Zhengkai Chen

Ru-Catalyzed Synthesis of Dihydrofuroquinolines from Azido-cyclopropyl Ketones

An efficient Ru-catalyzed synthesis of dihydrofuroquinolines from azido-cyclopropyl ketones via the reduction-cyclization-rearrangement process is reported. A plausible reaction mechanism for this process is depicted. Additionally, when the reaction was carried out under H2 (1 atm) in the presence of Pd/C, 4-quinolones were obtained in excellent yields.

I2-Catalyzed Oxidative Coupling Reactions of Hydrazones and Amines and the Application in the Synthesis of 1,3,5-Trisubstituted 1,2,4-Triazoles

A general and expeditious approach for the metal-free mediated synthesis of 1,3,5-trisubstituted 1,2,4-triazoles from hydrazones and aliphatic amines has been achieved under aerobic oxidative conditions. The reaction proceeds through a cascade C-H functionalization, double C-N bonds formation, and oxidative aromatization sequence.

Catalyst-Controlled Chemodivergent Modification of Indoles with 2-Furylcarbinols: Piancatelli Reaction vs Cross-Dehydrative Coupling Reaction

A divergent synthetic strategy to functionalize the indole nucleus with readily available 2-furylcarbinols was developed. It was found that the 3-(4-oxo-2-cyclopentenyl)indoles were obtained in moderate to good yields (up to 89%) through Piancatelli reaction catalyzed by ZnCl2, whereas employment of Brønsted acid TFA afforded directly coupled product 3-(2-furyl)indoles in moderate to good yields (up to 87%) via the deprotonation-rearomatization route.

Solvent-Controlled, Tunable Hydrosulfonylation of 3-Cyclopropylideneprop-2-en-1-ones

An interesting and tunable hydrosulfonylation of 3-cyclopropylideneprop-2-en-1-ones with sodium sulfinates and acetic acid is described. The corresponding β- or γ-addition products can be produced in good to excellent yields with high selectivities, respectively. A rationale for these transformations is proposed base on the controlled experiments.

Lewis Acid Catalyzed Regiospecific Cross-Dehydrative Coupling Reaction of 2-Furylcarbinols with β-Keto Amides or 4-Hydroxycoumarins: A Route to Furyl Enols

Lewis acid catalyzed directly dehydrative carbon-carbon bond formation reaction of 2-furylcarbinols with β-keto amides provides a straightforward method for regioselective synthesis of (Z)-furyl enols. Moreover, this Lewis acid catalyzed cross-coupling reaction can be extended to an interesting heterocyclic version featuring a functionalized 3-furyl-4-hydroxycoumarin synthesis.

1,2-Gold Carbene Transfer Empowers Regioselective Synthesis of Polysubstituted Furans

A gold-catalyzed cascade cycloisomerization/ring-opening reaction of allenyl ketones bearing a cyclopropyl moiety with a wide variety of alcohols or ketones is developed. This reaction involves an unprecedented 1,2-gold carbene transfer to provide regioselective and modular access to tri- or tetrasubstituted furans in moderate to high yields and with broad substrate tolerability.

A modular approach to highly functionalized 3-sulfonylfurans via conjugate addition of 3-cyclopropylideneprop-2-en-1-ones with sodium sulfinates and sequential 5-endo-trig iodocyclization

A highly efficient conjugate addition and 5-endo-trig cyclization reaction of 3-cyclopropylideneprop-2-en-1-ones with sodium sulfinates in the presence of iodine is described. A wide variety of densely functionalized 3-sulfonylfurans are furnished by single-step and one-pot methods, respectively. The results of such postcyclization modifications are also presented.

Strain-Promoted Nitration of 3-Cyclopropylideneprop-2-en-1-ones and the Application for the Synthesis of Pyrroles

The tunable nucleophilic nitration of 3-cyclopropylideneprop-2-en-1-ones with cheap sodium nitrite is described. This transformation proceeds with the assistance of a strained cyclopropane ring and allows for a divergent route to various synthetically useful β,γ-dinitro or γ-mononitro adducts in high yields with exclusive regio- and stereoselectivity. Additionally, a wide array of valuable functionalized N-unprotected pyrroles is achieved from the resulting β,γ-dinitro compounds via reductive cyclization strategy.

Transition-Metal-Free Arylation and Alkylation of Diarylmethyl p-Tolyl Sulfones with Zinc Reagents

The transition-metal-free synthesis of unsymmetrical and highly functionalized triarylmethanes through arylation of the situ generated o-QMs from diarylmethyl p-tolyl sulfones with aryl zinc reagents is described. Alkyl zinc reagents are also well tolerated in this reaction. Additionally, the straightforward synthesis of the analogue of the antituberculosis agent A and the key precursor of the anti-breast-cancer agent B are achieved by this strategy.

Transition metal-free tandem pyridinyl–allyl–allyl cross-coupling reaction

ABSTRACT A transition metal-free, direct one-pot domino allylation reaction of 2-pyridinyl Grignard reagents with polysubstituted allyl chlorides for the regioselective synthesis of pyridinyl-substituted 1,5-diene derivatives has been disclosed. The reaction presumably proceeded through the coupling of polysubstituted allyl chloride to 2-PyMgX, which was in situ generated from 2-bromopyridine with i-PrMgCl·LiCl. GRAPHICAL ABSTRACT