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Hydride Reagents

Mechanism + Description

Used for clevage of alkyl aryl ethers. Activation of the ether by coordination of a metal cation followed by SN2 cleavage by hydride.

General comments

Used historically, especially in dealkylation of natural products, but of limited use now due to hazards associated with the use of reactive metal hydrides like LiAlH4, DIBAL, L- Selectride. Occasionally selectivity can be seen with different alkyl ether functions.

Key references

Tetrahedron Letters, 1994, 35, 8727 Hydride-promoted demethylation of methyl phenyl ethers
J. Chem. Soc., Chem. Commun., 1980, 507 Reactions of lithium aluminium hydride in hydrocarbon solvents. Selective demethylation of some substituted methyl phenyl ethers

Relevant scale up example

2 kg scale
Org. Proc. Res. Dev., 2004, 8, 113