A stereospecific one-pot protocol for Methyl-(Z)-2-(7-methyl-3-oxo-5H-thiazolo[3,2-a]pyrimidin-2(3H)-ylidene)acetates was developed in methanol as a green solvent, achieving yields up to 99%. Compound 3p demonstrated a highly selective fluorescent probe for Cd²⁺ ions (limit of detection 7.5 μM and limit of quantification of 25 μM). Cytotoxicity and in silico Density functional theory and docking studies revealed that compounds 3g, 3h, 3p, and 3t exhibited promising anticancer potential.

Stereospecific synthesis of Methyl-(Z)-2-(7-methyl-3-oxo-5H-thiazolo[3,2-a]pyrimidin-2(3H)-ylidene)acetates 3(a– t) is designed and explored their application as fluorescent probes for Cd²⁺ ions for the first time. These analogs are synthesized via one-pot reaction of (R/S)-2-thioxo-3,4-dihydropyrimidine-5-carboxanilides (TDHPM-5-carboxanilides) with dimethyl acetylenedicarboxylate in MeOH (methanol) as a reusable green solvent at room temperature (RT). Two new C(sp²)N, C(sp²)S sigma bonds, and one new C-N π-bond are formed during this transformation, achieving yields of up to 99%. This protocol demonstrates a low environmental factor (E-factor) (0.09 to 0.35), high atom economy (94.83%), and carbon efficiency (142.68%), reflecting a significant advancement in green chemistry. Compound 3a is synthesized in 99% yield on a gram scale. Compound 3p proves to be an excellent fluorescent probe for Cd²⁺ ions, showing a ninefold increase in fluorescence intensity. The limit of detection and limit of quantification for 3p with Cd²⁺ ions are 7.5 and 25 μM, respectively, with an R² value of 0.9903. Density functional theory calculations revealed that Cd²⁺ ions bind effectively in the cavity of 3p through a ligand-to-metal charge transfer mechanism. Cell viability assays and docking studies show that compounds 3g, 3h, 3p, and 3t exhibited potent activity against the DU145 prostate cancer cell line, with binding affinities of −7.7, −6.8, −8.1, and −7.5 kcal mol^{− 1}.