3,4,5-Trimethylphenol and Lewis Acid Dual-Catalyzed Cascade Ring-Opening/Cyclization: Direct Synthesis of Naphthalenes

A 3,4,5-trimethylphenol and Lewis acid dual-catalyzed cascade reaction of donor–acceptor (D–A) cyclopropanes via ring-opening and cyclization is developed. In this reaction, a phenolic compound was used as a covalent catalyst for the first time. Additionally, control experiments proved that 3,4,5-trimethylphenol completed the catalytic cycle by accomplishing the C–C bond cleavage. Using this strategy, a wide variety of substituted naphthalenes has been synthesized from D–A cyclopropanes in moderate to high yields under mild conditions

Sc(OTf)₃ Catalyzed [4 + 2]-Annulation Reaction between Electron-Rich Phenols and Donor–Acceptor Cyclopropanes: Synthesis of Polysubstituted Dihydronaphthols

On the basis of the Lewis acid-catalyzed Friedel–Crafts alkylation between 1-acyl-2-arylcyclopropanecarboxylate esters and electron-rich phenols, a Sc­(OTf)₃ catalyzed cascade [4 + 2]-annulation reaction was developed for the direct synthesis of polysubstituted dihydronaphthols from phenols. In this reaction, the structure of products is dominated by the directing effect of the substituent groups on phenols. Meanwhile, a one-pot Friedel–Crafts alkylation/oxidative cyclization reaction was also developed for the synthesis of <i>spiro</i>-fused 2,5-cyclohexadienones

Visible-Light-Induced Aza-Pinacol Rearrangement: Ring Expansion of Alkylidenecyclopropanes

A novel visible-light-induced aza-pinacol rearrangement was developed for the first time. In this approach, the addition of the N-centered radical to the CC bond of alkylidenecyclopropanes delivers a variety of cyclobutanimines and γ-butyrolactones, with all-carbon quaternary centers via the ring expansion of the cyclopropyl group, in moderate to good yields under mild reaction conditions

Catalyst-Free Chemoselective Synthesis of 3,4-Dihydroquinazoline-2-thiones and 2‑Imino[1,3]benzothiazines

A solvent-controlled catalyst-free chemoselective reaction was developed. Both 3,4-dihydroquinazoline-2-thiones and 2-imino­[1,3]­benzothiazines could be efficiently constructed by the reaction of 2-amino chalcones with isothiocyanates via two different chemoselective reactions depending on the solvents. The reaction was modulated by the solvents to proceed via either aza-Michael addition or thia-Michael addition as the major reaction with excellent yields

Synthesis of Spirocyclic Oxindole Dihydrothiophenes by DBU-Catalyzed [3 + 2] Annulation of Morita–Baylis–Hillman Carbonates with Isothiocyanates

A highly regioselective DBU-catalyzed [3 + 2] annulation of Morita–Baylis–Hillman carbonates with isothiocyanates was developed. This method allows rapid and efficient synthesis of spirocyclic oxindole dihydrothiophene products in moderate to high yields with excellent regioselectivities under simple conditions. A plausible reaction mechanism is also proposed

Regiospecific Three-Component Aminofluorination of Olefins via Photoredox Catalysis

Direct visible-light-mediated aminofluorination of styrenes has been developed with high regioselectivity. Shelf-stable <i>N</i>-Ts-protected 1-aminopyridine salt was used as the nitrogen-radical precursor, and the commercially available hydrogen fluoride-pyridine was used as the nucleophilic fluoride source. The synthesis of an analogue of <b>LY503430</b> was performed to demonstrate the synthetic value of this strategy

Enantioselective Amine-Catalyzed [4 + 2] Annulations of Allene Ketones and 2,3-Dioxopyrrolidine Derivatives: Synthesis of 4<i>H</i>‑Pyran Derivatives

An efficient cinchona alkaloid-derived amine catalyzed asymmetric [4 + 2] cycloaddition is successfully developed. 4<i>H</i>-Pyran fused pyrrolin-2-one products are readily obtained in moderate to high yields with good enantioselectivites by employing allene ketones and 2,3-dioxopyrrolidine derivatives as substrates