The reactivity of Δ3- and Δ2- 3-bromomethylcephems toward carboxylate nucleophiles has been studied . The Δ3- 3-bromomethylcephem 1, less reactive than the Δ2-analogue 4, is converted in high yields into 3-acyloxy-3cephems 2a-d, generally with no isomerization of the double bond, only within a narrow range of conditions. In particular, the Δ3-7-aminocephalosporanic acid (7-ACA) derivative 2a has been obtained as the only product in 91% yield by treatment of 1 with triethylammonium acetate in acetic acid. The Δ2 bromomethylcephem 4 is easily converted into the Δ2-acyloxymethyl-cephems 5a-d without double bond isomerization, in very high yields.
Studies related to cephalosporins. Part 2(1a): displacement reactions of 3-bromomethylcephems with salts of carboxylic acids / M., Botta; F., De Angelis; Grgurina, Ingeborg; M., Marzi; R., Nicoletti. - In: JOURNAL OF HETEROCYCLIC CHEMISTRY. - ISSN 0022-152X. - STAMPA. - 22:(1985), pp. 1001-1007. [10.1002/jhet.5570220414]
Studies related to cephalosporins. Part 2(1a): displacement reactions of 3-bromomethylcephems with salts of carboxylic acids
GRGURINA, Ingeborg;
1985
Abstract
The reactivity of Δ3- and Δ2- 3-bromomethylcephems toward carboxylate nucleophiles has been studied . The Δ3- 3-bromomethylcephem 1, less reactive than the Δ2-analogue 4, is converted in high yields into 3-acyloxy-3cephems 2a-d, generally with no isomerization of the double bond, only within a narrow range of conditions. In particular, the Δ3-7-aminocephalosporanic acid (7-ACA) derivative 2a has been obtained as the only product in 91% yield by treatment of 1 with triethylammonium acetate in acetic acid. The Δ2 bromomethylcephem 4 is easily converted into the Δ2-acyloxymethyl-cephems 5a-d without double bond isomerization, in very high yields.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.