Reactions of Alkyl Azides with Epoxides

Epoxides are another viable electrophilic partner for alkyl azides. Baskaran and coworkers found that azido-tethered epoxides afforded bicyclic, tertiary amines bearing a hydroxymethyl substituent upon treatment with a Lewis acid followed by reduction. This one-pot procedure was applicable to bicyclic azido epoxides with varying ring sizes, affording the corresponding bicyclic amines in preparatively useful yields (Table 7.8). These reactions probably involve the initial Lewis acid-assisted formation of a cation followed by azide attack. Migration and concomitant loss of N2 then generates an iminium ion, which persists until stereoselective reduction by hydride (Schane 7.32). 

Murphy and coworkers have also reported rearrangement reactions of azido-tethered epoxides in which the azide tether was attached directly to a phenyl-substituted epoxide. Thus, when they treated epoxide 36 with SnCLt at 0°C in THE, ketone 37 was isolated 

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Scheme 4.16 Intramolecular reactions of alkyl azides with epoxides.

Table 7.8 Reactions of alkyl azides with epoxides in the presence of EtAICl2 followed by NaBH4 workup...

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