Novel herbicides and methods for preparation thereof

Abstract

A series of herbicidal molecules derived from 3-acetyl-4-hydroxy-5-sec-butylpyrroline-2-ketone, a natural substance, and their potential use in agriculture for weed control. Through the modification of the 5-sec-butyl hydrocarbon chain and 3-acetyl group and the analysis of their biological functioning, newly designed molecules are superior to the original compound in herbicidal activity. These molecules inhibit the photosynthesis of the plants. The treated plants show significant damage in 24 hours and die within 3-5 days after the chemical treatment. In addition, the new molecule has relatively simple structure, they are easy to make and they have better physical properties. They are broad-spectrum, high potency herbicides.

1 . A compound represented by the general formula (I), or (II), or a salt thereof 
       
         
           
           
               
               
           
         
       
       wherein
 R 1  independently and at each occurrence represents H; or —C k H 2k+1 , —OC k H 2k+1 , —(C═O)C k H 2k+1 , —COOC k H 2k+1 , —C k H 2k−1 , —OC k H 2k−1 , —(C═O)C k H 2k−1 , or —COOC k H 2k−1 , each unsubstituted or substituted by one or more substituents selected from a heterocycle, an aryl, a phenylalkyl, a heterocycloalkyl phenyl, a heterocycloalkyl, a heterocycloalkoxyl, a phenoxyl; a phenoxy phenyl; a halogen, a cyano, a nitro, an alkoxyalkyl, an alkoxycarbonyl, and/or an amido; 
 R 2 , and R 3  each independently and at each occurrence represent H, C n H 2n+1 , C n H 2n−1 , a halogen, —CN, a phenyl, a halogenated alkyl, a cyano-alkyl, a phenylalkyl, a halogenoalkenyl, a cyanoalkenyl, or a phenylalkenyl; 
 k represents an integer from 1 to 8; and 
 n represent an integer from 1 to 15. 
 
     
     
         2 . A compound of  claim 1 , represented by the general formula (III), (IV) or (V) 
       
         
           
           
               
               
           
         
       
       wherein
 X independently and at each occurrence represents H; or —C m H 2m+1 , or —OC m H 2m+1 , each unsubstituted or substituted by one or more substituents selected from a heterocyclic alkyl, a heterocyclic aryl, an aryl, a phenylalkyl, a heterocycloalkyl phenyl, a heterocycloalkyl, a heterocycloalkoxyl, a phenoxyl; a phenoxy phenyl; a halogen, a cyano, a nitro, an alkoxyalkyl, an alkoxycarbonyl, and/or an amido; 
 R 2 , and R 3  each independently and at each occurrence represent H, C n H 2n+1 , C n H 2n−1 , a halogen, —CN, a phenyl, a halogenated alkyl, a cyano-alkyl, a phenylalkyl, a halogenoalkenyl, a cyanoalkenyl, or a phenylalkenyl; and 
 m represents an integer from 1 to 7. 
 
     
     
         3 . The compound of  claim 1 , wherein R 2  and R 3  each independently and at each occurrence represent H, —CH 3 , —C 2 H 5 , —CH 2 CH 2 CH 3 , —CH(CH 3 ) 2 , —(CH 2 ) 3 CH 3 , —C(CH 3 ) 3 , —CH 2 CH(CH 3 )CH 3 , —CH(CH 3 )CH 2 CH 3 , —(CH 2 ) 4 CH 3 , —CH(CH 3 )CH 2 CH 2 CH 3 , —CH 2 CH(CH 3 )CH 2 CH 3 , —CH 2 CH 2 CH(CH 3 ) 2 , —CH(CH 2 CH 3 ) 2 , —C(CH 2 ) 2 C 2 H 5 , —(CH 2 ) 5 CH 3 , —CH(CH 3 )(CH 2 ) 3 CH 3 , —CH 2 CH(CH 3 )(CH 2 ) 2 CH 3 , —CH 2 CH 2 CH(CH 3 )CH 2 CH 3 , —(CH 2 ) 3 CH(CH 3 ) 2 , —CH(CH 2 CH 3 )CH 2 CH 2 CH 3 , —CH 2 CH(CH 2 CH 3 ) 2 , —C(CH 3 ) 2 (CH 2 ) 2 CH 3 , —C(CH 3 )CH 2 CH 3 ) 2 , —(CH 2 ) 6 CH 3 , —CH(CH 2 CH 2 CH 3 ) 2 , —CH 2 CH 2 CH(CH 2 CH 3 ) 2 , —CH(CH 2 CH 3 )(CH 2 ) 3 CH 3 , —CH 2 CH(CH 2 CH 3 )CH 2 CH 2 CH 3 , —CH(CH 3 )(CH 2 ) 4 CH 3 , —CH 2 CH(CH 3 )(CH 2 ) 3 CH 3 , —(CH 2 ) 2 CH(CH 3 )(CH 2 ) 2 CH 3 , —(CH 2 ) 3 CH(CH 3 )CH 2 CH 3 , —(CH 2 ) 7 CH 3 , —CH 2 CH(CH 2 CH 2 CH 3 ) 2 , —CH(CH 2 CH 2 CH 3 )(CH 2 ) 3 CH 3 , —CH(CH 3 )(CH 2 ) 5 CH 3 , —CH 2 CH(CH 3 )(CH 2 ) 4 CH 3 , —(CH 2 ) 2 CH(CH 3 )(CH 2 ) 3 CH 3 , —(CH 2 ) 3 CH(CH 3 )(CH 2 ) 2 CH 3 , —(CH 2 ) 4 CH(CH 3 )CH 2 CH 3 , —CH(CH 2 CH 3 )(CH 2 ) 4 CH 3 , —(CH 2 ) 3 CH(CH 2 CH 3 ) 2 , —CH 2 CH(CH 2 CH 3 )(CH 2 ) 3 CH 3 , —(CH 2 ) 2 CH(CH 2 CH 3 )(CH 2 ) 2 CH 3 , —CH═CH 2 , —CH═CHCH 3 , —CH 2 CH═CH 2 , —CH═CHCH 2 CH 3 , —CH 2 CH 2 CH═CH 2 , —CH 2  CH═CHCH 3 , or —CH═CH—CH═CH 2 . 
     
