Process for preparing substituted 2-nitrobiphenyls

摘要

The present invention relates to a process for preparing substituted 2-nitrobiphenyls and to specific 2-nitrobiphenyls. The invention further relates to a process for preparing 2-aminobiphenyls from such 2-nitrobiphenyls and to a process for preparing (het)arylamides of such 2-aminobiphenyls.

主权项

1. A process for preparing a compound of formula (I) wherein R1, R2, R3, R4 and R5 are independently of each other selected from hydrogen; halogen; cyano; hydroxyl; C1-C6-alkyl, wherein the alkyl group may carry 1, 2 or 3 substituents R6; C1-C6-haloalkyl; C3-C10-cycloalkyl which may carry 1, 2, 3 or 4 C1-C4-alkyl substituents; C3-C10-halocycloalkyl; C1-C6-alkoxy; C1-C6-haloalkoxy; C1-C6-alkylthio; C1-C6-haloalkylthio; aryl; aryl-C1-C4-alkyl; wherein aryl in the two last-mentioned radicals may carry 1, 2, 3 or 4 substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl and a radical R6; amino; C1-C4- alkylamino; and di-(C1-C4-alkyl)-amino; each R6 is independently selected from the group consisting of C3-C10-cycloalkyl which may carry 1, 2, 3 or 4 C1-C4-alkyl substituents; C3-C10-halocycloalkyl; C1-C4-alkoxy; C1-C4-haloalkoxy; amino; C1-C4-alkylamino; di-(C1-C4-alkyl)-amino; carboxyl; hydroxyl; SH and aryl; each R7 is independently selected from the group consisting of C1-C4-alkyl, OR8, amino, C1-C4-alkylamino, di-(C1-C4-alkyl)-amino and halogen; wherein R8 is selected from the group consisting of hydrogen, C1-C4-alkyl, a protecting group, and aryl, wherein aryl may carry 1, 2, 3 or 4 substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl and a radical R6; 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) R7 are not bound to the same carbon atom, and wherein when a′ is 1 or 2, the substituent(s) R7 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.