Measuring aromaticity with the dimethyldihydropyrene ring current probe. Experimental and computational studies of the fulvenes and the strongly antiaromatic cyclopentadienone reveal large Mills-Nixon-type bond localization effects. Synthesis of fulvene-fused dihydropyrenes

Journal of the American Chemical Society
Reginald H MitchellRichard Vaughan Williams

Abstract

The synthesis of the methylfulvene- and phenylfulvene-annelated dihydropyrenes 10 and 22 from the cyclopentadiene-fused dihydropyrene 7 in 68% and 80% yields, respectively, are reported. However, the attempted formation of the parent fulvene-fused dihydropyrene 18 failed, both from the cyclopentadiene 7 with formaldehyde and from the cyclopentadienone 5 in Wittig-type reactions. Chemical shift data for the methylfulvene (35) and phenylfulvene (36)-fused dihydropyrenes 10 and 22 were used to estimate the reduction in the dihydropyrene nucleus aromaticity (DHPN) (relative to benzene fusion) in 10 and 22 (12-16% and 22-25% respectively). Calculations revealed that this reduction in diatropicity, contrary to the situation with benzene fusion, is not due to any aromaticity of the annelating fulvenes but instead is caused by Mills-Nixon-type effects. We conclude that methyl- and phenylfulvene are nonaromatic. An improved synthetic route to the cyclopentadienone 5 was found in an unprecedented cyclization of the trans-cinnamic acid analogue 29 in 80% yield. This enabled an X-ray structure of 5 to be obtained, for comparison to that of the saturated ketone 4. Even though crystals of 5 and 4 show diastereomeric disorder, when the averag...Continue Reading

References

Nov 17, 2001·Chemical Reviews·R H Mitchell
Mar 2, 2002·The Journal of Organic Chemistry·Frank StahlPeter R Schreiner
Aug 17, 2002·The Journal of Organic Chemistry·Beata T StepieńMichał K Cyrański
Nov 7, 2002·Journal of the American Chemical Society·Richard Vaughan WilliamsSubhajit Bandyopadhyay
Dec 7, 2002·The Journal of Organic Chemistry·David B KimballJohn R Armantrout
Oct 31, 2003·Organic & Biomolecular Chemistry·Katayoun NajafianThomas T Tidwell
Oct 28, 2004·Journal of the American Chemical Society·Helene MöllerstedtHenrik Ottosson
Jan 18, 2005·The Journal of Organic Chemistry·Reginald H MitchellBrendan Twamley
Nov 17, 2005·Journal of the American Chemical Society·Reginald H MitchellDavid J Berg
Jul 3, 1996·Journal of the American Chemical Society·Paul von Ragué SchleyerNicolaas J R van Eikema Hommes

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Citations

Oct 1, 2016·The Journal of Organic Chemistry·Nicholas P GodmanScott T Iacono
Feb 24, 2016·Organic & Biomolecular Chemistry·V Siva Rama KrishnaSubhajit Bandyopadhyay
Jun 7, 2016·Dalton Transactions : an International Journal of Inorganic Chemistry·Assil BakkarEric Saint-Aman
Oct 19, 2016·Dalton Transactions : an International Journal of Inorganic Chemistry·A BakkarE Saint Aman
Nov 28, 2013·Chemistry : a European Journal·Satoshi MuratsuguHiroshi Nishihara
Jul 1, 2017·ChemPlusChem·Yves GarmshausenStefan Hecht
Jul 12, 2012·Chemical Communications : Chem Comm·Reginald H MitchellRichard Vaughan Williams
Oct 10, 2012·Journal of the American Chemical Society·Aaron D FinkeFrançois Diederich
Feb 6, 2017·Chemical Reviews·Preethanuj PreethalayamK V Radhakrishnan

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