This chapter reports on the literature published during 2010 concerning the elemental halogens and compounds containing these elements in their positive oxidation states. Its intent is to highlight discovery and provide insight into current research trends.
HighlightsHighlights of the 2010 literature concerning the halogens include the preparation of the first examples of dialkyl chloronium ions, 15 a new class of electrophilic halogen sources 18 and continued vibrancy in hypervalent bromine chemistry. [56][57][58][59][60] Elemental halogens Fully 30% of the top pharmaceuticals in sale contain a fluorine atom as highlighted by a recent review. 1 Furthermore, the innate nuclear properties of 18 F as a radiotracer for positron emission tomography (PET) and 19 F as an active nucleus for magnetic resonance imaging (MRI) fosters development of methodology for the selective fluorination of biomolecules. One recent review outlines the synthesis of fluorinated nucleosides toward their use as probes for the study of biomolecular pathways. 2 It has been noted that there is an apparent monotony of structural motifs by which fluorine is incorporated into biomolecules. To address this, a greater understanding of ''emergent'' fluorinated groups such as a-fluorinated ethers, thioethers, amines and phosphines has been suggested. 3 Furthermore, the stereoselective introduction of fluorine atoms can be exploited as a conformational tool for the synthesis of shape-controlled biomolecules. 4 The use of N-F electrophilic fluorination reagents such as Selectfluor s (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-(tetrafluoroborate)) and NFSI (N-fluorobenzenesulfonimide) continues to receive the majority of focus in organic synthesis. A versatile one-pot method for converting aromatic and heteroaromatic halides by halide-Mg exchange and electrophilic fluorination of organomagnesium reagents with NFSI has now been developed which can even be applied to sterically congested substrates. 5 A potentially new role for fluorine in