Highly efficient solid-phase synthesis of thiazolo[2,3,b]quinazolines under mild conditions was developed using resin-bound 2-amino-terephthalamic acid, Fmoc-NCS, and bromoketones. Primary amines immobilized to an acid-cleavable backbone amide linker were acylated with 1-methyl-2-aminoterephtalate. Following cleavage of the methyl ester, Fmoc-NCS was used to form a resin-bound thiourea. Bromoketones were subsequently added to form an aminothiazole ring and the cyclization was performed using DIC/HOBt to afford thiazolo[2,3,b]quinazolines. Highly efficient solid-phase synthesis is amenable to high throughput/combinatorial synthesis.