Cyclopropane ring nitro

In the presence of even only mild electrophiles, cycloproparenes react via cleavage of the cyclopropane ring. However, the extremely bulky bis(triisopropyl-silyl) group offers efficient steric protection, and 302 is unreactive towards Br2. It reacts however with 67% HNO at 25 °C to afford the 3-nitro derivative 303 in 58% yield. The nitro group of 303 has been reduced to the amine which was acetylated. Reaction of 303 with LiAlH, in turn, afforded the corresponding azo compound. ... 

Another application of rhodium carbenoid chemistry relates to the synthesis of strained-ring nitro compounds as high energy-density materials. Nitrocyclo-propanes are the simplest members of this class of compounds and catalyzed additions of a nitrocarbene to an olefin have only been described recently [40], Detailed studies have shown that the success of the reaction is, as expected, dependent on both the alkene and the nitrodiazo precursor. Consistently with the electrophilic character of rhodium carbenoids, only electron-rich alkenes are cyclopropanated. The reaction has been extended to the synthesis of nitrocyclo-propenes but the yields are good for terminal acetylenes only [41]. 

Azolopyridazines bearing no nitro substituent are, nevertheless, sufficiently active electrophiles to enter the VNS reaction. However, similar to the series of quinoxalines [127] and pyridazinones [67], in the reactions of azolopyridazines with the carbanion of bromomethyl phenyl sulfone, two ways for conversion of the intermediate adducts are observed, depending on the structure of these heterocyclic compounds - p-elimination, leading to the VNS product, or intramolecular substitution, resulting in formation of the cyclopropane ring (Scheme 34) [128]. 

In cyclopropane, the C,C bond between the atom bearing the nitro group and the most substituted atom of the ring is cleaved. 

Die Addition von Nitro-alkanen an 1 -(1 -Alkenyl)-1 -trimethylsilyloxy-cyclopropane in me-thanolischer Benzyl-trimethyl-ammonium-hydroxid-Losung (Triton B) liefert unter Ring-offnung 7-Nitro-4-oxo-alkansaure-Derivate z.B.1 ... 

Acid-catalyzed seven-membered ring formation to afford the first stable A-oxo-2,1 -benzoxazepinium ions has been reported, based on reaction of l-chloro-2-(2-nitrobenzyl)cyclopropane with H2S04 and FSO3H nitro group trapping of an intermediate carbocation was proposed in this process <1996ZOR852>. 

A number of alkyl- and arylnitrile oxides have been reacted with methylenecyclopropane to give 4-oxa-5-azaspiro[2.4]hept-5-enes 1 (4,5-dihydrospiro[isoxazole-5-cyclopropane]). The nitrile oxides were usually generated in situ from the appropriate primary nitro compound with phenyl isocyanate and triethylamine. The addition is usually regioselective in such a way that the oxygen atom forms a bond with Cl of the three-membered ring. 

Step (Scheme 1.220) [306]. The treatment of nitro compounds with Ag20, DBU, and iodine resulted in bicyclic cyclopropanes 470 and 471 in good yields. The stereoselectivity was generally high. The stereoselectivity depended on the size of the formed ring. The precursors 469 were readily prepared by the conjugate addition of allylic or homoallylic nucleophiles to nitroalkenes. A similar cyclo-propanation has also been reported [307]. 

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