Lactam
A lactam is a cyclic amide. The term is a portmanteau of the words lactone + amide.
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.
Nomenclature
Greek prefixes in alphabetical order indicate ring size:
- α-Lactam (3-atom rings)
- β-Lactam (4-atom rings)
- γ-Lactam (5-atom rings)
- δ-Lactam (6-atom rings)
- ε-Lactam (7-atom rings)
This ring-size nomenclature stems from the fact that a hydrolyzed α-Lactam leads to an α-amino acid and a β-Lactam to a β-amino acid, etc.
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 a 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 lactims
A lactim is a cyclic carboximidic acid compound characterized by an endocyclic carbon-nitrogen double bond. They are formed when lactams undergo tautomerization.
Reactions
- Lactams can polymerize to polyamides.
gollark: I vote it be called `hell` (Haskell shELL).
gollark: We need a shell with haskellulous syntax.
gollark: They're still evil.
gollark: Haskell is clearly ***evil***:```haskellunsafeCoerceunsafePerformIOundefinederrorunsafeLaunchMissilesunsafeCreateSkynet```
gollark: ```To be fair, when Obi-wan asked Han if the Falcon was a fast ship, he wasn't interested in how well it would perform in a drag race. He was interested in getting to Alderaan quickly because he had an urgent message to deliver. The Kessel Run being made in 12 parsecs demonstrates that the Falcon is capable of shaving off a significant amount of distance (and therefore, more than likely, time) travelled in Hyperspace, which was exactly what Obi-wan and Luke needed at the time.```
See also
- Lactone, a cyclic ester.
- β-Lactam
- β-Lactam antibiotics, which includes penicillins
- 2-Pyrrolidone
- 2-Piperidinone
- Caprolactam
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.
External links
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.