A highly regioselective functionalization of 7-bromofluorene-2-carbaldehydes, potent organic chromophores, in position C3 using a mild ortho-metallation strategy (DoM) with TMPMgCl·LiCl has been developed. This approach allows the preparation of highly functionalized fluorene derivatives by conversion of the in situ generated metalated species with various electrophiles giving a fast access to novel organic phosphorescent dyes.