LE of azide group

Triplet State. A remarkable feature of the T1 state of phenyl azide is the large contribution of the LE function of azide group. 

The lowest triplet state energy calculated by the PPP method is 18755 cm"1 in accordance with the observed value. The MIM calculations show that the main contribution to Ti is the LE of cinnamoyloxy group (69 ) and the energy difference between Ti and T2 is only 3200 cm . We can understand from the small difference that the only one vibrational structure appears in Pig.5(b) and can also estimate that the vibrational structiure arises from the central double bond of cinnamoyloxy group and not from azide. The T2 state has the same character as the Ti state of phenylazide where the contribution of the LE function of azide group is remarkable(55.02 in this case). 

Renaudie L, Le Narvor C, Lepleux E, Roger P (2007) Functionalization of poly(ethylene terephthalate) fibers by photografting of a carhohydrate derivatized with a phenyl azide group. Biomacromolecules 8(2) 679-685... 

Forosamine is an amino sugar component of the antibiotic Lepicidin. Since Le-picidin is sensitive to acid and catalytic hydrogenation, an Fmoc group was selected to protect the amino function. A rather unconventional method was used to introduce it [Scheme 8.94].230 A Curtius rearrangement on the acyl azide derived from carboxylic acid 94.1 proceeded with retention of configuration to give the isocyanate intermediate 94.2 that was trapped with 9-fluorenylmethanol to afford the N-Fmoc derivative 94J in 72% yield. 

For the synthesis of le, the intermediate 11 was prepared from die 3 9-N3 derivative 10 of mediyl deoi cholate by oxidation of the hydroxy group with C1O3 in H2S04/acetone followed by Pd/C catalyzed hydrogenation of the azide moiety (Figure 2). 

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