Alicyclic azides—

B. Synthesis of Azides by Nucleophilic Substitution I. Aliphatic and alicyclic azides... 

As expected, substitution by azide ion occurs more readily when the alkyl substrate bears electron-withdrawing groups. For example phenacyl bromide and its derivatives give high yields of azides when treated with sodium azide in the cold °. Secondary alkyl substrates undergo Sj,2 reactions with azide ion ° ° but with less facility than primary alkyl substrates in accordance with the normal polar influences and primary steric eflfects in reactions . Selective substitution is therefore possible and this has been effectively applied in carbohydrate and steroid synthesis (sections II.B.5,6). These effects are also exemplified in the alicyclic series where it has been reported that menthyl halides and 2-methylcyclohexyl halides afford unsatisfactory yields of azide ° . The unsubstituted alicyclic azides, however, are obtained in good yields by the procedures outlined above(Table 1). 

Some syntheses of alkyl and alicyclic azides are considered to proceed... 

The Schmidt reaction of ketones works best with aliphatic and alicyclic ketones alkyl aryl ketones and diaryl ketones are considerably less reactive. The reaction is only seldom applied to aldehydes as starting materials. The hydrazoic acid used as reagent is usually prepared in situ by treatment of sodium azide with sulfuric acid. Hydrazoic acid is highly toxic, and can detonate upon contact with hot laboratory equipment. 

Bowman and co-workers synthesized 2-azido-2-nitropropane by treating the sodium salt of 2-nitropropane with a mixture of sodium azide and potassium ferricyanide. Olah and co-workers used the same methodology for the synthesis of alicyclic gem-azidonitroalkanes from secondary nitroalkanes. Isomeric azidonitronorbornanes (38) and (39) were synthesized from 2,5-dinitronorbornane (37). Some of the gem-azidonitroalkanes synthesized during this work have poor chemical and thermal stability. 

Whereas a number of 5-aryl thiatriazoles have been reported, the only previously known true aliphatic and alicyclic representatives were 5-tert-butyl31 and cyclohexyl thiatriazole.32 These are unstable oils that decompose at 0° with nitrogen evolution and formation of sulfur. They are prepared from the corresponding thioacylhydrazides and nitrous acid, but the method is not generally applicable because of difficulties in obtaining the required aliphatic thioacylhydrazides.1 Wijers et o/.17 have found that aliphatic thiatriazoles can be prepared from 1-acetylthio-l-alkynes. Thus a substance believed to be 5-pentylthiatriazole was isolated from the reaction between 1-acetylthio-l-hexyne and ammonium azide. It is an oil that solidifies at about —16° and could not be analyzed because of its explosive character and poor stability at room temperature. Its formation is explained by the following scheme [Eq. 

The Curtius reaction can be performed on aliphatic, alicyclic, aromatic, or heterocyclic azides. 

Epoxides which are fused to alicyclic systems undergo ring opening with azide ion in the usual tram diaxial manner This is demonstrated by the formation of the /ran5-2-azidoalcohols (66) and (67) from cyclohexene oxide and cyclopentene oxide respectively . 

In the following section, we discuss in some depth the dissolution mechanism of phenolic polymer resists such as novolac and poly(hydroxy styrene) resins, as well as those of acrylate and alicyclic resist polymer platforms. The development of phenolic polymer resins involves similar dissolution stages. Unlike their counterparts that are solvent developable, such as his-azide/cis-polyisoprene negative resists that require some degree of swelling for their dissolution, these phenolic polymer resists do not require such adverse swelling for dissolution. ... 

More widely used as a source of aliphatic and alicyclic amines is the reduction of azides (reaction 93), many of which are available by... 

The first report of the reaction of 2//-l-benzopyran (139) with various 1,3-dipoles has appeared/ Good yields of single cycloaddition products (140) were obtained upon reaction with nitrile-imines, whereas nitrile oxides gave 1 1 mixtures of the regioisomers (141) and (142), The reactions with diazomethane gave rather inconclusive results, and phenyl azide and diphenyl nitrone failed to react. Similar types of reactions have been carried out using a variety of enones in which the overall conclusion appears to be that simple aliphatic or alicyclic enones produce mixtures of regioisomers upon reaction with nitrile oxides and nitrile imines whereas enones of the chalcone type show only one product. Experts in FMO theory will probably declare these results... 

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