Reactions of 2-pyrone (2P) and 1,4-oxazinone (OXZ) with hetero alkynes viz., phosphines (HA1) and silanes (HA2) have been scanned at B3LYP/6-31G(d) level. NBO, FOE and variation in magnetic susceptibility isotropy have been analysed and the results have been compared with that of acetylene (Ace). On account of heteroatomic influence on frontier orbitals, hetero alkynes are faster than simple ones. The order of reactivity is observed as HA2>HA1>Ace.