A Convenient Approach to a Novel Group of Quaternary Amino Acids Containing a Geminal Bisphosphonate Moiety
Quaternary amino acids containing a geminal bisphosphonate moiety have been synthesized for the first time. The developed two-step reaction sequence utilizes the Michael addition of α-substituted azlactones to a vinylidene bisphosphonate as the key step. The reaction proceeds under catalytic conditions with excellent regioselectivity. Subsequent, acid-mediated azlactone ring opening affords the target quaternary amino acids with good overall yields. Attempts to develop an enantioselective version of the synthetic strategy are described.
azlactones, quaternary amino acids, geminal bisphosphonates, Michael addition, biologically relevant molecules
Synthesis, Vol. 46 no.23 , s. 3233-3238