SYNTHESIS AND ACTIVITY OF BUTIROSIN DERIVATIVES WITH 5"-AMIDINO AND 5"-GUANIDINO SUBSTITUENTS

The preparation and antibacterial activity of the 5"-guanidino (6) and 5"-amidino (7) derivatives of 4'-deoxybutirosin A (1) as well as the 5"-guanidino derivative (8) of butirosin A are described. The key intermediates, tetra-N-benzyloxycarbonyl-5"-azido derivatives were selectively reduced with NiCl2-NaBH4 to give the corresponding 5"-amino derivatives. Subsequent guanidination or amidination followed by deblocking afforded the final compounds 6, 7 and 8. The 5"-guanidino derivatives (6 and 8) were more active against Gram-positive and Gram-negative bacteria than the corresponding 5"-hydroxy derivatives (1 and butirosin A). Compound 6 was also active against a variety of methicillin-resistant Staphylococcus aureus (MRSA).