Cyclopyrimorate

Cyclopyrimorate is a selective pyridazine herbicide, used to control broadleaf weeds and grassy weeds, on cereals and rice. It was launched in 2019 in Japan, and is also used in China.^[1] Its mode of action is new, and cyclopyrimorate is the first member of the HRAC Group 33, (Group T, global), coming after decades of no new mode-of-action discoveries.^[2]

Cyclopyrimorate

Names
Preferred IUPAC name 6-chloro-3-(2-cyclopropyl-6-methylphenoxy)pyridazin-4-yl morpholine-4-carboxylate
Other names H-965 6-chloro-3-(2-cyclopropyl-6-methylphenoxy)-4-pyridazinyl 4-morpholinecarboxylate
Identifiers
CAS Number	499231-24-2
3D model (JSmol)	Interactive image
ChEBI	CHEBI:142780
ChemSpider	16050194
EC Number	952-668-6
PubChem CID	23013854
UNII	0SVL4HSS2F
CompTox Dashboard (EPA)	DTXSID40198157
InChI InChI=1S/C19H20ClN3O4/c1-12-3-2-4-14(13-5-6-13)17(12)27-18-15(11-16(20)21-22-18)26-19(24)23-7-9-25-10-8-23/h2-4,11,13H,5-10H2,1H3 Key: BXIGJZDQFDFASM-UHFFFAOYSA-N
SMILES CC1=C(C(=CC=C1)C2CC2)OC3=NN=C(C=C3OC(=O)N4CCOCC4)Cl
Properties
Chemical formula	C19H20ClN3O4
Molar mass	389.84 g·mol−1
Hazards
Lethal dose or concentration (LD, LC):
LD50 (median dose)	>5000 mg/kg (rat, oral)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

It was invented by Mitsui Chemicals Agro,^[3] who sell it tradenamed "Cyra".^[1] They discovered it by modifying the structures of other pyridazine herbicides, such as pyridafol and credazine.^[3]

Cyclopyrimorate works by a novel target site, of homogentisate solanesyltransferase (HST). The new mechanism avoids resistance to acetolactate synthase inhibitor herbicides.^[3] It symptomatically causes bleaching, similar to other cartenoid biosynthesis inhibitors like mesotrione and norflurazon, however cyclopyrimorate is the only one to inhibit HST.^[4]