Patent EA-000682-B1 (EA)
Title: PROCESS FOR PREPARING BENZO[b]THIOPHENES, INTERMEDIATE COMPOUNDS AND PROCESS FOR PREPARING THEREFOR
Inventor: HOARD DAVID W
IPC: C07D333/56
Filed: 1996-06-04
Abstract: 1. A compound of the formula   wherein R1 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, halo, or amino; R2 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, halo, or amino; 2. The compound of claim 1 wherein: R1 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups. and R2 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups. 3. The compound of claim 2 wherein: R1 is hydrogen or C1-C4 alkoxy; and R2 is hydrogen or C1-C4 alkoxy. 4. The compound of claim 3 wherein R1 and R2 are C1-C4 alkoxy. 5. The compound of claim 4 wherein R1 and R2 are methoxy. 6. A process for preparing a compound of the formula   wherein R1 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, halo, or amino; and R2 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, halo, or amino; which comprises reacting a compound of the formula   wherein R1 and R2 are as defined above, and R3 is a thermally-labile or acid-labile C2-C10 alkyl, C4-C10 alkenyl, or aryl(C1-C10 alkyl) group; with an acid catalyst at a temperature of about 100 degree C to about 140 degree C, wherein the concentration of the formula II compound is about 0.05 M to about 0.2 M. 7. The process of claim 6 wherein: R1 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, R2 is hydrogen, Ci-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups. 8. The process of claim 7 wherein the acid catalyst is selected from the group consisting of methanesulfonic acid, benzenesulfonic acid, 1-naphthalenesulfonic acid, 1-butanesulfonic acid, ethanesulfonic acid, 4-ethylbenzenesulfonic acid, 1-hexanesulfonic acid, 1,5-naphthalenedisulfonic acid, 1-octanesulfonic. acid, camphorsulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, ion-exchange resin. 9. The process of claim 8 wherein the acid catalyst is selected form the group consisting of methanesulfonic acid, benzenesulfonic acid, camphorsulfonic acid, p-toluenesulfonic acid, ion-exchange resin. 10. The process of claim 9 wherein the acid catalyst is selected from the group consisting of methanesulfonic acid, p-toluenesulfonic acid, ion-exchange resin. 11. The process of claim 10 wherein R3 is a thermally-labile or acid-labile C2-C10 alkyl, C4-C10 alkenyl, or aryl(C1-C10 alkyl) group. 12. The process of claim 11 wherein R3 is a thermally-labile or acid-labile C2-C10 alkyl group. 13. The process of claim 12 wherein R3 is t-butyl. 14. The process of claim 13 wherein R1 and R2 are C1-C4 alkoxy. 15. The process of claim 14 wherein R1 and R2 are methoxy. 16. The process of claim 15 wherein the acid catalyst is p-toluenesulfonic acid. 17. A process for preparing a compound of the formula   wherein R1 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, halo, or amino; R2 is hydrogen, C1-C4 alkoxy, C1-C4 alkoxy group, substituted by from 1 to 3 phenyl or substituted by phenyl groups, halo, or amino; which comprises treating a compound of the formula   wherein R1 and R2 are as defined above, with an acid catalyst.