Methylenation
In organic chemistry, methylenation is a chemical reaction that inserts a methylene (−CH2−) group into a chemical compound:
Typically, the reaction is used to prepare terminal alkenes from aldehydes and, less frequently, ketones.
Methods
Methylene-for-oxo reactions
A common method for methylenation involves the
A related reaction can be accomplished with Tebbe's reagent, which is sufficiently versatile to allow methylenation of esters:[2]
Other less well-defined titanium reagents, e.g., Lombardo's reagent, effect similar transformations.[3][4]
Carbanions derived from methylsulfones have also been employed, equivalently to the Wittig reaction.[5]
Other approaches
Ethenolysis is a method for methylenation of internal alkene as illustrated by the following example:
In principle, the addition of CH2 across a C=C double bond could be classified as a methylenation, but such transformations are commonly described as cyclopropanations.
References
- .
- ISBN 0471936235.
- .
- PMID 16542018.
- PMID 32608238.