Schmidt reaction scope

An extensive review of the chemistry of aliphatic and aromatic azides is given by Boyer and Canter [167] and Gray [168]. Organic azides are subject to various reactions such as the Bergmann degradation and the synthesis of peptides, the well known Curtius rearrangement, the Darapsky synthesis of a-aminoacids [169], for synthesis of triazoles [170], tetrazoles ( Schmidt reaction ) [169] and [171] etc. These reactions lie beyond the scope of the present book. 

In recent reviews of the chemistry of organic azido compounds attention has been focused mainly on the reactions rather than the synthesis of azides ". The last comprehensive account of the introduction of the azido group was published by Boyer and Canter in 1954 and for the purposes of this chapter we have concerned ourselves primarily with developments subsequent to this review. Reference to work cited in the review of Boyer and Canter is made only where it is pertinent to the discussion. Because of the very large number of azide syntheses described in the chemical literature no attempt has been made at an encyclopaedic coverage. Instead, each major synthetic method has been discussed from a mechanistic viewpoint with representative examples being used as illustration. Only reactions in which a carbon-azide bond is formed are considered reactions in which organic azides are implicated as intermediates but are not isolated, e.g. the Schmidt reaction, were deemed to be outside the scope of this chapter. 

The scope of the Schmidt reaction has been extended to include dialkyl acylphosphonates. Although acylphosphonic esters are known for their relative ease of cleavage at the P-C bond, it was found possible to carry out Schmidt reactions by using the diester in chloroform solution at 0 which is treated with an excess of HN3 in the... 

Azodicarboxylates and related compounds have been widely used as dienophiles over the last six decades. A thorough description of these reactions is beyond the scope of this review. In a recent representative example of such a cycloaddition, Schmidt and coworkers found that diene (147) adds to diethyl azodicarboxylate to yield (148). This product was used in synthesis of aminoxylose derivative (149) (equation 59). 

Schmidt, H. L., and Medina, R. (1991). Possibilities and scope of the double isotope effect method in the elucidation of mechanisms of enzyme catalyzed reactions. Isotopenpraxis 21, 1—4. 

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