A short and practical method for the synthesis of 4-(N-Boc-3-aminopropyl)-5-(N-tritylamino)- 1-methylpyrazole (3), side chain of an anti-Pseudomonas aeruginosa cephalosporine FR259647, 1, was established by utilizing a regioselective enamine exchange with N- methylhydrazine and 1, 4, 5, 6-tetrahydro-pyridine-3-carbonitrile (8), followed by a subsequently occurring intramolecular cyclization and aromatization, starting from a ...
