- Stereospecific diaza-cope rearrangement driven by steric strain
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(Chemical Equation Presented) Bucklingunder the strain: Steric strain was used to drive the diaza-Cope rearrangement to completion (see scheme) with a high degree of stereospecificity (>99.5% ee), as evidenced by chiral-phase HPLC and crystal data. There is good agreement between the experimental and computational values for the rate and equilibrium constants for the rearrangement.
- Kim, Hyunwoo,Nguyen, Yen,Lough, Alan J.,Chin, Jik
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- Organic chemistry: Preparative synthesis of the Corey chiral controller for enantioselective dihydroxylation of olefins
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A five-step synthesis of both enantiomers of 1,2-di(2,4,6-trimethylbenzylamino)-1,2-diphenylethane, i.e., Corey (R,R)- and (S,S)-controllers for enantioselective dihydroxylation of olefins by osmium tetroxide, starting from α,α'-diphenylglyoxime, has been developed. The key operations in the synthesis are the optical resolution of intermediate rac-1,2-diamino-1,2-diphenylethane into two enantiomers using only (R,R)-tartaric acid and the subsequent enhancement of the enantiomeric purity to >98% by crystallizations of the corresponding Schiff's bis-bases. Analysis of the enantiomeric purity of the controllers can be easily performed using 1H NMR spectra of their salts with (R)-α-methoxy-α-(trifluoromethyl)phenylacetic acid (Mosher R-acid).
- Lapitskaya,Pivnitsky
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