Process for the preparation of 2-substituted-5-(1-alkylthio)alkylpyridines

1. A process for the preparation of 2-substituted-5-(1-alkylthio)alkylpyridine (I),

wherein

R 1 and R 2 independently represent H or C 1 -C 4 alkyl;

R 3 represents C 1 -C 4 alkyl; and

R 4 represents C 1 -C 4 alkyl or C 1 -C 4 haloalkyl;

which comprises:

a) condensing a substituted enone (II),

wherein

R 4 as previously defined; and

R 5 and R 6 independently represent C 1 -C 4 alkyl;

with an enamine (III),

wherein

R 1 , R 2 and R 3 are as previously defined; and

R 7 and R 8 independently represent C 1 -C 4 alkyl or R 7 and R 8 taken together with N represent a 5-membered saturated or unsaturated ring;

b) cyclizing the reaction mixture from step a) in the presence of ammonia or a reagent capable of generating ammonia to produce a 2,3,5-substituted pyridine (IV),

wherein

R 1 , R 2 , R 3 , R 4 and R 6 are as previously defined; and

saponifying and decarboxylating the 2,3,5-substituted pyridine (IV) to give 2-substituted-5-(1-alkylthio)alkylpyridine (I).

2. The process of claim 1 in which R 4 represents CF 3 .

3. The process of claim 2 in which R 1 represents H, R 2 represents CH 3 , and R 3 represents CH 3 .