Quinazolines belong to heterocyclic chemistry, also known as 1,3-naphthalenes. The backbone consists of two six-membered aromatic rings fused to each other, with two nitrogen atoms at positions 1 and 3 on the backbone. The presence of these two nitrogen atoms in quinazoline increases its importance in pharmaceutical and biological reactions. Quinazolines and their derivatives are among the most important heterocyclic compounds due to their diverse chemical reactivity and important range of biological activities.
Thiazolines are a group of isomeric five-membered heterocyclic compounds containing both sulfur and nitrogen. Thiazoline exists in three isomeric forms namely 2-thiazoline, 3-thiazoline and 4-thiazoline. Oxazolines, oxazoles, thiazolines, and thiazoles form the characteristic heterocyclic building blocks of lissoclinum peptide alkaloids.