The Journal of antibiotics vol:30 issue:10 pages:847-55
The preparation of 6-epi-ampicillin by hydrolysis of 6-epihetacillin is described. During this conversion, the formation of a diketopiperazine was also observed. The best yield was obtained at pH 7.0 and room temperature for 3 approximately 7 hours. The lowest yield of 6-epi-ampicillin and the highest formation of the diketopiperazine occurred in pyridine - acetic acid - water. Treatment of ampicillin (with D-aminophenylacetyl side chain) with nitrous acid gave alpha-hydroxybenzylpenicillin with about 66% of L- and 34% mandelyl side chain. Reaction 6-epi-ampicillin gave 6-epi-alpha-hydroxybenzylpenicillin with practically the same ratio of L- and D-isomers.