Benzoannelated centropolyquinanes. Part 21. Centrohexaindane: three complementary syntheses of the highest member of the centropolyindane family

2,3,6,7,10,11‐Hexamethoxytribenzotriquinacene: Synthesis, Solid‐State Structure, and Functionalization of a Rigid Analogue of Cyclotriveratrylene

“…147°C (144Ϫ146°C [34b] ), R f (n-hexane/ EtOAc, 3:1) ϭ 0. Ϫ1 , 3005, 2975, 2938, 1754, 1632, 1574, 1511, 1465, 1451, 1416, 1295, 1240, 1220, 1170, 1151, 1141, 1122, 1022, 892, 880, 818, 795, 771, 750, 724, 619 (19), 144 (6), 128 (9), 115 (10), 107 (5).…”

The First Centrohexaindane Bearing Twelve Functional Groups at Its Outer Molecular Periphery and Related Lower Veratrole‐Derived Centropolyindanes

“…Different from the recently described synthesis of several tetramethoxy-substituted congeners of 1 [22] which was achieved following the "fenestrane route" to the centrohexacyclic framework, [5,19] the title compound 2 was obtained by following the complementary "propellane route", [5,19,23] making use of appropriate synthons derived from veratrole (Scheme 2). Starting from 5,6-dimethoxyindane-1,3-dione (6), the preparation of which was improved recently, [20] the conventional sequence, that is, condensation of 6 with 3,4-dimethoxybenzaldehyde (7), reduction of the product, chalcone 8, with sodium borohydride and subsequent benzylation of the dihydrochalcone 9 with dimethoxybenzyl chloride (10), furnished the 1,3-indanedione 12 in good overall yield (58 % from 6).…”

“…Due to the presence of the peripheral methoxy groups, the electrophilicity of the triketone should be markedly reduced as compared to the parent triptindanetrione, which was found to undergo threefold addition of nucleophiles, such as phenyllithium and methyl-and benzylmagnesium bromide. [5,23,28,31] In the present case, the addition of three veratryl residues to the triketone 15 was carried out by use of 4-veratrylmagnesium bromide, prepared from 4-bromoveratrole (16) ·+ at m/z = 774 and m/z = 912, respectively). Similarly rapid, and highly stereospecific, loss of water is known for other preoriented bridgehead-hydroxylated centropolyindanes and simpler cyclic alcohols.…”

“…[5,6] Centrohexaindane may be considered a "Cartesian hexabenzene" owing to the fact that the aromatic rings are sticking out from the center of the molecule into the six directions of the three-dimensional space. [6] In view of the lively interest in building blocks with rigid, well-defined 3D-geometry of the framework and the pendant functionalities, [7][8][9][10][11][12][13][14][15][16][17][18] access to derivatives of 1 that bear functional groups at the twelve arene positions of the outer periphery of this C 41 H 24 hydrocarbon is a promising goal.…”

Centrohexacyclic or “K5” Molecules: Development of a Growing Family of Topologically Nonplanar Organic Compounds

“…A further step would require a second spiroannellation, again perpendicular to the first one (B -+ D). In fact, the "fenestrane route" [39] to centrohexacyclanes (path b, Scheme 6) turned out to be the and most versatile strategy. For further alternative approaches, other tricyclic substrates may be selected as starting…”