| Abstract |
Chiral halogenated substances have many applications in pharmaceuticals, agrochemicals, and materials, such as polymers, liquid crystals and as intermediates in synthesis. The presence of a halogen atom in a molecule can have a large effect in its properties; for instance, halogens are used in drugs to improve lipophilicity, membrane permeability and absorption, and even the blood-brain barrier permeability. As highlighted in this review, there are nowadays a range of highly selective, versatile halogenating reagents, electrophilic, nucleophilic or radical in nature, which operate under mild conditions, allowing late-stage functionalization of complex molecules in cascade reactions. Recent developments in organocatalyst design revealed novel Cinchona alkaloids derivatives, chiral phosphoric acids, amines, phosphines and several bifunctional catalysts, mostly thiourea- or squaramide-based, which introduced chirality, with high levels of enantio- and diastereoselection, in the formation of one or multiple chiral centers in a single synthetic operation, as shown. In this review we survey the literature published in this field from 2014 to 2020. |
