2-Chloroquinazoline. Synthesis and reactivity of a versatile heterocyclic building block

Starting from 2,4-dichloroquinazoline, various methods for the selective removal of the 4-chloro substituent were tested, including catalytic hydrogenation, metal–halogen exchange, metal hydride reduction and reduction with tributyltin hydride—the latter both in a radical and in a Stille-type reaction. Amongst these, the most efficient method was found to be the Stille-type coupling. Furthermore, we have studied the reactivity of 2-chloroquinazoline and found it to act as a versatile building block for the direct introduction of the 2-quinazolinyl moiety.