Abstract:
This invention relates to novel 2-aryl-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-diones, to agricultural compositions containing them and to the method of use of these compounds as pre- or postemergence herbicides for general control of undesirable vegetation. The invention also includes novel intermediate compounds for making the novel compounds.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of my copending application U.S. Ser. No. 764,582 filed Feb. 1, 1977, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     A number of isoindole-type compounds are known in the prior art. Recently, in German Offenlegungsschrift No. 2,165,651 a group of isoindole-1,3-diones was disclosed as herbicides. The general formula for the isoindole-1,3-diones is as follows: ##STR1## wherein R may be an aryl, aralkyl, or benzyl with optional substituents. U.S. Pat. No. 3,958,976 has disclosed compounds of the following formula as useful for selective weed control in certain crops or for total vegetation control. ##STR2## The preparation of 2-phenyl-5,6,8,8A-tetrahydro-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-dione has been reported in J Med Pharm Chem 2 553 (1960) and J Chem Soc, Perkin I, 132 (1973). The synthesis of 3-carbethoxy-4-phenylaminocarbonyl-5,6-dihydrothiazine has been reported in Gazz. Chin. Ital., 92, 1367 (1962). No agricultural utility was disclosed for either of these compounds. It has now been found that placing proper substituents(s) on the benzene ring in this class of compounds significantly enhances their herbicidal activity. 
     SUMMARY OF THE INVENTION 
     This invention relates to novel compounds of Formulae Ia, Ib and Ic to agricultural compositions containing them and to the method of use of these compounds as pre- or post-emergence herbicides for the general control of undesired vegetation. The invention also includes the novel intermediates of Formula Id. ##STR3## where n is 0, 1 or 2; 
     W is oxygen or sulfur; 
     X is hydrogen, fluorine, chlorine, bromine, cyano, methyl, methoxy or nitro; 
     Y is hydrogen, fluorine, chlorine or methyl; 
     Z is hydrogen, fluorine or methyl; 
     V is hydrogen, fluorine, chlorine or OR; and 
     R is propargyl or alkyl of 1 to 4 carbon atoms with the proviso that (1) X, Y, Z and V cannot all be hydrogen when n is 0 and W is oxygen; (2) when V is other than H, at least one of X, Y and Z must be other than H; and (3) n is 0 when W is sulfur for compounds of Formula Ic. Preferred for their high herbicidal activity are 
     those compounds of Formulae Ia, Ib and Ic where, independently, 
     (a) n is 1 or 2; 
     (b) W is oxygen; 
     (c) X is fluorine, chlorine, bromine or cyano; 
     (d) Y is hydrogen, fluorine or chlorine; 
     (e) Z is hydrogen or fluorine; or 
     (f) V is hydrogen, fluorine or chlorine or OR where R is alkyl of 1 to 3 carbon atoms with the proviso that when V is other than H, at least one of X, Y and Z must be other than H. 
     More preferred for their higher herbicidal activity are those compounds of Formulae Ia, Ib and Ic where n is 2, X is fluorine, chlorine or bromine, Y is hydrogen, fluorine or chlorine, V is hydrogen or alkoxy of 1-3 carbons and Z is hydrogen, provided X and Y are chlorine when V is alkoxy of 1-3 carbons. 
     Specifically preferred for their outstanding herbicidal activity are: 
     (1) 2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 224°-226° C.; 
     (2) 2-(4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 255°-257° C.; 
     (3) 2-(3,4-dichlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 234°-236° C.; 
     (4) 2-(4-chloro-2-fluorophenyl)-5,6-dihydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 187.5°-189° C. 
     (5) 2-(2,4-dichloro-5-methoxyphenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 246°-247.5° C. 
     (6) 2-(2,4-dichloro-5-isopropoxyphenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 196°-199° C. 
     (7) 2-(4-chloro-2-fluorophenyl)-8-chloro-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 250°-252° C. 2-(2,4-dichloro-5-methoxyphenyl)-8-chloro-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]-thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 228.5-229.5. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Synthesis of the compounds 
     The novel compounds of Formula Ia can be prepared as shown in Scheme I: ##STR4## 
     Preparation of compounds of Formula Ia requires the use of a thiomorpholine-3-carboxylate such as 3-carbethoxythiomorpholine (II). Compound II can be synthesized by the reaction of 2-aminoethanethiol and ethyl 2,3-dibromopropionate in a mixture of benzene and chloroform as reported in J. Chem. Soc. Perkin II, 203 (1976). 
     The reaction of a thiomorpholine-3-carboxylate and an aryl isocyanate or isothiocyanate of Formula III can be carried out in various aprotic solvents or in water/organic solvent combinations under atmospheric pressure. The reaction takes place at 0° to 100° C. in 10 minutes to several hours. For convenience the preparation of compounds of Formula IV is carried out in hexanes or a mixture of hexanes and ether at 10° to 30° C. over a period of one to three hours. The product is precipitated and collected by filtration. In some instances, ring closure to compounds of Formula Ia occurs too rapidly for IV to be isolated. 
     The cyclization of compounds of Formula IV to compounds of Formula Ia is an acid-catalyzed reaction [J. Med. Pharm. Chem. 2, 553 (1960); J. Chem. Soc. Perkin I, 132 (1973)] as well as a base catalyzed reaction. The above cited references disclose the preparation of 2-phenyl-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione (Ia:W=O; X=Y=Z=V=H; n=0) in an acidic medium. It has now been found that ring closure can also be effectively promoted by the presence of catalytic amounts of base, e.g. metal hydroxide or metal alkoxide. In general, cyclization of compunds of Formula IV can be carried out in either protic or aprotic solvents at 0° to 150° C. under atmospheric pressure for 10 minutes to 20 hours. It is preferred that the reaction be carried out in refluxing methanol or ethanol for 10 minutes to 2 hours. The sulfides of Formula Ia, where W=oxygen, can be selectively oxidized to sulfoxides or sulfones of Formula Ia by using stoichiometric amounts of oxidizing agents such as peroxyacetic acid or m-chloroperoxybenzoic acid in an inert solvent such as methylene chloride or chloroform at 0° to 40° C. It is preferred to run the reaction in methylene chloride at 5° to 25° C. for 2 to 5 hours. 
     The sulfoxides of Formula Ia where W=sulfur can be prepared by selective oxidation of the sulfides with a suitable oxidizing agent such as m-chloroperoxybenzoic acid usually at 0° to 10° C. 
     The sulfones of Formula Ia in which W is sulfur can be prepared by the reaction of aryl isothiocyanate and 3-carbethoxythiomorpholine-1,1-dioxide (V). Intermediate VI undergoes ring closure rapidly under reaction conditions. Compound V can be prepared by selective oxidation of a corresponding hydrochloride salt of II at -5° to 15° C. The reaction sequences of this preparation is illustrated by Scheme II in which Ar designates the aromatic ring of Formula Ia: ##STR5## 
     Compounds of Formula Ib can be prepared by two different pathways as shown by Scheme III. ##STR6## 
     The reaction of a sulfide of Ia and phosphorus pentachloride takes place at room temperature to give Ib (n=0). For practical purposes, the chlorination reaction is carried out under reflux in chloroform for one to five hours. The product Ib can be isolated and purified by recrystallization. The sulfide of Ib can also be conveniently prepared by treatment at room temperature of Ia (n=0) with N-chlorosuccinimide (NCS) in a chlorinated solvent such as methylene chloride, carbon tetrachloride or chloroform. 
     Compounds of formula Ic can be prepared from those of formula Ib by elimination of hydrogen chloride as shown in Scheme IV. Elimination occurs in neutral dimethylsulfoxide, or in other suitable solvents, such as chloroform, when base catalyzed. Generally, organic as well as inorganic bases are sufficient to promote the formation of Ic from Ib. Dialkylarylamines or trialkylamines such as triethylamine are preferred. ##STR7## 
     An alternative pathway to prepare Ib is the reaction of an arylisocyanate or arylisothiocyanate with 5,6-dihydro-1,4-thiazine-3-carboxylate under the conditions that compounds Ia were prepared. Compound VII can be synthesized by the reaction of 2-aminoethanethiol and bromopyruvate [Gazz. Chim. Ital., 92, 1367 (1962)]. The reaction of compound VII and an arylisocyanate or arylisothiocyanate takes place instantaneously in ether or a mixture of ether and hexanes. The intermediate ureas (VIII) need not be isolated. The reaction mixture is allowed to stand at ambient temperature for 3 to 24 hours. The product usually crystallizes from solution and can be collected by filtration. 
     The corresponding sulfones and sulfoxides of Ib and Ic (W=O) are prepared by selective oxidation of the sulfides of Ib and Ic by a suitable oxidizing agent such as m-chloroperoxybenzoic acid. 
    
