Quadricyclane, oxidation

The process is induced photochemically and involves the single-electron transfer oxidation of cubane then completed with a backward electron transfer to the transient radical cations. A Li+ salt with a weakly coordinating anion is able to induce pericyclic transformations, including the rearrangement of cubane to cuneane, quadricyclane to norbomadiene, and basketene to Nenitzescu s hydrocarbon 392... 

Dicarhonylation of strained bonds.2 The acyltetracarbonylferracycle (2), obtained on irradiation of quadricyclane (1) in the presence of excess Fe(CO)5, is oxidized to the a-diketone 3 in 81% yield by CuCl2 in aqueous CH3CN. 

Fused 1,2-thiazetidine A-oxides 22 are produced in one step from readily available aryl sulfonamides by cycloaddition with quadricyclane (Equation 13) <1997SL167, 1997SL634>. 

Oxidative cleavage of a P-P bond in the quadricyclane 62a was achieved by treatment with Bu N=VCl3 in toluene within 1 week to afford tricyclic compound 142 as a colorless powder in 18% yield. Excessive Bu N=VCl3 did not lead to an oxidative cleavage of the remaining P-P bond in 142 (Equation 14) <2001ZN951>. 

Murray and coworkers extended their studies of the novel oxidant dimethyldioxirane (19) to the reaction of quadricyclane (18 equation 7). The epoxide (15) was the nearly exclusive monooxidation product when the acetone solution of the oxidant was carefully dried, but in the presence of water a considerable amount of (17) was formed. 

A method to synthesize amino sulfoxides 212 and 213 was developed based on the rearrangement of sulfinamides 211300 (equation 81). The adduct of phenyl sulfonylamine and quadricyclane, i.e. 1,2-thiazetidine-A-oxide 214, underwent smooth rearrangement to furnish the fused 1,4-thiazine-A-oxide 215301 (equation 82). 

Acyltetracarbonylferracycle 1, derived by irradiation of quadricyclane in the presence of an excess of pentacarbonyliron in diethyl ether, was oxidized with copper(II) chloride in aqueous acetonitrile to give diketone 2 in good yield." ... 

Silver(I) ions generally catalyze the rearrangement of strained polycyclic systems which contain cyclopropane groups. It was shown, however, that silver(I) cleaved one or two of the strained cyclopropane bonds in quadricyclane (13) in an oxidation reaction. A complex mixture was obtained on treatment of quadricyclane (13) with silver(I) trifluoroacetate. The main addition products contained two oxygen functions and one intact cyclopropane ring." °... 

Stearns and Ortiz de Montellano have suggested a single-electron transfer mechanism for the oxidation of quadricyclane (30) by P-450 (109). this substrate has a very low oxidation potential for an alkane (0.9 V), and the oxidation product (31) was characteristic of an intermediate cation radical (Scheme Xlll)... 

Scheme XIII. A single-electron transfer mechanism proposed for the oxidation of quadricyclane by P-450.

Figure 6.10. The cytochrome P450-catalyzed oxidation of quadricyclane involving an initial electron abstraction step.

Methylene blue-sensitized oxidation of quadricyclane (61) in methanol leads to a complex mixture, and reduction of hydroperoxides to alcohols gives the major products shown in Scheme 9.124 The methoxynortricyclyl alcohols (62) and... 

It should be pointed out that the oxidation of quadricyclane-bis(trifluoromethyl)-thioketene cycloadduct 46 by MCPBA (25°C, 2 days) was reported to proceed without oxidation of either hydrocarbon or fluorinated double bonds, leading to selective formation of the corresponding sulfone, isolated in 92% yield. ... 

PET is the key feature of many other photo-oxidations involving aromatic substrates. It has been shown, for example, that pyrene and anthracene which are covalently attached to silica, gold or indium-doped tin oxide (ITO), undergo a photo-oxidation forming dihydroxy/dione derivatives. The reaction involves 02, formed by ET between excited pyrene, or anthracene, and O2, and it is suggested that the implications of such a photodegradation need to be considered when polycyclic aromatic hydrocarbons (PAHs) are used as spectroscopic probes in surface adlayers. The redox photosensitized amination of 1,2-benzo-1,3-cycloalkadienes, arylcyclopropanes, and quadricyclane with ammonia and primary amines, using 1,2,4-triphenylbenzene (1,2,4-TPB) or 2,2 -methylenedioxy-1,1 -binaphthalene in the presence of m- or p-dicyano-benzene (DCB), has been described (Scheme 51). The process involves the formation of the radical cation of 1,2,4-TPB, for example, by PET to the DCB, followed by hole transfer from the radical cation to the substrate, the latter... 

The catalytic rearrangement of strained alkanes is common. Cassar and Halpern showed that in the [RhCl(CO)2]2-catalyzed rearrangement of quadricyclane to norbornadiene, the admission of CO led to the formation of an acyl complex that seemed to be formed by trapping the initial oxidative addition product by a migratory insertion (equation 28). On the other hand, the Ag -catalyzed rearrangement of strained alkanes goes via carbonium ion intermediates which can be trapped by such nucleophiles as MeOH. ... 

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