Saccharin derivatives

Details Saccharin derivatives Saccharin derivatives

1997-02-03

1998-02-10

Richter, Johann

Plant protecting and regulating compositions

Plant growth regulating compositions

Organic active compound containing

548210, C07D27506, A01N 4380

Patent

active

057169055

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP95/02977 filed Jul. 27, 1995.
The present invention relates to saccharin derivatives of the formula I ##STR2## where the substituents have the following meanings: L and M are hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkylthio, chlorine, cyano, methylsulfonyl, nitro or trifluoromethyl; C.sub.3 -C.sub.6 -alkenyl, C.sub.3 -C.sub.5 -alkynyl, C.sub.1 -C.sub.4 -acyl, benzyl or phenyl, the phenyl rings being unsubstituted or substituted by halogen or C.sub.1 -C.sub.4 -alkyl; tert-butyl;
The invention further relates to herbicidal compositions containing the compounds I, and methods of controlling undesired plant growth using the saccharin derivatives I.
Saccharin derivatives having herbicidal action cannot be inferred from the prior art. However, unsubstituted saccharin (o-sulfobenzimide, ie. L, M, Q and Z in formula I=H) has been known as a synthetic sweetener for a long time. 4-Hydroxysaccharin is further known as a sweetener (German Offenlegungsschrift 3 607 343). The use of saccharin derivatives in pest control is also known, eg. JP publication 72/00419, 73/35457 (fungicides) and in pharmacy, eg. EP-A 594 257 and literature references mentioned therein.
Heterocyclic compounds having a sulfonamide-containing ring have been disclosed as herbicides, a typical representative which can be mentioned here being bentazone ##STR3##
It is an object of the present invention to make available novel herbicides having a basic structure which was hitherto unknown for this indication. We have found that this object is achieved by the compounds I defined at the outset.
Compounds of the formula I are obtained by acylating the magnesium enolate A2 of a cyano ketone of the formula A1 ##STR4## with a saccharincarbonyl chloride of the formula III to give the enolized compound I.1. ##STR5##
In the abovementioned formulae, L and M have the meaning given at the outset and Z is hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, C.sub.3 -C.sub.6 -alkenyl, C.sub.3 -C.sub.5 -alkynyl, C.sub.1 -C.sub.4 -acyl or benzyl or phenyl which is unsubstituted or substituted by halogen or C.sub.1 -C.sub.4 -alkyl.
The first step of the reaction sequence is carried out by treating a methanolic solution of a cyano ketone of the formula A1 with magnesium and a small amount of CCl.sub.4 and allowing this to react to give the magnesium enolate. Analogous C acylations of cyano ketones are described eg. in EP-A 496 630 and EP-A 496 631.
After removing the methanol, the resulting magnesium enolate of the formula A2 is dissolved in toluene or acetonitrile, acetonitrile being preferred, and then the amount of the acid chloride of the formula III equivalent to A1 is added dropwise as an acetonitrile solution. After stirring at from 25.degree. C. to 50.degree. C. for 1-16 hours, the reaction is complete. For working up, it is concentrated under reduced pressure, the residue which remains is taken up in a solvent such as ethyl acetate or methylene chloride and washed with 10 percent HCl to decompose the magnesium salt. After washing the organic phase with water, it is dried with a drying agent such as sodium sulfate and concentrated. The product. is precipitated from the residue which remains by rubbing with a hydrocarbon such as petroleum ether, cyclohexane or n-pentane.
The cyano ketones of the formula A1 used as starting materials are generally known compounds. They can be obtained, for example, by reaction of cyanoacetic acid with butyllithium and then with an acid chloride R.sup.1 --COCl.
The acid chlorides R.sup.1 --COCl are obtained in a manner known per se from the corresponding carboxylic acids R.sup.1 -COOH by reaction with thionyl chloride. The carboxylic acids R.sup.1 -COOH are compounds which are known from the literature: pivalic acid and cyclopropanecarboxylic acid are commercially available compounds. 1-Methylcyclopropanecarboxylic acid is obtained either by hydrolysis of the commercially available ethyl ester or in a known manner by methylation of lithium 1-Met

REFERENCES:
Chem Abst. 83-828727/48 (1983).
Chem Abst. 24278T-C (1972).

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