    
     The preparation of compounds in the present invention can be more clearly demonstrated by the following specific examples. 
     EXAMPLE 1 
     3-Carbethoxy-4-(4-chloro-2-fluorophenylaminocarbonyl)thiomorpholine 
     An emulsion of 14 g of 3-carbethoxythiomorpholine in 50 ml of n-hexane was added dropwise to a solution of 14 g of 4-chloro-2-fluorophenylisocyanate in 60 ml of anhydrous ether at 15° to 28° C. with stirring. A heavy oil formed after the addition. The oil crystallized after stirring at room temperature for 15 min. The precipitate was collected by filtration to give 24.3 g of 3-carbethoxy-4-(4-chloro-2-fluorophenylaminocarbonyl)thiomorpholine, m.p. 111.5°-112.5° C. 
     The following compounds of this type can be prepared by using the procedure of Example 1. 
     
         ______________________________________ ##STR8##X     Y      Z      V            Melting Point ° C.______________________________________Cl    H      H      H            152.5°-154.5°Cl    Cl     H      H            94°-96°CH.sub.3 O H      H      H            144°-146°CH.sub.3 H      H      H            134°-135.5°F     H      H      H            110°-114°H     F      H      H            97°-101°H     Cl     H      Cl           124.5°-125.5°CH.sub.3 CH.sub.3        CH.sub.3               H            153.5°-155°Br    H      H      HBr    F      H      H            119°-122°Cl    Cl     H      CH.sub.3 O   83°-85°Cl    Cl     H      i-PrOCl    H      H      ClF     F      H      HCH.sub.3 O Cl     H      HH     F      F      HCN    H      H      HCl    Cl     H      n-BuOH     Cl     H      FCl    Cl     H      Cl           125°-131°H     C.sub.3        CH.sub.3               H            173°-175°NO.sub.2 Cl     H      H            135°-137.5°Cl    Cl     H      CH CCH.sub.2 O______________________________________ 
    
