A novel chiral DMAP–thiourea bifunctional catalyst catalyzed enantioselective Steglich and Black rearrangement reactions

Abstract

A novel chiral DMAP–thiourea bifunctional catalyst has been prepared and applied in the highly enantioselective Steglich and Black rearrangement reactions.

Recent advances in catalytic asymmetric [1,3]-rearrangement reactions

“…The group of Lin reported in 2019 a novel chiral DMAPthiourea bifunctional catalyst C5 for carboxyl migration of 1,3oxazolyl carbonates 12 or 2-benzofuranylcarbonates 14 (Scheme 8). 28 Inspired by the dual-catalytic system developed by Seidel, 29 the authors envisioned an elegant strategy in which the DMAP-derived moiety activates the acyl cation group and there is a close association of the thiourea group with the substrate via hydrogen bonding interaction facilitated stereoinduction; hence high reactivity and excellent enantioselectivity would be achieved (up to 92% yield and 97% ee).…”

Catalytic Enantioselective Steglich-Type Rearrangement of Enol Lactones: Asymmetric Synthesis of Spirocyclic 1,3-Diketones

“…In 1970, Steglich and co-workers disclosed an interesting acyl migration reaction of O -acylated azlactones to their C -acylated isomers . As such rearrangement provides an efficacious approach to access useful 1,3-dicarbonyl compounds with an α-quaternary stereocenter, studies on its variant asymmetric transformations have received considerable efforts over the past two decades. − Pioneering work from Ruble and Fu described the first catalytic asymmetric rearrangement of O -acylated azlactones taking advantage of chiral Lewis base catalysis . Since then, a wide range of chiral nucleophilic catalysts, such as N , N -dimethylaminopyridine (DMAP) and 4-pyrrolidinopyridine (PPY) derivatives, phosphines, N -heterocyclic carbenes, isothioureas, imidazoles, and DMAP- N -oxides, have been designed, developed, and evaluated in this enantioselective reaction.…”

Chiral 4-Aryl-pyridine-N-oxide Nucleophilic Catalysts: Design, Synthesis, and Application in Acylative Dynamic Kinetic Resolution

“…Chiral 4-(dimethylamino)­pyridine (DMAP) is a classic nucleophilic organocatalyst, in which the dialkylamino group is linked at the C-4 position of pyridine to enhance its nucleophilicity and in-turn its catalytic ability (Scheme a) . Since the pioneering studies of Vedejs and Fu, , numerous chiral DMAP analogues C1 have been developed and applied to various asymmetric nucleophilic reactions, especially acyl transfer reactions . Based on DMAP’s skeleton, chiral DMAP- N -oxides have recently emerged, albeit in infancy (Scheme a). − In 2017, Spivey and co-workers first developed an atropisomeric chiral DMAP- N -oxide C2 for enantioselective N -sulfonylation of 2-substituted indolines .…”