Formylolefination of carbonyl compounds

Abstract

Diethyl cyclohexyliminovinylphosphonate derivatives (IX) have been synthesised. The carbanions generated from these phosphonates reacted readily with ketones and aldehydes giving the αβ-unsaturated aldimines (XI), which underwent acid hydrolysis in a two-layer system to produce the αβ-unsaturated aldehydes (XII) in good yields. This two-step conversion provides a new and potential route to αβ-unsaturated aldehydes from ketones as well as aldehydes. Several advantages of this process, including high efficiency, simplicity, and high selectivity giving trans-formylolefins, are demonstrated. An ester and a hydroxy-group react also with the reagents and therefore these groups in substrates should be preferably changed or protected in the form of an ether function such as a tetrahydropyranyl ether.