Haibo Mei

Cu-Catalyzed Deoxygenative C2-Sulfonylation Reaction of Quinoline N-Oxides with Sodium Sulfinate

An unexpected Cu-catalyzed deoxygenative C2-sulfonylation reaction of quinoline N-oxides in the presence of radical initiator K2S2O8 was developed that used sodium sulfinate as a sulfonyl coupling partner. The mechanism studies indicate that the reaction proceeds via Minisci-like radical coupling step to give sulfonylated quinoline with good chemical yields.

LDA-promoted asymmetric synthesis of β-trifluoromethyl-β-amino indanone derivatives with virtually complete stereochemical outcome

We demonstrate that reactions between various 1-indanones and (SS)-N-tert-butanesulfinyl-(3,3,3)-trifluoroacetaldimine, conducted in the presence of catalytic amounts of LDA, occur with virtually complete stereochemical outcome, offering reliable and generalized access to biologically relevant β-trifluoromethyl-β-amino indanone derivatives. The products can be isolated in diastereomerically pure form simply by washing the crude reaction mixture with hexanes, underscoring practicality of the present method.

Oxidative Difunctionalization of Alkynoates through Alkylation and Migration Decarboxylative Arylation

A cascade oxidative difunctionalization reaction of alkynoates for the construction of trisubstituted olefins has been developed. The process undergoes alkylation of a C-C triple bond, 1,4-aryl migration, and decarboxylation, which demonstrates a multistep radical cascade reaction for the difunctionalization of alkynoates and also represents a strategy of direct decarboxylation of esters.

Transition-metal-free oxidative reaction of hydrazines and potassium metabisulfite for preparation of sulfonohydrazides

A transition-metal-free oxidative coupling reaction for the synthesis of sulfonohydrazides from two types of hydrazines and potassium metabisulfite under air has been developed. This highly selective reaction used one arylhydrazine as an aryl coupling partner and potassium metabisulfite as a sulfur dioxide precursor, which provides a new and green strategy to sulfonohydrazides.

Hydroxyalkylation-initiated radical cyclization of N-allylbenzamide for direct construction of isoquinolinone.

A metal-free hydroxyalkylation-initiated radical six-membered heterocycle formation reaction of N-allylbenzamide is developed. This reaction proceeds through C(sp(3))-H bond cleavage, oxyalkylation of the double bond, and intramolecular cyclization, which provides a new route toward 4-substituted 3,4-dihydroisoquinolin-1(2H)-one derivatives.

Metal-Free Oxidative Functionalization of a C(sp3)–H Bond Adjacent to Nitrogen and Intramolecular Aromatic Cyclization for the Preparation of 6-Amidophenanthridines

A metal-free cyclization reaction of 2-isocyanobiphenyls with amide derivatives by using tert-butyl peroxybenzoate (TBPB) as oxidant was developed, which provided an access to pharmacologically interesting 6-amidophenanthridine compounds. The reactions proceeded through a sequence of functionalization of the C(sp(3))-H bond adjacent to the nitrogen atom and intramolecular radical aromatic cyclization with good chemistry yields.

Asymmetric Friedel-Crafts reactions of N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines: general access to enantiomerically pure indoles containing a 1-amino-2,2,2-trifluoroethyl group.

We have demonstrated that 3,3,3-trifluoroacetaldimine (S)-1 easily reacts with indole derivatives under Friedel-Crafts reactions to provide reliable and generalized access to biologically interesting compounds containing the CF3CH(NH2)- pharmacophoric group. The reactions proceed with high rates and generally excellent yields (>90%) and stereochemical outcomes (99:1 dr).

Ni-Catalyzed Reductive Cross-Coupling of Amides with Aryl Iodide Electrophiles via C–N Bond Activation

A Ni-catalyzed reductive cross-coupling reaction between two electrophiles, amides and aryl iodides, has been developed. This work is the first example using amide as an electrophile to couple with another electrophile, instead of using highly basic and pyrophoric nucleophiles. Furthermore, the Ni catalyst chemoselectively inserting the C-N bond of amide triggered the reductive cross-coupling reaction, which solves the problem that the Ni catalyst preferentially inserts the more reactive C-I bond to form a self-coupling product.

Sunlight-promoted cyclization versus decarboxylation in the reaction of alkynoates with N-iodosuccinimide: easy access to 3-iodocoumarins

A sunlight-initiated radical conversion of aryl alkynoates to 3-iodocoumarins has been achieved using N-iodosuccinimide as the iodine source without the use of a catalyst or additive. Experimental, X-ray analysis, and computational studies indicate that the reaction under sunlight proceeds through iodination, spirocyclization and ring expansion to form the kinetic product. The sunlight-driven reaction provides a green pathway to especially valuable 3-halocoumarins derivatives.

Synthesis of Trifluoromethyl-Containing Vicinal Diamines by Asymmetric Decarboxylative Mannich Addition Reactions

Herein is reported a study of asymmetric decarboxylative Mannich addition reactions between (Ss)-N-t-butylsulfinyl-3,3,3-trifluoroacetaldimine and Schiff bases derived from various aldehydes and lithium 2,2-diphenylglycinate. These reactions proceed with excellent diastereoselectivities and good chemical yields, providing a practical method for preparation of trifluoromethyl-containing vicinal diamines. The procedures can be conducted under convenient conditions, rendering this approach of high synthetic value.