     EXAMPLE 2 
     2-(4-Chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]-thiazine-1,3(2H)-dione 
     Seven grams of 3-carbethoxythiomorpholine and 6.5 g of 4-chlorophenyl isocyanate were added to 60 ml of hexanes containing 10 drops of triethylamine as a catalyst. A mild exothermic reaction took place as the reactants mixed. After the mixture cooled to room temperature, the precipitate was collected by filtration and recrystallized from a mixture of methylene chloride and ether to give 4 g of 3-carbethoxy-4-(4-chlorophenylaminocarbonyl)thiomorpholine, mp 152.5°-154.5° C. 
     The mother liquors were combined and evaporated to dryness. The residue was refluxed with 0.5 g of sodium methoxide in 50 ml of methanol for 1.5 hr. On cooling, the precipitate was collected by filtration to give 4.8 g of 2-(4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione, mp 178.5°-180° C. 
     EXAMPLE 3 
     2-(4-Chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]-thiazine-1,3(2H)-dione-7-oxide 
     A solution of 2.8 g of m-chloroperoxybenzoic acid in 30 ml of methylene chloride was added dropwise to a solution of 3.8 g of 2-(4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione in 40 ml of methylene chloride at 0° to 5° C. The resulting suspension was stirred in an ice bath for 3 hr. At the end of the reaction time, the suspension was washed with two portions of 80 ml of saturated sodium bicarbonate solution, washed once with 50 ml of water, dried over anhydrous magnesium sulfate and filtered. The filtrate was concentrated in a rotary evaporator to remove solvent. The residue was crystallized from a mixture of methylene chloride and ether to give 3 g of 2-(4-chlorophenyl)-5,6,8, 8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7-oxide, m.p. 195.5°-205° C. Recrystallization from 98:2 ethanol/benzene gave m.p. 203°-205° C. Molecular weight, as determined by mass spectrometry (M + ), is 298. The mass spectral pattern indicated one chlorine atom to be present. 
     EXAMPLE 4 
     2-(2-Fluoro-4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-dione 
     A solution of 7.5 g of 2-fluoro-4-chlorophenyl isocyanate in 30 ml of hexanes was added dropwise to a stirred solution of 7.8 g of 3-carbethoxythiomorpholine and 10 drops of triethylamine in 30 ml of hexanes. An exothermic reaction took place and a heavy oil formed during the addition. As the mixture cooled to room temperature the oil crystallized. The suspension was kept at ambient temperature for 21/2 days. The precipitate was collected by filtration to give 11.4 g of 2-(2-fluoro-4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione, mp 138°-141° C. 
     EXAMPLE 5 
     2-(2-Fluoro-4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide 
     A solution of 5.6 g of m-chloroperoxybenzoic acid in 60 ml of methylene chloride was added dropwise to a solution of 2-(2-fluoro-4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione in 40 ml of methylene chloride at 0°-10° C. and then stirred at ambient temperature for 5.5 hr. The solution was extracted with two 50 ml portions of saturated sodium bicarbonate solution, washed once with 50 ml of water, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated and diluted with ethanol to give 3.3 g of 2-(2-fluoro-4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide, mp 224°-226° C. 
     EXAMPLE 6 
     2-(4-Chlorophenyl)-2,3,5,6,8,8A-hexahydro-3-thioxo-1H-imidazo[5,1-c][1,4]thiazine-1-one-7,7-dioxide 
     Three ml of concentrated HCl was added to a cold solution of 5 g of 3-carbethoxythiomorpholine in 100 ml of methylene chloride. The mixture was stirred at room temperature for 30 min. The solution was cooled in an ice bath and 11.6 g of m-chloroperoxybenzoic acid was added in portions. After stirring at 0° to 5° C. for 3 hr., the suspension was made alkaline with 50% potassium carbonate solution. Suspended m-chlorobenzoic acid was removed by filtration. The filtrate was extracted once with each of 80 ml of saturated sodium bicarbonate solution, 80 ml of water, dried over anhydrous magnesium sulfate and filtered. The filtrate was then evaporated to give 2.3 g of crude 3-carbethoxythiomorpholine-1,1-dioxide as a yellow oil. 
     A solution of 1.9 g of 4-chlorophenyl isothiocyanate in 20 ml of ether was added dropwise to a solution of 2.3 g of crude 3-carbethoxythiomorpholine-1,1-dioxide in a mixture of 40 ml of ether and 20 ml of methylene chloride. The mixture was stirred at room temperature for 1.5 hr. Solvent was removed by a rotary evaporator. The oil was crystallized from methylene chloride-ether to give 2-(4-chlorophenyl)-2,3,5,6,8,8A-hexahydro-3-thioxo-1H-imidazo[5,1-c][1,4]thiazine-1-one-7,7-dioxide, mp 215°-217° C. Recrystallization from ethanol-methylene chloride gave 0.6 g, mp 222.5°-224° C. (dec.). 
     Other useful compounds of this invention that can be prepared by the preceding procedures include the following examples. 
     
