Herbicidal tetrahydrofuran derivatives

Abstract

Certain benzyloxymethyltetrahydrofuran derivatives are useful as herbicides.

What we claim is: 
     
       1. A tetrahydrofuran derivative of the formula ##STR4## wherein R 1  and R 2  each individually represents a hydrogen atom, a methyl group, or R 1  and R 2  together represents a pentamethylene moiety; R 3 , R 4 , R 5 , and R 6  each individually represents a hydrogen atom or one of R 3  and R 4  and one of R 5  and R 6  together represent a carbon-carbon bond; R 7  represents an ethyl group; R 8  and R 9  each individually represents a hydrogen atom; and Ar represents a phenyl group or a phenyl group substituted with a 2-methyl-, 2-fluoro- or a 2,6-dichloro group. 
     
     
       2. 2-Ethyl-5,5-dimethyl-2-benzyloxymethyl-tetrahydrofuran. 
     
     
       3. 2-Ethyl-5,5-dimethyl-2-(2,6-dichlorobenzyloxymethyl)-tetrahydrofuran. 
     
     
       4. 2-Ethyl-2-benzyloxymethyl-tetrahydrofuran-5-spirocyclohexane. 
     
     
       5. 2,5,5-Trimethyl-2-benzyloxymethyl-tetrahydrofuran. 
     
     
       6. 2-Ethyl-5,5-dimethyl-2-benzyloxymethyl-dihydrofuran. 
     
     
       7. 2-Ethyl-2-benzyloxymethyl-dihydrofuran-5-spirocyclohexane. 
     
     
       8. 2,5,5-Trimethyl-4-ethyl-2-benzyloxymethyl-tetrahydrofuran. 
     
     
       9. A herbicidal composition comprising as active ingredient a herbicidally effective amount of a tetrahydrofuran derivative according to claim 1, and at least one .Iadd.inert .Iaddend.carrier or a surface-active agent. 
     
     
       10. A herbicidal composition according to claim 9 wherein the tetrahydrofuran derivative is selected from 2-ethyl-5,5-dimethyl-2-benzyloxymethyl-tetrahydrofuran, 2-ethyl-5,5-dimethyl-2-(2,6-dichlorobenzyloxymethyl)-tetrahydrofuran, 2-ethyl-2-benzyloxymethyl-tetrahydrofuran-5-spirocyclohexane, .Badd..[.2,5,5-trimethyl-2-benzyloxymethyl-tetrahydrofuran,.]..Baddend. .Iadd.or .Iaddend.2-ethyl-5,5-dimethyl-2-benzyloxymethyl-dihydrofuran.[.,.]. .Iadd.or .Iaddend.2-ethyl-2-benzyloxymethyl-dihydrofuran-5-spirocyclohexane, .Badd..[.2,5,5-trimethyl-4-ethyl-2-benzyloxymethyl-tetrahydrofuran.]..Baddend.. 
     
     
       11. A method of eradicating or controlling weeds infesting cereal crops at a locus by applying .Iadd.to the weeds or a locus .Iaddend.a herbicidally .[.active.]. .Iadd.effective .Iaddend.amount of a tetrahydrofuran derivative of the formula ##STR5## wherein R 1  and R 2  each individually represents a hydrogen atom, an alkyl group of up to 6 carbon atoms or a phenyl group; or together represent an alkylene moiety of up to 6 carbon atoms; R 3 , R 4 , R 5  and R 6  each individually represents a hydrogen atom, a halogen atom or an alkyl group of up to 6 carbon atoms or one of R 3  and R 4  and one of R 5  and R 6  together represent a carbon-carbon bond; R 7  represents a hydrogen atom or an alkyl group of up to 6 carbon atoms; R 8  and R 9  each individually represents a hydrogen atom or an alkyl group of up to 6 carbon atoms; and Ar represents a phenyl group or a phenyl group substituted by one or more halogen atoms or alkyl or alkoxy groups of up to 6 carbon atoms. 
     
     
       12. A method according to claim 11, wherein in the tetrahydrofuran derivative R 1  and R 2  each individually represents a hydrogen atom, methyl group or R 1  and R 2  together represent a pentamethylene moiety; R 3 , R 4 , R 5  and R 6  each individually represents a hydrogen atom or one of R 3  and R 4  and one of R 5  and R 6  together represents a carbon-carbon bond; R 7  represents a hydrogen atom, a methyl group or an ethyl group; R 8  and R 9  each individually represents a hydrogen atom; and Ar represents a phenyl group or a phenyl group substituted with a 2-methyl, 2-fluoro-, or a 2,6-dichloro group. 
     
