Tethered bis-azides

Scheme 1.24. Regioselective addition to Cgo of a 2,3-O-isopropylidene-L-threitol-tethered bis-azide under formation of diaza-bishomo-[60]fullerene 252, and regioselective interconversion between the azahomo- (252) and the epiminofullerene (254) isomers.

Other tethers have been employed in the search for regioselectivity in multiple additions to fullerenes. Some of these methodologies include the use of bis(o-quinodimethanes) connected by a, oo-dioxamethylene tethers [40], tethered nucleophilic vinylcarbenes [41] or azides [42],... 

Bis-[5,6]-bridged iminofullerenes with another addition pattern can only be obtained in good yields if a tether directed synthesis is applied. If the tether between two azide groups is rigid enough than the second addition is forced to occur at specific regions of the fullerene cage [128]. 

The first synthetically useful Schmidt reactions of alkyl azides with ketones were intramolecular. Thus, it was shown that azido-tethered ketones, when treated with Brpnsted or Lewis adds in CH2CI2 at room temperature, were converted to lactams in good to excellent yields (Table 7.1). Mono- and bicyclic ketones are attractive substrates for the preparation of fused bi- and tricyclic lactams and the range of ring sizes accommodated... 

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