We disclosed a novel water-soluble photocatalyst that could promote aerobic oxidative hydroxylation of arylboronic acids to furnish phenols in excellent yields. This transformation uses visible-light irradiation under environmentally friendly conditions, that is, water-soluble catalyst, metal-free, green oxidant, room temperature.

A highly selective para C–H amination of unprotected phenols with iminoquinone acetals was realized, giving the functional phenols in good to excellent yields. Overall, this transformation is operationally simple, proceeds with readily available phenols, and has wide substrate scope and low catalyst loading. The biarylamine product is stochastically formed via [5,5]-sigmatropic rearrangement of a mixed acetal species which is generated in situ under the reaction conditions.

AbstractA high-yielding, copper-catalyzed dearomatization reaction of indole from 2-methylindole-derived oxime acetates was realized, providing access to structurally novel spiro[indoline-3,2′-pyrrolidine] derivatives in 67–98% yields. When the C-2 position of the indole was not substituted, azacarbazole derivatives were obtained in moderate yields. This transformation provides an efficient approach to access nitrogen-containing spiroindolenine and azacarbazole derivatives with wide substrate scope.

The [1,5]-hydride shift/cyclization process as a new Csp³–H bond functionalization has made tremendous advances over the past decades. Herein, we describe reaction pathways for a [1,5]-hydride shift that is triggered by acid. In these transformations, the diene isoindoles are generated in situ and undergo a reaction with different dienophiles to provide access to a series of bridged-ring heterocycles and polycycles in good yields (up to 94 %). In addition, we found that the choice of acid played a critical role and could be used to control the structure of the final product.

A formal [4 + 2] cycloaddition reaction of 1,3-disubstituted indoles and alkylquinones was realized to furnish polycyclic indolines in good yields. This protocol proceeded smoothly under basic conditions, with high atom-economy and broad substrate scope.

Herein we disclose a scalable organocatalytic direct arylation approach for the regio- and atroposelective synthesis of non-C2-symmetric 2,2′-dihydroxy-1,1′-binaphthalenes (BINOLs). In the presence of catalytic amounts of axially chiral phosphoric acids, phenols and naphthols are coupled with iminoquinones via a cascade process that involves sequential aminal formation, sigmatropic rearrangement, and rearomatization to afford enantiomerically enriched BINOL derivatives in good to excellent yields. Our studies suggest that the (local) symmetry of the initially formed aminal intermediate has a dramatic impact on the level of enantioinduction in the final product. Aminals with a plane of symmetry give rise to BINOL derivatives with significantly lower enantiomeric excess than unsymmetrical ones featuring a stereogenic center. Presumably asymmetric induction in the sigmatropic rearrangement step is significantly more challenging than during aminal formation. Sigmatropic rearrangement of the enantiomerically enriched aminal and subsequent rearomatization transfers the central chirality into axial chirality with high fidelity.

The Rh(II)-catalyzed sulfur ylide [1,2]-rearrangement of carbenoids generated from aryldiazoacetates has been realized via N–S bond insertion, generating tertiary sulfides in moderate to excellent yields. This demonstrates the first use of the sulfur ylide [1,2]-rearrangement undergoing N–S bond insertion. This protocol could proceed smoothly with high regioselectivity, low catalyst loading (0.1 mol% Rh2(OAc)4), gram-scale reaction and broad substrate scope. And the product could be converted into glycine derivatives through simple procedures.

Visible-light induced isoindole formation triggered an intermolecular Diels–Alder reaction with dienophiles such as acetylenedicarboxylate and maleimides in the presence of air. The reaction resulted in excellent diastereoselctivity and high yields under mild reaction conditions. This protocol provides an atom-economical, transition-metal-free (TM-free) and straightforward approach to structurally diverse bridged-ring heterocycles from easily accessible molecules.

An efficient and straightforward method for the rapid synthesis of 2-substituted dihydrobenzofurans has been developed via reaction of sulfur ylides with o-quinone methides (o-QMs), which were generated under mild conditions. The products could be obtained in excellent yields with various kinds of sulfur ylides.

A concise synthesis of spiroindolenines from 2-substituted (Me, Et) indoles and 2-(pyrrolidin-1-yl)benzaldehydes has been developed via a [1,5]-hydride shift/cyclization sequence. This method features a wide substrate scope and an operationally simple procedure, affording the spiroindolenines in good to excellent yields and moderate diastereoselectivity (3.5/1 dr). When the inseparable mixture of spiroindolenine isomers were washed with isopropyl ether after flash chromatography, the major isomers could be obtained in up to >20/1 dr.

A practical method to synthesize N-aryl pyrrole derivatives involving O-alkylated quinone methides as hydride acceptors has been developed via [1, 5]-hydride shift/isomerization cascade under acidic condition. The desired product could be obtained in moderate to good yields with broad substrate scope.

A practical and efficient stereoselective synthesis of arylglycine derivatives was realized via palladium-catalyzed α-arylation of a chiral nickel(II) glycinate complex with aryl bromides. The structurally diverse arylglycine products were obtained in excellent isolated yields and with good diastereoselectivity. A simple acidic hydrolysis furnished optically pure arylglycines in high yield, and the chiral ligand (S)-BPB could be efficiently recovered and reused.

Expeditious access to oxadiazepines via 1,5-hydride shift/cyclization of pyrrolidine- or tetrahydroisoquinoline-containing nitrones has been developed. With 1,3-dipole nitrones serving as the hydride acceptors, this transformation was promoted by a Lewis acid, providing access to structurally diverse oxadiazepines in good yields. A one-pot process for in situ nitrone formation, a 1,5-hydride shift, and ring cyclization was also realized.

The Rh(II)-catalyzed sulfur ylide [1,2]-rearrangement of carbenoids generated from aryldiazoacetates has been realized via N–S bond insertion, generating tertiary sulfides in moderate to excellent yields. This demonstrates the first use of the sulfur ylide [1,2]-rearrangement undergoing N–S bond insertion. This protocol could proceed smoothly with high regioselectivity, low catalyst loading (0.1 mol% Rh2(OAc)4), gram-scale reaction and broad substrate scope. And the product could be converted into glycine derivatives through simple procedures.

A formal [4 + 2] cycloaddition reaction of 1,3-disubstituted indoles and alkylquinones was realized to furnish polycyclic indolines in good yields. This protocol proceeded smoothly under basic conditions, with high atom-economy and broad substrate scope.