Phosphine‐Catalyzed α‐ and Vicinal Bis‐Addition of P(O)H Compounds to Alkynoates

Abstract

AbstractThe efficient route to phosphine‐catalyzed preparation of α‐phosphoryl acrylates and vicinal bis‐phosphoryl propanoates was developed. The products of diarylphosphine oxide monoaddition and dibenzyl‐H‐phosphonate vicinal bis‐addition to ethylphenylpropiolate were obtained by using previously data on the reactivity and prototropic tautomerism of various classes of P(O)H compounds. In previous works devoted to the phosphine‐catalyzed addition of P(O)H compounds to this activated alkyne, the use of secondary phosphine oxides gave only vicinal bisphosphine oxides, while the addition of H‐phosphonates led only to α‐products. On the basis of this work and our previous studies, a series of the reactivity increase of P(O)H compounds in the phosphine‐catalyzed β‐addition reaction can be assumed: (AlkO)2P(O)H≤Ph(EtO)P(O)H<(BnO)2P(O)H<(m‐(CH3)2C6H3)2P(O)H<p‐Tol2P(O)H<Ph2P(O)H. The α‐umpolung addition is less dependent on nature of P(O)H compounds. The increased reactivity of Ph2P(O)H can be used for the introduction of several groups at once: phosphonate and phosphine oxide at the multiple bond of alkyne with or without the isolation of the α‐addition intermediate.