Hexasilylated Total Carbomer of Benzene

1,4‐Dialkynylbutatrienes: Synthesis, Stability, and Perspectives in the Chemistry of carbo‐Benzenes

“…The same conditions were thus applied after complexation of one of the triple bonds of 25 with a [Co 2 (CO) 6 ] unit; eliminative reduction of 1,4-dioxybut-2-yne moieties by stabilization of the propargylic carbenium intermediates as Nicholas complexes was indeed previously reported in the particular case of a hexaalkynylhexaoxy [6]pericyclyne. [30] The targeted butatriene derivative 24 was, however, not observed, and the triyne precursor 25 was recovered after treatment with cerium(IV) ammonium nitrate (CAN). To explain this failure, it can be proposed that complexation of the [Co 2 (CO) 6 ] unit occurred at the central, less hindered, triple bond (the external triple bonds are hindered by the bulky TIPS groups), and could thus block the elimination process, even if the cobalt-stabilized carbenium ion was produced (Scheme 12).…”

“…Attempted preparation of the butatriene 24 by reductive elimination from the dioxytriyne 25, and proposed explanation for the failure of the cobalt method. [30] [Co] = [Co 2 (CO) 6 ].…”

Reductive Aromatization/Dearomatization and Elimination Reactions to Access Conjugated Polycyclic Hydrocarbons, Heteroacenes, and Cumulenes

“…[101] Following this initial synthesis, both Ueda and co-workers and Chauvin andc o-workers developed synthetic routes to carbo-benzenes 58 [102] and 59 (Scheme 21). [103] Chauvin andc o-workers have published several syntheses on other carbo-mers [104] including the monumental 19-step synthesis of carbo-naphthalene 60. [105] The synthesis of 60 is notable as the final step with SnCl 2 features the reductivee limination of eight methoxy and two hydroxy groups.…”

carbo‐Naphthalene: A Polycyclic carbo‐Benzenoid Fragment of α‐Graphyne

“…Tw oc arbo-benzene references are also described, C 18 Ar 6 and o-C 18 Ar 4 (CC-SiiPr 3 ) 2 .T he carbo-naphthalene bicycle is locally aromatic according to structural and magnetic criteria, as revealed by strong diatropic ring current effects on the deshielding of 1 Hn uclei of the Ar groups and on the negative value of the DFT-calculated NICS at the center of the C 18 rings (À12.8 ppm). [2, 3b, 7] Whereas acyclic and unicyclic molecular fragments of agraphyne have been exemplified by carbo-oligoacetylenes [8] and carbo-benzenes, [6,9] afirst fused bicyclicfragment is envisaged in a carbo-naphthalene.With av iew to securing both stability and solubility,t he selected target was octa(p-n-pentylphenyl)-carbo-naphthalene (1). [3] Besides putative variants (a-, b-, 6,6,12-graphynes), the existence of graphdiyne is today demonstrated, [4] and g-graphyne has been approached through several polycyclic molecular fragments.…”

“…[5] Them ost homogeneous variant is agraphyne (with only two types of CÀC bonds), that is,t he total carbo-mer of graphene ( Figure 1), [6] or al ayer of agraphityne. [2, 3b, 7] Whereas acyclic and unicyclic molecular fragments of agraphyne have been exemplified by carbo-oligoacetylenes [8] and carbo-benzenes, [6,9] afirst fused bicyclicfragment is envisaged in a carbo-naphthalene.…”