     
       13. A method according to claim 12 wherein in the tetrahydrofuran derivative R 7  is an ethyl group. 
     
     
       14. A method according to claim 12 wherein the tetrahydrofuran derivative is selected from 2-ethyl-5,5-dimethyl-2-benzyloxymethyl-tetrahydrofuran, 2-ethyl-5,5-dimethyl-2-(2,6-dichlorobenzyloxymethyl)-tetrahydrofuran, 2-ethyl-2-benzyloxymethyl-tetrahydrofuran-5-spirocyclohexane, 2,5,5-trimethyl-2-benzyloxymethyl-tetrahydrofuran, 2-ethyl-5,5-dimethyl-2-benzyloxymethyl-dihydrofuran, 2-ethyl-2-benzyloxymethyl-dihydrofuran-5-spirocyclohexane, 2,5,5-trimethyl-4-ethyl-2-benzyloxymethyl-tetrahydrofuran. .Iadd. 15. A method of controlling plant growth comprises applying to the plant or a locus a herbicidally effective amount of a compound of the formula ##STR6## wherein R 1  and R 2  each individually represents a hydrogen atom, an alkyl group of up to 6 carbon atoms or a phenyl group; or together represent an alkylene moiety of up to 6 carbon atoms; R 3 , R 4 , R 5  and R 6  each individually represent a hydrogen atom, a halogen atom, or an alkyl group of up to 6 carbon atoms or one of R 3  and R 4  and one of R 5  and R 6  together represent a carbon-carbon bond; R 7  represents a hydrogen atom or an alkyl group of up to 6 carbon atoms; R 8  and R 9  each individually represents a hydrogen atom or an alkyl group of up to 6 carbon atoms; and Ar represents a phenyl group or a phenyl group substituted by one or more halogen atoms or alkyl 
     
     
        or alkoxy groups of up to 6 carbon atoms. .Iaddend..Iadd. 16.  A method according to claim 15, wherein in the tetrahydrofuran derivative R 1  and R 2  each individually represents a hydrogen atom, methyl group or R 1  and R 2  together represent a pentamethylene moiety; R 3 , R 4 , R 5 , and R 6  each individually represents a hydrogen atom or one of R 3  and R 4  and one of R 5  and R 6  together represents a carbon-carbon bond; R 7  represents a hydrogen atom, a methyl group or an ethyl group; R 8  and R 9  each individually represents a hydrogen atom; and Ar represents a phenyl group or a phenyl group substituted with a 2-methyl, 2-fluoro-, or a 2,6-dichloro group. .Iaddend. .Iadd. 17. A method according to claim 16 wherein in the tetrahydrofuran derivative R 7  is an ethyl group. .Iaddend..Iadd. 18. A method according to claim 17 wherein the tetrahydrofuran derivative is 2-ethyl-5,5-dimethyl-2-benzyloxymethyl-tetrahydrofuran. .Iaddend..Iadd. 19. A method according to claim 17 wherein the tetrahydrofuran derivative is 2-ethyl-5,5-dimethyl-2-(2,6-dichlorobenzyloxymethyl)-tetrahydrofuran. .Iaddend..Iadd. 20. A method according to claim 17 wherein the tetrahydrofuran derivative is 2-ethyl-2-benzyloxymethyl-tetrahydrofuran-5-spirocyclohexane. .Iaddend..Iadd. 21. A method according to claim 17 wherein the tetrahydrofuran derivative is 2-ethyl-5,5-dimethyl-2-benzyloxymethyl-dihydrofuran. .Iaddend..Iadd. 22. A method according to claim 17 wherein the tetrahydrofuran derivative is 2-ethyl-2-benzyloxymethyl-dihydrofuran-5-spirocyclohexane. .Iaddend..Iadd. 23. A method according to claim 17 wherein the tetrahydrofuran derivative is 2-ethyl-2-(2-fluorobenzyloxymethyl)-tetrahydrofuran-5-spirocyclohexane. .Iaddend..Iadd. 24. A method according to claim 16 wherein the tetrahydrofuran derivative is 2-methyl-2-(2-fluorobenzyloxymethyl)-tetrahydrofuran-5-spirocyclohexane. .Iaddend..Iadd. 25. A method according to claim 16 wherein the tetrahydrofuran derivative is 2,5,5-trimethyl-2-benzyloxymethyl-tetrahydrofuran. .Iaddend..Iadd. 26. A method according to claim 16 wherein the tetrahydrofuran derivative is 2,5,5-trimethyl-4-ethyl-2-benzyloxymethyl-tetrahydrofuran. .Iaddend. .Iadd. 27. 2-Ethyl-2-(2-fluorobenzyloxymethyl)-tetrahydrofuran-5-spirocyclohexane. .Iaddend..Iadd. 28. 2-Methyl-2-(2-fluorobenzyloxymethyl)-tetrahydrofuran-5-spirocyclohexane. .Iaddend.