Maitland-Japp reaction

What is Maitland-Japp reaction?

Japp and Maitland first reported this reaction in 1904. It is a three-component condensation reaction that forms multisubstituted tetrahydropyran-4-ones using a ketone and two equivalents of aldehydes in a single step. Although the reaction should be called the Japp-Maitland reaction according to the naming convention, it is commonly referred to as the Maitland-Japp reaction, not to be confused with Japp-Maitland  condensation.

Maitland-Japp reaction - general reaction scheme - Japp-Maitland reaction
Maitland-Japp reaction

When carried out in a basic medium, the reaction yields a mixture of stereoisomers in low yields, as demonstrated in Japp and Maitland’s original preparation of 2,6-diphenylmethyltetrahydro-4-pyranones from benzaldehyde and 2-butanone. Due to the reaction’s long reaction time, requirement for excess aqueous reagents, low yield, and lack of generality, the reaction was not widely known for many years. In contrast, using a Lewis acid as a promoter, the enantioenriched aldol products can be converted into enantioenriched tetrahydropyran-4-ones without loss of enantiomeric integrity.

This method allows for the production of high yields of enantiomerically pure 2,6-cis-disubstituted tetrahydropyran-4-ones.

References

Japp, F. R., & Maitland, W. (1904). CXLVIII.—Reduction products of αβ-dimethylanhydracetonebenzil, and condensation products of benzaldehyde with ketones. Journal of the Chemical Society, Transactions, 85(0), 1473-1489. DOI: 10.1039/CT9048501473

Shares