HERBICIDAL ARYLDIHYDROFURANE CARBOXYLATES

Abstract

The invention relates to compounds of formula (I), and their use as herbicides. In said formula, R.sup.1 to R.sup.10 represent groups such as hydrogen, halo-gen or linear or cyclic organic groups such as alkyl, alkenyl, alkynyl, cycloalkyl, or alkoxy. The invention further refers to a composition comprising such compound and to the use thereof for controlling unwanted vegetation.

##STR00001##

Claims

1. A compound of formula (I) ##STR00283## wherein the substituents have the following meanings: R.sup.1 hydrogen or (C.sub.1-C.sub.6)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.3-C.sub.6)-cycloalkyl-(C.sub.1-C.sub.3)-alkyl, (C.sub.2-C.sub.4)-alkenyl, (C.sub.2-C.sub.4)-alkynyl, each of which is substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, cyano, Z, CO.sub.2R.sup.a, CONR.sup.bR.sup.h, (C.sub.1-C.sub.2)-alkoxy, (C.sub.1-C.sub.2)-haloalkoxy, (C.sub.1-C.sub.3)-alkylthio, (C.sub.1-C.sub.3)-alkylsulfinyl, (C.sub.1-C.sub.3)-alkylsulfonyl, phenylthio, phenylsulfinyl, and phenylsulfonyl; R.sup.2 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, (C.sub.1-C.sub.3)-alkoxy, (C.sub.1-C.sub.3)-haloalkoxy; R.sup.3 hydrogen, halogen, nitro, hydroxyl, cyano, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, hydroxy-(C.sub.1-C.sub.3)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.3-C.sub.6)-halocycloalkyl, hydroxy-(C.sub.3-C.sub.6)-cycloalkyl, (C.sub.1-C.sub.3)-alkoxy, (C.sub.1-C.sub.3)-haloalkoxy, (C.sub.1-C.sub.3)-alkoxycarbonyl, (C.sub.2-C.sub.3) alkenyl, (C.sub.2-C.sub.3)-haloalkenyl, (C.sub.2-C.sub.3) alkynyl, (C.sub.2-C.sub.3)-haloalkynyl, (C.sub.1-C.sub.3)-alkylthio, (C.sub.1-C.sub.3)-alkylsulfinyl, (C.sub.1-C.sub.3)-alkylsulfonyl; R.sup.4 hydrogen, halogen, hydroxyl, cyano, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, (C.sub.3-C.sub.4)-halocycloalkyl, (C.sub.1-C.sub.3)-haloalkoxy, (C.sub.2-C.sub.3)-haloalkenyl, (C.sub.2-C.sub.3)-haloalkynyl; R.sup.5 hydrogen, halogen, nitro, hydroxyl, cyano, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, hydroxy-(C.sub.1-C.sub.3)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.3-C.sub.6)-halocycloalkyl, hydroxy-(C.sub.3-C.sub.6)-cycloalkyl, (C.sub.1-C.sub.3)-alkoxy, (C.sub.1-C.sub.3)-haloalkoxy, (C.sub.1-C.sub.3)-alkoxycarbonyl, (C.sub.2-C.sub.3) alkenyl, (C.sub.2-C.sub.3)-haloalkenyl, (C.sub.2-C.sub.3) alkynyl, (C.sub.2-C.sub.3)haloalkynyl, (C.sub.1-C.sub.3)-alkylthio, (C.sub.1-C.sub.3)-alkylsulfinyl, (C.sub.1-C.sub.3)-alkylsulfonyl; R.sup.6 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, (C.sub.1-C.sub.3)-alkoxy, (C.sub.1-C.sub.3)-haloalkoxy; R.sup.7 hydrogen, halogen, cyano, or (C.sub.1-C.sub.6)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.2-C.sub.6)-alkenyl, (C.sub.2-C.sub.6)-alkynyl, (C.sub.1-C.sub.6)-alkoxy, each substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, iodine, hydroxyl, cyano, and (C.sub.1-C.sub.6)-alkoxy; R.sup.8 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, and (C.sub.3-C.sub.6)-cycloalkyl; R.sup.9, R.sup.10 each independently hydrogen, halogen, cyano, or (C.sub.1-C.sub.6)-alkyl, (C.sub.1-C.sub.6)-alkoxy, each substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, iodine, and cyano; or R.sup.9 and R.sup.10 form, together with the carbon atom to which they are bound, a saturated, partially or fully unsaturated three to six-membered ring containing, in addition to this carbon atom, q carbon atoms and n oxygen atoms; R.sup.a (C.sub.1-C.sub.6)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, or phenyl, each of which is substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, iodine, cyano, hydroxy, and (C.sub.1-C.sub.3)-alkoxy; R.sup.b hydrogen, (C.sub.1-C.sub.3)-alkoxy or R.sup.a; R.sup.h hydrogen or (C.sub.1-C.sub.6)-alkyl, (C.sub.1-C.sub.2)-alkoxy, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.2-C.sub.4)-alkenyl, (C.sub.1-C.sub.6)-alkoxycarbonyl-(C.sub.1-C.sub.6)-alkyl, or (C.sub.2-C.sub.4)-alkynyl, each of which is substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, cyano, CO.sub.2R.sup.a, and (C.sub.1-C.sub.2)-alkoxy; Z is a three-, four-, five- or six-membered saturated, partly unsaturated, fully unsaturated, or aromatic ring, which is formed from r carbon atoms, n nitrogen atoms, n sulfur atoms and n oxygen atoms, and which is substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, cyano, (C.sub.1-C.sub.2)-alkoxy, and (C.sub.1-C.sub.2)-haloalkoxy; each m is independently 0, 1, 2, 3, 4, or 5; each n is independently 0, 1, or 2; q 1, 2, 3, 4, or 5; r 1,2,3, 4, 5, or 6; including agriculturally acceptable salts and thioesters thereof, provided the compound of formula (I) has a carboxyl group; except the compounds methyl 2,3-dihydro-4-phenyl-2-furancarboxylate and methyl 2,3-dihydro-5-methyl-4-phenyl-2-furancarboxylate.

2. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.1 hydrogen or (C.sub.1-C.sub.6)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.2-C.sub.4)-alkenyl, (C.sub.3-C.sub.6)-cycloalkyl-(C.sub.1-C.sub.3)-alkyl, (C.sub.2-C.sub.4)-alkynyl, each of which is substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, cyano, and Z.

3. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.1 hydrogen or (C.sub.1-C.sub.6)-alkyl.

4. The compound as claimed in, wherein the substituents have the following meaning: R.sup.2 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl; R.sup.6 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl.

5. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.3 hydrogen, halogen, hydroxyl, cyano, (C.sub.1-C.sub.3)-alkyl; R.sup.5 hydrogen, halogen, hydroxyl, cyano, (C.sub.1-C.sub.3)-alkyl.

6. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.4 hydrogen, halogen.

7. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.7 hydrogen, (C.sub.1-C.sub.2)-alkyl, (C.sub.1-C.sub.2)-haloalkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.2-C.sub.6)-alkenyl, (C.sub.2-C.sub.6)-alkynyl, (C.sub.1-C.sub.6)-alkoxy; R.sup.8 hydrogen or halogen.

8. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.9 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl; R.sup.10 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl.

9. The compound as claimed in claim 1, wherein the substituents have the following meaning: R.sup.1 hydrogen or (C.sub.1-C.sub.6)-alkyl; R.sup.2 hydrogen; R.sup.3 halogen, cyano, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, (C.sub.1-C.sub.3)-haloalkoxy; R.sup.4 hydrogen or halogen; R.sup.5 halogen, cyano, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl, (C.sub.1-C.sub.3)-haloalkoxy; R.sup.6 hydrogen; R.sup.7 (C.sub.1-C.sub.6)-alkyl, (C.sub.3-C.sub.6)-cycloalkyl, (C.sub.2-C.sub.6)-alkenyl, (C.sub.2-C.sub.6)-alkynyl, (C.sub.1-C.sub.6)-alkoxy, each substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, iodine, hydroxyl, cyano, and (C.sub.1-C.sub.6)-alkoxy; R.sup.8 hydrogen, halogen, (C.sub.1-C.sub.3)-alkyl, (C.sub.1-C.sub.3)-haloalkyl; R.sup.9, R.sup.10 each independently hydrogen, halogen, cyano, or (C.sub.1-C.sub.6)-alkyl, (C.sub.1-C.sub.6)-alkoxy, each substituted by m radicals selected from the group consisting of fluorine, chlorine, bromine, iodine, and cyano; or R.sup.9 and R.sup.10 form, together with the carbon atom to which they are bound, a saturated, partially or fully unsaturated three to six-membered ring containing, in addition to this carbon atom, q carbon atoms, and n oxygen atoms; each m is independently 0, 1, 2, 3, 4, or 5; each n is independently 0, 1, or 2; q 1, 2, 3, 4, or 5.

