| abstract |
Penicillins of formula (I): (where in formula (I) R1 is a gp. of formula (a)-(d): where R2 is Br or NH2) are prepd. by reacting a 6-aminopenicillanate of formula (II): (where in formula (II) R3 is alkali metal, SiMe3, SiHMe2, phenacyl, a benzaldoxime residue, p-nitrobenzyl or triphenylmethyl) with R1COX (III) (where X=OH or halogen) in an inert solvent to give (I) where R2 is Br, and opt. reacting this (when R3 is a protecting gp.) with hexamethylenetetramine (HMTA) in an inert solvent at -25 to +30 degrees C to give (I) where R2 is NH2. Cpds. (I) are broad-spectrum antibacterials with high resistance to acids and penicillinase. The process avoids the use of N-protected amino acids. |