Aziridines from azido alcohols

As described above, 1,2-azido alcohols can be stereospecifically prepared from epoxides. 1,2-Azido alcohols thus prepared reacted with triphenylphosphine or trialkyl phosphites to afford aziridines, where inversion of both centers of the original epoxides takes place (Scheme Intramolecular oxirane... 

Synthesis of aziridines from epoxides via amino alcohols or azido alcohols and reaction with phosphines or phosphites (see 1 edition). 

Y. Utah, Y. Sasson, I. Shahak, S. Tsaroom, and J. Blum, A new aziridine synthesis from 2-azido alcohols and tertiary phosphines. Preparation of phenanthrene 9,10-imine, J. Org. 

P. Pochlauer, E. P. Muller, and P. Peringer, Mechanism of aziridine synthesis from 2-azido alcohols and triphenylphosphine, Helv. Chim. Acta, 67 (1984) 1238-1247. 

Researchers at Lexicon Pharmaceuticals found that limonene aziridines could be efficiently prepared from the corresponding limonene oxides using the Blum aziridine synthesis. Epoxide 32 was opened with sodium azide to produce the regioisomeric azido-alcohols 33 and 34 in an approximate 1 1 ratio. The secondary azide was reductively cyclized with triphenylphosphine at ambient temperature, whereas the tertiary azide required heating to effect the same transformation. In this way, the desired aziridines 35 and 36 were prepared in good yield on multigram scale. 

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