Stereochemistry of the Horner-Emmons reaction between 3-functionally substituted 2-methyl-2-propenylphosphonates and aliphatic aldehydes. 4. Effect of the nature of the aliphatic aldehyde and concentration of the starting reagents

Abstract

The double bond formed in the Horner-Emmons reaction has only E configuration independently of the structure of the saturated linear, α-branched, and β-branched aliphatic aldehydes upon their reaction with the diethyl ester of 3-ethoxycarbonyl-2-methyl-2-propenylphosphonic acid, while the ratio of the2E,4E and2Z,4E isomers in the reaction product varies only from 58∶42 to 62∶38. An increase in the aldehyde concentration leads to an increase in the fraction of the2Z,4E isomer in the ethyl ester of 2E/Z,4E-3,7-dimethyl-2,4-octadienoic acid formed.