Showing papers by "Branko Stanovnik published in 1996"

The Transformations of 4‐Heteroarylaminomethylene‐5(4H)‐oxazolones into Dehydropeptide Derivatives.

Abstract: 2-Phenyl-4-heteroarylaminomethylene-5(4H)-oxazolones 3, which were prepared from the corresponding N,N-dimethyl-N'-heteroarylformamidines 1 and hippuric acid 2 in acetic anhydride, react with amino acids giving dehydropeptide derivatives 4, 5, and 6 as products. Dehydration of N-protected peptides 7–10, containing glycine at the C-terminal, followed by the reaction with formamidines 1 gave 2-substituted-4-heteroarylaminomethylene-5(4H)-oxazolones 11–14.

The Synthesis of 5‐Substituted 3‐Benzoylamino‐6‐(2‐substituted amino‐1‐ ethenyl)‐2H‐pyran‐2‐ones and Their Transformations into 2H‐Pyrano(3,2‐ c)pyridine Derivatives.

Abstract: A new approach to the 2H-pyrano[3,2-c]pyridine system is described. 5,6-Disubstituted 3-benzoylamino-2H-pyran-2-ones 3a,b, prepared from the corresponding 1,3-dicarbonyl compounds 1a,b and methyl (Z)-2-benzoylamino-3-dimethylaminopropenoate (2), were converted into 3-benzoylamino-6-(2-dimethylamino-1-ethenyl)-5-ethoxycarbonyl-2H-pyran-2-one (4a) and 5-acetyl derivative 4b. The exchange of the dimethylamino group in 4a,b with aromatic amines 5a-f,m, heteroaromatic amines 5g-i, and benzylamines 5j-l produced 5-ethoxycarbonyl-3-benzoylamino-6-(2-arylamino- or heteroarylamino-or benzylamino-1-ethenyl)-2H-pyran-2-ones 6a-l, and its 5-acetyl analog 6m. The compounds 6 were cyclized in basic media into 2H-pyrano[3,2-c]pyridine derivatives 7a-h. Analogously react also α-amino acid derivatives 8a-c and 11 as nitrogen nucleophiles producing 9a-c, 10 and 12.