Synthesis of BODIPY dyes through postfunctionalization of the boron dipyrromethene core

Fluorophores based on the 4-bora-3a,4a-diaza-s-indacene (aka boron dipyrromethene, boron dipyrrin, or BODIPY) platform have found diverse applications in different fields of modern science, medicine and (bio)technology. In this review we describe the numerous postfunctionalization methodologies of the boron dipyrromethene core designed and realized by research groups around the globe. In the postfunctionalization approach, boron dipyrromethenes with reactive functionalities attached directly to the core (halogen or hydrogen atoms, methyl, formyl, or alkylthio groups) are used as starting materials for further derivatization. The various synthetic methods towards these starting compounds and their postmodification are reviewed. We discuss the different strategies devised for postderivatization of the BODIPY nucleus at all possible positions (the pyrrole carbons, the meso-carbon, and the boron atom) and compare them concisely with the standard prefunctionalization methodology. Important properties and applications of a number of substituted BODIPYs made by the methods described in this review are also presented. (C) 2019 Elsevier B.V. All rights reserved.