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Title: The Pursuit of Perphenylterphenyls
Abstract

Tetradecaphenyl‐p‐terphenyl (2) was synthesized from 2,3,5,6‐tetraphenyl‐1,4‐diiodobenzene (11) by two methods. Ullmann coupling of11with pentaphenyliodobenzene (9) gave compound2in 1.7 % yield, and Sonogashira coupling of11with phenylacetylene, followed by a double Diels‐Alder reaction of the product diyne12with tetracyclone (6), gave2in 1.5 % overall yield. The latter reaction also gave the monoaddition product 4‐(phenylethynyl)‐2,2′,3,3′,4′,5,5′,6,6′‐nonaphenylbiphenyl (13) in 4 % overall yield. The X‐ray structures of compounds2and13show them to possess core aromatic rings distorted into shallow boat conformations. Density functional calculations indicate that these unusual structures are not the lowest energy conformations in the gas phase and may be the result of packing forces in the crystal. In addition, while uncorrected DFT calculations indicate that the strain energy in compound2is approximately 50 kcal/mol, dispersion‐corrected DFT calculations suggest that it is essentially unstrained, due to compensating, favorable, intramolecular interactions of its many phenyl rings. An attempted synthesis of tetradecaphenyl‐o‐terphenyl (4) by reaction of diphenylhexatriyne (14) with three equivalents of tetracyclone at 350 °C gave only the diadduct 2‐(phenylethynyl)‐2′,3,3′,4,4′,5,5′,6,6′‐nonaphenylbiphenyl (15) in 17 % yield. Even higher temperatures failed to produce4and lowered the yield of15, perhaps due to rapid decomposition of the starting materials. Ullmann coupling of 3,4,5,6‐tetraphenyl‐1,2‐diiodobenzene (16) and compound9also failed to give compound4.

 
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Award ID(s):
1762452
NSF-PAR ID:
10446024
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Chemistry – A European Journal
Volume:
28
Issue:
41
ISSN:
0947-6539
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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