Toward the Understanding of Benzannelated Annulenes: Synthesis and Properties of an - and -Ring Dibenzannelated Dihydropyrenes

Article abstract of DOI:10.1021/ja00373a038

The dibenzannelated - and dihydropyrenes 5 and 7 and dimethyldihydropyrenes 4 and 6 were synthesized from 1,3-bis- and 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 Kekule 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.