Lactam
From Wikipedia, the free encyclopedia
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.
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.
- 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[2] is obtained.[3]
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.
See also
- β-lactam with a four-membered ring found in beta-lactam antibiotics. Penicillin, considered the most famous antibiotic, is a β-lactam antibiotic.
- Lactone, a cyclic ester.
- Caprolactam
- 2-Piperidinone
References
- ↑ Spencer Knapp, Frank S. Gibson Organic Syntheses, Coll. Vol. 9, p.516 (1998); Vol. 70, p.101 (1992) Online article
- ↑ 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"
- ↑ Pham, P.-T.; Vince, R. Phosphorus, Sulphur and Silicon 2007, 779-791.
This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.