Process for producing 4-substituted benzopyran derivatives

A process for producing a 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2 H-1-benzopyran-4-carboxylic acid represented by the general formula [1], the process comprising the steps of:

• (c) reacting a 4-(perfluoroalkyl)alkoxybenzene, represented by the general formula [6], with acetic anhydride or an acyl halide in the presence of a Lewis acid, thereby obtaining a 2-alkoxy-5-(perfluoroalkyl)acetophenone represented by the general formula [7];
• (d) dealkylating the 2-alkoxy-5-(perfluoroalkyl) acetophenone by a dealkylating agent, thereby obtaining a 2-hydroxy-5-(perfluoroalkyl)acetophenone represented by the general formula [5];
• (e) reacting the 2-hydroxy-5-(perfluoroalkyl) acetophenone with 1,3-difluoroacetone in the presence of a base, thereby obtaining a 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2H-1-benzopyran-4-one represented by the general formula [2];
• (a) reacting the 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2H-1-benzopyran-4-one with a perfluoroalkanesulfonic acid anhydride, represented by the general formula [3], in the presence of a base, thereby obtaining a perfluoroalkanesulfonic 2,2-bis(fluoromethyl)- 6-(perfluoroalkyl)-2H- 1-benzopyran-4-yl ester represented by the general formula [4];
• and
• (b) reacting the benzopyranyl ester with carbon monoxide in the presence of a palladium complex compound and a base, thereby obtaining the carboxylic acid,
• where R1 is a perfluoroalkyl group that is represented by CnF2n+1 where n is an integer of 1-10 and that optionally has a branch in a carbon structure of the perfluoroalkyl group;
• each of R2 and R3 is independently a lower perfluoroalkyl group that is represented by CnF2n+1 where n is an integer of 1-10 and that optionally has a branch in a carbon structure of the lower perfluoroalkyl group;
• R4 is identical with the R2 or R3;
• and
• R5 is a straight-chain or non-straight-chain alkyl group having a carbon atom number of 1-20.

A process for producing a 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2 H-1-benzopyran-4-carboxylic acid represented by the general formula [1], the process comprising the steps of:

• (f) reacting a 4-perfluoroalkylphenol, represented by the general formula [8], with an alkylation agent, or reacting a 4-(perfluoroalkyl)halogenobenzene, represented by the general formula [9], with a metal alcoholate, thereby obtaining a 4-(perfluoroalkyl)alkoxybenzene, represented by the general formula [6];
• (c) reacting the 4-(perfluoroalkyl)alkoxybenzene with acetic anhydride or an acyl halide in the presence of a Lewis acid, thereby obtaining a 2-alkoxy-5-(perfluoroalkyl) acetophenone represented by the general formula [7];
• (d) dealkylating the 2-alkoxy-5-(perfluoroalkyl) acetophenone by a dealkylating agent, thereby obtaining a 2-hydroxy-5-(perfluoroalkyl)acetophenone represented by the general formula [5];
• (e) reacting the 2-hydroxy-5-(perfluoroalkyl) acetophenone with 1,3-difluoroacetone in the presence of a base, thereby obtaining a 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2 H-1-benzopyran-4-one represented by the general formula [2];
• (a) reacting the 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2 H-1-benzopyran-4-one with a perfluoroalkanesulfonic acid anhydride, represented by the general formula [3], in the presence of a base, thereby obtaining a perfluoroalkanesulfonic 2,2-bis(fluoromethyl)-6-(perfluoroalkyl)-2 H- 1-benzopyran-4-yl ester represented by the general formula [4];
• and
• (b) reacting the benzopyranyl ester with carbon monoxide in the presence of a palladium complex compound and a base, thereby obtaining the carboxylic acid,
• where R1 is a perfluoroalkyl group that is represented by CnF2n+1 where n is an integer of 1-10 and that optionally has a branch in a carbon structure of the perfluoroalkyl group;
• each of R2 and R3 is independently a lower perfluoroalkyl group that is represented by CnF2n+1 where n is an integer of 1-10 and that optionally has a branch in a carbon structure of the lower perfluoroalkyl group;
• R4 is identical with the R2 or R3;
• R5 is a straight-chain or non-straight-chain alkyl group having a carbon atom number of 1-20;
• and
• X is a fluorine, chlorine, bromine or iodine.

A process for producing a 2-hydroxy-5-(perfluoroalkyl) acetophenone represented by the general formula [5], the process comprising the steps of:

• (c) reacting a 4-(perfluoroalkyl)alkoxybenzene, represented by the general formula [6], with acetic anhydride or an acyl halide in the presence of a Lewis acid, thereby obtaining a 2-alkoxy-5-(perfluoroalkyl)acetophenone represented by the general formula [7];
• and
• (d) dealkylating the 2-alkoxy-5-(perfluoroalkyl) acetophenone by a dealkylating agent, thereby obtaining the 2-hydroxy- 5-(perfluoroalkyl)acetophenone,
• where R1 is a perfluoroalkyl group that is represented by CnF2n+1 where n is an integer of 1-10 and that optionally has a branch in a carbon structure of the perfluoroalkyl group;
• and
• R5 is a straight-chain or non-straight-chain alkyl group.