Recently, ALMA made it possible to spatially resolve the central region of a few hundred au radii (i.e. several times the size of the solar system) around a low-mass protostar. This region is of special interest not only for the star formation processes but also for the chemical evolution of interstellar matter to ingredients of planetary systems. We have been investigating this chemical evolution by combining the reaction rate equations with realistic physical (e.g. radiation-hydrodynamics) models of star- and planetary-system formation. In the intermediate temperature range of 10 K to 300 K around protostars, various chemical reactions which are not active in the conventional interstellar chemistry at 10 K play important roles by overcoming activation barriers and diffusion barriers on grain surfaces. Branching ratios of reaction products are also expected to change as a function of temperature. Elucidation of such reaction rates and branching ratios at intermediate temperatures is a new frontier in theoretical chemistry. It requires not only the potential energy surface but also the reaction dynamics. In this project, experts on astrochemistry modeling, quantum chemical calculations, and astrophysical hydrodynamics will collaborate to construct a next-generation astrochemistry with quantitative predictability in a wide range of temperatures.