Assuming that the behavioural specification of a concurrent system is given in the form of a step transition system, where the arcs between states are labelled by steps (multisets of executed actions), we focus on the problem of synthesising a Petri net generating a reachability graph isomorphic to a given step transition system. To deal with step transition systems more complicated than those generated by standard Place/Transition nets, we consider in this paper Petri nets with wholeplace operations, localities, and a/sync places. We adapt and extend the general approach developed within the framework of τ -nets and the theory of regions of step transition systems. Building on the results presented in [23], emphasis here is on the role of a/sync places with their potential for an instantaneous transfer of tokens within a step. In a series of results we demonstrate the robustness of the notion of region for Petri net synthesis.