A highly abstract coordination model for distributed workflow enactment where decentralized control, autonomy, adaptation to high dynamics and partial lack of information are primary concerns is presented in this paper. The model is based on a nature metaphor and envisioned as a chemical reaction where molecules react autonomously according to local and actual conditions. The chemical workflow enactment is formalized using the gamma-calculus where control, dependencies and the state of the computation are all represented in a single uniform declarative formalism that has a mathematically founded semantics. The work captures the modeling aspect of artificial chemistries; the paper shows that the abstract coordination expressed in gamma-calculus provides a framework where advanced workflow patterns and complex issues of enactment can be modeled