Aromatic azides bicyclic

The question now arises as to whether the Chapman mechanism is applicable to the decomposition of other aryl azides. Bicyclic aryl azides, for example, have a considerable degree of double-bond fixation in their aromatic rings. This might be expected to make them behave more like vinyl azides, which are known to give azirines on photolysis. It is therefore useful to compare the nature of the products formed on photolysis in nucleophilic solvents by a series of azides that have an increasing degree of vinyl azide character ... 

Diamines are usually formed on irradiation of bicyclic aromatic azides in the presence of secondary aliphatic amines" only rarely have azepines been obtained" ... 

The photochemical reaction of azide-functionalized tetrazole derivatives such as 38 leads to the formation of the 5-5 bicyclic ring system 40 (Scheme 5) in very moderate yields <1999JHC863>. This reaction is believed to proceed via the singlet nitrene intermediate 39. Attack at the aromatic substituent in ortho position leads to product 40 <1974JOG2546> by subsequent cyclization. This intermediate is deprotonated during the workup conditions to the mesoionic tricyclic derivative 41. 

Phthalein type dyes have been prepared from 2,3-dicarboxypyrazine by heating with phenols or aromatic amines and zinc chloride. For example, compound (25) was obtained with resorcinol (1353). Efforts to prepare 2,6-diaminopyrazine through a Curtius-Schmidt reaction on 2-acetamido-6-carboxypyrazine (with sodium azide, sulfuric acid, and trichloroacetic acid) proved unsuccessful (434). The preparation of bicyclic heterocyles from 2-amino-3-carboxypyrazines has been described in Section VIII. 1D(6). 

Kita and coworkers have reported the direct a-azidation of cyclic sulfides using the iodosylbenzene/TMSNs reagent system [569], This method is applicable to substrates that are easily aromatized under oxidative conditions, such as monocyclic and bicyclic sulfides 488, to give the corresponding a-azido sulfides 489 in... 

Heating aryl azides in a mixture of a carboxylic acid and polyphosphoric acid affords a useful, fairly general method of fusing an oxazole ring to aromatics and heterocycles.The method suffers from the limitation that bicyclic azides in which the azido substituent is a- to the ring junction give 0-diacetyl derivatives of the 1,4-aminohydroxy compound as, for example, the formation of 98 from a-naphthyl azide ... 

The above cascade of reactions does not occur with the aromatic enediynyl azide 3.731, since conjugation with the benzene ring deactivates the alkyne [336]. Both aromatic and nonaromatic enediynes are unstable even in ambient conditions. The aromatic enediynyl azide 3.731 in boiling benzene in the presence of 1,4-cyclohexadiene for 5 hours produces the expected intramolecular cycloaddition to the side of alkene branch to form a bridged bicyclic triazoline enediyne 3.733 (42%, Scheme 3.84) [336]. The cycloaddition was monitored by the disappearance of the characteristic bands of the azide group at 2120 cm in the... 

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