Chiral heterocycles

Enantioselective synthesis of chiral heterocycles containing both chroman and pyrazolone derivatives catalysed by a chiral squaramide.

An efficient chiral squaramide-catalysed enantioselective Michael addition of pyrazolin-5-ones to 3-nitro-2H-chromenes for the synthesis of chiral heterocyclic systems containing both chroman and pyrazolone derivatives has been developed. This reaction afforded the desired products in high to excellent yields (up to 98%) with high enantioselectivities (up to 96%) and excellent diastereoselectiv...

Does Nature Prefer Heterocycles?

Enantioselective synthesis of fused heterocycles with contiguous stereogenic centers by chiral phosphoric acid catalyzed symmetry breaking.

Described herein is a highly enantioselective synthesis of fused piperidine and pyrrolidine derivatives with all-carbon stereogenic centers. The enantioselective reductive amination from C(s)-symmetric 1,3-dione derivatives proceeded in a highly stereoselective manner by taking advantage of the desymmetrization approach to afford fused heterocycles with contiguous stereogenic centers in good to...

Catalytic Kinetic Resolution of Saturated N-Heterocycles by Enantioselective Amidation with Chiral Hydroxamic Acids.

The preparation of enantioenriched chiral compounds by kinetic resolution dates back to the laboratories of Louis Pasteur in the middle of the 19th century. Unlike asymmetric synthesis, this process can always deliver enantiopure material (ee > 99%) if the reactions are allowed to proceed to sufficient conversion and the selectivity of the process is not unity (s > 1). One of the most appealing...

Recent developments in the use of aza-Heck cyclizations for the synthesis of chiral N-heterocycles

Aza-Heck cyclizations are an emerging method for the construction of chiral N-heterocyclic systems. In these processes, an activated N-O bond replaces the C-X bond (X = halide, OTf) used in conventional Heck reactions, with the associated aza-Pd(ii)-intermediate engaging pendant alkenes in a Heck-like manner. This perspective article commences with an historical overview of the area, which stem...