Patent ID: 7057052

Claim:
An acid-catalyzed method of producing a compound of formula I: wherein: R 1 and R 3 are each chlorine; R 2 is hydrogen, aryl, alkyl, alkoxy, phenoxy, anilino, amino, halo, acyloxy, or (acyloxy)alkyl; R 5 is hydrogen, C 1 –C 7 alkyl, C 2 –C 7 alkenyl, C 2 –C 7 alkynyl, arylalkyl, or aryl; R 4 is, alkylcarboxy, C 2 –C m alkenyl, alkynyl, alkenylcarboxy, hydroxy, hydroxyalkyl, C 1 –C n alkoxy, nitro, halo, trihalomethyl, amido, carboxamido, carboxy, sulfonyl, sulfonamido, amino, mercapto, or 2-methylbut-2-en-4-yl, wherein n is an integer from 2–12, and m is an integer from 3–12; and R 6 and R 7 form part of an aromatic ring wherein said aromatic ring may be substituted; which method comprises: reacting a substituted or unsubstituted 2,5-dichloro-1,4-benzoquinone compound of formula II: wherein R 1 , R 2 and R 3 are as defined above; with at least one pyrrole of the formula III: wherein R 4 –R 7 are as defined above; in a polar organic solvent and in the presence of an acid to produce a first intermediate; and then reacting the first intermediate with an oxidization agent to produce said compound of formula I.