Adamantane nitration

Adamantanol has been prepared by oxidation of adamantane with peroxyacetic acetic" and by hydrolysis of 1-bromoadamantane with silver nitrate s or hydrochloric acid. ... 

Dinitrogen pentoxide reacts with alkanes in carbon tetrachloride at 0 °C via a radical mechanism to give nitration products which can include nitrate esters.Reactions of alkanes with dinitrogen pentoxide in nitric acid are complex and of little synthetic value. 1-Adamantyl nitrate is one of the products obtained from the photochemical irradiation of a solution of adamantane and dinitrogen pentoxide in methylene chloride. ... 

Adamantane can be nitrated with N02 in the presence of ozone (Kyodai nitration) to afford 1-nitroadamantane with high regioselectivity.301 Product formation is interpreted by hydrogen abstraction by NO3 followed by rapid trapping of the resulting admantyl radical by N02. 

Small hydrogen KIEs of k /k y = 1.2-1.3 have been observed480 in the reaction of an equimolar mixture of adamantane and 1,3,5,7-tetradeuterio-adamantane (k /ku = 1.30 0.05-1.31 0.05) with nitronium tetrafluoroborate, and in nitration of 1-deuterioadamantane with pure nitronium tetrafluoroborate in nitroethane solvent (k jk y = 1.20 0.05) and interpreted as indicating a non-linear highly unsymmetrical TS in the RDS of the reaction 232. 

The unique hydride abstraction property has been gainfully employed in developing novel synthetic reactions.530 Reactive hydrocarbons such as triphenylmethane, adamantane, and diamantane are readily fluorinated in the presence of nitrosonium ion in HF-pyridine media.537 In the presence of a suitable oxygen donor such as dimethyl sulfoxide, the nitrosonium ion can act as a nitrating agent538 [Eq. (4.152)]. The initially formed nitrito onium ion 223 transfer nitrates aromatics rather readily.245 The NO+-induced reactions are further reviewed in Chapter 5. 

Nitration of 1-phenyladamantane occurs at the para position of the phenyl ring 1981. The resulting nitrobenzene brominates on the adamantane nucleus. If, however, the nitro group is converted to an acetamide function, bromine enters the aromatic ring (Scheme 16) I98 ... 

Frontside attack by the electrophile, as suggested, should result in retention of optical activity, if reaction was carried out on an optically active hydrocarbon. Our studies in this regard are not yet completed. We have, however, been able to carry out N02 nitration of rigid systems, like adamantane. 

At 25°, 0.1 of nitrcmethane was obtained in the nitration of methane. Substantially (at least tenfold) increased yields are, however, obtained in HF and HSO3F (or other superacid) solutions as solvent (see subsequent discussion). Higher alkanes and isoal-kanes gave yields of 2- % and adamantane was nitrated in 10% yield. 

Nitration and nitratation. Nitronium 1 and TfjO. Adamantane gives 1-nitro- or I -nitra nitromethane or dichloromethane, respecmeU... 

Probing the mechanism of the reaction, a kinetic hydrogen isotope efiect study of the rate of nitration of 1,3,5,7-tetradeuterioadamaniane compared with that of light adamantane showed a kinetic hydrogen isotope effect (/cH/ko) = 1-3). This would indicate a highly unsymmetrical trasition state (or hig lying intermediate) of carbocationic nature. 

When the nitration of adamantane with NOJBF4 is carried out in acetonitrile upon aqueous workup JV-(l-adamantyI)acetamide is obtained in 88% yield. Similarly, norbomane yields N-(exo-2-norbonyl)acetamide in 77% yield. Bicyclo[2.2.2]octane gives in 73% yield the corresponding amides. 

The highly selective N- and 0-functionalisation of adamantane based on the nitration procedure at -78 °C has been found [17]. Because of the symmetrical nature and high stability of the carbon framework, adamantane is a good model compound for examining the behaviour of alkanes toward the Kyodai nitration. 

Mechanistically, the reactions of adamantane and ethers with NO are rationally explained by considering the formation of carbocations as transient intermediates (Scheme 6.14). The generation of PINO from NHPI in the presence of NO is confirmed by ESR measurements [170], but the formation of PINO by this method may be due to traces of NO2 contained in the reaction system. On the other hand, Suzuki has suggested the formation of a cationic species via a diazonium nitrate in the nitration of alkenes with N O [ 17 5 ]. The nucleophilic attack of the benzonitrile and water on the adamantyl and benzylic cations would result in the amide and aldehyde, respectively [170]. 

The Ritter-type reaction of adamantane is accomplished using the NHPI/NO system. In this section, we show that NHPI combined with cerium ammonium nitrate (CAN) serves as an efficient system for the generation of both PINO from NHPI and carbocations from alkyl radicals. Thus, benzyhc compounds first undergo the amidation with alkyl nitrile under mild conditions to form amides in good yields. The reaction of ethylbenzene in the presence of CAN and NHPI in EtCN under argon at 80 °C for 6h produced N-(l-phenylethyl)propionamide in 84% yield at 61% conversion (Eq. (6.32)). The NHPI/CAN system can apply to the Ritter-type reaction of various alkylbenzenes and adamanatanes. 

Polynitroadamantanes represent a class of potentially powerful explosives of low sensitivity To date 1,3,5,7-tetranitro adamantane (1,3,5,7-TNA) was successfully synthesized in multi-gram quantities and was tested for explosive properties. The data for 1,3,5,7-TNA and TNT are shown in Table 7. It should be noted that TNA is very insensitive to impact. In recent months, the 2,2,4,4-TNA isomer has been synthesized. The optimally nitrated adamantane as determined by theoretical calculations is un-decanitro adamantane (11 nitro groups) predicted to be about 15% more powerful than HMX. 

Synthesis of compound 68 by oxidative decarboxylation of adamantane carboxylic acid is described in [25], Initially, for the synthesis of 2-(l-adamantyl)benzimidazole (68), adamantan radical was obtained in sulphuric acid diluted by silver nitrate in the presence of ammonia persulfate. Then, the synthesized radical was inserted directly into the heterocycle. After N-methylation, 2-(l-adamantyl)benzimidazole (68) was transferred in l-methyl-2-(l-adamantyl)-benzimidazole (79). The experiments carried out on chicken embryo revealed high antiviral activity of both obtained compounds [25] ... 

Aza-adamantanes.—1-Aza-adamantanes are easily available in a convenient two-step synthesis from a-pinene (Scheme 83)." The synthesis is dependent on the serendipitous discovery that solvomercuration-demercuration of a-pinene with acetonitrile in the presence of mercuric nitrate followed by in situ boro-hydride reduction led not to the expected allylic amide but instead to azabicy-clo[3,3,l]nonene which is readily converted into aza-adamantane by reaction with formaldehyde. Rearrangement of A-chloro-N-acetyl-l-aminoadamantane... 

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