Preparation of halogen analogs of picloram
US11401242B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 18, 2019 |
| Grant date | Aug 2, 2022 |
| Priority date | — |
| Expiry date | Sep 18, 2039 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D213/79
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.