     
         4 . The compound of  claim 1 , wherein R 2  and R 3  each independently and at each occurrence represent —CN or a phenyl group substituted at positions 1-3 by a substituent selected from: —CHClCH 3 , —CHClCH 2 CH 3 , —CHClC 3 H 7 , —CHClC 4 H 9 , —CHClC 5 H 11 , —CHClC 6 H 13 , —CHClC 7 H 15 , —CHFCH 3 , —CHFCH 2 CH 3 , —CHFC 3 H 7 , —CHFC 4 H 9 , —CHFC 5 H 11 , —CHFC 6 H 13 , —CHFC 7 H 15 , —CHCNCH 3 , —CHCNCH 2 CH 3 , —CHCNC 3 H 7 , —CHCNC 4 H 9 , —CHCNC 5 H 11 , —CHCNC 6 H 13 , —CHCNC 7 H 15 , —CH(C 6 H 5 )CH 3 , —CH(C 6 H 5 )CH 2 CH 3 , —CH(C 6 H 5 )C 3 H 7 , —CH(C 6 H 5 )C 4 H 9 , —CH(C 6 H 5 )C 5 H 11 , —CH(C 6 H 5 )C 6 H 13 , —CH(C 6 H 5 )C 7 H 15 , —CHClCH═CH 2 , or —CHClCH 2 CH═CH 2 , or a corresponding isomeric halogenate. 
     
     
         5 . The compound of  claim 2 , wherein X is CN, a C 1  to C 5  amido, a benzyl, a naphthalenyl, a phenyl, a pyrrolyl, a furyl, a thiazolyl, a heterocyclic alkyl phenyl; each phenyl or heterocycle being unsubstituted or substituted by a substituent selected from a C 1  to C 6  alkyl, a C 1  to C 4  alkoxy, a halogenated C 1  to C 5  alkyl, a halogen, a C 1  to C 5  amido, a nitro, a cyano, an alkoxycarbonyl, and/or a C 1  to C 5  sulfonyl group. 
     
     
         6 . The compound of  claim 1  being a calcium, a magnesium, a copper, an iron, a nickel, a sodium, a potassium, a magnesium, a zinc or an ammonium salt. 
     
     
         7 . A method for preparation of a compound of  claim 1  comprising the following steps:
 (a) reacting an aminoacid of formula:   
       
         
           
           
               
               
           
         
       
       with an alcohol under acidic reaction conditions;
 (b) neutralizing with sodium ethoxide; and 
 (c) adding a compound of formula XCOCH 2 COY or cyclobutane-1,3-dione in the presence of a sodium alkoxide, wherein 
 X independently and at each occurrence represents H; or —C m H 2m+1 , or —OC m H 2m+1 , each unsubstituted or substituted by one or more substituents selected from a heterocyclic alkyl, a heterocyclic aryl, an aryl, a phenylalkyl, a heterocycloalkyl phenyl, a heterocycloalkyl, a heterocycloalkoxyl, a phenoxyl; a phenoxy phenyl; a halogen, a cyano, a nitro, an alkoxyalkyl, an alkoxycarbonyl, and/or an amido; 
 m represents an integer from 1 to 7; and 
 Y is Cl or Br. 
 
     
     
         8 . The method of  claim 7 , wherein the steps are carried out in situ without purification of intermediates. 
     
     
         9 . A method of eradicating weeds, comprising applying to the weeds a compound of  claim 1 . 
     
     
         10 . The method of  claim 9 , wherein the compound is applied in a solution having a concentration of 10-800 μg of the compound per 1 g of the solution. 
     
     
         11 . The method of  claim 9 , wherein the weeds are broadleaf weeds, grassy weeds, or sedge weeds. 
     
     
         12 . The method of  claim 9 , wherein the compound is applied under exposure to sun light. 
     
     
         13 . The method of  claim 9 , wherein said compound inhibits photosynthesis and metabolism of the plant cell, which causes a rapid accumulation of large amounts of active oxygen in cells of the weeds and subsequent death of the cells.