Regio- and stereocontrolled preparation of α-substituted phosphonocrotonate derivatives

Under suitable reaction conditions, monoalkylation of triethyl phosphonocrotonate 11 could be efficiently accomplished, leading to the preparation of α-substituted phosphonates 15. The reaction is totally regioselective and completely (E)-selective. The novel phosphonocrotonate 19 underwent smooth Horner–Emmons condensation, producing a key-precursor for the synthesis of the middle core of the manzamine alkaloids.