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2,3,6,7,10,11‐Hexamethoxytribenzotriquinacene: Synthesis, Solid‐State Structure, and Functionalization of a Rigid Analogue of Cyclotriveratrylene
Author(s) -
Harig Marco,
Neumann Beate,
Stammler HansGeorg,
Kuck Dietmar
Publication year - 2004
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300782
Subject(s) - chemistry , electrophile , halogenation , nitration , crystal structure , solid state , cleavage (geology) , ring (chemistry) , stereochemistry , surface modification , synthon , derivative (finance) , crystallography , organic chemistry , catalysis , geotechnical engineering , fracture (geology) , financial economics , engineering , economics
The syntheses of several tribenzotriquinacenes bearing six methoxy groups at the outer peripheral positions of the aromatic rings are reported. The centro ‐methyl derivative is accessible in surprisingly good yield through two‐fold cyclodehydration in the final step of a synthesis route which requires special care in the preparation of some electron‐rich key intermediates, such as 5,6‐dimethoxy‐2‐methylindane‐1,3‐dione and bis(3,4‐dimethoxyphenyl)methanol. X‐ray single‐crystal structure analysis of the centro ‐methyl derivative confirms its C 3v ‐symmetrical molecular structure but, at variance from the parent centro ‐methyltribenzotriquinacene and the similarly shaped cyclotriveratrylene, the hexamethoxytribenzotriquinacene analog does not form columnar stacks in the solid state. Functionalization of the three benzhydrylic bridgehead positions leads to the tetramethyl analog and the bridgehead triol in good yields. In contrast, attempts to functionalize the ortho positions by nitration or bromination mainly give rise to ring cleavage through electrophilic ipso attack, which parallels the behavior of cyclotribenzylenes and cyclotriveratrylenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)