Desymmetrization ofmeso-Aziridines with TMSNCS Using Metal Salts of Novel Chiral Imidazoline–Phosphoric Acid Catalysts

Abstract

Highly enantioselective desymmetrization of aziridines with TMSNCS has been developed. Good yield and enantioselectivity were observed by using novel chiral imidazoline-phosphoric acid catalysts. The obtained product can be converted to a chiral β-aminothiol and a β-aminosulfonic acid.

Synthesis of chiral pyridine-oxazolines via a catalytic asymmetric Heine reaction of meso-N-(2-picolinoyl)-aziridines

“…The chiral catalyst promoted reaction of 1q proceeded well, implying that the S N i mechanism is dominant, and the anion-involved S N 2 mechanism could be ruled out in this system, 17 and it is also different from previous intermolecular desymmetric processes. [6][7][8][9][10][11][12][13] Based on the absolute configuration of the product 2a and the single-crystal structure of the catalyst L 3 -RaEt 2 /Yb(OTf ) 3 , 18 possible work modes to unveil the enantiocontrol are provided in Scheme 3d. Initially, the chiral Yb(III) catalyst bonds 2-picolinoyl-aziridine 1a with the two nitrogens, and the pyridine ring is located above the bicyclic ring of the ligand where CH-π interaction could stabilize the state to extend based on our previous study.…”

Enantioselective Reaction Using Palladium Pincer Complexes with <i>C</i>₂-Symmetric Chiral Bis(imidazoline)s

“…Further experiments are in progress to study the scope of this process and the potential application of imidazoline catalysts to other reactions. 30 …”

“…The reaction with isatin ketimine having a triphenylmethyl group (trityl group: Tr) gave the product with higher enantioselectivity than that from the reaction of N benzyl ketimine (entry 7). A lower reaction temperature ( 30 ) can improve the enantioselectivity of the product (entry 8). Decreasing the catalyst loading to 1 mol% had little effect on reactivity and enantioselectivity (entry 9).…”

Chiral Imidazoline Ligands and Their Applications in Metal‐Catalyzed Asymmetric Synthesis†

“…The imidazoline‐phosphoric acid ligand 36 was found effective in ring‐opening desymmetrization of aziridines with TMSNCS (Scheme 34). [ 80 ] This reaction required a heteroarenesulfonyl group as a bidentate auxiliary for aziridines. Meso ‐ aziridines possessing a 5‐, 6‐, or 7‐membered ring could be transformed to the corresponding products.…”