Reactivity of pyrimidinylphosphazenes with acetylenic esters: Competitive [4 + 2] and [2 + 2] tandem cycloaddition or retro-cycloaddition approaches

1. Cobo, J.
2. Molina, S.
3. Sánchez, A.
4. Nogueras, M.
5. Insuasty, B.
6. Orozco-López, F.