5346-88-3Relevant academic research and scientific papers
Chiral Ligands for Organometallic Catalysis containing Two Dioxolane Rings
Brown, John M.,Dayrit, Fabian M.,Sinou, Denis
, p. 91 - 96 (2007/10/02)
Treatment of D-mannitol 1,6-dibenzoate with a catalytic quantity of toluene-p-sulphonic acid in 2,2-dimethoxypropane leads to the formation of two cyclic acetals, 4R,8R,9R,10R-2,2',6,6'-tetramethyl-4,8-bis(benzoyloxymethyl)-1,3,5,7-tetraoxadecalin and R,R'-4,4'-bi-(2,2-dimethyl-5-benzoyloxymethyldioxolanyl) in comparable amounts.Successive reaction with sodium methoxide in methanol, methanesulphonyl chloride, and lithium or potassium diphenylphosphide gave the corresponding phosphines namely 4S,8S,9S,10S-2,2',6,6'-tetramethyl-4,8-di-1,3,5,7-tetraoxadecalin and S,S-4,4'-bi-.Similarly, starting from L-iditol, the diphosphines 4R,8S,9S,10R-2,2',6,6'-tetramethyl-4,8-di-1,3,5,7-tetraoxadecalin and S,R-4,4'-bi- were obtained.It was demonstrated through (31)P n.m.r. studies that both cis- and trans-chelate complexes of rhodium were formed by these biphosphine ligands.Their potential in asymmetric hydrogenation was demonstrated, for low to moderate yields of amino acids were formed from a variety of enamide precursors.
