Enantioselective Synthesis of Optically Active Pyridine Derivatives and C₂‐Symmetric 2,2′‐Bipyridines

Abstract

Optically active pyridine derivatives 2, 15, 18, 19, 21, 26, and 27 are obtained by enantioselective reduction of the corresponding ketones 5, 7, 11–13, 24, and 25 using the chiral borane reagent chlorodiisopinocampheylborane [(Ipc)2BCl]. Nickel(0)‐mediated coupling of bromopyridines 2, 15, and 31 gives C2‐symmetric 2,2′‐bipyridines (R,R)‐32, (R,R′)‐33, and (S,S)‐38, respectively, which form metal complexes with CoII, PdII, CuI, and AgI. Aryl‐substituted pyridines 26, and 39–41 are synthesized by palladium(0)‐catalyzed cross couplings of 2 and 15 with boronic acids 42–44.

Pyridyl Phosphinites and Pyridyl Phosphites from Chiral Pyridyl Alcohols — A Modular Approach

“…67% for 1c; Entries 6 and 3), whereas we observed the opposite effect for 1d and, previously, for 2-(1-hydroxy-2,2-dimethylpropyl)pyridine. [22] The introduction of a phenyl or a p-substituted aryl substituent in the 6-position of the pyridine ring in the neomenthyl derivatives (1hϪ1j) resulted in a somewhat increased enantioselectivity (Entries 8Ϫ10), whereas for the mandelic acid derivatives 1kϪ1n we observed enantioselectivities Yield (%) [b] ee (%) [c] [a] The reactions were performed in toluene at 0°C with 10 mol % ligand and 2.0 equiv. Et 2 Zn (1.1  in toluene).…”

Asymmetric Reduction of Heteroaryl Methyl Ketones Using <i>Daucus carota</i>

“…UV detector at 210 nm, varying the mobile phase conditions depending on the specific substrate/product. The structures of the products were determined by mass, infrared spectra, 1 H and 13 C NMR spectroscopic studies and also confirmed by the spectral data of the products obtained through chemical synthesis of the compounds (1a -1g) by NaBH 4 reduction and compared with literature values [33][34][35][36][37][38][39][40]. The enantiomeric excess (ee) and absolute configuration of chiral compounds 2a -2j were determined by the sign of specific rotation or by HPLC using chiral columns.…”

Highly Productive CNN Pincer Ruthenium Catalysts for the Asymmetric Reduction of Alkyl Aryl Ketones

“…[8b] 1-(6-phenylpyridin-2-yl)ethanone, [20] 2,2-dimethyl-1-(6-phenylpyridin-2-yl)propan-1-one, [20] H} NMR. Elemental analyses (C, H, and N) were carried out with a Carlo Erba 1106 elemental analyzer.…”