Lactam

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This editable Main Article is under development and subject to a disclaimer.

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(CC) Image: David E. Volk
Lactam structures.

In chemistry, a lactam is a cyclic amide. The name is derived from two chemical terms, lactone, referring to a cyclic ketone, and amide, a compound containing a nitrogen atom next to a carbonyl group. Lactams are named according to the size of the cyclic ring in the lactam: α-lactams, β-lactams, γ-lactams and δ-lactams contain rings made of three, four, five or six atoms, respectively. α-lactams are also called aziridinones. Many widely used antibiotic drugs, including the penicillins and cephalosporins, owe their activity to the presence of a β-lactam structure. The lactams may have substitutions added to the nitrogen atom or any of the non-carbonyl carbon atoms in the base structure.

## Contents

* 1 Synthesis of lactams
* 1.1 Synthesis of alpha-lactams
* 2 Antibiotics
* 3 References

## Synthesis of lactams[edit]

### Synthesis of alpha-lactams[edit]

(CC) Image: David E. Volk
A general purpose alpha-lactam synthesis

The cyclization reaction of an α-haloamide precuror in the presence of sodium hydride and 15-crown-5 ether at room temperature in dichloromethane (CH2Cl2) is a high-yielding, general route to α-lactam (aziridinone) products. The hydrogen gas and sodium halide by-products are readily removed.[1]

## Antibiotics[edit]

(CC) Image: David E. Volk
Base structure of all cephalosporins.

The β-lactam forms the center structure of many antibiotic drugs, such as the cephalosporins and the penicillins, as shown above. In the penicillins, the non-lactam ring is one atom smaller compared to the cephalosporins. The activity of cephalosporins, penicillins, and some other antibiotics are due to the presence of the beta-lactam, which binds irreversibly, via acylation, to penicillin-binding proteins, thereby inhibiting the peptidogycan layer of bacterial cell wall synthesis. Cephalosporins and penicillins are often made semi-synthetically, using a core structure obtained from a natural organism, such as a fungus, due to the difficulty and expense of synthesizing these lactams.

## References[edit]

1. ↑ V. Cesare, T. M. Lyons and I. Lengyel (2002). "A High-Yielding General Synthesis of α-Lactams". Synthesis 2002: 1716-1720.