Highly Enantioselective Hydrogenation of Amides via Dynamic Kinetic Resolution Under Low Pressure and Room Temperature
作者:Loorthuraja Rasu、Jeremy M. John、Elanna Stephenson、Riley Endean、Suneth Kalapugama、Roxanne Clément、Steven H. Bergens
DOI:10.1021/jacs.6b12254
日期:2017.3.1
High-throughput screening and lab-scale optimization were combined to develop the catalytic system trans-RuCl2((S,S)-skewphos)((R,R)-dpen), 2-PrONa, and 2-PrOH. This system hydrogenates functionalized α-phenoxy and related amides at room temperature under 4 atm H2 pressure to give chiralalcohols with up to 99% yield and in greater than 99% enantiomericexcess via dynamic kinetic resolution.
Highly regioselective and stereospecific functionalization of 1,2-propanediol with trimethyl(X)silanes employing the 1,3,2.lambda.5-dioxaphospholane methodology
作者:Isabel Mathieu-Pelta、Slayton A. Evans
DOI:10.1021/jo00038a032
日期:1992.6
The regioselective ring opening of (S)-4-methyl-2,2,2-triphenyl-1,3,2-lambda-5-dioxaphospholane (2) [prepared from the bis(transoxyphosphoranylation) of (S)-1,2-propanediol (1) with diethoxytriphenylphosphorane (DTPP)] was initiated with several trimethylsilyl reagents (Me3SiX: X = PhS, I, Br, Cl, CN, and N3) to afford the regioisomeric (silyloxy)phosphonium salts. A stereospecific extrusion of triphenylphosphine oxide from these oxyphosphonium salts gave predominantly the thermodynamically less stable C-2-X-substituted derivatives with nearly complete inversion of stereochemistry at the C-2 stereogenic center (i.e., X = PhS).