We have seen in the previous post that crossed aldol reactions allow us to prepare β-hydroxy carbonyl compounds by reacting an enolate (formed from one carbonyl compound) with another aldehyde or ketone, followed by protonation. A nice variation/type … Read more
In Knoevenagel condensation, we take a molecule where a methylene (CH2) is connected to (preferably) two electron-withdrawing groups, so we can deprotonate it and react with an aldehyde or a ketone. This allows the formation of a carbon-carbon double bond … Read more
Pethidine, also known as meperidine and marketed under the name Demerol, is a fully synthetic opioid of the phenylpiperidine class. Unlike morphine-based analgesics, its structure arises entirely from laboratory synthesis, making it a classic example of how multiple fundamental organic … Read more
When a beta hydroxy carbonyl compound is treated with a moderately strong base, such as a hydroxide or an alkoxide, an elimination occurs by expelling the hydroxyl group. The most common example is the aldol condensation reaction: So, … Read more
In this chapter on alpha carbon chemistry, you are going to come across the term “enol” almost in any new reaction. So, what is an enol? As the name suggests, these are species that contain an alkene (ene) and an … Read more
Decarboxylation is the loss of carbon dioxide upon heating, typically characteristic of carboxylic acids with a β-carbonyl group. These are most often beta-keto acids, malonic acid, or its derivatives: Carboxylic acids by themselves are very stable and do … Read more
We have seen, in different reactions such as the aldol condensation, alkylation, and alpha halogenation, that enolates are very good nucleophiles capable of attacking electrophilic centers. Interestingly, the halogenation of aldehydes and ketones at the alpha position works with both acid … Read more
In the previous post, we talked about the aldol reaction, which occurs when an aldehyde is treated with a base. The role of the base here is to deprotonate the ɑ position of the aldehyde and thus convert it into … Read more
We know that base-catalyzed halogenation of aldehydes and ketones replaces all the ɑ hydrogens: The reaction is difficult to stop at monohalogenation because the product, after the first step, is more reactive than the starting carbonyl, and therefore keeps … Read more
We talked about the Michael reaction in which the nucleophile is a doubly stabilized enolate performing a conjugate (1, 4) addition: Remember, at the same time, that regular enolates are not efficient Michael donors since they are stronger … Read more
