Cyano-dienes, halopyridines, intermediates and a process for the

Details Cyano-dienes, halopyridines, intermediates and a process for the Cyano-dienes, halopyridines, intermediates and a process for the

1990-06-12

1992-04-21

Rotman, Alan L.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

546294, 546316, 546317, C07D21312, C07D21356, C07D21362, C07C25507

Patent

active

051070570

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to certain cyano-dienes and halopyridines and the processes for their preparation from a protected 1,3-dialdehyde and a cyano-diene.
The "sulfonylurea" herbicides are an extremely potent class of herbicides discovered within the last few years which generally consist of a sulfonylurea bridge, --SO.sub.2 NHCONH--, linking two aromatic or heteroaromatic rings. Research directed to methods for preparing sulfonylurea herbicides is continually producing new processes. The search for improved methods for more effectively preparing such compounds and intermediates required for preparing such compounds continues.
South African Patent Application 870,436 filed Jan. 21, 1987 discloses the use of compounds of Formula I in the preparation of pyridine sulfonylureas. ##STR1##
EP-A-237,292 published Sep. 16, 1987 discloses the use of compounds of the above Formula I in the preparation of pyridine sulfonylureas.
J. Org. Chem. 41, 2066 (1976) discloses the preparation of 2-bromonicotinic esters according to the following procedure. ##STR2##
J. Org. Chem. 38, 3436 (1974) discloses the preparation of nicotinamide from the 2-bromonicotinic esters according to the following procedure. ##STR3##
Japanese Patent 80-76,863, priority date Dec. 6, 1978, discloses the preparation of 2-chloro- nicotinic acids according to the following procedure. ##STR4##


SUMMARY OF THE INVENTION

A process for making intermediates useful for the preparation of herbicidally active sulfonylureas has been discovered as well as novel intermediate compounds. In accordance with the invention, the process for preparing a compound of formula I and its corresponding salts, ##STR5## wherein
R.sub.1 is COR.sub.2 or SO.sub.2 CH.sub.2 CH.sub.3 ; III ##STR6## wherein R is --CH.sub.3 or --CH.sub.2 CH.sub.3 and R.sub.1 is as defined above; in the presence of acetic anhydride, a ZnX.sub.2 catalyst where X is as defined above and optionally acetic acid at a temperature of 110.degree. to 150.degree. C. to form a compound of the formula ##STR7## wherein R.sub.1 and R are as defined above; and reacting in the presence of acetic acid at a temperature of 0.degree. to 60.degree. C. the compound of Formula IV with HX where X is as defined above.
The compounds of Formula IV ##STR8## wherein R and R.sub.1 are as defined; prepared by the process of the invention are novel and useful for preparing intermediates for the preparation of sulfonylurea herbicides.
Compounds of the Formula I ##STR9## wherein R.sub.1 and X are defined as above; novel and useful compounds for the preparation of sulfonylurea herbicides.
Preferred for reasons of ease of synthesis and efficiency are: dialkylamino. CH.sub.3. is the HBr salt.
The compounds of the invention preferred for their efficiency and ease of synthesis are: dialkylamino. CH.sub.3. is F or Br. CH.sub.3.
The process of the invention can generally be carried out by reacting 1.0 to 3 moles of Compound II, preferably 1.2 to 1.5 moles, per mole of Compound III in the presence of with 1-5 moles of acetic anhydride, preferably 1.5-2.5 moles. Acetic acid can be advantageously used but is not required. Lower temperatures can be used with acetic acid. ZnX.sub.2, the catalyst, can be used in amounts of 0.5-2% by weight based on Compound II. The temperature for the reaction may be generally 110.degree.-150.degree. C., preferably 120.degree.-130.degree. C.: the yield of Compound II will vary depending on the condition but yields of 85-90% are achievable.
The second step for the process involving the reaction of Compound IV with HX can generally be carried out with 0.5-8 moles of HX, preferably 2-4 moles of HX. The amount of acetic acid required is generally from 0.2 to 1 liter per mole of reactant, preferably 0.4 to 0.6 liter. The temperature may range from 0.degree.-60.degree. C., preferably 10.degree.-30.degree. C.
By C.sub.1 -C.sub.2 dialkylamino is meant dimethylamino and diethylamino.


DETAILED DESCRIPTION OF THE INVENTION

More specifically, the process of this invention may be carried out

REFERENCES:
Chemical Abstracts, vol. 87, No. 13, Abst. No. 102,266e, Sep. 26, 1977.
Chemical Abstracts, vol. 108, No. 9, Abst. No. 75,417y, Feb. 29, 1988.

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