LACTAM
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 total), δ-lactam (4 and 6 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.
- In iodolactamization 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 is obtained.
why beta lactam more liked in the lower temperature than high temperature?????
BalasHapusBecause to form a reaction so that result beta lactam ,we must use lower temperature, because this beta lactam has propertise not heat resistant and it will easily damaged in an acid anda base. So, if the beta lactam is formed in high temperature, so the reaction won’t form. And gamma lactam will form only optimum temperature.
yuli actually i still confused about lactam,, actually from what lactam was formed
BalasHapusactually, i also still confused about lactam. But yesteday, i read an article in internet, there i read that lactam is a cyclic amide. And the cyclic amide formed from amino carboxylic acids by elimination of water. So, i think that a lactam formed from amino carboxylic acids,too. And in the synthesis of lactam, a lactam form from different reaction. And you can see it in the article.
BalasHapusHow about you?
What are you thinking about forming a lactam from article which you read?