Radical Chemistry with Azides

University of Bern, Department of Chemistry and Biochemistry, Freiestrasse 3, CH-3012 Bern, Switzerland 

Organic Azides Syntheses and Applications Edited by Stefan BrSse and Klaus Banert 2010 John Wiley Sons, Ltd. ISBN 978-0-470-51998-1 

The use of the azidyl radical in organic synthesis offers the opportunity to functionalize olefins into the corresponding alkylazides, which are equivalent forms of the ubiquitous amino group. The reaction with olefins is especially interesting due to the electrophilic character of the azidyl radical.  

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Radical Chemistry with Azides 253 PhSOjNa (Bu3Sn)2 O... 

During the time frame covered by this chapter, stannanes have been reported to have been involved in radical chemistry not involving the more traditional functionalities. For example, Marzi and coworkers reported that the reduction of cyclic thionocarbonates (e.g. 82) with BusSnH under standard radical conditions affords cyclic acetals that can then be further transformed into 1,2-diols (equation 57)219. This transformation represents a new approach to the protection of these diols. Zehl and Cech described the use of Bu3SnH in the reduction of azide (83) to the corresponding amine (equation 58)305, while Hanessian and his associates reported the Ph3SnH-mediated free-radical reduction of the tertiary oxalate (84) (equation 59)309. This transformation represents a departure from the more typical reduction of a pyridinethioneoxycarbonyl (PTOC) oxalate ester321. 

The chemistry of halogen azides is well reviewed . The insertion of alkenes into the N-X bond occurs via either ionic or radical processes to produce both regioisomeric azides. Such products are useful intermediates for the subsequent formation of vinylaz-ides by treatment with base (e.g., t-BuOK) ... 

Photochemical and Radical Reactions Most photoreactions in the field of nanotube chemistry serve to the generation of reactive intermediates that attack the nanotube afterward. The functionalizing step itself is rarely photochemical. Examples of such a preparatory step prior to functionalization include the conversion of azides into nitrenes or the radical generation from acyl peroxides, iodoalkanes, etc. In the photochemical reaction of nanotubes with osmium tetroxide, on the other hand, the essential step occurs only under irradiation. 

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