The enantioselective [2+2+2] cycloisomerisation of the aromatic triynes under nickel(0) catalysis to afford nonracemic - and helicene derivatives has been systematically studied. A collection of mono-and bidentate phosphines, phosphites, phosphinites and phosphinous amides possessing stereogenic units such as chiral centre, axis or plane (or their combinations) has been tested and axially chiral binaphthyl-derived monodentate MOP-type phosphine ligands were the optimal class of ligands. Nickel complexes of these ligands afforded nonracemic tetrahydro helicene in up to 64% ee in a model reaction.
|Number of pages||18|
|Journal||Collection of Czechoslovak Chemical Communications|
|Publication status||Published - 2011|