Process for the oxidation of certain substituted sulfilimines to insecticidal sulfoximines

1. A process for the preparation of insecticidal sulfoximines (Ia),

wherein

Het represents:

X represents halogen, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl, C 2 -C 4 haloalkenyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, CN, NO 2 , SO m R 6 where m is an integer from 0-2, COOR 4 or CONR 4 R 5 ;

Y represents hydrogen, halogen, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl, C 2 -C 4 haloalkenyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, CN, NO 2 , SO m R 1 where m is an integer from 0-2, COOR 4 , CONR 4 R 5 , aryl or heteroaryl;

n is an integer from 0-3;

L represents either a single bond, —CH(CH 2 ) p — where R 1 , S and L taken together represent a 4-, 5-, or 6-membered ring and p is an integer from 1-3, —CH(CH 2 OCH 2 )— where R 1 , S and L taken together represent a 6-membered ring, or —CH— where L, R 2 and the common carbon to which they connect taken together represent a 4-, 5-, or 6-membered ring with up to, but no more than, 1 heteroatom;

R 1 represents C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 3 -C 6 alkenyl, C 3 -C 6 alkynyl, C 3 -C 6 haloalkenyl, arylalkyl, heteroarylalkyl, or —CH 2 — in cases where R 1 , S and L taken together represent a 4-, 5-, or 6-membered ring;

R 2 and R 3 independently represent hydrogen, halogen, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl, C 2 -C 4 haloalkenyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, CN, SO m R 6 where m is an integer from 0-2, COOR 4 , CONR 4 R 5 , arylalkyl, heteroarylalkyl, or R 2 and R 3 and the common carbon to which they attach form a 3-6 membered ring;

R 4 and R 5 independently represent hydrogen, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl; C 3 -C 6 alkenyl, C 3 -C 6 alkynyl, C 3 -C 6 haloakenyl, aryl, heteroaryl, arylalkyl or heteroarylalkyl; and

R 6 represents C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 3 -C 6 alkenyl, C 3 -C 6 alkynyl, C 3 -C 6 haloalkenyl, arylalkyl or heteroarylalkyl;

which comprises oxidizing a sulfilimine of formula (I)

wherein

R 1 , R 2 , R 3 , L, Het and n are as previously defined

by contacting the sulfilimine in a suitable organic solvent that is essentially inert to the strong oxidizing conditions with an oxidizing agent comprising ruthenium tetraoxide or an alkali metal permanganate at a temperature from about −10 to about 45° C.

2. The process of claim 1 in which Het is (6-substituted)pyridin-3-yl or (2-substituted)thiazol-5-yl and where X is halogen or C 1 -C 2 haloalkyl and Y is hydrogen.

3. The process of claim 1 in which the starting sulfilimine has the structure

wherein

Het, R 2 and R 3 are as previously defined, R 1 is methyl, n is 1, and L is a single bond.

4. The process of claim 1 in which the starting sulfilimine has the structure

wherein

n is 1, R 1 , S and L taken together form a standard 4-, 5-, or 6-membered ring such that L is —CH(CH 2 ) p — and p is an integer from 1-3, and R 1 is —CH 2 — and Het, R 2 and R 3 are as previously defined.

5. The process of claim 1 in which the starting sulfilimine has the structure

wherein

n is 0, R 1 , S and L taken together form a standard 4-, 5-, or 6-membered ring such that L is —CH(CH 2 ) p — and p is an integer from 1-3, and R 1 is —CH 2 — and Het is as previously defined.

6. The process of claim 1 in which the temperature is from about 10° C. to about 30° C.

7. The process of claim 1 in which the oxidizing agent is an alkali metal permanganate.

8. The process of claim 1 in which the oxidizing agent is ruthenium tetraoxide.

9. The process of claim 8 in which the ruthenium tetraoxide is generated in situ from an alkali metal periodate in the presence of a water soluble ruthenium salt capable of being converted to ruthenium tetraoxide.

10. The process of claim 9 in which the water soluble ruthenium salt capable of being converted to ruthenium tetraoxide is ruthenium chloride.

11. The process of claim 1 in which the organic solvent is a halogenated aliphatic or halogenated aromatic hydrocarbon or an aliphatic or aromatic nitrile.

12. The process of claim 1 in which the process is conducted in a biphasic solvent system comprising a mixture a halogenated aliphatic hydrocarbon and water.