| 主权项 |
1. A process for synthesis of functionalised pyrazolidines of formula I with enantioselectivity in the range of 75 to 98% ee and diastereoselectivity in the range of 99 to 100% de wherein, R is selected from the group consisting of H, halogen, C1 to C10 branched or unbranched alkyl, C1 to C10 cycloalkyl which may optionally be substituted with halo, —OH; aryl which may optionally be as mono or di or tri substituted by halo, hydroxy, nitro, amino, CN, COOH, CONH2, heteroaryl with N, O and/or S atoms as hetero atoms, naphthyl, which may optionally be substituted with halo, hydroxy, nitro, amino, CN, COOH, CONH2, and R′ is selected from ter-butyl, iso-propyl and benzyl groups, via tandem α-amination-Corey Chaykovsky reaction of α-hydrazino aldehydes and the said process comprising the steps of: a) reacting an alpha-unsubstituted aldehyde with azodicarboxylates at a temperature in the range of 0 to 20° C. in presence of L-proline in a solvent to obtain α-hydrazino aldehydes; and b) subjecting the α-hydrazino aldehydes to Corey Chaykovsky reaction insitu at a temperature in the range of (−)4 to (−)6° C. to obtain functionalised pyrazolidines of formula I. |
