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From left to right, general structures of a β-lactam, a γ-lactam, a δ-lactam, and an ε-lactam. The specific structures are β-propiolactam, γ-butyrolactam, δ-valerolactam, and ε-caprolactam.

A lactam is a cyclic amide. The term is a portmanteau of the words lactone + amide. Prefixes indicate how many carbon atoms apart from the carbonyl moiety are present in the ring, for example:

  • β-lactam (2 carbon atoms outside the carbonyl, 4 ring atoms in total)
  • γ-lactam (3 carbon atoms outside the carbonyl, and 5 carbon total)
  • δ-lactam (4 carbon atoms outside the carbonyl, and 6 carbon total)

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

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. ^ Singh, 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"
  3. ^ Pham, P.-T.; Vince, R. Phosphorus, Sulphur and Silicon 2007, 779-791.

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