Synthesis and transformations of a pyrazole containing alpha, beta-didehydro-alpha-amino acid derivatives.
2H-Pyran-2-ones 1 were transformed with various hydrazines into (E)- or (Z)-alpha, beta-didehydro-alpha-amino acid (DDAA) derivatives 4 (and 7) containing a highly substituted pyrazolyl moiety attached at the beta-position. With heterocyclic hydrazines, the products 4 were accompanied also by decarboxylated enamines E-6. In order to separate (E/Z)-mixtures of acids, they were transformed to the corresponding methyl esters 9 and 10 by the application of diazomethane. Catalytic hydrogenation under high pressures with Pd/C as a catalyst resulted in the formation of racemic alanine derivatives 11.
Vranicar
L
L
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, SI-1000 Ljubljana, Slovenia.
Pozgan
F
F
Polanc
S
S
Kocevar
M
M
D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D008956:Models, Chemical; D015394:Molecular Structure; D011714:Pyrans / Q000737:chemistry; D011720:Pyrazoles / Q000737:chemistry*
D000596:Amino Acids; D011714:Pyrans; D011720:Pyrazoles; C031280:pyrazole