         ______________________________________ ##STR9##X     Y      Z      V         W   n   Melting Point ° C.______________________________________Cl    H      H      H         O   2   255°-257°Cl    F      H      H         O   1   218°-221°Cl    H      H      Cl        O   0   154°-156°Cl    H      H      Cl        O   2   234°-236°Cl    Cl     H      H         O   0   112°-114°Cl    Cl     H      H         O   2   202°-205°H     CH.sub.3        H      H         O   0H     CH.sub.3        H      H         O   2H     F      F      H         O   2CH.sub.3 CH.sub.3        CH.sub.3               H         O   2   124°-125°CH.sub.3 CH.sub.3        CH.sub.3               H         O   0   172°-172.5°H     F      H      H         O   2Br    H      H      H         O   2CN    H      H      H         O   2CH.sub.3 O H      F      H         O   2Cl    Cl     H      CH CCH.sub.2 O                         O   0Cl    Cl     H      CH CCH.sub.2 O                         O   2Cl    H      H      H         S   O   215°-217°Cl    F      H      H         S   O   152.5°-153.5°CN    F      H      H         O   2NO.sub.2 H      H      H         O   O   171°-173°NO.sub.2 H      H      H         O   2   270°-273° (dec.)Cl    Cl     H      i-C.sub.3 H.sub.7 O                         O   2   196°-199°Cl    Cl     H      i-C.sub.3 H.sub.7 O                         O   1Cl    Cl     H      i-C.sub.3 H.sub.7 O                         O   0   130°-133°Cl    Cl     H      i-C.sub.3 H.sub.7 O                         S   2H     Me     Me     H         O   0   135°-136.5°H     Me     Me     H         O   2   207.5°-209.5°Cl    Cl     H      OCH.sub.3 O   2   240°-247.5°Cl    Cl     H      OCH.sub.3 O   1Cl    Cl     H      OCH.sub.3 O   0   125°-130°Cl    Cl     H      n-C.sub.4 H.sub.9 O                         O   2F     F      F      H         O   2NO.sub.2 F      H      H         O   2Cl    Cl     H      OCH.sub.3 S   0Cl    H      H      F         O   2Cl    H      H      H         S   1   199°-200.5°Cl    F      H      H         S   1   214°-215° (dec.)Cl    F      H      H         S   2   203.5°-204° (dec.)CH.sub.3 O H      H      H         O   0   182°-184°CH.sub.3 O H      H      H         O   2   206°-209°Cl    CH.sub.3        H      H         O   2   198°-200°Cl    CH.sub.3        H      H         O   0   143°-145°NO.sub.2 Cl     H      H         O   0   205°-207.5°NO.sub.2 Cl     H      H         O   2   254°-266°Cl    Cl     H      Cl        O   0   142°-144.5°Cl    Cl     H      Cl        O   2   214°-216.5°Br    F      H      H         O   0   132°-135°Br    F      H      H         O   1   203°-209°Br    F      H      H         O   2   228°-230°CH.sub.3 H      H      H         O   0   196°-198°CH.sub.3 H      H      H         O   2   222°-224°F     H      H      H         O   0   160°-162°F     H      H      H         O   2   223°-228°Cl    Cl     H      H         S   0   158.5°-160°H     Cl     H      Cl        O   0   165.5°-168°H     Cl     H      Cl        O   2   216°-218°______________________________________ 
    
     EXAMPLE 7 
     2-(4-Chlorophenyl)-5,6,8,8A-tetrahydro-8-chloro-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-dione and 2-(4-chlorophenyl)-5,6-dihydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dion 
     To a solution of 14 g of phosphorous pentachloride in 150 ml of chloroform was added 15.7 g of 2-(4-chlorophenyl)-5,6,8,8A-tetrahyhdro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione. The solution was refluxed 1.5 hr under anhydrous conditions, cooled to room temperature and neutralized by addition of saturated sodium bicarbonate solution. The chloroform layer was separated, extracted with 50 ml each of saturated sodium bicarbonate solution and water. The chloroform solution was then dried over anhydrous magnesium sulfate. and filtered. The filtrate was concentrated and diluted with ether to give 12 g of crude material which was shown by NMR to contain about 50% starting material. Recrystallization from chloroform gave 3 g of 2-(4-chlorophenyl)-5,6,8,8A-tetrahydro-8-chloro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione, m.p. 144°-145.5° (dec.). The structure was confirmed by  13  C NMR spectroscopy. 
     The mother liquors were combined and evaporated. The residue was refluxed with 7 g of phosphorous pentachloride in 75 ml of chloroform for 1 hr. To the mixture 5 ml of triethylamine was added and refluxed for an additional 3 hrs. On cooling, the solution was extracted with two 100 ml portions of 5% sodium hydroxide solution, 100 ml of water, dried over anhydrous magnesium sulfate and filtered. The filtrate was concentrated and diluted with ether to give 8.4 g of 2-(4-chlorophenyl)-5,6-dihydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione, m.p. 155°-157.5° C. 
     EXAMPLE 8 
     8-Chloro-2-(4-chloro-2-flurorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione 
     To a solution of 4.4 g of 2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione in 100 ml of methyl chloride was added 2 g of N-chlorosuccinimide. The resulting suspension was stirred at room temperature for 4 hours and filtered. The filtrate was concentrated and diluted with ether. The precipitate was collected by filtration, washed thoroughfully with water, and air-dried to give 4.1 g of 8-chloro-2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3-(2H)-dione, m.p. 108-109 (dec.) 
     EXAMPLE 9 
     8-Chloro-2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide 
     m-Chloroperoxybenzoic acid (2.6 g) was added in portions to a cold solution of 2.1 g of 8-chloro-2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H)-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione in 30 ml of methylene chloride. The mixture was stirred on an ice bath for 3.5 hours and then sufficient amount of saturated sodium bicarbonate solution to effect precipitation was added with stirring. The resulting precipitate was collected by filtration, washed with water, and air-dried to give 1.0 g of 8-chloro-2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4-thiazine-1,3(2H)-dione-7,7-dioxide, m.p. 250°-252°. 
     Useful compounds that can be prepared by the preceding procedures include the following examples: 
     
