Chiral Copper Complexes of Phosphino Sulfenyl Ferrocenes as Efficient Catalysts for Enantioselective Formal Aza Diels−Alder Reactions of N-Sulfonyl Imines

Abstract

In the presence of a catalytic amount of silver perchlorate, copper(I) bromide complexes of planar chiral 1-phosphino-2-sulfenylferrocenes behave as very efficient chiral Lewis acids catalysts in the formal Aza Diels-Alder reaction of N-arylsulfonyl aldimines with electron-rich dienes (Danishefsky's and related dienes). Mixing of equimolar amounts of the readily available enantiopure ferrocenyl P,S-bidentate ligand and CuBr quantitatively affords the precatalyst Cu complex as an air-stable solid. This catalytic asymmetric procedure has a broad structural scope: aldimines of aromatic, alpha,beta-unsaturated, and even enolizable aliphatic aldehydes have been successfully used. The corresponding 2,3-dihydro-4-pyridones were obtained in good yields (57-90%) and with homogeneously high enantioselectivity (82-97% ee).

Synthesis of planar chiral ferrocenyl sulfides and evaluation as catalysts for the asymmetric epoxidation of aldehydes

“…Most of the sulfides bear two functional groups and may be used as bidentate ligands for various purposes of asymmetric synthesis, especially as alternative to phosphines with semi-labile metal interactions. [39][40][41] The reaction rates of epoxidation were not improved, as compared to previous results with aliphatic sulfides. The t-butyl group was introduced in order to secure differentiation of the sulfur lone pairs.…”

Synthesis, structure, and antifungal activity of dihydropyridones containing boronate esters

“…3 and 4), and the average B O bond distances of 1.357(4) (2e) and 1.365(4) (2f)Å are consistent with threecoordinate boron compounds. Bond distances and angles within the pyridone ring are well within the range observed in related compounds [29]. No appreciable intra-or intermolecular interactions between the Lewis acidic boron atom and the nitrogen groups are observed in the solid state.…”

The investigation of NMR spectra of dihydropyridones derived from Curcumin

“…Many approaches to their synthesis have been developed. [9][10][11][12][13] Two main approaches are used in general, from acyclic precursors [14][15][16][17][18][19] and from pyridines. 19,20 In previous paper, 21 we reported the microwave assisted synthesis of dihydropyridones from the reaction of curcumin and amines.…”