p-Toluenesulfonic acid → HCID 178499021, compound

Participants

Reaction Steps

According to the foregoing reaction Scheme 2, 2,3-dibromopropionic acid (8) is treated with sodium bisulfide (NaSH) followed by esterification with HCl in methanol to give methyl 2,3-dimercaptopropenoate (9). This dithiol (9) is condensed with 3-pyridine carboxaldehyde in the presence of an acid catalyst, preferably p-toluenesulfonic acid, to afford methyl 2-(3-pyridinyl)-4-dithiolanecarboxylate (10). The dithiolane ester is hydrolyzed to the corresponding acid (11) by treatment with aqueous base, preferably lithium hydroxide. This acid is coupled to an amine (3) using a coupling agent such as dicyclohexylcarbodiimide or BOPCl (bis(2-oxo-3-oxazolidinyl)phosphinic chloride) to yield the amide 12. ##STR8##

Provenance & Evidence