LACTAM

A lactam (the noun is a portmanteau of the words lactone + amide) is a cyclic amide. Prefixes indicate how many carbon atoms (apart from the carbonyl moiety) are present in the ring: β-lactam (2 carbon atoms outside the carbonyl, 4 ring atoms in total), γ-lactam (3 and 5 total), δ-lactam (4 and 6 total). Beta β, gamma γ and delta δ are the second, third and fourth letters in the alphabetical order of the Greek alphabet, respectively.
Contents

    1 Synthesis
    2 Tautomerization to Lactim
    3 Reactions
    4 See also
    5 References

Synthesis

General synthetic methods exist for the organic synthesis of lactams.

    Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement.
    Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction.
    Lactams form from cyclisation of amino acids.
    Lactams form from intramolecular attack of linear acyl derivatives from the nucleophilic abstraction reaction.
    In iodolactamization [1] an iminium ion reacts with an halonium ion formed in situ by reaction of an alkene with iodine.

    Iodolactamization reaction

    Lactams form by copper catalyzed 1,3-dipolar cycloaddition of alkynes and nitrones in the Kinugasa reaction
    Diels-Alder reaction between cyclopentadiene and chlorosulfonyl isocyanate (CSI) can be utilized to obtain both β- as well as γ-lactam. At lower temp (−78 °C) β-lactam is the preferred product. At optimum temperatures, a highly useful γ-lactam known as Vince Lactam is obtained.[2]

Preparation of VL and beta lactam
Tautomerization to Lactim

Lactim is a cyclic carboximidic acid compound characterized by an endocyclic carbon-nitrogen double bond. It is formed when lactam undergoes tautomerization.
Reactions

    Lactams can polymerize to polyamides.

    β-lactam with a four-membered ring found in beta-lactam antibiotics. Penicillin, considered the most famous antibiotic, is a β-lactam antibiotic.