Hao-Yue Xiang

Visible-Light-Driven, Radical-Triggered Tandem Cyclization of o-Hydroxyaryl Enaminones: Facile Access to 3-CF2 /CF3-Containing Chromones

A practical and straightforward synthetic route to construct a variety of 3-CF2/CF3-containing chromones via photoredox catalysis was developed. This novel protocol features a visible-light-induced radical-triggered tandem cyclization.

L-Pyroglutamic Sulphonamide as Hydrogen-Bonding Organocatalyst: Enantioselective Diels–Alder Cyclization to Construct Carbazolespirooxindoles

Hydrogen-bonding organocatalysts L-pyroglutamic sulphonamides were readily synthesized for the first time by fully exploiting the potentials of L-pyroglutamic acid. The newly designed catalyst was successfully applied in catalyzing asymmetric Diels-Alder cyclization of methyleneindolinones with 2-vinyl-1H-indoles to efficiently assemble carbazolespirooxindoles in excellent stereoselectivity (up to 99% ee, >20:1 dr) and yields (up to 99%). Mechanistic studies disclosed that the well-designed hydrogen-bonding modes between L-pyroglutamic sulphonamide and substrates were crucial for stereocontrol in the cyclization.

Visible-Light-Induced External Radical-Triggered Annulation To Access CF2-Containing Benzoxepine Derivatives

A facile and diversified synthesis of functionalized CF2-containing benzoxepine derivatives via photoredox catalysis was achieved in this work. This novel protocol features broad substrate scope, mild reaction conditions, operational simplicity, easy scale-up, and versatile derivatization, which would facilitate its practical and broad applications in the construction of valuable and synthetically challenging heterocycles.

Solvent-Minimized, Chromatography-Free, Diastereoselective Synthesis of Oxazolidine-Dispirooxindoles via oxa-1,3-Dipolar Cycloaddition of 3-Oxindole

An efficient and diastereoselective decarboxylative oxa-1,3-dipolar cycloaddition between 3-oxindoles and diverse amino acids is developed to access novel oxazolidine-dispirooxindole skeletons bearing vicinal quaternary carbon centers. This protocol features operational simplicity, a broad substrate scope, and good to excellent chemical yields and diastereoselectivities. In particular, minimal solvent (1 mL/10 mmol) and chromatography-free purification render this synthetic process more efficient and environmentally benign in the context of green chemistry.

Selectfluor-Triggered Tandem Cyclization of o-Hydroxyarylenaminones To Access Difluorinated 2-Amino-Substituted Chromanones

A practical and straightforward synthetic route through a Selectfluor-triggered tandem cyclization of o-hydroxyarylenaminone was developed to construct a variety of difluorinated 2-amino-substituted chromanones. This novel protocol features mild reaction conditions, operational simplicity, and broad substrate scope. The enamine moiety in o-hydroxyarylenaminone played dual roles to enable high efficiency in the difluorination and intramolecular cyclization, leading to the accomplishment of a new class of difluorinated 2-amino-substituted chromanones for pharmaceutical studies.

Photoredox-catalyzed direct aminoalkylation of isatins: diastereoselective access to 3-hydroxy-3-aminoalkylindolin-2-ones analogues

A practical protocol for the direct aminoalkylation of isatins with tetrahydroisoquinolines and other amines via a photoredox catalyzed radical–radical cross-coupling process is described. Various 3-hydroxy-3-aminoalkylindolin-2-ones with eminent diastereoselectivity were efficiently assembled in good to excellent yield under mild conditions, thus providing a facile route to rapidly access 3-substituted-3-hydroxyindolin-2-ones of potential biological importance.

Organocatalytic Domino Entry to an Octahydroacridine Scaffold Bearing Three Contiguous Stereocenters

A facile and enantioselective access to a functionalized octahydroacridine scaffold was developed via an organocatalytic domino sequence between cyclohexenone and 2- N-substituted benzaldehyde. High levels of yields (up to 99%) and enantioselectivities (up to 99:1 er) were readily achieved in this developed organocatalytic transformation, which holds promising applications in the construction of complex multicyclic systems for further pharmacological studies.

Facile oxidative cyclization to access C2-quaternary 2-hydroxy-indolin-3-ones: synthetic studies towards matemone

A concise and facile approach for the construction of 2-hydroxy-2-substituted indol-3-ones was developed through an oxidative cyclization of 2-aminophenyl-1,3-dione. Using CAN and TEMPO as oxidants, C2-quaternary 2-hydroxy-indolin-3-ones were efficiently installed in moderate to excellent yields (up to 99%). Moreover, this developed protocol was further applied to synthetic studies towards natural product matemone by starting from readily available 2-amino-4-bromobenzoic acid, and the precursor for matemone was efficiently installed.

Organocatalytic Asymmetric Allylic Alkylation of Morita–Baylis–Hillman Carbonates with Diethyl 2-Aminomalonate Assisted by In Situ Protection

With the aid of in situ protection by N-(2-formylphenyl)-4-methyl-benzenesulfonamide, enantioselective allylic alkylation of Morita-Baylis-Hillman carbonates with diethyl 2-aminomalonate was successfully realized. The corresponding adducts can be obtained in up to 99% yield with up to 98% ee as well as excellent regioselectivity. Besides, the adducts with opposite configurations were readily prepared by utilizing easily available and inexpensive quinine or quinidine as organocatalyst. Facile deprotection of the resulting adduct provides straightforward access to enantiopure α-methylene-γ-lactam.