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8096785 
Journal Article 
Toward the Understanding of Benzannelated Annulenes: Synthesis and Properties of [a,h]- and [a,i]-Ring Dibenzannelated Dihydropyrenes 
Mitchell, RH; Williams, RV; Dingle, TW 
1982 
Yes 
Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 
AMER CHEMICAL SOC 
WASHINGTON 
104 
9 
2560-2571 
English 
WOS:A1982NN22100038 
The dibenzannelated [a,h]- and [a,i] dihydropyrenes 5 and 7 and dimethyldihydropyrenes 4 and 6 were synthesized from 1,3-bis(bromomethyl)naphthalene (23) and 1,3-bis(bromomethyl)-2-methylnaphthalene (24), respectively, using Wittig rearrangement-Hofmann elimination sequences on the corresponding dithiacyclophanes, followed by valence tautomerization of the resulting cyclophanedienes. The dihydropyrenes 5 and 7 could not be isolated, but rapidly dehydrogenated to dibenzo[a,h]-and-[a,i] pyrene. The dimethyldihydropyrenes 4 and 6 are relatively stable and their diatropicities are discussed in relation to each other and to other benzannulenes in terms of Kekulé structures and bond order calculations. It is shown that transoid fusion of the benzene rings on the annulene only somewhat perturbs the diatropicity of the annulene, whereas cisoid fusion strongly localizes the annulene macroring. Annulenes such as 6 which have transoid-fused benzenoid rings are also shown to display radicaloid properties. © 1982, American Chemical Society. All rights reserved.