Cyclopentyl azide

The preparation of compound 175, a structurally diverse analogue of the carbocyclic nucleoside ribavarine 176, was reported using an intermolecular 1,3-dipolar cycloaddition of the cyclopentyl azide 174 with methyl propiolate (37) (Scheme 9.37). 

A dry 50-mL flask equipped with septum inlet, reflux condenser, and magnetic stirrer is flushed with N2. The flask is charged with 12 mL of DME and 12 mmol of dich]oro[(lS,2S)-2-methylcyclopentyl]borane-dimethyl sulfide complex. The solution is heated to 60 °C and attached to a gas burette. Then, 1.4 g (13 mmol) of cyclopentyl azide is added dropwise (ca. 2 h) and the evolved N2 is measured. After the addition is complete, the solution is stirred for an additional 30 min. Gas evolution has ceased at this point. The solution iscooled toO°C and very carefully hydrolyzed by slowly adding 10 mL of H,0 (exothermic ). Then the mixture is made strongly basic with 40% KOH. The liberated amine is extracted with Et20. The ether solution is dried over anhyd K2C03 and the solvent is removed at reduced pressure. On distillation, 1.2 g (72%) of the amine are collected, bp 100 CC/15 Torr. The amine is further purified as its hydrochloride salt, mp 159-160 aC [a] 3 +39.13 (c = 10, CH3OH). 

The heats of formation of various azides were determined firom their heats of combustion and decomposition (some of the data are collected in reference 1). The heats of formation of HN3, cyclopentyl azide and cyclohexyl azide were compared with those calculated for the canoni-... 

Boyer and co-workers studied the sulphuric acid-catalysed decomposition of three secondary cyclic azides cyclopentyl, cyclohexyl and cycloheptyl, and found that ring expansion, i.e. alkyl migration, competes quite favourably with hydrogen migration. For example, cyclopentyl azide in chloroform, gave cyclopentanone (as its 2,4-dinitrophenylhydrazone, 2-2%) and piperideine (5) (79 8%), on... 

Thermolysis, 1-phenylcyclopen-tanecarboxylic acid azide to 1-phenyl-cyclopentyl isocyanate, 51, 49 4i/-l,4-THIAZINE 1,1-DIOXIDE,... 

Secondary amines have been prepared from organoboron compounds R1315, R12 BC1 or R1BCI2 (R1 = Et, Bu, /-Bu,, v-Bu, 3-hexyl, cyclopentyl etc.) by treatment with azides R2N3 (R2 = Bu, /-Bu, i-Bu, cyclohexyl, Ph etc.) and aqueous work-up. It is suggested that the reactions proceed by way of anionotropic rearrangements (equation 61)176. 

The following sequence (equation 6) constitutes a convenient alternative to the conversion of alkyl halides into alkylamines by the Gabriel reaction with potassium phthaUmide. In this one-pot procedure, an alkyl bromide RBr (R = Bu, -Bu, 2-pentyl, 2-octyl, PhCH2CH2, HC=C, PhCH=CHCH2, cyclopentyl, cyclohexyl etc.) is treated with sodium azide in benzene in the presence of tetrabutylammonium bromide under phase-transfer conditions. Triethyl phosphite is then added and the resulting iminophosphorane is decomposed to the alkyl amine hydrochloride by adding benzene and hydrogen chloride. ... 

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