Corteva Agriscience LLC

Rongrong [mandy] Lin

Gregory T Whiteker

Noormohamed Mohamed Niyaz

Chunming Zhang

Ronald B Leng

Jeremy Kister

Rong Ling

Nicholas Martin Irvine

Abraham D Schuitman

Siyu Tu

Jayachandran Devaraj

Nugzar Ghavtadze

Melissa Lee

Aaron A Shinkle

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.

Preparation of halogen analogs of picloram

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EDMONTON, Canada

Rongrong [mandy] Lin