Author/Authors :
Haddad، نويسنده , , Nizar and Qu، نويسنده , , Bo and Rodriguez، نويسنده , , Sonia and van der Veen، نويسنده , , Lars and Reeves، نويسنده , , Diana C. and Gonnella، نويسنده , , Nina C. and Lee، نويسنده , , Heewon and Grinberg، نويسنده , , Nelu and Ma، نويسنده , , Shengli and Krishnamurthy، نويسنده , , Dhileepkumar and Wunberg، نويسنده , , Tobias and Senanayake، نويسنده , , Chris H.، نويسنده ,
Abstract :
An enantioselective hydrogenation of hydrazones derived from heterocyclic ketones was developed with up to 85% ee. The enantiomeric purity was enriched to >99% ee by crystallization from EtOAc in >80% yield. Optimization studies have revealed a notable solvent effect that resulted in inversion of enantioselectivity from 85% ee in MeOH to −27% ee in DCE. The hydrazone geometry and possible hydrogenation via endocyclic alkene were examined as possible factors for the inversion of enantioselectivity.
Keywords :
Chiral hydrazenes , Hydrazones , asymmetric hydrogenation , Reversed enantioselectivity
