Indeno indol-6-one

The aromaticity obtained by means of the DE values and their differences in the single pseudoazulene systems are also the result of calculations of the bond orders (Fig. 1). The calculated bond alternations46 57-77-79-82-117118-129 are in line with the heteroaromaticity of the systems. Similar relationships were calculated for azulene.219 The extent of the bond alternation, however, differs from one system to the other (see Fig. 1). In indeno[2.1-f>]-l-benzo-pyran (44a) the bond lengths of the central cyclo[fo]pyran system indicate pronounced bond alternation, and in the opinion of the authors, the systems have little aromatic character.129 Calculations with 1 //-pyrindines (26) and 2//-pyrindines (29) show that 26 is more stable than 29, but both are less aromatic than indole.63 A comparison of SCF calculations for pseudoazulenes 26 and 29 with their aza analogs 68 and 69-73, which contain a pyrrole-type nitrogen, shows only minor perturbations of carbon-carbon bond lengths on replacing a =CH— moiety by =N—.66... 

The complete and assignments of eight bioactive indeno[l,2-Z)]indole-10-one derivatives have been accomplished by Al Chab et al. by the of NMR speetroscopy for all these compounds /hh couplings have been reported. 

Dai, W., Petersen, J.L. and Wang, K.K. (2005) Synthesis of indeno-fused derivatives of quinolizinium salts, imidazo[l,2-a]pyridine, Pyrido[l,2-a]indole, and 4ff-quinolizin-4-one via benzannulated enyne-allenes. Journal of Organic Chemistry, 70(17), 6647-6652. 

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