Studies on amino acids and peptides—IV

Synthesis of furo[2',3':4,5]pyrrolo[1,2-d][1,2,4]triazine derivatives and their antibacterial activity

“…16,17 The second method involves the cyclisation of N-thioacyl-α-aminoester with hydrazine. 18 The title compounds 5 are well accessible 16,19 from methyl 4H-furo[3,2-b]pyrrole-5-carboxylate 1 via its transformation to carbohydrazide 2. Hydrazinolysis was achieved in 80% yield by heating of 1 with hydrazine hydrate in ethanol for 20h 16 .…”

Diels–Alder reactions of trifluoromethyl alkenes with 5-ethoxyoxazoles: synthesis of trifluoromethylated pyridine derivatives

“…5-Ethoxyoxazoles 1 and 2 were prepared in the usual manner from DL-alanine ethyl ester hydrochloride by Nacylation [22] and N-formylation [23], respectively, followed by cyclodehydration using phosphorous pentoxide [24].…”

“…2,4-Dimethyl 5-ethoxyoxazole 1 and 4-methyl 5-ethoxyoxazole 2 were prepared by literature procedures [22][23][24]. Other starting materials were obtained commercially (Sigma-Aldrich) and solvents were dried using literature procedures.…”

Dihydro-1,2,4-triazin-6(1H)-ones. II Synthesis of Several Methylated 3-Phenyl- 4,5-dihydro-1,2,4-triazin-6(1H)-ones

“…The 1,4-dimethyl derivative (12) was also the product formed on stepwise dimethylation of 3-phenyl-4,5-dihydro-1,2,4-triazin-6(1H )-one (15) with sodium hydride and methyl iodide. (20) 1-Alkyl-4,5-dihydro-1,2,4-triazin-6(1H )-ones (16) were found to be susceptible to aerial oxidation to the corresponding dehydro derivatives (17) and 5,6-dioxo derivatives (18). * Therefore it was necessary to determine if the net biological activity observed for compounds of type (16) was due to the parent compound or its aerial oxidation products (Scheme 4).…”