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Updated: Apr 11, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Synthesis of Novel Fluoropicolinate Herbicides by Cascade Cyclization of Fluoroalkyl Alkynylimines
Peter L Johnson1, James M Renga1, Christopher V Galliford1
1†Discovery Chemistry and ‡Process Chemistry, Dow AgroSciences, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States.
Abstract:
The cascade cyclization of fluoroalkyl alkynylimines with primary amines has been modified to allow the synthesis of 4-amino-5-fluoropicolinates. Use of N-trityl and acetal protecting groups in the cyclization precursor led to 5-fluoropyridines that were easily deprotected to picolinaldehyde derivatives for further elaboration to structures of interest as potential herbicides. This method provided access to picolinic acids with alkyl or aryl substituents at the 6-position that were previously inaccessible via cross-coupling chemistry.
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