In the previous post, we talked about a simple strategy you can use for changing the position of a double bond. A similar tool-set, commonly used in organic synthesis, is the change of the position for a leaving group: … Read more
Changing the position of a double bond is a very important tool in organic synthesis. For example, let’s try to figure out what happens in this transformation: The double bond has suddenly moved to produce a new regioisomer … Read more
This is a comprehensive problem that covers the following topics and will serve as a review of all of them: Substitution and elimination reactions. Particularly, substitution and elimination reactions of alcohols, the regio– and stereochemistry of E2 reactions and E2 reaction … Read more
Diols and Epoxidation Dihydroxylation is the addition of two OH groups to an Alkene: This can be achieved in several ways depending on the structure of the target diol, mainly, whether we need it in a cis or … Read more
In the previous post, we learned that the anti-dihydroxylation of alkenes is achieved by converting them to epoxides, followed by acid or base-catalyzed ring-opening of the epoxide: To convert alkenes into cis-diols by syn dihydroxylation, they are reacted … Read more
Ozonolysis is an efficient way of oxidizing alkenes (and alkynes as well) into their corresponding aldehydes and ketones: One of the advantages of ozonolysis compared to other oxidative cleavage reactions is that it does not over-oxidize the alkene … Read more
The halogens Br2 and Cl2 add to the double bond of an alkene, producing vicinal dihalides – a compound bearing the halogens on adjacent carbons (vicinus, Latin: adjacent). These are also called 1,2-dihalides: The reaction with bromine is … Read more
The Regiochemistry of Hydroboration-Oxidation In the previous post, we mentioned that Hydroboration-oxidation places the OH group on the less substituted carbon of an alkene: There are two reasons for this: steric and electronic. This is a result of … Read more
Hydroboration-oxidation converts alkenes into alcohols: THF (tetrahydrofuran) is the solvent that is used to stabilize the BH3, which otherwise tends to form a dimer, B2H6 – a flammable, toxic, and explosive gas: It is a few-step … Read more
From Acid-Catalyzed Hydration of Alkenes In the previous post, we talked about the acid-catalyzed hydration of alkenes, which, in general, is a “Markovnikov” addition of water, giving the corresponding alcohol. A quick reminder, Markovnikov’s rule is followed when the X component … Read more