10. A composition comprising at least one compound as claimed in claim 1, and at least one auxiliary, which is customary for formulating crop protection compounds.

11. The composition as claimed in claim 10, comprising a further herbicide.

12. (canceled)

13. A method for controlling unwanted vegetation comprising applying an herbicidally effective amount of at least one compound as claimed in claim 1 to act on plants, their seed, and/or their habitat.

Description

EXAMPLE 1

[0329] Synthesis of ethyl 4-(3,5-difluorophenyl)-2,3-dihydrofuran-2-carboxylate (Cpd I)

##STR00265##

[0330] To a mixture of aryl bromide (1) (40 g, 209 mmol) in dimethoxyethane (500 mL) was added compound 11 (35.2 g, 209 mmol), aq. sat, Na.sub.2CO.sub.3 (500 mL) and tetrakis(triphenylphosphine)-palladium(0) (Pd(PPh.sub.3).sub.4, CAS: 14221-01-3 (7.26 g, 6.28 mmol) at 15? C. and stirred at 90? C. for 16 h under nitrogen atmosphere. The mixture was poured into water (500 mL) and extracted with EtOAc (2?500 mL). The combined organics were washed with brine, dried and concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=9:1) to give compound III (26 g, 81%) as yellow oil. .sup.1H-NMR (400 MHz, CDC.sub.3): ?=6.97 (dd, J=9.1, 2.1 Hz, 2H), 6.72 (tt, J=8.8, 2.3 Hr, 1H), 5.41 (s, 1H), 2.12 (s, 3H).

##STR00266##

[0331] To a mixture of compound III (20 g, 129 mmol) in acetonitrile (200 mL) was added glyoxylic acid ethyl ester (40 g, 389 mmol) and Yb(OTf).sub.3 (16 g, 25.67 mmol) at 15? C. and stirred at the same temparature for 16 h. The mixture was concentrated, diluted with H.sub.2O (200 mL) and extracted with EtOAc (2?200 mL). The combined organics were washed with brine, dried and concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=9:1) to give compound V (14 g, 42%) as a yellow oil. .sup.1H-NMR (400 MHz, CDC.sub.3): ?=6.98-6.92 (m, 2H), 6.74 (tt, J=8.8, 2.3 Hz, 1H), 5.45 (s, 1H), 5.30 (d, J=5.0 Hz, 1H), 4.27 (ddd, J=7.4, 5.9, 4.6 Hz, 1H), 4.22-4.10 (m, 2H), 3.00 (dd, J=14.6, 4.3 Hz, 1H), 2.83-2.73 (m, 2H), 1.28 (t, J=7.1 Hz, 3H).

##STR00267##

[0332] To a mixture of compound V (14 g, 55 mmol) in ethyl vinyl ether (105 mL) was added trifluoroacetic acid (21 mL) at 15? C. and stirred at 50? C. for 16 h. After concentrating the mixture, the crude was purified by flash column chromatography (hexane/EtOAc=10:1) to afford compound VI (12.5 g, 69%) as a yellow oil. .sup.1H-NMR (400 MHz, CDC.sub.3): ?=7.02-6.91 (m, 2H), 6.80-6.69 (m, 1H), 5.44 (d, J=7.3 Hz, 1H), 5.31-5.25 (m, 1H), 4.76-4.84 (m, 1H), 4.32-4.05 (m, 4H), 3.64-3.31 (m, 2H), 2.98-2.78 (m, 2H), 1.31-1.25 (m, 5H), 1.12-1.02 (m, 3H).

