A new synthesis of (R)-3-methyl-5-phenyl-5H-thiazolo [2, 3-b] quinazoline 1, a serum HDL cholesterol raising agent, is described utilizing a resolution of the racemic compound with D- tartaric acid. The undesired S-enantiomer was recycled using either a photochemical or thermal electrocyclic ring opening/closing reaction making the synthesis economical.
