We investigate the molecular evolution that develops as star formation proceeds from molecular cloud cores to first hydrostatic cores in three spatial dimensions. We perform a radiation hydrodynamic simulation in order to trace fluid parcels, in which molecular evolution is investigated, using a gas-grain chemical network model. The abundances of gaseous molecules in the warm envelope and the outer layer of the first core (T < 500 K) are mainly determined via evaporation of ice mantles, which are formed in a cold era (˜10 K). We find that large organic molecules, such as CH3OH, are associated with the first core (r < 10 AU). This result suggest that first cores and the surrounding warm envelopes could be observed as very compact hot corinos without stellar signatures, and large organic molecules could be useful to trace first cores.