the gamma-tert-butyl ester ( 1 ) , gamma-hydrazide ( 2 ) , gamma-n-butylamide ( 3 ) , and gamma-benzylamide ( 4 ) derivatives of methotrexate ( mtx ) were synthesized from 4-amino-4-deoxy-n10-methylpteroic acid ( apa ) and the appropriate blocked l-glutamic acid precursors with the aid of the peptide bond forming reagent diethyl phosphorocyanidate .
C0002520
amino
C0061472
l-glutamic acid