Total synthesis of .beta.-lactam antibiotics. Epimerization of 6(7)-aminopenicillins and cephalosporins from .alpha. to .beta.

Abstract

Addition of tris(dipivalomethanate)europium(III) resulted in chemical shifts which revealed the characteristic coupling pattern for the -pyrone protons: -H, d,

Degradation of Mecillinam in Aqueous Solution

“…Recrystallization from isopropanol-isopropyl ether yielded 3.8 g ( (12) (1.7 g, 5.5 mmoles) was stirred in hexamethyleneiminecarboxaldehyde dimethyl acetal(15 ml) for a few minutes. The resultant solution was kept at room temperature overnight, followed by stirring for 10 min at 0-5' with water (30 ml).…”

Direct diazo-transfer reaction on β-lactam: Synthesis and preliminary biological activities of 6-triazolylpenicillanic acids

“…The synthesis of protected 6-azidopenicillanates similar to 2a-c has been described in the literature. [27][28][29][30] These compounds are generally synthesized, in moderate yields, using multi-step reactions. For example, Barrett and Sakadarat described the synthesis of benzyl protected 6azidopecillanate, the final intermediate in their total synthesis of 6-aminopenicillanic acid (6-APA), in a six-step reaction scheme with a total yield of about 15%.…”

Structure and Reactivity of β‐Lactams

“…Although the treatment of a penicillin derivative with an imine at C(6) with phenyllithium in tetrahydrofuran appears to lead to abstraction of the C(6) proton, reprotonation regenerates the 6-b epimer despite being the less stable epimer [136,137]. Even more strange is the observation that reprotonation with D 2 O/CD 3 CO 2 D does not incorporate deuterium.…”