4-Quinolyl azide

Matrix photolysis of 4-quinolyl azide gives 4-quinolylnitrene (Scheme 73) ... 

Diamines formed upon photolysis of 6-quinolyl azide in isopropyl-, n-butyl-, and n-hexylamines are very unstable, so they were cyclized to the corresponding 1-substituted imidazo[4,5-/]quinolines by heating the residue obtained after evaporation of the photolysis solvent with formic acid at reflux (82JCS(P 1)421). Instead... 

The nature of the intermediate involved in the thermolysis and photolysis of aryl azides in solution under the much less extreme conditions employed for the synthesis of 3H-azepines is still an open question. Notwithstanding, the method has been used extensively for the synthesis of 2-amino-3H-azepines. In addition, and despite early disappointments, the method is now applicable to the synthesis of benzazepines from naphthyl azides and that of pyridoazepines from quinolyl and isoquinolyl azides <82JCS(Pl)43l, 79AG(E)900). 

The cycloaddition of diazomethane to SchifT bases from heterocyclic aldehydes and anilines provides a useful route to heterocyclic substituted triazolines. Unlike olefins bearing heterocyclic substituents, the heterocyclic imines can be obtained readily by reaction of the appropriate aldehyde and amine thus the diazomethane-imine addition has greater scope than the olefin-azide reaction. NMR spectroscopic studies of the orientation of addition are in accord with previously reported mechanistic considerations (see, e.g., Scheme 93).329 In addition to the influence of the N-aryl group, the electron-withdrawing power of the heterocyclic substituent on the Schiff-base carbon also has a substantial effect on imine reactivity, in the order 2-quinolyl 2-, 3-, or 4-pyridyl > phenyl > 2-thienyl as 2-furyl.329... 

In the quinolyl- and isoquinolyl series good yields of ring contraction products (777,172) can be obtained from both triazoles, tetrazoles, and azides 168,175). In the pyridine series best 3delds were obtained from tetrazoles (Section V. 2.-3.). 

This approach has now been applied to the preparation of many naturally occurring and pharmacologically active compounds. In addition, two papers have been published > in which the photolysis reactions of quinolyl and isoquinolyl azides are discussed. Azepine and diazepine derivatives (200) and (201) may be obtained, and guidelines have been proposed to allow one to predict... 

H. Sawanishi, T. Hirai, T. Tsuchiya, Photolysis and thermolysis of quinolyl and isoquinolyl azides in ethanethiol. Heterocycles, 1984,22,1501-1504. 

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