         ______________________________________ ##STR10##X    Y      Z      V           n    melting point ° C.______________________________________Cl   F      H      H           1    219.5°-221° (dec.)Cl   Cl     H      OCH.sub.3   0    201°-203°Cl   Cl     H      OCH.sub.3   2    228.5°-229.5°Cl   Cl     H      OCH.sub.3   1Br   F      H      H           0Br   F      H      H           1Br   F      H      H           2Cl   H      H      H           2Cl   Cl     H      i-C.sub.3 H.sub.7 O                          0Cl   Cl     H      i-C.sub.3 H.sub.7 O                          2Cl   Cl     H      Cl          0Cl   Cl     H      Cl          2Cl   H      H      Cl          0Cl   H      H      Cl          2Cl   Cl     H      CH CCH.sub. 2 O                          0Cl   Cl     H      CH CCH.sub.2 O                          2______________________________________ 
    
     EXAMPLE 10 
     2-(4-Chloro-2-fluorophenyl)-5,6-dihydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione 
     A solution of 8.6 g of 4-chloro-2-fluorophenylisocyanate in 20 ml of anhydrous ether was added dropwise to a mixture of 9.8 g of crude 3-carbethoxy-5,6-dihydro-1,4-thiazine and 10 drops of triethylamine in 20 ml of ether. After the addition, 30 ml of hexane was added dropwise in 20 min. The solution was stirred at room temperature for 3 hrs. The solution was concentrated in vacuo to remove solvent. The resulting oil was crystallized from ether to give 10 g of 2-(Chloro-2-fluorophenyl)-5,6-dihydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione, m.p. 117.5°-120.5° C. 
     Useful compound that can be prepared by the preceding procedures include the following: 
     
         ______________________________________ ##STR11##X     Y      Z      V         W   n   Melting Point ° C.______________________________________Cl    H      H      H         O   1   206°-208°Cl    H      H      H         O   2   239°-240°Cl    H      H      H         S   0   184°-185.5°Cl    H      H      Cl        O   0   171°-173°Cl    H      H      Cl        O   2   227.5°-229°Cl    F      H      H         O   2   187.5°-189°Cl    F      H      H         O   1   174°-175°Cl    F      H      H         S   0   134°-137°Cl    Cl     H      H         S   0   130°-132°Cl    Cl     H      H         O   0   143°-144.5°Cl    Cl     H      H         O   1   226°-228°Cl    Cl     H      H         O   2   244°-245°H     Cl     H      Cl        O   0   183°-185°H     Cl     H      Cl        O   1   204.5°-205.5°H     Cl     H      Cl        O   2   253°-255° (dec.)Cl    Cl     H      CH.sub.3 O                         O   0   203°-205°Cl    Cl     H      CH.sub.3 O                         O   1   167°-171°Cl    Cl     H      CH.sub.3 O                         O   2   203°-205°Cl    Cl     H      i-Pro     O   0Cl    Cl     H      i-Pro     O   1Cl    Cl     H      i-Pro     O   2Cl    Cl     H      n-Buo     O   1F     F      H      F         O   1Br    H      H      H         O   1Br    F      H      H         S   0Br    F      H      H         O   0Br    F      H      H         O   1Br    F      H      H         O   2F     F      F      H         O   2CH.sub.3 CH.sub.3        CH.sub.3               H         O   2CH.sub.3 CH.sub.3        H      H         O   2CH.sub.3 O Cl     H      H         O   0CH.sub.3 O Cl     H      H         O   1CH.sub.3 O Cl     H      H         O   2CN    H      H      H         O   1NO.sub.2 H      F      H         O   2Cl    Cl     H      CHCCH.sub.2 O                         O   0Cl    Cl     H      CHCCH.sub.2 O                         O   2______________________________________ 
    
     Useful formulations of the compounds of Formulae Ia and Ib can be prepared in conventional ways. They include granules, pellets, solutions, suspensions, emulsions, wettable powders, emulsifiable concentrates and the like. Many of these may be applied directly to the plants. Sprayable formulations can be extended in suitable media and used at spray volumes of from a few pints to several hundred gallons per acre. High strength compositions are primarily used as intermediates for further formulation. The formulations, broadly, contain about 1% to 99% by weight of active ingredient(s) and at least one of a) about 0.1% to 20% surfactant(s) and b) about 1% to 99% solid or liquid diluent(s). More specifically, they will contain these ingredients in the following approximate proportions: 
     
         ______________________________________       Percent by Weight       Active       Ingredient               Diluent(s)                         Surfactant(s)______________________________________Wettable Powders         20-90     0-74      1-10Oil Suspensions,Emulsions, Solutions(including Emulsifi-able Concentrates)          5-50     40-95     0-15Aqueous Suspensions         10-50     40-84     1-20Granules and Pellets          1-95      5-99     0-15High StrengthCompositions  90-99      0-10     0-2______________________________________ 
    