##STR00268##

[0333] To a solution of compound VI (12.5 g, 36.6 mmol) in dichloromethane (130 mL) was added triethylamine (7.6 mL, 55 mmol) and trimethylsilyl triflate (8.75 mL, 47.5 mmol) at 0? C. und a nitrogen atmosphere. After stirring for 16 h at room temperature, the mixture was diluted with water (100 mL) and extracted with dichloromethane (2?100 mL). The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The residue was purified by flash column chromatography (hexane/EtOAc=10:1) to afford compound VII (7.2 g, 60%) as a yellow oil. .sup.1H-NMR (400 MHz, CDC.sub.3): ?=6.99-6.87 (m, 2H), 6.76-6.71 (m, 1H), 6.34 (dd, J=14.3, 6.8 Hz, 1H), 5.44 (s, 1H), 5.28 (s, 1H), 4.37-4.32 (m, 1H), 4.25-4.13 (m, 3H), 4.07 (dd, J=6.8, 2.5 Hz, 1H), 3.01-2.93 (m, 2H), 1.27 (t, J=7.1 Hz, 3H).

##STR00269##

[0334] To a solution of compound VII (2.0 g, 6.1 mmol) in 1,2-dichloroethane (1 L) was added Grubb's second generation catalyst (CAS: 301224-40-8) (2.0 g, 2.4 mmol) at 0? C. under a nitrogen atmosphere. After stirring for 16 h at 90? C. under nitrogen, the mixture was diluted with water (10 mL) and stirred for 30 min at room temperature. After concentrating the mixture, the residue was purified by flash column chromatography (hexane/EtOAc=10:1) to afford compound Cpd 11 (3.0 g, 64%) as a yellow oil. .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=6.93 (s, 1H), 6.76-6.69 (m, 2H), 6.65-6.58 (m, 1H), 5.16 (dd, J=11.5, 7.3 Hz, 1H), 4.29 (q, J=7.2 Hz, 2H), 3.34-3.25 (m, 1H), 3.11 (ddd, J=14.8, 7.2, 1.8 Hz, 1H), 1.34 (t, J=7.1 Hz, 3H).

EXAMPLE 2

[0335] Synthesis of ethyl 4-(3,5-difluorophenyl)-2-methyl-3H-furan-2-carboxylic acid (Cpd I2)

##STR00270##

[0336] To a solution of Cpd I1 (2.0 g, 7.9 mmol) in THF (100 mL) was added methyl iodide (5.6 g, 39 mmol) and a solution of lithium bis(trimethylsilyl)amide (1 M in THF, 23.6 mL, 23.6 mmol) at 0? C. under a nitrogen atmosphere. After stirring for 2 h at 0? C. under nitrogen, the mixture was poured into water (50 mL), acidified with aq. HCl (1 M) to pH=3 and extracted with EtOAc (2?100 mL). The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The residue was purified by flash column chromatography (hexane/EtOAc=10:1) to afford compound Cpd I2 (1.0 g, 47%) as a yellow oil. .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=6.87 (t, J=1.8 Hz, 1H), 6.74-6.69 (m, 2H), 6.63-6.59 (m, 1H), 4.31-4.23 (m, 2H), 3.36 (dd, J=14.9, 2.0 Hz, 1H), 2.84 (dd, J=14.9, 2.0 Hz, 1H), 1.68 (s, 3H), 1.33 (t, J=7.2 Hz, 3H).

EXAMPLE 3

[0337] Synthesis of 4-(3,5-difluorophenyl)-2-methyl-3H-furan-2-carboxylic acid (Cpd I3)

##STR00271##

[0338] To a solution of compound Cpd I2 (0.78 g, 2.9 mmol) in THF (9 mL) was added lithium hydroxide hydrate (367 mg, 8.73 mmol) and water (3 mL). After stirring for 2 h at room temperature, the mixture was diluted with water (10 mL), acidified with aq. HCl (1 M) until pH=3 and extracted with EtOAc (3?10 mL). The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated to provide compound Cpd I3 (1.0 g, quantitative) as a yellow oil. This product was used without further purification in the next step. LC-MS (M+H).sup.+:240.0.

EXAMPLE 4

[0339] Synthesis of ethyl 4-(3,5-dichlorophenyl)-2-methyl-3H-furan-2-carboxylic acid (Cpd I4):

##STR00272##

[0340] To a solution of ethyl pyruvate (VIII) (50 g, 431 mmol) in THF (200 mL) was added propargyl bromide (IX) (103 g, 862 mmol) and Zn (64.5 g, 1.08 mol) at room temperature. After heating the reaction to 80? C., the suspension was stirred for 3 h. After cooling to room temperature, the mixture was filtered and the filtrate was quenched with HCl (2N) and extracted with EtOAc. The combined organics were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=100:0 to 7:3) to give the compound X (34.6 g, 51.6%) as a yellow oil. .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=4.36-4.16 (m, 2H), 2.72-2.50 (m, 2H), 2.06 (t, J=2.57 Hz, 1H), 1.47 (s, 3H), 1.34-1.28 (m, 3H).

