Continuous Flow Chiral Amine Racemization Applied to Continuously Recirculating Dynamic Diastereomeric Crystallizations.

A new, dynamic diastereomeric crystallization method has been developed, in which the mother liquors are continuously separated, racemized over a fixed-bed catalyst, and recirculated to the crystallizer in a resolution-racemization-recycle (R) process. Separating the racemization from crystallization overcomes problems of using catalysts , that suffer conflicting sets of conditions, inhibition, and separation. Continuous racemization has been achieved through the covalent attachment of [IrCp*I] SCRAM catalyst to Wang resin solid support to give a fixed-bed catalyst.

Continuous gas/liquid-liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination.

4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid-liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials.