N‐Protection Dependent Phosphorylation of Dehydroamino Acids: Facile Synthesis of Phosphono‐ Amino Acids and Short Peptides

An efficient Mn(III)‐promoted phosphorylation of dehydroalanine (Dha) has been developed to give unusual α‐amino acids bearing phosphonates/phosphine oxides and β‐vinyl phosphonates/phosphinates depending on N‐protection of amino acid. N,N‐diprotected dehydroalanine reacted with H‐phosphonates and H‐phosphine oxides to give structurally diverse phosphorylated α‐amino acids through conjugate addition of phosphorous radical generated by Mn(OAc)3.2H2O. Whereas, a highly Z‐selective phosphorylation was observed in the case of mono N‐Boc protected dehydroalanine via cross dehydrogenative coupling to give (Z)‐ β ‐vinyl phosphono amino acid. The method is successfully applied to short peptides to derive unusual phosphono‐peptides under mild conditions.