     Lower or higher levels of active ingredient can, of course, be present depending on the intended use and the physical properties of the compound. Higher ratios of surfactant to active ingredient are sometimes desirable, and are achieved by incorporation into the formulation or by tank mixing. 
     Typical solid diluents are described in Watkins, et al., &#34;Handbood of Insecticide Dust Diluents and Carriers&#34;, 2nd. Edn., Dorland Books, Caldwell, N.J. The more absorptive diluents are preferred for wettable powders. Typical liquid diluents and solvents are described in Marsden, &#34;Solvents Guide&#34;, 2nd. Edn., Interscience, New York, 1950. Solubility under 0.1% is preferred for suspension concentrates; solution concentrates are preferably stable against phase separation at 0° C. &#34;McCutcheon&#39;s Detergents and Emulsifiers Annual&#34;, MC Publishing Co., Ridgewood, N.J., as well as Sisely and Wood, &#34;Encyclopedia of Surface Active Agents&#34;, Chemical Publ. Co., Inc., New York, 1964, list surfactants and recommended uses. All formulations can contain minor amounts of additives to reduce foam, caking, corrosion, microbiological growth, etc. 
     The methods of making such compositions are well known. Solutions are prepared by simply mixing the ingredients. Fine solid compositions are made by blending and, usually, grinding as in a hammer or fluid energy mill. Suspensions are prepared by wet milling (see, for example, Littler, U.S. Pat. No. 3,060,084). Granules and pellets may be made by spraying the active material upon preformed granular carriers or by agglomeration techniques. See J. E. Browning, &#34;Agglomeration&#34;, Chemical Engineering, Dec. 4, 1967, pp. 147ff. and &#34;Perry&#39;s Chemical Engineer&#39;s Handbook&#34;, 4th Edn., McGraw-Hill, N.Y., 1963, pp. 8-59ff. 
     For further information regarding the art of formulation, see for example: 
     H. M. Loux, U.S. Pat. No. 3,235,361, Feb. 15, 1966, Col. 6, Line 16 through Col. 7, Line 19 and Examples 10 through 41. 
     R. W. Luckenbaugh, U.S. Pat. No. 3,309,192, Mar. 14, 1967, Col. 5, Line 43 through Col. 7, Line 62 and Ex. 8, 12, 15, 39, 41, 52, 53, 58, 132, 138-140, 162-164, 166, 167, 169-182. 
     H. Gysin and E. Knusli, U.S. Pat. No. 2,891,855, June 23, 1959, Col. 3, Line 66 through Col. 5, Line 17 and Examples 1-4. 
     G. C. Klingman, &#34;Weed Control as a Science&#34;, John Wiley &amp; Sons, Inc., New York, 1961, pp. 81-96. 
     J. D. Fryer and S. A. Evans, &#34;Weed Control Handbook&#34;, 5th Edn. Blackwell Scientific Publications, Oxford, 1968, pp. 101-103. 
     In the following examples, unless indicated otherwise all parts are by weight and all temperatures in degrees centigrade. 
     EXAMPLE 11 
     Solution 
     
         ______________________________________2-(3,4-dichlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide                   40%dimethylformamide         60%______________________________________ 
    
     The ingredients are combined and stirred to produce a solution, which can be used for low volume applications. 
     EXAMPLE 12 
     Extruded Pellet 
     
         ______________________________________2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide 25%anhydrous sodium sulfate  10%crude calcium ligninsulfonate                      5%sodium alkylnaphthalenesulfonate                      1%calcium/magnesium bentonite                     59%______________________________________ 
    
     The ingredients are blended, hammer milled and then moistened with about 12% water. The mixture is extruded as cylinders about 3 mm diameter which are cut to produce pellets about 3 mm long. These may be used directly after drying, or the dried pellets may be crushed to pass a U.S.S. No. 20 sieve (0.84 mm openings). The granules held on a U.S.S. No. 40 sieve (0.42 mm openings) may be packaged for use and the fines recycled. 
     EXAMPLE 13 
     Emulsifiable Concentrate 
     
         ______________________________________2-(3,4-dichlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo-[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide               25%blend of oil soluble sulfonatesand polyoxyethylene ethers                      4%xylene                    71%______________________________________ 
    
     The ingredients are combined and stirred with gentle warming to speed solution. A fine screen filter is included in packaging operation to insure the absence of any extraneous undissolved material in the product. 
     EXAMPLE 14 
     Wettable Powder 
     
         ______________________________________2-(4-chloro-2-fluorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide                     50%sodium alkylnapthalenesulfonate                      2%sodium ligninsulfonate     2%synthetic amorphous silica                      3%kaolinite                 43%______________________________________ 
    
     The ingredients are thoroughly blended, coarsely hammermilled and finally airmilled to produce particles essentially all under 15 microns. The material is reblended and sifted through a U.S.S. No. 50 sieve before packaging. 
     All compounds of Formulae Ia, Ib and Ic may be formulated in the same manner. 
     EXAMPLE 15 
     Granule 
     
         ______________________________________wettable powder of Example 9                     10%attapulgite granules      90%(U.S.S. #20-40; 0.84-0.42 mm)______________________________________ 
    
     A slurry of wettable powder containing 50% active is sprayed on the surface of attapulgite granules in a double-cone blender. The granules are dried and packaged. 
     EXAMPLE 16 
     Aqueous Suspension 
     
         ______________________________________2-(4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3-(2H)-dione-7,7-dioxide    60%polyacrylic acid thickener                      0.3%dodecylphenol polyethylene glycolether                      0.5%disodium phosphate         1.0%monosodium phosphate       0.5%polyvinyl alcohol          1.0%pentachlorophenol          0.4%water                     36.3%______________________________________ 
    
     The ingredients are ground together in a sand mill to produce particles essentially all under five microns in size. 
     EXAMPLE 17 
     High Strength Concentrate 
     
         ______________________________________2-(4-chlorophenyl)-5,6,8,8A-tetrahydro-1H-imidazo[5,1-c][1,4]thiazine-1,3(2H)-dione-7,7-dioxide               98.5%silica aerogel             0.5%synthetic amorphous fine silica                      1.0%______________________________________ 
    
