Lingkai Kong

LDA-Promoted Synthesis of 3-Amino Furans by Selective Lithiation of Enaminones

An efficient cascade β-metalation/addition/cyclization reaction promoted by LDA is described in which 3-amino furans were constructed from enaminones and aldehydes. A broad range of substituents on the starting compounds was tolerated, and the polysubstituted furans were gained with moderate to excellent yields within 2 h.

Transition-Metal-Free Ring Expansion Reactions of Indene-1,3-dione: Synthesis of Functionalized Benzoannulated Seven-Membered Ring Compounds

A novel ring expansion reaction of indene-1,3-dione with alkynyl ketones under transition-metal-free conditions has been developed. This process offers an efficient and direct way to synthesize benzoannulated seven-membered rings or fused-ring compounds through C-C σ-bond activation. Notable features of the procedure include easily accessible starting materials, good functional group tolerance, and high atom economy.

Cobalt-catalyzed regioselective syntheses of indeno[2,1-c]pyridines from nitriles and diynes bearing propargyl fragments

A highly efficient CoI2/o-phenanthroline catalyzed cycloaddition reaction of diynes bearing TBS protected propargylic alcohol fragments with nitriles has been developed. This methodology offers regioselective access, with good functional group tolerance, to various indeno[2,1-c]pyridine derivatives in moderate to excellent yields. It was found that o-phenanthroline as a bidentate nitrogen ligand showed high efficacy in this cycloaddition reaction.

Sequential C–C σ-Bond Cleavage/(sp2) C–O Bond Formation via C–H Functionalization toward Pyranoindolones Fused with Medium-Sized Rings

An atom-economical procedure for the synthesis of pyranoindolones fused with 7- or 8-membered rings has been developed. This process is realized through the sequential Cs2CO3-promoted C-C σ-bond cleavage of cyclic ketoesters and a ZnI2-mediated selective C-H/O-H coupling reaction. Two of the C-C σ-bonds are cleaved and one of the sp2 C-H bonds is functionalized during the reaction process. Easily accessible starting materials and broad substrate scope make this protocol attractive in synthetic organic chemistry.