Process for preparing 3-acylaminobenzofuran-2-carboxylic acid derivative

A process for preparing a compound of the formula [VII″]:

• wherein R01 is a hydrogen atom and the formula:
• NR41R51 is a substituted amino group or a substituted nitrogen-containing heterocyclic group, which comprises subjecting a compound of the formula [VI″]:
• wherein the symbols are the same as defined above to catalytic reduction under low pressure and neutral to slightly basic conditions in the presence of a rhodium-carbon catalyst.

A process for preparing a trans-form compound of the formula [VIII′]:

• wherein R6 is a substituent, or a carboxylic acid derivative thereof, which comprises isomerizing a cis-form or a mixture of cis- and trans-forms of a carboxylic acid derivative of the formula [VII′]:
• wherein the symbol is the same as defined above in the presence of a slight amount of water, and also in the presence of an alkali metal alkoxide or an alkali metal amide.

A process for preparing a compound of the formula [X′]:

• wherein Ring B′ is an optionally substituted aromatic ring, which comprises cyanation of a compound of the formula [IX′]:
• wherein X4 is a leaving group and other symbol is the same as defined above in the presence of a group VIII metal compound supported by a solid phase and a phosphine ligand.

A process for preparing a compound of the formula [VII′″]:

• wherein R02 is a lower alkyl group and the formula:
• NR42R52 is a substituted amino group or a substituted nitrogen-containing heterocyclic group, which comprises subjecting a compound of the formula [VI′″]:
• wherein the symbols are the same as defined above to catalytic reduction under low pressure in the presence of a rhodium-carbon catalyst.

A process for preparing a compound of the formula [VII″″]:

• wherein R03 is a lower alkyl group and the formula:
• NR43R53 is an unsubstituted amino group, which comprises subjecting a compound of the formula [VI″″]:
• wherein the symbols are the same as defined above to catalytic reduction under low pressure and neutral to slightly basic conditions in the presence of a rhodium-carbon catalyst.