Tandem Horner-Wadsworth-Emmons olefination/claisen rearrangement/hydrolysis sequence: Remarkable acceleration in water with microwave irradiation

A tandem three-step, one-pot method for the conversion of aldellydes into beta-substituted-2-oxohex-5-enoic acids 1 in good to excellent yield is described. The optimised sequence is carried out in water with microwave irradiation and involves sequential Horner-Wadsworth-Enitnons (HWE) olefination, Claisen rearrangeittent and ester hydrolysis. The outcome of this domino sequence can be controlled by the temperature of the process.