Triptycene oxide

Triptycene cyclopentenedione 47 underwent 1,3-DC with nitrile oxides affording polycyclic isoxazolines 48 bearing the triptycene moiety. The adducts 48 exist in solution in their two enolic forms 49 and 50, in equimolecular amounts <02JOC4612>. 

Perfluorodistibatriptycene is unaffected by cold, concentrated nitric acid but dissolves with oxidation on boiling (ff) dilution of the solution with water results in the deposition of Sb2(C6F4)3(N03)2(0H)2 as needlelike, colorless crystals. This nitrate slowly hydrolyzes on repeated crystallization from water to give Sb2(C6F4)3(OH)4 attempts to dehydrate this tetrahydroxo derivative to the above polymeric oxide have so far failed. The stereochemistry of these Sb(V)-substituted triptycenes would be of great interest but all the crystals yet studied have proved to be twinned. 

However, in certain cases under photolytic conditions, spectra of the corresponding arylmercury radical cations 6 developed, whereas no mercuration occurred in dark [81] signifying collapse of the ArH +,Hg(TFA)2 radical ion pair 4, provides an alternative path way to Wheeland complex 2 and hence to ArHg(TFA) + 6. Arene radical cations can also be generated from arene and thallium(III) tris-(trifluoroacetate) in trifluoroacetic acid [82], but with a different mechanism proposed by Eberson et al. [83]. Oxidation of anthracene showed 9-trifluoroacetoxy and 9,10-bis(trifluoroacetoxy)anthracene [84, 85], benzo[a]pyrene, 7-methylbenzo-[a]pyrene and 12-methylbenzo[a]pyrene yielded radical cations of 7- and/or 12-trifluoroacetates [86], triptycene (9,10-dihydro-9,10-[l,2]benzanthracene) showed... 

Reaction of the monocyanoethyl-protected TTF 738 with cesium hydroxide in a mixture of methanol and DMF led to the deprotected thiolate, which was further alkylated with the bromobutyl-substituted MOM-triptycene 739 to give the MOM-TTF 740 in 89% yield (MOM = methoxymethyl). The MOM protecting group was removed quantitatively under acidic conditions and the resulting hydroquinone was oxidized to yield the TTF-quinone 741 in 54% yield (Scheme 109). The preparation of the pyrrolo-TTF derivatives 25 was accomplished in a similar way <1998JOC1198>. 

The reactive intermediate 1,2-dehydrobenzene (benzyne) is generated by oxidation of 1-aminobenzotriazole with lead(IV) acetate. It can be trapped with anthracene to form triptycene ... 

The high reactivity of benzynes as dienophiles in Diels-Alder reactions has also been observed in reactions with aromatic hydrocarbons, a class of compounds usually considered as inert as dienes. In a two-step synthesis of triptycene di- and tetracarboxylic acids, arynes generated in situ from anthranUic adds 158 cydized with anthracenes 159 affording di- or tetramethyltriptycenes 160 in 41-69% yields (Scheme 12.47) [85], Acids 161 were obtained after subsequent oxidation of the cycloadducts 160 with potassium permanganate. 

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