Computational study of an oxetane 4 H -pyrazole as a Diels-Alder diene.

We combine the effects of spirocyclization and hyperconjugation to increase the Diels-Alder reactivity of the 4 H -pyrazole scaffold. A density functional theory (DFT) investigation predicts that 4 H -pyrazoles containing an oxetane functionality at the saturated center are extremely reactive despite having a relatively high-lying lowest unoccupied molecular orbital (LUMO) energy.