Acylated thiosemicarbazides as herbicides

A compound of Formula Ia:

• wherein:
• Ar1 is a five or six-membered aromatic ring selected from phenyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, furyl, thienyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, pyrrolyl, imidazolyl, or pyrazolyl;
• where Ra, Rb, Rc, Rd, and Re are, when present, each independently H, halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, alkoxy, alkylthio, haloalkoxy, haloalkylthio, cyano, nitro, or aryl or heteroaryl optionally substituted with halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, alkoxy, alkylthio, haloalkoxy, haloalkylthio, cyano, or nitro,
• or where two of the Ra, Rb, Rc, Rd, and Re are taken together to form another 5 or 6 membered ring containing C, N, O and/or S atoms, optionally substituted with halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, alkoxy, alkylthio, haloalkoxy, haloalkylthio, cyano, or nitro,
• R′ is, when present, H or alkyl, and
• R is alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, acyl, or alkoxycarbonyl, or aryl optionally substituted with halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, alkoxy, alkylthio, haloalkoxy, haloalkylthio, cyano, or nitro;
• or R is heteroaryl optionally substituted with halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, alkoxy, alkylthio, haloalkoxy, haloalkylthio, cyano, or nitro;
• R1, R2, and R3 are each independently H, halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, alkoxy, alkylthio, haloalkoxy, haloalkylthio, cyano, or nitro;
• or a salt thereof.