Pseudo-octahedral addition pattern

In ( )-49 it-electron conjugation between the two free poles is maintained through two tran.v-stilbcnc-likc bridges. As a result of this extended conjugation, the compound is red in solution, with an end absorption extending to 600 nm. This contrasts with the light-yellow color (end adsorption around 450 nm) of the hexakis adducts with a pseudo-octahedral addition pattern, in which the residual tt-electron chromophore is reduced to a benzenoid cubic cyclophane -type substructure [15,54],... 

Upon further functionalization, the regioselectivity of the additions becomes remarkably enhanced. A third di(ethoxycarbonyl)methano addend is preferentially introduced (40%) into the equatorial (e) position. Starting from e,e,e-tris-adduct, a remarkable sequence of stepwise e additions, with regard to the previous addends, affords hexakis-adduct 8 [12]. TTiis compound features a pseudo-octahedral addition pattern and can also be directly obtained in 14% yield by reacting C o with 8 equiv of diethyl 2-bromomalo-nate/l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) [12],... 

Scheme 7-4 Preparation of bis-adducts 24 (7,47] and 26 [41,47] and tris-adduct 28 [7, 47] by tether-directed remote functionalization. A sequence of e attacks starting from 28 gives hexakis-adduct 30 with a pseudo-octahedral addition pattern [7, 47]. DCC=A(,A("-dicyclohexylcarbodi-imide, HOBT = 1-hydroxy-IW-benzotriazole, DMAP=4-(dimethylamino)pyridine.

A Ci-symmetric hexakis-adduct of C6o including an azahomofullerene substructure (addition pattern analogue of homo[60]fullerene derivative ( )-26, Scheme 1.2) was obtained as a side product upon nitrogen extrusion from a fullerene derivative bearing five Bingel type addends and a fused triazoline arranged in a pseudo-octahedral manner.120... 

Hirsch and co-workers subsequently discovered that the yield of hexakis-adducts such as 8 or 9 can be greatly increased and their separation from side products substantially facilitated, if 9,10-dimethylanthracene (DMA) is used as a template (Scheme 7-2) [14, 15]. Anthracene derivatives such as DMA are well known to undergo reversible Diels-Alder additions with fullerenes at ambient temperamre [16-18]. After addition to the fullerene, the template directs diethyl malonate addends in the Bingel addition tegio-selectively into e positions, ultimately yielding the hexakis-adducts with a pseudo-octahedral, all-e addition pattern. The templated activation of e 6-6 bonds (bonds between two six-membered rings) is also efficient starting from C o mono-adducts, and several examples are shown in Scheme 7-2. Thus, bis(alkynyl)methanofullerene 10 [19] reacted with diethyl 2-bromomalonate/DBU (8 equiv) and DMA (12 equiv) to provide hexakis-... 

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