Transition-Metal-Catalyzed Intramolecular Nucleophilic Addition of Carbonyl Groups to Alkynes

Unusual Reactivity of Isoquinolinones Generated by Silver-Catalyzed Cycloisomerizations of Imines Derived from ortho-Alkynylsalicylaldehydes

8-Isoquinolinones derived from a silver-catalyzed cycloisomerization of in situ formed ortho-alkynylsalicylaldimines react with 1 equiv of acetylenedicarboxylate derivatives to give pyrano[2,3,4- ij]isoquinolines through a [4 + 2]-cycloaddition reaction. When 2 equiv of the alkyne are used, structurally complex benzo[ de]chromenes are obtained through an intricate cascade process comprising unusual formal [4 + 2]- and [2 + 2]-cycloadditions followed by several ring-opening and ring-closing processes.

A Strategy To Obtain o-Naphthoquinone Methides: Ag(I)-Catalyzed Cyclization of Enynones for the Synthesis of Benzo[ h]chromanes and Naphthopyryliums

A new strategy to obtain o-NQM intermediates through a ring-formation strategy by Ag(I)-catalyzed cyclization of 2-alkenylphenyl alkynyl ketones and its [4 + 2] annulations with styrenes has been developed. This reaction features high efficiency, mild reaction conditions, as well as flexible substitutions and atom economy. The obtained benzo[ h]chromane products were further oxidized to naphthopyryliums, which displayed tunable photophysical properties.

Synthesis of 4-(1H-isochromen-1-yl)isoquinolines through the silver-catalysed homodimerization of ortho-alkynylarylaldehydes and subsequent condensation of the 1,5-dicarbonyl motif with NH3

4-(1H-Isochromen-1-yl)isoquinoline derivatives were synthesized in high yields via the AgBF₄-catalyzed self-reaction of ortho-alkynylarylaldehydes to give isochromene intermediates, followed by the dehydration of the 1,5-dicarbonyl motif with NH₃. Compared with electron-rich aromatic substituents, this strategy can provide the desired isochromene products with an electron-deficient isoquinoline unit. The reactions feature simple experimental operations, mild reaction conditions and high product yields.

We demonstrate a strategy that can provide isochromenes with an electron-deficient isoquinoline unit. The reactions feature simple operations, mild conditions and high yields.

Recent advances in catalytic asymmetric intermolecular oxidation of alkynes

In recent years, gold-metal-catalyzed intermolecular alkyne oxidation by an N-oxide oxidant, which presumably involves a gold carbenoid intermediate, has attracted increasing attention because it circumvents the employment of hazardous and potentially explosive diazocarbonyl compounds as starting materials for carbene generation.

Synergistic silver/scandium catalytic spiroketalization of β-alkynyl ketones for the atom economical synthesis of skeletally diverse spirocyclic isochromenes

Two types of new synergistic silver/scandium catalytic spiroketalizations of β-alkynyl ketones have been achieved, delivering a variety of skeletally diverse spirocyclic isochromenes in generally good yields.

Gold-catalyzed generation of azafulvenium from an enyne sulfonamide: rapid access to fully substituted pyrroles

A one-pot gold-catalyzed protocol for the synthesis of fully substituted pyrroles from enyne sulfonamides has been developed.

Enynone-enabled migratory insertion and Schmittel cyclization cascade for the synthesis of furan-fused fluorenes

A new method for the synthesis of furan-/benzo-fused fluorenes through copper(i)-catalyzed coupling of conjugated enynones or α-diazocarbonyl compounds with dialkynylbenzenes has been developed.

Palladium-catalyzed oxidative borylation of conjugated enynones through carbene migratory insertion: synthesis of furyl-substituted alkenylboronates

A new method for the synthesis of furyl-substituted alkenylboronates has been developed by palladium-catalyzed oxidative borylation reaction of conjugated enynones.

Harnessing the Polarizability of Conjugated Alkynes toward [2 + 2] Cycloaddition, Alkenylation, and Ring Expansion of Indoles

Reported is the utilization of electronically biased conjugated alkynes in the development of highly diastereo- and regioselective dearomative [2 + 2] cycloadditions, alkenylations, and ring expansions of electron-rich indoles. Regioselective protonations of cross- and linear-conjugated alkynes were found to be crucial for accessing various cyclobutene-fused indoline and alkenylated indole derivatives. Furthermore, the facile ring expansion of [2 + 2] keto adducts, which were successfully synthesized from ynones, provided 1 H-benzo[ b]azepine scaffolds.

Directing group assisted ZnI2-catalyzed cyclopropanation of indoles via 2-furylcarbenoids

An efficient method for the synthesis of cyclopropane-fused indolines via a Zn₂I catalyzed cyclopropanation of indoles and enynones was reported.

Donor- and acceptor-enynals/enynones

Three kinds of transformations based on benzo-fused donor- and acceptor-enynals/enynones, including reactions with alkenes, alkynes, and H₂O, were discussed.

Cu(i)-Catalyzed stereoselective synthesis of trisubstituted Z-enol esters via interrupting the 1,3-O-transposition reaction

An efficient Cu(i)-catalyzed stereoselective synthesis of trisubstituted Z-enol esters via interrupting the 1,3-O-transposition process is reported, which provided a convenient approach to highly functionalized Z-enol esters.