Cubane dicarboxylic acid

Cubane-1,2-dicarboxylic acid 12 (see Fig. 2.19), a precursor for 1,2-dihalocubanes was prepared from commercially available cubane-1,4-dicarboxylic acid in 65% yield. The other acids 14a and 14c were similarly prepared from the cubane-1,4-dicarboxylic acid 14b according to the literature procedures. 

Cubane- 1,2-dicarboxylic acid 12 (see Fig. 2.19), a precursor for 1,2-dihalocubanes was prepared from commercially available cubane-1,4-dicarboxylic acid in 65% yield. The other acids 14a and 14c were similarly prepared from the cubane-l,4-dicarboxylic acid 14b according to the literature procedures. 1H NMR spectra of the compound 13a showed a broad singlet at 4.41 for the clibyl protons, whereas compound 13b showed two multiplets. Conversion of bridgehead carboxylic acids to the corresponding halides using Pb(OAc)4 and iodine in refluxing benzene under illumination is reported. This is considered to be an alternative to Barton s method, because of its simplicity and ease of preparation, but it involves toxic lead compounds. 

Photolysis of alkyl carboxylic acids with lead (IV) acetates can generate alkyl radicals by decarboxylation and this has been used to place an aryl group on a cubane. Thus photolysis of a benzene solution of the cubane dicarboxylic acid (136) containing lead tetraacetate yields the phenyl cubane (137). A mechanistically related procedure uses iodosobenzene diacetate for the photochemical arylation of cyclohexane carboxylic acid with heteroaromatics such as pyridine or quinoline. 

Because the Shioiri modification avoids isolation of the intermediate acyl azide, it is particularly well suited for cases in which the azide intermediate would be particularly unstable. The case of 1,3,5-benzenetricarbonyl azide (45) was mentioned earlier. Another instance is the diacyl azide derived from 1,4-cubane dicarboxylic acid An early attempt to prepare diaminocubane via Curtius rearrangement of the diacyl azide was abandoned when the first sample of the crystalline eizide exploded violently. However, the Shioiri-Ninomiya-Yamada conditions smoothly... 

In cases where the diene is unstable, a dihalo starting material may be used with the iron carbonyl acting as a reducing agent. Both the trimethylene methane complex 10.5 (Scheme 10.3) and the cyclobutadiene complex 10.7 (Scheme 10.4) have been made in this way. The cyclobutadiene-iron complex 10.7 is a convenient storable form of this highly unstable diene. It can be liberated by oxidation and, if this is done in the presence of a dienophile, the Diels-Alder product is obtained. The Diels-Alder reaction with 2,5-dibromobenzoquinone gave the expected e do-product 10.8. An intramolecular photochemical [2-1-2] cycloaddition, followed by a Favorskii reaction, gave a cubane dicarboxylic acid 10.10. ... 

Pentacyclo[4.2.0.02 5.03 8.04 7]octane-l,2-dicarboxylic acid (Cubane-1,2-dicarboxylic acid)... 

Dinitrocubane (28) has been synthesized by Eaton and co-workers via two routes both starting from cubane-l,4-dicarboxylic acid (25). The first of these routes uses diphenylphos-phoryl azide in the presence of a base and tert-butyl alcohol to effect direct conversion of the carboxylic acid (25) to the tert-butylcarbamate (26). Hydrolysis of (26) with mineral acid, followed by direct oxidation of the diamine (27) with m-CPBA, yields 1,4-diiutrocubane (28). Initial attempts to convert cubane-l,4-dicarboxylic acid (25) to 1,4-diaminocubane (27) via a Curtins rearrangement of the corresponding diacylazide (29) were abandoned due to the extremely explosive nature of the latter. However, subsequent experiments showed that treatment of the acid chloride of cubane-l,4-dicarboxylic acid with trimethylsilyl azide allows the formation of the diisocyanate (30) without prior isolation of the dangerous diacylazide (29) from solution. Oxidation of the diisocyanate (30) to 1,4-dinitrocubane (28) was achieved with dimethyldioxirane in wet acetone. Dimethyldioxirane is also reported to oxidize both the diamine (27) and its hydrochloride salt to 1,4-dinitrocubane (28) in excellent yield. ... 

Crown-6 , see 1,4,7,10,13,16-Hexaoxacyclooctadecane, 3555 Crown ethers , see Cyclic poly(ethylene oxides), 0826 CS gas , see 2-Chlorobenzylidenemalononitrile, 3232b Cubane-l,2-dicarboxylic acid, see Pentacyclo[4.2.0.02 5.03,8.04,7]octane-1,2-dicarboxylic acid, 3255... 

Cubane-l,4-dicarboxylic acid rearranges to cuneane-2,6-dicarboxylic acid in a water-promoted transformation via the hydrogen cubane-l,4-dicarboxylate (Scheme 215). Solutions of tetrakis(guanidino)phosphazenium salts have been prepared. Unsaturated seven-membered lactams have been converted to fused pyrrolidinolac-tones by a process that involves the formation of an ammonium salt and subsequently a nitrogen ylide which initiates the rearrangement reaction. ... 

A convenient synthesis of a cubane system, in which the cyclobutadiene transfer reaction plays a key role, was reported by Pettit et al. (Scheme 11). By the oxidative decomposition of cyclobutadiene-iron tricarbonyl 56 with Ce + ion in the presence of a dienophile, a molecule of cyclobutadiene can be transferred from the iron to the dienophile. Decomposition of 56 in the presence of 2,5-dibromobenzoquinone 57 yielded the Diels-Alder adduct 58 with e do-configuration. Irradiation of 58 in benzene with a high-pressure Hg lamp afforded the bishomocubane derivative 59, which gave cubane-1,3-dicarboxylic acid 60 (80%) by treatment of 59 with aqueous KOH at 100°C. 

DPPA has been utilized in the synthesis of 1,4-dinitrocubane by Eaton and co-workers. Refluxing cubane-l,4-dicarboxylic acid with DPPA and Triethylamine in r-butanol forms the intermediate... 

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