##STR00273##

[0341] To a mixture of compound X (17 g, 110 mmol) in acetone (300 ml) was added Ag.sub.20 (12.6 g, 55 mmol) and triethylamine (11.1 g, 110 mmol) at room temperature. After stirring the reaction at 50? C. for 2 h, the suspension was filtered and the filtrate was concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=100:0 to 1:1) to give the compound XI (17 g, 100%) as a yellow oil. .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=6.30 (q, J=2.4 Hz, 1H), 4.87 (q, J=2.5 Hz, 1H), 4.30-4.18 (m, 2H), 3.04 (dt, J=15.7, 2.3 Hz, 1H) 2.54 (dt, J=15.7, 2.32 Hz, 1H), 1.58 (s, 3H), 1.29-1.33 (t, 3H).

##STR00274##

[0342] To a solution of compound XI (17 g, 110 mmol) in dichloromethane (250 mL) was added bromine (17.4 g, 110 mmol) in dichloromethane (50 mL) dropwise at ?78? C. and stirred at ?78? C. for 10 min. 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU, CAS: 6674-22-2) (67 g, 440 mmol) was added at ?78? C. dropwise. After removing the cold bath, the mixture was stirred for 1 h at room temperature. The mixture was quenched with HCl (1 M) and extracted with dichloromethane (2?50 mL). The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=100:0 to 1:1) to give the compound XII (16.5 g, 65%) as a yellow amorphous solid. .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=6.37 (t, J=2.1 Hz, 1H), 4.32-4.20 (m, 2H), 3.26 (dd, J=15.3, 2.1 Hz, 1H), 2.74 (dd, J=15.4, 2.2 Hz, 1H), 1.62 (s, 3H), 1.32 (t, J=7.15 Hz, 3H).

##STR00275##

[0343] To the emulsion of compound XII (1.5 g, 6.4 mmol) in a 5:1-mixture of toluene (30 mL) and water (6 mL), aryl boronic acid XIII (1.35 g, 7.05 mmol), Cs.sub.2CO.sub.3 (10 g, 32 mmol) and Pd(dppf)Cl.sub.2 (CAS: 72287-26-4) (300 mg, 0.41 mmol) were added at room temperature and the mixture was stirred at 110? C. for 2 h under nitrogen atmosphere. The reaction was quenched with H.sub.2O (20 mL) and extracted with EtOAc (3?30 mL). The combined organics were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=100:0 to 1:1) to provide compound Cpd I4 (1.3 g, 68%) as a yellow oil. .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=7.14 (t, J=1.6 Hz, 1H), 7.07 (d, J=1.6 Hz, 2H), 6.88 (s, 1H), 4.27 (q, J=7.3 Hz, 2H), 3.36 (dd, J=14.9, 1.9 Hz, 1H), 2.84 (dd, J=14.9, 1.9 Hz, 1H), 1.67 (s, 3H), 1.33 (t, J=7.2 Hz, 3H).

EXAMPLE 5

[0344] Synthesis of 4-(3,5-dichlorophenyl)-2-methyl-3H-furan-2-carboxylic acid (Cpd I5):

##STR00276##

[0345] To a solution of compound Cpd I4 (1.3 g, 4.3 mmol) in a 3:1 mixture of THF (15 mL) and water (5 mL) was added lithium hydroxide (364 mg, 3.34 mmol) at room temperature. After stirring for 2 h, the mixture was quenched with H.sub.2O, acidified with aq. HCl (6 M) until pH=3 and extracted with EtOAc (3?20 mL). The combined organics were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated to give Cpd I5 (900 mg, 77%) as an amorphous yellow solid. The crude was used without further purification. For analytic purposes a small sample of Cpd I5 was purified by prep-HPLC (TFA,CH.sub.3CNH.sub.2O). .sup.1H-NMR (400 MHz, DMSO-d.sub.6): ?=13.09 (br s, 1H), 7.44 (s, 1 H), 7.35 (d, J=1.6 Hz, 2H), 7.31 (s, 1H), 3.24 (br d, J=13.8 Hz, 1H), 2.85 (br d, J=13.7 Hz, 1H), 1.53 (s, 3H).

