The cyclization of pyridine-3-carbaldehyde (II) with L-cysteine (I) in ethanol gives the thiazolidine derivative (III), which is treated with formic acid yielding the 3-formylthiazolidine derivative (IV). The cyclization of (IV) with 2-chloropropenenitrile (V) by means of acetic anhydride affords 3-(3-pyridil)-1H,3H-pyrrolo[1,2-c]thiazole-7-carbonitrile (VI), which is finally hydrolyzed to the target carboxamide by means of KOH in tert-butanol.

The cyclization of pyridine-3-carbaldehyde (II) with L-cysteine (I) in ethanol gives the thiazolidine derivative (III), which is treated with formic acid yielding the 3-formylthiazolidine derivative (IV). The cyclization of (IV) with 2-chloropropenenitrile (V) by means of acetic anhydride affords 3-(3-pyridil)-1H,3H-pyrrolo[1,2-c]thiazole-7-carbonitrile (VI), which is finally hydrolyzed to the target carboxamide by means of KOH in tert-butanol.

The cyclization of pyridine-3-carbaldehyde (II) with L-cysteine (I) in ethanol gives the thiazolidine derivative (III), which is treated with formic acid, yielding a diastereomeric mixture of formyl derivatives from which the desired (2R,4R)-(IV) is isolated by crystallization. The cyclization of (2R,4R)-(IV) with ethyl 2,3-dichloropropionate (V) by means of TsCl and Et3N affords (2R)-(3-pyridyl)-1H,3H-pyrrolo[1,2-c]thiazole-7-carboxylic acid ethyl ester (VI), which is hydrolyzed with NaOH to the corresponding free acid (VII). Finally, this compound is condensed with 3-aminobenzophenone (VIII) by means of SOCl2 to provide the target amide.