Cu(ii) catalyzed oxidation-[3+2] cycloaddition-aromatization cascade: Efficient synthesis of pyrrolo [2, 1-a] isoquinolines

Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

Pyrrolo[2,1-a]isoquinoline alkaloids have been prepared via a visible light photoredox catalyzed oxidation/[3 + 2] cycloaddition/oxidative aromatization cascade using Rose Bengal as an organo-photocatalyst. A variety of pyrroloisoquinolines have been obtained in good yields under mild and metal-free reaction conditions.

A general, simple and green process to access pyrrolo[2,1-a]isoquinolines using a KI/TBHP catalytic system

A novel KI/TBHP-catalyzed 1,3-dipolar cycloaddition/oxidation/aromatization cascade reaction provided a general, efficient and green access to biologically important pyrrolo[2,1-a]isoquinolines.

Molecular iodine induced/1,3-dipolar cycloaddition/oxidative aromatization sequence: an efficient strategy to construct 2-substituted benzo[f]isoindole-1,3-dicarboxylates

A useful method for a molecular iodine induced 1,3-dipolar cycloaddition/oxidative aromatization sequence to construct 2-substituted-benzo[f]isoindole-1,3-dicarboxylates is reported.

Selective synthesis of polyfunctionalized hydroisoquinoline derivatives via a three-component domino reaction

Two series of novel polyfunctionalized hydroisoquinoline derivatives have been synthesized via a three-component domino reaction under microwave irradiation conditions.

Copper-catalyzed reductive coupling of aryl sulfonyl chlorides with H-phosphonates leading to S-aryl phosphorothioates

An efficient protocol for copper-catalyzed direct cross-coupling of aryl sulfonyl chlorides with H-phosphonates has been developed. The various S-aryl phosphorothioates were afforded in up to 86% yield for 20 examples.

Synthesis of pyrrolo[2,1-a]isoquinolines by multicomponent 1,3-dipolar cycloaddition

Pyrrolo[2,1-a]isoquinoline derivatives were synthesized by one-pot three-component reactions starting from isoquinoline, 2-bromoacetophenones and different non-symmetrical acetylenic dipolarophiles using 1,2-epoxypropane as solvent. The structure of the compounds was assigned by IR and NMR spectroscopy.

Development of cascade reactions for the concise construction of diverse heterocyclic architectures

Heterocyclic structural architectures occur in many bioactive natural products and synthetic drugs, and these structural units serve as important intermediates in organic synthesis. This Account documents our recent progress in the development of cascade reactions to construct complex carbocycles and heterocycles. We describe the rational design of cascade reactions and in-depth investigations of their mechanism as well as their applications in the synthesis of drugs, natural products, and related molecular analogs. Relying on knowledge about the dipole-type reactivity of sulfur ylides, we have developed three different types of cascade reactions: a [4 + 1] annulation/rearrangement cascade, a [4 + 1]/[3 + 2] cycloaddition cascade, and a Michael addition/N-alkylation cascade. Using these processes, we can generate oxazolidinones, fused heterocycles, and pyrrolines starting with simple and readily available substances such as nitroolefins and unsaturated imines. We have also developed corresponding enantioselective reactions, which are guided by axial chirality and asymmetric H-bonding control. In addition, by relying on the reactivity characteristics of newly designed acrylate-linked nitroolefins, we have disclosed an asymmetric Michael/Michael/retro-Michael addition cascade using the combination of a protected hydroxylamine and a bifunctional organocatalyst. Using this methodology, we prepared chiral chromenes in good yields and with high enantioselectivities. Moreover, a series of double Michael addition cascade reactions with anilines, thiophenols, and benzotriazoles generated highly functionalized chromanes. Via mechanistically distinct cascade processes that start with vinyl-linked indoles, we have synthesized polycyclic indoles. Intermolecular cross-metathesis/intramolecular Friedel-Crafts alkylation cascades, promoted by either a single ruthenium alkylidene catalyst or a sequence involving Grubbs' ruthenium catalyst and MacMillan's imidazolidinone catalyst, converted ω-indolyl alkenes into tetrahydrocarbazoles, tetrahydropyranoindoles, and tetrahydrocarbolines. In addition, we constructed tetrahydrocarbazoles and tetrahydroquinones using organocatalytic Friedel-Crafts alkylation/Michael addition cascades that used 2-vinyl indoles as common starting materials. Most green plants carry out photosynthesis to produce organic substances relying on readily available and renewable solar energy. In a related manner, we have also developed two cascade reactions that merge visible light-induced aerobic oxidation with either [3 + 2] cycloaddition/oxidative aromatization or intramolecular cyclization. These processes lead to the formation of pyrrolo[2,1-a]isoquinolines and enantiopure tetrahydroimidazoles, respectively.

Recent advances in copper-catalyzed dehydrogenative functionalization via a single electron transfer (SET) process

Copper salts have been developed as versatile catalysts for oxidative coupling reactions in organic synthesis. During these processes, Cu-catalysts are often proposed to serve as a one-electron oxidant to promote the single-electron transfer process. Recently, the transition-metal catalyzed direct dehydrogenative transformation has attracted considerable attention. This tutorial review summarizes the recent advances in the copper-catalyzed dehydrogenative functionalization via a single electron transfer (SET) process achieving C-C, C-N, C-O, C-halogen atoms, C-P, and N-N bond formation.

2,4-Diphenyl-6-trifluoro-methyl-2,3-dihydro-1H,5H-pyrrolo-[3,4-c]pyrrole-1,3-dione

The asymmetric unit of the title compound, C₁₉H₁₁F₃N₂O₂, contains two crystallographically unique mol­ecules which differ in the rotation of a phenyl ring and a –CF₃ substituent. The dihedral angles involving the pyrrole ring and the attached phenyl ring are 62.82 (8) and 71.54 (7)° in the two molecules. The difference in the rotation of the CF₃ groups with respect to the pyrrolo rings to which they are attached is 23.5(1)°. For one mol­ecule, there is a close contact between an H atom and the centroid of the phenyl ring of an adjacent mol­ecule (2.572 Å). A similar contact is lacking in the second mol­ecule. In the crystal, N—H⋯O inter­actions connect adjacent mol­ecules into a chain normal to (01). Crystallographically unique mol­ecules alternate along the hydrogen-bonded chains.

Three-component synthesis of polysubstituted pyrroles from α-diazoketones, nitroalkenes, and amines

Polysubstituted pyrroles are regiospecifically synthesized via the copper-catalyzed three-component reaction of α-diazoketones, nitroalkenes, and amines under aerobic conditions. The cascade process involves an N-H insertion of carbene, a copper-catalyzed oxidative dehydrogenation of amine, and a [3 + 2] cycloaddition of azomethine ylide.

Visible light mediated azomethine ylide formation-photoredox catalyzed [3+2] cycloadditions

The synthesis of highly functionalised N-heterocycles has been achieved by the visible light mediated photoredox conversion of tertiary amines to azomethine ylides and their further reaction with maleimide derivatives as dipolarophiles.