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Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.50B [2011] >
IJC-B Vol.50B(09) [September 2011] >
| Title: | Effect of substituents on enantioselectivity in chiral oxazaborolidine mediated asymmetric ketone reduction reaction |
| Authors: | Balakrishnan, U
Ananthi, N
Velmathi, S |
| Keywords: | L-Valine
Prochiral ketone reduction
Oxazaborolidine
Chiral amines
Asymmetric synthesis |
| Issue Date: | Sep-2011 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Various new chiral ligands have been
synthesized by the condensation of different esters of l-Valine with different substituted salicylaldehydes in order
to find the most effective catalyst for the enantioselctive ketone reduction.
Chiral amine synthesized from l-Valine
methyl ester and 5-chloro salicylaldehyde is found to catalyse the
enantioselective reduction of prochiral ketone with high yield (99%) and
enantiomeric excess (91%) with 20 mol% of the catalyst using borane
dimethylsulphide as a stoichiometric reducutant. Different subsituted prochiral
ketones have also been reduced in high yield upto 90% and the corresponding
secondary alcohols are formed with good enantiomeric excess upto 99%. The
mechanism of this reduction can be very well explained by considering a
plausible mechanism for the CBS catalyst. |
| Page(s): | 1157-1164 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0983(Online); 0376-4699(Print) |
| Source: | IJC-B Vol.50B(09) [September 2011]
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