EXAMPLE 6

[0346] Synthesis of ethyl 4-(3,5-difluorophenyl)-2-(trifluoromethyl)-3H-furan-2-carboxylic acid (Cpd I6)

##STR00277##

[0347] According to the synthesis of Inter C, to a solution of compound XIV (20 g, 13 mmol) in THF (200 mL) was added propargyl bromide (XV) (30.5 g, 256 mmol) and Zn (20.5 g, 321 mmol) at room temperature. After stirring for 2 h, the mixture was filtered, poured into water (100 mL), acidified with HCl (6 M) to pH=3 and extracted with methyl tert-butyl ether (3?100 mL). The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=100:0 to 0:100) to give the compound XVI (36 g, 40%) as a yellow oil. The analytical and spectroscopic data are in alignment with the reported data from Tetrahedron 2003, 59, 1389-1394.

##STR00278##

[0348] To a mixture of compound XVI (36 g, 0.18 mol) in acetone (700 ml) was added Ag.sub.20 (21.3 g, 91.8 mmol) and triethylamine (25.5 mL, 114 mmol) at room temperature. After stirring the reaction for 2 h in the dark, the suspension was filtered and the filtrate was concentrated. The crude was purified by flash column chromatography (hexane/EtOAc=100:0 to 0:100) to give the compound XVII (20 g, 55%) as a yellow oil. .sup.1H-NMR (400 MHz, CDC.sub.3): ?=6.37 (d, J=2.3 Hz, 1H), 5.03 (d, J=2.3 Hz, 1H), 3.89 (s, 3H), 3.13 (d, J=2.4 Hz, 2H).

##STR00279##

[0349] To a solution of compound XVII (15 g, 77 mmol) in dichloromethane (200 mL) was added bromine (12 g, 77 mmol) dropwise at ?78? C. and stirred at ?78? C. for 15 min. 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU, CAS: 6674-22-2) (46.5 g, 306 mmol) was added at ?78? C. dropwise and stirred for 1 h at the same temperature. The mixture was poured into water (100 mL), acidified with HCl (6 M) to pH=3 and extracted with dichloromethane (2?50 mL). The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The crude (8.5 g) was used in the next step without further purification.

##STR00280##

[0350] To the emulsion of compound XVIII (7.5 g, 27 mmol) in a 5:1-mixture of toluene (80 mL) and water (16 mL), aryl boronic acid XIX (4.3 g, 27 mmol), Cs.sub.2CO.sub.3 (44.9 g, 137 mmol) and Pd(dppf)Cl.sub.2 (CAS: 72287-26-4) (1.28 g, 1.75 mmol) were added at room temperature and the mixture was stirred at 110? C. for 1 h under nitrogen atmosphere. The reaction was quenched with H.sub.2O (40 mL) and extracted with EtOAc (3?30 mL). The combined organics were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated. The crude (1.8 g, 7%) was used in the next step without further purification. For analytic purposes a small sample of compound Cpd I6 (55 mg) was purified by prep-HPLC (TFA,CH.sub.3CNH.sub.2O). .sup.1H-NMR (400 MHz, CDC.sub.3): ?=6.91 (s, 1H), 6.77-6.72 (m, 2H), 6.68 (tt, J=8.8, 2.1 Hz, 1H), 3.92 (s, 3H), 3.50-3.36 (m, 2H).

EXAMPLE 7

[0351] Synthesis of 4-(3,5-difluorophenyl)-2-(trifluoromethyl)-3H-furan-2-carboxylic acid (Cpd I7)

##STR00281##

[0352] To a solution of compound Cpd I6 (1.5 g, 4.9 mmol) in a 3:1 mixture of THF (15 mL) and water (5 mL) was added lithium hydroxide (0.31 g, 7.3 mmol) at room temperature. After stirring for 2 h, the mixture was quenched with H.sub.2O, acidified with aq. HCl (6 M) until pH=3 and extracted with EtOAc (3?20 mL). The combined organics were washed with brine, dried over Na.sub.2SO.sub.4 and concentrated to give Cpd I7 (900 mg, 77%) as an amorphous yellow solid. The crude (1.5 g, 21%) was used in the next step without further purification. For analytic purposes a small sample of Cpd I7 was purified by prep-HPLC (TFA,CH.sub.3CNH.sub.2O). .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=7.59 (s, 1H), 7.16 (br dd, J=9.3, 2.2 Hz, 2H), 7.05 (tt, J=9.3, 2.1 Hz, 1H), 3.45 (d, J=1.8 Hz, 2H).

