A new approach to the synthesis of alkene dipeptide isosteres is reported which features the use of the [2,3]-Wittig-Still rearrangement, carried out in hexane. As an example the synthesis of the alkene dipeptide isostere of Gly-Ala as part of the tripeptide isostere Z-Phe-Gly-PSI[E-CH = CH]-(R, S)Ala-OH is described.