ENANTIOSELECTIVE SYNTHESIS OF OPTICALLY-ACTIVE PYRIDINE-DERIVATIVES AND C-2-SYMMETRICAL 2,2'-BIPYRIDINES

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 (RR)-32, (RR)-33, and (SS)-38, respectively, which form metal complexes with Co(II), Pd(II), Cu(I), and Ag(I). Aryl-substituted pyridines 26, and 39-41 are synthesized by palladium(0)-catalyzed cross couplings of 2 and 15 with boronic acids 42-44.