C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
C07D295/22—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with hetero atoms directly attached to ring nitrogen atoms
C07D295/28—Nitrogen atoms
C07D295/32—Nitrogen atoms acylated with carboxylic or carbonic acids, or their nitrogen or sulfur analogues
New process for the industrial synthesis of tetraesters of 5-[bis(carboxymethyl)amino]-3carboxymethyl-4-cyano-2-thiophenecarboxylic acid, and application to the synthesis of bivalent salts of ranelic acid and their hydrates.