Efficient Synthesis of 1,5-Disubstituted Carbohydrazones Using K₂CO₃ As a Carbonyl Donor

A novel reaction that generates 1,5-disubstituted carbohydrazones via the carbonylation of tosylhydrazones has been developed. For the first time, the inexpensive, readily available, environmentally friendly, and nongaseous potassium carbonate is used as the carbonyl donor for the transformation. The reaction system exhibited tolerance with various functional groups and affords the desired products in good to excellent yields. This reaction is expected to be a powerful tool for the synthesis of carbohydrazone compounds

Cu-Catalyzed Carbon-Heteroatom Coupling Reactions under Mild Conditions Promoted by Resin-Bound Organic Ionic Bases

Resin-bound organic ionic bases (RBOIBs) were developed in which tetraalkyl-ammonium or phosphonium cations are covalently attached to solid resins. The application tests showed that the performance of the tetraalkyl-ammonium-type RBOIBs is slightly better than that of the corresponding Cs salts in Cu-catalyzed C−N cross-couplings, while the tetraalkylphosphonium-type RBOIBs are significantly better than all the inorganic bases. With these newly developed RBOIBs, room-temperature Cu-catalyzed C−N coupling with various nonactivated aryl iodides and even aryl bromides can be readily accomplished. Moreover, RBOIBs can be easily recycled and reused for a number of times without much drop of activity. The good performances of RBOIBs are proposed to arise from the relatively weak binding forces between the cationic polymer backbone and basic anions, as opposed to the strong metal−anion interactions in the inorganic bases. Further applications of RBOIBs in Ni-catalyzed Suzuki-type couplings at room temperature, Cu-catalyzed C−N couplings at −30 °C, a Pd-catalyzed Heck reaction at 60 °C, and Cu-catalyzed C−S couplings at room temperature demonstrate that RBOIBs are generally applicable bases with improved performance for many other types of organic transformations

Copper-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides and Tosylates with Secondary Alkyl Grignard Reagents

Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an S_N2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C–C bonds between two tertiary carbons from chiral secondary alcohols

Copper-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides and Tosylates with Secondary Alkyl Grignard Reagents

Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an S_N2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C–C bonds between two tertiary carbons from chiral secondary alcohols

Copper-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides and Tosylates with Secondary Alkyl Grignard Reagents

Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an S_N2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C–C bonds between two tertiary carbons from chiral secondary alcohols

Copper-Catalyzed/Promoted Cross-coupling of <i>gem</i>-Diborylalkanes with Nonactivated Primary Alkyl Halides: An Alternative Route to Alkylboronic Esters

The first copper-catalyzed/promoted sp³-C Suzuki–Miyaura coupling reaction of <i>gem</i>-diborylalkanes with nonactivated electrophilic reagents is reported. Not only 1, 1-diborylalkanes but also some other <i>gem</i>-diborylalkanes can be coupled with nonactivated primary alkyl halides, offering a new method for sp³C–sp³C bond formation and, simultaneously, providing a new strategy for the synthesis of alkylboronic esters