Synthesis of Some Triheterocyclic Compounds, Oxazolinic Precursors of Biheterocyclic α-Amino Acids, via Azide-Alkyne Cycloaddition

A series of triheterocyclic systems, oxazolinic precursors of biheterocyclic α-amino acids 6-13 were
obtained with good yields, via 1,3-dipolar cycloaddition reaction between 4-(azidomethyl)-4-
methyl(ethyl)-2-phenyl-4,5-dihydrooxazole 1 or 2 and synthetic terminal alkynes 3-5 in toluene at
reflux. The starting compounds 4-(azidomethyl)-4-methyl(ethyl)-2-phenyl-4,5-dihydrooxazole 1 and 2
were synthesized in three steps from corresponding 2-amino-2-methyl(ethyl)propan-1,3-diol using El
Hajji’s method. The structures of the synthesized products were established on the basis of NMR
spectroscopy (1H, 13C), Elemental Analysis and MS data.