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

Abstract

The first Td‐symmetrical derivative of centrohexaindane bearing twelve functional groups has been synthesized. Six pairs of methoxy groups, each of which belong to six veratrole units fused to the topologically nonplanar (K5) core, point outwards from the molecular center into the six directions of the Cartesian space. The synthesis of this first dodeca‐substituted centrohexaindane was achieved along the “propellane route” established previously for the parent centrohexaindane, but the electron‐rich character of some of the intermediates was found to require considerably modified methodology. Two hexamethoxy‐substituted centrotriindanes, representing lower congeners of the title compound and bearing three veratrole units, were also synthesized. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Dodecabromo‐ and Dodecaiodocentrohexaindane: Td‐Symmetrical Key Building Blocks for Twelve‐Fold Cross‐Coupling Reactions and Six‐Fold Orthogonal Extension

“…Nevertheless, both the 1 Ha nd the 13 CNMR spectra were measurable in this solvent and confirmed the identitya nd Cl) with the maximum at m/z 1497.8, in good agreement with the theoretically expected relative abundance of isotopomers ( Figure 2). However,i ti sn oteworthy that the mass spectra of compound 3 synthesized by use of NBS/TFSA notoriously exhibitedt he presence of either minor under-brominated or over-brominated analogues, or even both (for examples, see Supporting Information Figures S3a-d), whereas the 1 Ha nd 13 CNMR spectra did not. The observation that, in total, four additional bromine atoms can be incorporated suggestst hat, in spite of the severe steric hindrancei nt he four molecular cavities of 3,e ach of them can accept one (but only one!)…”

“…IR spectra were recorded with an FT-IR spectrometer model Nicolet-380. 1 HNMR spectra were measured with a Bruker DRX 500 instrument (500 MHz, CHCl 3 at d = 7.24 ppm as in-ternal standard), 13 CNMR spectra were recorded with aB ruker AvanceI II 500 instrument (125.7 MHz, CDCl 3 at d = 77.0 ppm as internal standard). Electron ionization (EI) mass spectra were recorded with aF isons VG Autospec Xd ouble-focusing mass spectrometer;e lectrospray ionization (ESI) mass spectra were obtained with a Bruker Daltonik Esquire 3000 ion trap mass spectrometer equipped with as tandard nanoESI source.…”

“… Perspective (top left) and schematic (top right) representation of centrohexaindane ( 1 ) and the twelve‐fold functionalized derivatives 2 and 3 and 4 (this work). Note that the three 2,2′‐spirobiindane units comprised in 1 are mutually fused at 90° to each other.…”

“…Twelve‐fold functionalization of 1 with a T d ‐symmetrical pattern has been both an extremely exciting and challenging goal of centropolyindane chemistry . So far, the only derivative of 1 bearing functional groups at all of the twelve peripheral positions is 2,3,6,7,10,11,14,15,20,21,26,27‐dodecamethoxycentrohexaindane ( 2 ), synthesized in low overall yield from veratrole‐based building blocks . Beside single functionalization of 1 , six‐fold peripheral nitration was achieved recently, promising an access to various highly N ‐functionalized congeners including the particularly interesting, but yet unknown dodecaamino derivative .…”

“…1 bearing functional groups at allo ft he twelve peripheral positions is 2, 3,6,7,10,11,14,15,20,21,26,27-dodecamethoxycentrohexaindane (2), synthesized in low overall yield from veratrolebased building blocks. [13] Beside single functionalization of 1, [14] six-fold peripheral nitration was achieved recently, [6] promising an access to various highly N-functionalized congeners including the particularly interesting, but yet unknown dodecaamino derivative. [2a] In the same vein, twelve-fold bromination and iodination of 1 represent mostdesirable key steps for "Cartesian" extension of the centrohexaindane core.…”