Biological resolution of racemic 2-oxazolidinones. Part VI. Stereochemical inversion of (R)-5-hydroxymethyl-3-tert-butyl-2-oxazolidinone or (R)-5-hydroxymethyl-3-isopropyl-2-oxazolidinone to the corresponding (S)-isomer.
Biological resolution of racemic 2-oxazolidinones. Part VI. Stereochemical inversion of (R)-5-hydroxymethyl-3-tert-butyl-2-oxazolidinone or (R)-5-hydroxymethyl-3-isopropyl-2-oxazolidinone to the corresponding (S)-isomer.
Selective Terminal Heck Arylation of Vinyl Ethers with Aryl Chlorides: A Combined Experimental−Computational Approach Including Synthesis of Betaxolol
作者:Gopal K. Datta、Henrik von Schenck、Anders Hallberg、Mats Larhed
DOI:10.1021/jo0602367
日期:2006.5.1
medium. The selectivity for linear β-product in PEG-200 is slightly higher than in aqueous DMF. DFT calculations support a ligand-driven selectivity rationale, where the electronic and steric influence of bulky P(t-Bu)3 ligand provides improved β-selectivity in the essential insertion step also with electron-rich aryl chlorides. A tentative computational rationalization of the improved selectivity in non-methylated
Biological resolution of racemic 2-oxazolidinones. Part VI. Stereochemical inversion of (R)-5-hydroxymethyl-3-tert-butyl-2-oxazolidinone or (R)-5-hydroxymethyl-3-isopropyl-2-oxazolidinone to the corresponding (S)-isomer.
The Stereochemical inversion of (R)-5-hydroxymethyl-3-tert-butyl-2-oxazolidinone (1a) or (R)-5-hydroxymethyl-3-isopropyl-2-oxazohdinone (1b) to the corresponding (S)-isomer was accomplished via a key intermediate, (R)-3-N-ethoxycarbonyl-N-tert-butylamino-1, 2-epoxypropane (5a) or (R)-3-N-ethoxycarbonyl-N-isopropylamino-1, 2-epoxypropane (5b), in a high enantiomeric excess. (S)-1a (99% e.e.) or (S)-1b (97% e.e.) was thus obtained from the respective (R)-isomer (1a; 99% e.e., 1b; 95% e.e.).