The Reaction Of 1-Phosphafulvene With 1,4-benzoquinone

Phosphafulvene are important structural units for the synthesis of phosphorus-containing polycyclic compounds and macrocyclic compounds,so it is important to study their chemical properties.The structure of the phophafulvene and the fulvene is very similar,and all contain three conjugated double bonds,which are prone to rich cycloaddition reactions.Phosphafulvenes act as 4? system in [4+2] cycloaddtion reaction,It act either as 2? system via their P=C double bond occurs a cycloaddition reaction of [4+2] or 6? system ccurs a cycloaddition reaction of [4+2].Highly active P=C double bond in phosphafulvene,which leads to some differences in the chemical properties of the fulvene.fulvene and p-benzoquinone are prone to occur [4+2] and [2+3] in the cycloaddition reaction,The reaction of 1-phosphafulvene with 1,4-benzoquinone and N-Phenylmaleimide at 100 °C provide phosphapolycyclic ring in normal to good yields.The possible mechanism included a oxidative addition of 1-phosphafulvene with 1,4-benzoquinone and successive Diels-Alder reaction with N-phenlmaleimide.The structure of 2H-phosphole and phosphafulvene have a carbon-phosphorus double bond,but 2H-phosphole does not react with p-benzoquinone,indicating that the extra-double bond of 1-phosphafulvene plays an important role.When the electron withdrawing group is attached to the double bond of the ring,the yield of the polycyclic compound containing phosphorus is higher;When a substituent is attached to a p-benzoquione,the influence of steric hindrance is not conducive to the reaction.Compared with the electron-donating group,the electron-withdrawing group is more favorable for the reaction,and when a larger sterically hindered group is attached to the benzoquinone,the reaction does not occur even at a high temperature...