As shown in Table 4, this modification of the one-pot protocol is compatible with the use of HWE organophosphorus reagents (Table 4, entry 1). However, the reaction with the non-stabilized ylide of pentadecyltriphenylphosphonium bromide resulted in loss of stereoselectivity (Table 4, entry 2). The method can be applied also to the N,N-dibenzylamino benzyl ester of L-threonine (5) albeit lower yields are obtained. It is remarkable that this protocol avoids using O-protecting groups or the Garner aldehyde which have been used extensively in the synthesis of related compounds.