Method of synthesizing 2-(2'-hydroxyphenyl) benzotriazole compounds

A method for preparing a compound of formula (VII):

• ##STR34## wherein:
• R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are, indepedently:
• H;
• halogen;
• cyano;
• --CO.sub.2 Y where Y is H or a 1 to 12 carbon alkyl or a 6 to 20 carbon atom aryl group;
• 1 to 12 carbon atom carbamoyl group;
• 0 to 12 carbon atom sulfoxido group;
• 0 to 12 carbon atom sulfonyl group;
• 0 to 12 carbon atom sulfonato group;
• 0 to 12 carbon atom sulfonamido group;
• 1 to 18 carbon atom alkyl group;
• 1 to 18 carbon atom alkoxy group;
• 6 to 20 carbon atom aryl group;
• 5 to 20 atom heteroaryl group having 1 to 4 heteroatoms selected from O, N or S;
• 6 to 20 carbon atom aryloxy group;
• or any two or more of adjacent ones of R.sub.1 through R.sub.4, or R.sub.6 and R.sub.7 together, or R.sub.6 and R.sub.5 together when they are adjacent one another, may together form a 1 to 10 cabon atom alicyclic group, or complete, together with the carbon atoms of the benzene ring to which they are attached, a 6 to 20 carbon atom aromatic group or a 5 to 20 atom heteroaryl group having 1 to 4 heteroatoms selected from O, N or S;
• or R.sub.7 is OH;
• X is O, S, or NR.sub.8 where R.sub.8 is H, 1 to 12 carbon alkyl or aryl group, or 5 to 20 atom heteroaryl group having 1 to 4 heteroatoms selected from O, N or S;
• the method comprising:
• diazotizing the compound of formula (I) with an aqueous acidic nitrite salt to obtain the compound of formula (II) and coupling the compound of formula (II) with the compound of formula (III) to obtain the compound of formula (IV) as shown below:
• ##STR35## wherein R.sub.1 to R.sub.7 and X are as defined above for formula (VII);
• protecting at least --XH on a compound of formula (IV) below to form a protected formula (IV) compound, by forming --X(PG) where PG is a group other than H which is not removed during a subsequent ring closure step;
• performing a ring closure by reacting the protected formula (IV) compound with a reducing agent to form a compound of formula (VI):
• ##STR36## wherein Z is H or a protecting group;
• deprotecting the compound of formula (VI) to form the compound of formula (VII) by replacing PG with H and, when Z is not H, also replacing Z with H.