Jr. Hanrahan et al., THE SYNTHESIS OF 3-PHOSPHONOCYCLOBUTYL AMINO-ACID-ANALOGS OF GLUTAMIC-ACID VIA DIETHYL 3-OXYCYCLOBUTYLPHOSPHONATE, A VERSATILE SYNTHETIC INTERMEDIATE, Journal of the Chemical Society. Perkin transactions. I, (4), 1997, pp. 493-502
A range of novel 3-phosphonocyclobutyl amino acids have been prepared
via the versatile synthetic intermediate, diethyl 3-oxocyclobutylphosp
honate, which is prepared in three steps from diethyl methylphosphonat
e. Elaboration of the 3-oxo functionality readily facilitates the synt
hesis of the 3-phosphonocyclobutyl amino acids.