lactam

Greek prefixes in alphabetical order indicate ring size.

This ring-size nomenclature stems from the fact that hydrolysis of an α-lactam gives an α-amino acid and that of a β-Lactam gives a β-amino acid, and so on.

==Synthesis==

General synthetic methods are used 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. Cyclohexanone with hydrazoic acid, forms ε - Caprolactum, which upon treatment with excess acid forms Cardiazole, a heart stimulant.

Lactams can be formed from cyclisation of amino acids via the coupling between an amine and a carboxylic acid within the same molecule.

Lactamization is most efficient in this way if the product is a γ-lactam. For example, Fmoc-Dab(Mtt)-OH, although its side-chain amine is sterically protected by extremely bulky 4-Methyltrityl (Mtt) group, the amine can still intramolecularly couple with the carboxylic acid to form a γ-lactam. This reaction almost finished within 5 minutes with many coupling reagents (e.g. HATU and PyAOP).{{cite journal |last1=Lam |first1=Pak-Lun |last2=Wu |first2=Yue |last3=Wong |first3=Ka-Leung |title=Incorporation of Fmoc-Dab(Mtt)-OH during solid-phase peptide synthesis: a word of caution |journal=Organic & Biomolecular Chemistry |date=30 March 2022 |volume=20 |issue=13 |pages=2601–2604 |doi=10.1039/D2OB00070A |pmid=35258068 |s2cid=247175352 |url=https://pubs.rsc.org/en/content/articlelanding/2022/ob/d2ob00070a |language=en |issn=1477-0539}}

Lactams form from intramolecular attack of linear acyl derivatives from the nucleophilic abstraction reaction.

An iminium ion reacts with a halonium ion formed in situ by reaction of an alkene with iodine.Spencer Knapp, Frank S. Gibson Organic Syntheses, Coll. Vol. 9, p.516 (1998); Vol. 70, p.101 (1992) [http://orgsynth.org/orgsyn/prep.asp?prep=cv9p0516 Online article]

:Image:Iodolactamization.svg

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 LactamSingh, R.; Vince, R. Chem. Rev. 2012, 112 (8), pp 4642–4686."2-Azabicyclo[2.2.1]hept-5-en-3-one: Chemical Profile of a Versatile Synthetic Building Block and its Impact on the Development of Therapeutics" is obtained.Pham, P.-T.; Vince, R. Phosphorus, Sulphur and Silicon 2007, 779-791.

:File:Preparation_of_gamma_and_beta_lactams.svg

A lactim is a cyclic imidic acid compound characterized by an endocyclic carbon-nitrogen double bond. They are formed when lactams undergo tautomerization.

:File:Lactam-Lactim-Tautomerie.svg

==Reactions==

• Lactams can polymerize to polyamides.

• Lactone, a cyclic ester.
• β-Lactam
• β-Lactam antibiotics, which includes penicillins
• 2-Pyrrolidone
• 2-Piperidinone
• Caprolactam

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• {{Commons category-inline|Lactams}}

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Category:Functional groups