     The ingredients are blended and ground in a hammer mill to produce a high strength concentrate essentially all passing a U.S.S. No. 50 sieve (0.3 mm openings). This material may then be formulated in a variety of ways. 
     Utility 
     The compounds of Formula I are useful for the pre/postemergence control of mixed stands of weeds, such as on industrial sites, railroad and utility rights-of-way, along fences, building foundations, oil storage tanks, parking and storage lots, etc. 
     The amount of the compounds of Formula I to be used in any given situation will vary according to the particular end result desired, the use involved, the weed species and soil type involved, the formulation used, the mode of application, prevailing weather conditions, foilage density and like factors. Since so many variables play a role, it is not possible to state a rate of application suitable for all situations. Broadly speaking, the compounds of the invention are used at levels at about 0.125 to about 20 kilograms, preferably about 0.25 to 10, per hectare. The lower rates in this range will generally be selected on lighter soils, soils low in organic matter content, or in situations where maximum persistence is not necessary. 
     Herbicidal activity of compounds of this invention was determined in a greenhouse test. 
     Test Procedure 
     Seeds of crabgrass (Digitaria spp.), barnyardgrass (Echinochloa crusgalli), wild oats (Avena fatua), Cassia tora morningglory (Ipomoea spp.), cocklebur (Xanthium spp.), sorghum, corn, soybean, rice, wheat and nutsedge tubers were planted in a growth medium and treated preemergence with the chemicals dissolved in a non-phytotoxic solvent. At the same time, cotton having five leaves (including cotyledonary ones), bush beans with the third trifoliate leaf expanding, crabgrass with two leaves, barnyardgrass with two leaves, wild oats with one leaf, cassia with three leaves (including cotyledonary ones), morningglory with four leaves (including the cotyledonary ones), cocklebur with four leaves (including the cotyledonary ones), sorghum with three leaves, corn with three leaves, soybeans with two cotyledonary leaves, rice with two leaves, wheat with one leaf, and nutsedge with three-five leaves were sprayed. Treated plants and controls were maintained in a greenhouse for sixteen days, then all species were compared to controls and visually rated for response to treatment. 
     A quantitative rating was made on a scale of extending from 0 to 10. A rating of 10 means complete kill, a rating of 0 means no injury. A qualitative rating for type of injury was also made; the letter &#34;B&#34; denotes foliage burn, &#34;C&#34; indicates chlorosis/necrosis, &#34;H&#34; stands for formative effects, &#34;D&#34; means defoliation, &#34;G&#34; is retardation and &#34;E&#34; denotes emergence inhibition. 
     Ratings for several of the compounds tested by this procedure are recorded in Table I. 
     The data in Table I show that the preferred compounds of the instant invention have high herbicidal activity. Specifically, it is seen that in both pre- and postemergence applications a broad spectrum of plant species is destroyed by the instant herbicides. 
     
