Publication number: 20210323923
Abstract: Methods for preparing 5-fluoro-6-(bromo or chloro)picloram analogs, or derivatives thereof, from picloram acid, picloram ester, or the nitrile analog of picloram are provided. The methods include chemical process steps that: (1) introduce a phthaloyl group onto the 4-amino substituent of picloram acid, picloram ester, or the nitrile analog of picloram, (2) add 2 fluorine atoms at the 5,6-positions of the pyridine ring using halex fluorination chemistry, (3) remove the phthaloyl group, hydrolyze the ester or nitrile substituent, and add chlorine or bromine to the 6-position by treatment with an acid and water, and finally, (4) esterify the 5-fluoro-6-(bromo or chloro)picloram acid produced in step (3) to a 5-fluoro-6-(bromo or chloro)picloram ester.
September 18, 2019
October 21, 2021
Corteva Agriscience LLC
Jayachandran Devaraj, Nugzar Ghavtadze, Nicholas M. Irvine, Jeremy Kister, Melissa Lee, Ronald B. Leng, Rongrong [Mandy] Lin, Rong Ling, Noormohamed M. Niyaz, Abraham D. Schuitman, Aaron A. Shinkle, Siyu Tu, Gregory T. Whiteker, Chunming Zhang