In the last post in this series on the Diels-Alder [See: Diels-Alder Reaction: Kinetic and Thermodynamic Control] we saw that if you apply enough heat, the Diels-Alder can operate in both the forward and reverse directions! The "retro-Diels Alder" reaction is the exact reverse of the … [Read more...]
The Cope Elimination
The "Cope Elimination" is a reaction where an amine is oxidized to an intermediate called an "N-oxide", which, when heated, acts as the base in an intramolecular elimination reaction. Treating a tertiary amine (which itself can be created through reductive elimination, for instance) with … [Read more...]
Nucleophilic Aromatic Substitution (2) – The Benzyne Mechanism
In this post we'll discuss nucleophilic aromatic substitution, but with a new twist; a nucleophilic aromatic substitution that passes through a strange-looking intermediate called an aryne (a generic term for a family of molecules that includes benzyne). Previously [see: Nucleophilic Aromatic … [Read more...]
Types of Isomers: Constitutional Isomers, Stereoisomers, Enantiomers, and Diastereomers
Classification of Isomers Given that this is a long post, here's a quick index. The concept of how molecules can be "related" Non-isomers versus isomers Constitutional isomers versus stereoisomers Enantiomers versus 'non-enantiomers' (a.k.a. diastereomers) Diastereomers are … [Read more...]
Diels-Alder Reaction: Kinetic and Thermodynamic Control
The Little Known Fact About Cyclopentadiene THEY Don't Want You To Know About Let's talk about cyclopentadiene, a commonly used diene for Diels-Alder reactions that, by the way, comes up all the time on tests and exams. Like here: Gather around closely folks, because I'm going to tell you a … [Read more...]
The Wolff-Kishner, Clemmensen, And Other Carbonyl Reductions
In this post we go through 4 ways of reducing C=O to CH2 including: The Wolff-Kishner reaction The Clemmensen reduction Catalytic hydrogenation Thioacetal formation and reduction But first: why might you want to do this? Well, it's a key component in a common little synthesis … [Read more...]
Nucleophilic Aromatic Substitution (NAS)
What is Nucleophilic Aromatic Substitution and how does it differ from Electrophilic Aromatic Substitution? And why does it tend to work best with electron-poor aromatics and excellent nucleophiles? Finally, how does it work? This post tries to answer all of these important questions. Here's a … [Read more...]
Some Reactions of Azides
The azide ion (N3– ) is one of those chemical entities that just plain looks weird. Three nitrogens in a row? check Two negative charges and a positive charge, for a net charge of –1 ? check Stable? check (as long as it's treated gently). As it turns out, the azide ion can … [Read more...]
Reactions on the “Benzylic” Carbon: Bromination And Oxidation
The carbon adjacent to an aromatic ring - the "benzylic" carbon - can participate in several useful and interesting reactions. Today we'll provide examples and mechanisms for two key examples: benzylic bromination and benzylic oxidation. Here's the quick summary: Alkyl Groups = Roughage In … [Read more...]
Protecting Groups for Amines – Carbamates
In this post we introduce carbamates as a useful protecting group for amines, particularly in the context of making peptides. Here's a quick summary image of what we'll go into in this post, with more details below. An Introduction To Simple Peptide Synthesis In a recent post [Amides: … [Read more...]
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