Irregular Centropolyindanes: Synthesis of 4b,9,13b,18-Tetrahydroindeno[1,2-a]indeno[2'',1''-b']indeno[1',2'-b]indene and Other Novel Centrotriindanes

Abstract

The syntheses of a novel tetraindan 6, containing two contiguous quaternary central carbon atoms, and of a number of other derivatives of the (unknown) "irregular" centrotriindan 5, is reported. Two-fold bridgehead benzylation of the C2-symmetrical diindandione 7 followed by reduction leads to the dibenzyldiindandiols 11, which undergo 2-fold acid-catalyzed cyclodehydration (H3POr/ chlorobenzene) in moderate yield (22 5% ) to 6. In contrast, use of xylene as the solvent gives rise to a Wagner-Meerwein rearrangement along with a single cyclodehydration step producing benzylidenetriindan 14 in good yield (70 5% 1. Monobenzyldiindandiols 10 incorporate a solvent molecule upon cyclodehydration in p-xylene to give triindan 12, whereas use of chlorobenzene yields complex mixtures of triindene 13 and its oligomers. These results shed some light on the relatively high strain of the tetraquinane skeleton of 6 and, in particular, on the reactivity of bridgehead [A(9b,lO)ldiindenes, in line with previous results. An independent attempt to generate 6 from 2,2'-biindanyltetrol 16 gave the dibenzodioxatetraquinane 17 in low yield.In 1981, Gund and Gund2 published a classification scheme of complex polycyclic organic ring systems bearing a carbon atom which is shared by all of the rings. Among these centropolycyclanes,2 centropolyquinunes, Le., those congeners bearing mutually fused cyclopentane units, have been of particular interest because of their relation to naturally occurring314 and non-natural m o d e F systems and because of the favorable steric fit of centrically fused five-membered rings.Centropolyindans, the benzoannelated analogues of centropolyquinanes, obey the same classification scheme.8 During the past decade, all higher members of the family of "regular" centropolyindans have been synthesized in our laboratory,"ll including various centrotriindans and centrotetraindans (e.g., l,lonJld and, respectively, 21°bJld and 319 and the highest possible congeners, centropentaindan12 and ~entr0hexaindan.l~ (2) Gund, P.; Gund, T. M.

Functionalized aromatics aligned with the three Cartesian axes: Extension of centropolyindane chemistry

“…Thus, five instead of six indane units being fused centrically form centropentaindane 4, four indane units give either the trifuso-centrotetraindane (5) or the tetrafuso-centrotetraindane (6), coined "fenestrindane", and only three mutually fused indanes lead to three triindanes, i.e., monofuso-(7), difuso-(8-), and trifuso-centrotriindane, which is represented as its centro-methyl derivative 9 here [25]. 2,2'-Spirobiindane and one of the fuso-diindanes (not shown) belong to the centropolyindane family as well, though not being true "poly"-indanes [23,24,26].…”

“…Oxidation to the corresponding triketone 24 turned out to be difficult; best but rather moderate yields were achieved only by use of chromium(VI) oxide in acetic acid at ambient temperature. Under suitable conditions, the rather electron-rich and sterically hindered triketone 24 did react twice and even thrice with 4-veratrylmagnesium bromide, and the mixture of the propellanediolone (25) and -triol (26) adducts was subjected to cyclodehydration. In fact, the three-fold cyclization took place, but some of the methoxy groups were cleaved concomitantly.…”

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

“…the hexamethoxycentrotriindanes 3 and 4, are reported as well. Together with the corresponding veratrole-derived tribenzotriquinacenes, such as isomer 5, published recently [20] and being part of the skeleton of 2 as well, compounds 3 and 4 complement the group of three possible regular centrotriindanes [19,21] bearing three veratrole nuclei in a symmetrical orientation.…”

“…[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. In this report, we disclose the synthesis of the first twelve-fold functionalized derivative of 1, namely 2, 3,6,7,10,11,14,15,20,21,26,27-dodecamethoxycentrohexaindane (2), bearing this particular, still T d -symmetrical pattern of peripheral substituents. In this context, the syntheses of two lower congeners of 2, which also belong to the centropolyindane family, [19] viz.…”

The Centropolyindanes and Related Centro-Fused Polycyclic Organic Compounds

“…Before doing so, however, some "irregular" centropolyindanes [49] will be mentioned briefly, the majority of which are not known to date (Scheme 2). In the following section, some structural relations of the centropolyindanes to well-known di-or polyindanes (hydro)carbon frameworks containing no quaternary atom will be pointed out (Schemes 3 and 4).…”