Patent ID: 8853455

Claim:
A process for preparing a compound of formula (I) wherein R 1 , R 2 , R 3 , R 4 and R 5 are independently of each other selected from hydrogen; halogen; cyano; hydroxyl; C 1 -C 6 -alkyl, wherein the alkyl group may carry 1, 2 or 3 substituents R 6 ; C 1 -C 6 -haloalkyl; C 3 -C 10 -cycloalkyl which may carry 1, 2, 3 or 4 C 1 -C 4 -alkyl substituents; C 3 -C 10 -halocycloalkyl; C 1 -C 6 -alkoxy; C 1 -C 6 -haloalkoxy; C 1 -C 6 -alkylthio; C 1 -C 6 -haloalkylthio; aryl; aryl-C 1 -C 4 -alkyl; wherein aryl in the two last-mentioned radicals may carry 1, 2, 3 or 4 substituents selected from the group consisting of halogen, C 1 -C 4 -alkyl, C 1 -C 4 -haloalkyl and a radical R 6 ; amino; C 1 -C 4 - alkylamino; and di-(C 1 -C 4 -alkyl)-amino; each R 6 is independently selected from the group consisting of C 3 -C 10 -cycloalkyl which may carry 1, 2, 3 or 4 C 1 -C 4 -alkyl substituents; C 3 -C 10 -halocycloalkyl; C 1 -C 4 -alkoxy; C 1 -C 4 -haloalkoxy; amino; C 1 -C 4 -alkylamino; di-(C 1 -C 4 -alkyl)-amino; carboxyl; hydroxyl; SH and aryl; each R 7 is independently selected from the group consisting of C 1 -C 4 -alkyl, OR 8 , amino, C 1 -C 4 -alkylamino, di-(C 1 -C 4 -alkyl)-amino and halogen; wherein R 8 is selected from the group consisting of hydrogen, C 1 -C 4 -alkyl, a protecting group, and aryl, wherein aryl may carry 1, 2, 3 or 4 substituents selected from the group consisting of halogen, C 1 -C 4 -alkyl, C 1 -C 4 -haloalkyl and a radical R 6 ; and a is 0, 1 or 2; comprising reacting a compound of formula (II) wherein a′ is 0, 1 or 2 and X is a halogen atom, wherein when a′ is 2, the two substituent(s) R 7 are not bound to the same carbon atom, and wherein when a′ is 1 or 2, the substituent(s) R 7 is/are not bound to the carbon atom carrying the phenyl substituent; with a base wherein HX is eliminated from compound II in a dehydrohalogenation reaction, and aromatizing the resulting product; wherein aromatization is accomplished by carrying out the dehydrohalogenation reaction under air atmosphere and/or by keeping the reaction mixture at air atmosphere after the completion of the dehydrohalogenation; or by sparkling air or oxygen through the reaction mixture during the dehydrohalogenation reaction and/or after its completion; or by oxidizing the product of the dehydrohalogenation reaction with an oxidizing agent.