[0353] High Performance Liquid Chromatography: HPLC-column Kinetex XB C18 1,7? (50?2.1 mm); eluent: acetonitrile/water+0.1% trifluoroacetic acid (gradient from 5:95 to 100:0 in 1.5 min at 60? C., flow gradient from 0.8 to 1.0 ml/min in 1.5 min).

[0354] In analogy to the examples described above, the following compounds of formula (I), wherein R.sup.8, R.sup.9 and R.sup.10 are hydrogen, were prepared using commercially available alcohols:

TABLE-US-00002 TABLE 2 [00282] Cpd. R.sup.1 R.sup.2 R.sup.3 R.sup.4 R.sup.5 R.sup.6 R.sup.7 HPLC/MS I1 CH.sub.2CH.sub.3 H F H F H H 255.1 I2 CH.sub.2CH.sub.3 H F H F H CH.sub.3 269.1 I3 H H F H F H CH.sub.3 241 I4 CH.sub.2CH.sub.3 H Cl H Cl H CH.sub.3 301 I5 H H Cl H Cl H CH.sub.3 273 I6 CH.sub.3 H F H F H CF.sub.3 309 I7 H H F H F H CF.sub.3 293 HPLC/MS = MassChargeRatio

B Use Examples

[0355] The herbicidal activity of the compounds of formula (I) was demonstrated by the following greenhouse experiments:

[0356] The culture containers used were plastic flowerpots containing loamy sand with approximately 3.0% of humus as the substrate. The seeds of the test plants were sown separately for each species.

[0357] For the pre-emergence treatment, the active ingredients, which had been suspended or emulsified in water, were applied directly after sowing by means of finely distributing nozzles. The containers were irrigated gently to promote germination and growth and subsequently covered with transparent plastic hoods until the test plants had rooted. This cover caused uniform germination of the test plants, unless this had been impaired by the active ingredients. For the post-emergence treatment, the test plants were first grown to a height of 3 to 15 cm, depending on the plant habit, and only then treated with the active ingredients which had been suspended or emulsified in water. For this purpose, the test plants were either sown directly and grown in the same containers, or they were first grown separately as seedlings and transplanted into the test containers a few days prior to treatment.

[0358] Depending on the species, the test plants were kept at 10-25? C. or 20-35? C., respectively. The test period extended over 2 to 4 weeks. During this time, the test plants were tended, and their response to the individual treatments was evaluated.

[0359] Evaluation was carried out using a scale from 0 to 100. 100 means no emergence of the test plants, or complete destruction of at least the aerial moieties, and 0 means no damage, or normal course of growth. A good herbicidal activity is given at values of 65 to 90 and a very good herbicidal activity is given at values of 90 to 100.

[0360] The test plants used in the greenhouse experiments were of the following species:

TABLE-US-00003 Bayer code Scientific name ALOMY Alopercurus myosuroides AMARE Amaranthus retroflexus APESV Apera spica-venti AVEFA Avena fatua ECHCG Echinocloa crus-galli

[0361] At an application rate of 1,000 kg/ha, applied by the pre-emergence method: [0362] compound 14 showed very good herbicidal activity against APESV. [0363] compounds 11, 17 showed good herbicidal activity against APESV. [0364] compound 12 showed good herbicidal activity against AMARE. [0365] compound 14 showed very good herbicidal activity against ECHCG. [0366] compound 12 showed good herbicidal activity against ECHCG.

[0367] At an application rate of 1,000 kg/ha, applied by the post-emergence method: [0368] compound 11 showed very good herbicidal activity against AMARE. [0369] compound 17 showed very good herbicidal activity against AVEFA. [0370] compounds 12, 13, 14, 15, 16 showed good herbicidal activity against AVEFA. [0371] compounds 13, 14, 15 showed good herbicidal activity against ALOMY. [0372] compounds 14, 16 showed very good herbicidal activity against ECHCG.