Mori-Ban indole synthesis

What is Mori-Ban indole synthesis?

The Mori-Ban indole synthesis is a reaction that was first reported by Mori and Ban in 1976. This method allows for the synthesis of indole derivatives through an intramolecular Heck reaction of o-halo-N-allylanilines. The reaction is catalyzed by a low-valent metal complex and is named after its discoverers.

Mori-Ban indole synthesis - general reaction scheme
Mori-Ban indole synthesis

Nickel or palladium can be used as the low-valent metal catalyst in this reaction, but it is essential that the ortho halogen is either bromine or iodine. It has been observed that o-iodo-N-allylaniline tends to be more reactive than the corresponding o-bromo substrate. However, the catalyst can be deactivated under the reaction conditions, which is why it is recommended to periodically provide fresh catalyst to achieve higher overall yields than using the same total amount of catalyst at once.

The application of Mori-Ban indole synthesis is broad and versatile, allowing for the synthesis of various indole and indoline derivatives.