HTR1A and breast cancer: This choice was made to investigate how the introduction of the 4,5‐dihydrothiazole moiety might influence the affinity/activity profile towards serotonergic receptors; moreover, this scaffold was already tested to study its influence to modulate 5‐HT1A, 5‐HT2A, and 5‐HT2C serotoninergic receptors involved in regulatory pathways of prostate and breast cancer cells viability.[14] All the new synthesized compounds, reported in this study, were tested for their functional activity or affinity to 5‐HT1A, 5‐HT2A, and 5‐HT2C receptors.