Processes to produce certain 2-(pyridine-3-yl)thiazoles
View Patent ↗The invention disclosed in this document is related to the field of processes to produce certain 2-(pyridine-3-yl)thiazoles as intermediates for the synthesis of pesticidal thiazole amides.
1. A process comprising
wherein
(i) reacting compound (I) with compound (II) in step a to produce compound (III), wherein said reacting is conducted in a polar protic solvent under ambient pressure; followed by
(ii) cyclizing compound (III) using a dehydrating agent to produce compound (IV) wherein said dehydrating agent is selected from the group consisting of POCl 3 , H 2 SO 4 , SOCl 2 , P 2 O 5 , polyphosphoric acid, p-toluene sulfonic acid, trifluoroacetic anhydride, or a mixture thereof, and wherein said cyclizing is conducted at ambient pressure, and temperatures from 60° C. to 120° C.;
wherein
(A) R 1 is H;
(B) R 2 is a (C 1 -C 6 )alkyl;
(C) R 3 is H or (C 1 -C 6 )alkyl; and
(D) R 4 is H, (C 1 -C 6 )alkyl, or cyclopropyl.
2. A process according to claim 1 wherein said polar protic solvent is formic acid, n-butanol, isopropanol, n-propanol, ethanol, methanol, acetic acid, water, or a mixture thereof.
3. A process according to claim 1 wherein said polar protic solvent is methanol.
4. A process according to claim 1 further comprising halogenating said R 3 of compound (IV) to F, Cl, Br, or I, in a polar solvent, at a temperature from 0° C. to ambient.
5. A process according to claim 4 wherein said halogenating is conducted in a polar solvent selected from dichloromethane, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, and dimethyl sulfoxide.
6. A process according to claim 5 wherein said polar solvent is dichloromethane.
7. A process according to any one of claims 4 , 5 , and 6 , wherein R 3 is Cl.