合成路线1

From the starting carbaldehyde (I) two different pathways can be followed: 1) A solution of carbaldehyde (I) in ether is treated with the vinyl Grignard reagent (A) in THF and oxidized with activated manganese dioxide to afford enone derivative (II). The derivative is then coupled with methyl 4-formylbenzoate (III) in refluxing ethanol in presence of 3-benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride (B) to yield diketone (IV). 2) Methyl 4-formylbenzoate (III) is treated with vinylmagnesium bromide (A) in THF, and oxidized with pyridinium dichromate to give methyl 4-acryloylbenzoate (V), which is coupled with carbaldehyde (I) by means of 3-benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride (B) and triethylamine in DMF to yield directly diketone (IV). The final step is the cyclization of diketone (IV) to afford the pyrrole-benzoic acid derivative by treatment of the diketone with ammonium acetate in refluxing methanol and hydrolysis with NaOH in refluxing ethanol followed by neutralization with dilute HCl.