A lactam is a cyclic
Cyclic compound
In chemistry, a cyclic compound is a compound in which a series of atoms is connected to form a loop or ring.While the vast majority of cyclic compounds are organic, a few inorganic substances form cyclic compounds as well, including sulfur, silanes, phosphanes, phosphoric acid, and triboric acid. ...

In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...

. Prefixes indicate how many carbon atoms (apart from the carbonyl moiety) are present in the ring: β-lactam
A β-lactam ring, is a four-membered lactam. It is named as such, because the nitrogen atom is attached to the β-carbon relative to the carbonyl...

 (2 carbon atoms outside the carbonyl, 4 ring atoms in total), γ-lactam (3 and 5), δ-lactam (4 and 6). Beta
Beta (letter)
Beta is the second letter of the Greek alphabet. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represents the voiced labiodental fricative ....

 β, gamma
Gamma is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. It was derived from the Phoenician letter Gimel . Letters that arose from Gamma include the Roman C and G and the Cyrillic letters Ge Г and Ghe Ґ.-Greek:In Ancient Greek, gamma represented a...

 γ and delta
Delta (letter)
Delta is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet...

 δ are the second, third and fourth letters in the alphabetical order of the Greek alphabet
Greek alphabet
The Greek alphabet is the script that has been used to write the Greek language since at least 730 BC . The alphabet in its classical and modern form consists of 24 letters ordered in sequence from alpha to omega...

, respectively.


General synthetic methods exist for the organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

 of lactams.
  • Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement
    Beckmann rearrangement
    The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann , is an acid-catalyzed rearrangement of an oxime to an amide...

  • Lactams form from cyclic ketones and hydrazoic acid
    Hydrazoic acid
    Hydrazoic acid, also known as hydrogen azide or azoimide, is a colorless, volatile, and extremely explosive liquid at room temperature and pressure. It is a compound of nitrogen and hydrogen, having chemical formula HN3. It was first isolated in 1890 by Theodor Curtius...

     in the Schmidt reaction
    Schmidt reaction
    The Schmidt reaction is an organic reaction involving alkyl migration over the carbon-nitrogen chemical bond in an azide with expulsion of nitrogen...

  • Lactams form from cyclisation of amino acids.
  • In iodolactamization an iminium
    An iminium salt or cation in organic chemistry has the general structure [R1R2C=NR3R4]+ and is as such a protonated or substituted imine. It is an intermediate in many organic reactions such as the Beckmann rearrangement, Vilsmeier-Haack reaction, Stephen reaction or the Duff reaction...

     ion reacts with an halonium ion
    Halonium ion
    A halonium ion in organic chemistry is any onium compound containing a halogen atom carrying a positive charge. This cation has the general structure R-X+-R where X is any halogen and R any organic residue and this structure can be cyclic or an open chain molecular structure...

     formed in situ by reaction of an alkene
    In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

     with iodine
    Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

  • Lactams form by copper catalyzed 1,3-dipolar cycloaddition of alkynes and nitrones in the Kinugasa reaction
  • Diels-Alder reaction
    Diels-Alder reaction
    The Diels–Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly formed ring are not carbon...

     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
    Vince lactam
    Vince lactam is the commercial name given to the bicyclic molecule γ-lactam 2-azabicyclo[2.2.1]hept-5-en-3-one. This lactam is a versatile chemical intermediate used in organic and medicinal chemistry. It is used as a synthetic precursor for three drugs...

     is obtained.

Tautomerization to Lactim

Lactim is a cyclic carboximidic acid compound characterized by an endocyclic carbon-nitrogen double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

. It is formed when lactam undergoes tautomerization
Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization. This reaction commonly results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond...


See also

  • β-lactam
    A β-lactam ring, is a four-membered lactam. It is named as such, because the nitrogen atom is attached to the β-carbon relative to the carbonyl...

     with a four-membered ring found in beta-lactam antibiotic
    Beta-lactam antibiotic
    β-Lactam antibiotics are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in its molecular structure. This includes penicillin derivatives , cephalosporins , monobactams, and carbapenems...

    s. Penicillin
    Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

    , considered the most famous antibiotic, is a β-lactam antibiotic.
  • Lactone
    In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...

    , a cyclic ester
    Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

  • Caprolactam
    Caprolactam is an organic compound with the formula 5CNH. This colourless solid is a lactam or a cyclic amide of caproic acid. Approximately 2 billion kilograms are produced annually...

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