From left to right, general structures of a β-lactam, a γ-lactam, a δ-lactam and a ε-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), δ-lactam (4 and 6). Beta β, gamma γ and delta δ are the second, third and fourth letters in the alphabetical order of the Greek alphabet, respectively.



General synthetic methods exist for the organic synthesis of lactams.

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 oC) 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.


See also


  1. ^ Spencer Knapp, Frank S. Gibson Organic Syntheses, Coll. Vol. 9, p.516 (1998); Vol. 70, p.101 (1992) Online article
  2. ^ Pham, P.-T.; Vince, R. Phosphorus, Sulphur and Silicon 2007, 779-791.

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  • Lactam — Lac tam, n. [Lactone + amido.] (Chem.) One of a series of anhydrides of an amido type, analogous to the lactones, as oxindol; a cyclic amide. [1913 Webster] {beta lactam} or {[beta] lactam}, (a) a lactam in which the amide bond is contained… …   The Collaborative International Dictionary of English

  • lactam — Amida cíclica que se forma mediante la eliminación de una molécula de agua de una molécula de ácido aminocarboxílico. Diccionario Mosby Medicina, Enfermería y Ciencias de la Salud, Ediciones Hancourt, S.A. 1999 …   Diccionario médico

  • lactam — [lak′tam΄] n. [ LACT(ONE) + AM(INO)] any of a group of organic cyclic compounds containing the NHCO group in the ring, formed by the elimination of water from the amino and carboxyl groups; inner anhydride of an amino acid …   English World dictionary

  • Lactam — Allgemeine Struktur von β , γ und δ Lactamen. Als Lactame (Singular: das Lactam; Synonym: intramolekulares, cyclisches Amid, Kunstwort aus Lacton und Amin) bezeichnet man Moleküle in der …   Deutsch Wikipedia

  • Lactam — Lac|tam 〈n. 11; Biochem.〉 zyklisches Säureamid, z. B. Caprolactam; oV Laktam [<lat. lac, Gen. lactis „Milch“] * * * Lac|tam [↑ Lacton u. ↑ Amid], das; s, e: Gruppenbez. für aus Aminosäuren durch intramol. Dehydratisierung entstandene cycl.… …   Universal-Lexikon

  • lactam — laktamas statusas T sritis chemija apibrėžtis Vidinis ciklinis aminorūgšties amidas, turintis žiede –CONH– grupę. atitikmenys: angl. lactam rus. лактам …   Chemijos terminų aiškinamasis žodynas

  • Lactam-Lactim-Tautomerie — Lactam Lactim Tautomerie,   Lactime …   Universal-Lexikon

  • Lactam-Antibiotikum — Lac|tam| An|ti|bi|o|ti|kum, hier β Lactam Antibiotikum: Sammelbez. für Antibiotika, die die β Lactam oder 2 Azetidinon Gruppierung (↑ Azetidinon) enthalten, z. B. aus der Gruppe der Penicilline, Cephalosporine u. Monobactame …   Universal-Lexikon

  • lactam — /lak tam/, n. Chem. any of a group of cyclic amides characterized by the NHCO group, derived from aminocarboxylic acids by the intramolecular elimination of water from the amino and carboxylic groups. [1880 85; LACT(ONE) + AM(IDE)] * * * …   Universalium

  • lactam — noun Any of a class of cyclic amides, that are the nitrogen analogs of lactones, formed by heating amino acids; the tautomeric enol forms are known as lactims …   Wiktionary

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