                                           TABLE I__________________________________________________________________________         POST EMERGENCE               Morn-              Barn-      kg/         Bush            Cot-               ing-                   Cock-                       Cas-                          Nut-                              Crab-                                  yard                                      Wild      Soy-  Sor-Compound   ha Bean            ton               glory                   lebur                       sia                          sedge                              grass                                  Grass                                      Oats                                         Wheat                                             Corn                                                bean                                                   Rice                                                      ghum__________________________________________________________________________ ##STR12## 2 0.4         10B 9B            9B 9B               10B 10B                   10B 9B                       10B 9B                          9B 9B                              10B 9B                                  10B 10B                                      10B 8B                                         9B 5B                                             9B 6B                                                10B 10B                                                   10B 9B                                                      10B 9B ##STR13## 2  9B 8B 8D               10B 7B  8B 5C  10B 9B  2B 3H                                         1B  6B 9B 6B 9B ##STR14## 2  9B 5B 4B  7B  3B 3B  7B  6B  2B 1B  3B 7B 2B 3B ##STR15## 2  1B 2B 1B  1B  1B 0   0   1B  0  0   0  1B 0  1B ##STR16## 2 0.4         10B 10B            9B 9B               10B 9B                   10B 9B                       10B 9B                          9C 5B                              10B 10B 9B                                      9B 3B                                         9B 3B                                             9B 3B                                                9B 9B                                                   10B 5B                                                      9B 5B ##STR17## 2  9B 8B 8D               9B  7B  7B 2B  2B 5H                                  6B  2B 2B  4B 9B 3B 6B ##STR18## 2 0.4         10B 10B            9B 9B               10B 9B                   10B 8B                       10B 10B                          7B 4B                              10B 4B 6H                                  10B 9B                                      10B 5B                                         7B 4B                                             9B 5B                                                9B 9B                                                   8B 4B                                                      10B 7B ##STR19## 2  9B 9B 8D               10B 5B  5B 1B  9B  6B  2B 2B  2B 4G                                                9B 6B 6B ##STR20## 2  8B 6B 1B  2B  1B 1B  1B  4B  1B 1B  2B 2B 2B 1B ##STR21## 2  5B 6B 5D               1B  1B  1B 0   1B  1B  1B 1B  2B 3B 1B 1B ##STR22## 2  10B            9B 8B  2B  9B 3B  7B  7B  8B 9B  9B 7B 6B 6B ##STR23## 0.4         9B 7B 3B  2B  8B 1B  3B  3B  2B 7B  5B 5B 3B 3B ##STR24## 0.4         6B 4B 1B  1B  2B 0   1B  0   1B 1B  2B 1B 1B 1B ##STR25## 0.4         9B 10B               6B  7B  9B 3B  4B  6B  9B 10B 10B                                                8B 10B                                                      8B ##STR26## 0.4         9B 8B 7D               6B  4B  7B 2B  5B 8H                                  6B  9B 9B  8B 8B 6B 2G ##STR27## 2  9B 9B 9B  7B  5B 5B  8B  8B  4B 4B  6B 8B 7B 5B ##STR28## 2  10B            10B               10B 10B 10B                          5B  10B 10B 10B                                         9B  8B 10B                                                   10B                                                      10B ##STR29##  2 0.4          -- --             -- --                10B 10B                    10B 6B                        10B 10B                           9B 4B 7G                               10B 9B                                   10B 9B                                      6B 9H 4B 7H                                         6B 9H 4B                                             6B 9H 4B                                                 9B 9B                                                    10B 8C                                                       9B 8B ##STR30## 2 0.4         9B 9B            -- --               10B 10B                   9B 9B                       9B 9B                          7C 1B 5G                              9B 9B                                  10C 9B 9B                                      3B 8H 4B 6H                                         5B 9H 4B 6H                                             5B 9H 3B 7H                                                9B 9B                                                   9B 5B 8G                                                      5B 9H 5B 9H ##STR31## 2 0.4         8B 7B            -- --               10B 8B                   5B 3B                       -- 1B 6G                          1B 5C 0                              4B 9H 2B  9H                                  5B 9H 7B                                      4B 7H 2B                                         5B 2B                                             4B 2B                                                9B 7B                                                   4B 8G 7B                                                      4B 7H 4B ##STR32## 2  3B 4B 9D 9G               2B  2B  1B 1B 5C                              4B 9H                                  5B 8H                                      4B 7H                                         3B  1B 4C                                                4B 8G                                                   4B 7G                                                      5B 9H__________________________________________________________________________         PRE-EMERGENCE               Morn-              Barn-      kg/         Bush            Cot-               ing-                   Cock-                       Cas-                          Nut-                              Crab-                                  yard                                      Wild      Soy-  Sor-Compound   ha Bean            ton               glory                   lebur                       sia                          sedge                              grass                                  Grass                                      Oats                                         Wheat                                             Corn                                                bean                                                   Rice                                                      ghum__________________________________________________________________________ ##STR33## 2 0.4         10C 10C            10C 10C               10C 10C                   10C 10C                       10c 10C                          10C 10C                              10C 10C                                  10C 10C                                      10C 10C                                         10C 10C                                             10C 10C                                                10C 10C ##STR34## 2  10C            10C               10C 10C 10C                          10C 10C 10C 10C                                         10C 10C                                                10C ##STR35## 2  10C            10C               10C 9C  10C                          10C 10C 10C 10C                                         2C 9H                                             9C 10C ##STR36## 2  0  0  0   0   0  0   0   0   0  0   0  0 ##STR37## 2 0.4         10C 10C            10C 10C               10C 10C                   10C 10C                       10C 10C                          10C 10C                              10C 10C                                  10C 10C                                      10C 5C 9H                                         10C 9C                                             10C 9C                                                10C 10C ##STR38## 2  10C            10C               10C 9C  10C                          10C 10C 9C  10C                                         10C 10C                                                10C ##STR39## 2 0.4         10C 10C            10C 10C               10C 10C                   10C 7C                       10C 10E                          10C 10C                              10C 10C                                  10C 10C                                      10C 10C                                         10C 9C                                             10C 9C                                                10C 10C ##STR40## 2  10C            10C               10C 9C  10C                          10C 10C 10C 9C 10C 9C 10C ##STR41## 2  1C 9G            1C 7G               1C 5G                   2C  10C                          10C 9C  9C  4C 8H                                         2C 6H                                             7C 9C ##STR42## 2  0  0  9C  0   0  0   0   0   0  0   0  0 ##STR43## 2  9C 9C 2H               2C 5G                   9C  9C 9C  9C  9C  10C                                         10C 9C 6C ##STR44## 0.4         8C 0  5C  7C  8C 8C  9C  9C  6C 7C  10C                                                0 ##STR45## 0.4         10C            5C 9H               3C 9H                   9C  9C 9C  9C  10C 9C 9C  10C                                                8C ##STR46## 0.4         9C 3C 9H               5C 9H                   9C  9C 8C  4C 9H                                  2C 9H                                      10C                                         10C    1C 5G ##STR47## 0.4         10C            9C 10C 10C 10C                          10C 10C 10C 10C                                         10C 10C                                                10C ##STR48## 2  2C 9G            2C 9G               10C 5C  9H 5C 9H                              9C  9C  3C 9H                                         9H  9C 10C ##STR49## 2  10C            9C 10C 9C  10C                          10C 10C 9C  9H 9H  9C 9H ##STR50## 2 0.4         10C 10C            -- --               10C 9C 9C                       10C 10C                          10C 10C                              10C 10C                                  10C 10C                                      9H 9H                                         9H 10H                                             9C 9C                                                10C 10C ##STR51## 2 0.4         10C 10C            10C 10C               10C 10C                   9C 9C                       10C 10C                          10C 10C                              10C 10C                                  10C 10C                                      9H 9H                                         10C 10H                                             10C 10C                                                10C 10C ##STR52## 2 0.4         2C 9H 1C  6G            3H 3H               10C 1C 4H                   8C 1C                       9H 5H                          9C 4C 8H                              9C 5C 9H                                  9C 5C 8H                                      2C 9H 2C 7H                                         3C 6G 0                                             9C 8C                                                9C 8H ##STR53## 2  10C            3C 9H               10C 6C  9H 10H 10C 10C 9C 9H  9C 9H__________________________________________________________________________