstituted pyrroles via base-promoted C–C bond cleavage reaction of N-propargyl β-enaminones is reported.

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

A new approach towards the synthesis of multisubstituted thiophenes is elaborated based on Rh(II)-catalyzed domino reactions of acyclic diazoesters with α-cyanothioacetamides. It provides a way for the preparation of 5-amino-3-(alkoxycarbonylamino)thiophene-2-carboxylates, 2-(5-amino-2-methoxycarbonylthiophene-3-yl)aminomalonates and (2-cyano-5-aminothiophene-3-yl)carbamates with the preparative yields of up to 67%. It was also shown that α-cyanothioacetamides easily interact with dirhodium carboxylates to give rather stable 2:1 complexes, resulting in an evident decrease in the efficiency of the catalytic process at moderate temperatures (20–30 °C).

Recent developments in the group-1B-metal-catalyzed synthesis of pyrroles

Pyrroles are important synthetic targets as a result of their occurrence in numerous biologically active molecules, their important roles in diverse living processes, and their utility as versatile intermediates.

In situ generation of nitrilium from nitrile ylide and the subsequent Mumm rearrangement: copper-catalyzed synthesis of unsymmetrical diacylglycine esters

A novel in situ generation of nitrilium from nitrile ylide and the subsequent Mumm rearrangement of carboxylic acid, nitrile, and diazo compounds gave various unsymmetrical diacylglycine esters.

Access to steroidal pyridazines via modified thiohydrazides

Cytotoxic effects against breast cancer cells.

Iodine catalyzed one-pot synthesis of highly substituted N-methyl pyrroles via [3 + 2] annulation and their in vitro evaluation as antibacterial agents

A new class of highly substituted pyrroles have been synthesized via a simple, fast, and efficient method using environmentally friendly iodine catalyzed [3 + 2] annulation.

Metal-free, one-pot conversion of proline derivatives into 2-aryl-3-iodo pyrrolidines by a sequential scission-iodination-arylation process

The metal-free, direct conversion of readily available proline derivatives into 2-aryl-3-iodopyrrolidines is carried out under mild conditions and in good yields, using a sequential radical decarboxylation-oxidation-iodination-arylation reaction. These iodinated pyrrolidines are valuable precursors of other compounds. For instance, they can be cyclized to tricyclic compounds or undergo dehalogenation to 2-aryl-2,5-dihydro-1H-pyrroles, which are iminosugar and 2-arylpyrrole precursors. This process provides a short pathway to a variety of alkaloid and drug analogues of potential pharmaceutical interest.

A mild and efficient AgSbF6-catalyzed synthesis of fully substituted pyrroles through a sequential propargylation/amination/cycloisomerization reaction

Development of an efficient synthesis of fully substituted pyrroles via a sequential as a catalyst. The propargylation/amination/cycloisomerization was accomplished using AgSbF₆ one-pot three-component reaction of propargylic alcohols, 1,3-dicarbonyl compounds, and primary amines proceeds at a mild temperature, which prevents the formation of furan by-product. The reaction was also successfully applied to the more basic aliphatic amines with the addition of 1.1 eq. of acetic acid.

Synthesis of polysubstituted pyrroles via [3 + 2]-annulation of aziridines and β-nitroalkenes under aerobic conditions

Polysubstituted pyrroles are regioselectively synthesizedviathe copper acetate-catalyzed [3 + 2] annulation reaction of aziridines and nitroalkenes under aerobic conditions.