An Experimental Estimation of Aromaticity Relative to That of Benzene. The Synthesis and NMR Properties of a Series of Highly Annelated Dimethyldihydropyrenes: Bridged Benzannulenes
作者:Reginald H. Mitchell、Vivekanantan S. Iyer、Nasr Khalifa、Ramanathan Mahadevan、Santhanagopalan Venugopalan、Sirimevan Ananda Weerawarna、Pengzu Zhou
DOI:10.1021/ja00110a008
日期:1995.2
The synthesis of 13 trans-dimethyldihydropyrenes (bridged [14]annulenes) fused to one or more benzene, naphthalene, phenanthrene, phenalene, or quinoxaline rings and 6 cis-dihydropyrene derivatives from benzenoid precursors using either a thiacyclophane route or an electrocyclic addition of a furan to an annulyne followed by deoxygenation is reported. Their H-1 NMR spectra are studied in detail to obtain correlations between (3)J(H,H) coupling constants and the internal methyl proton chemical shifts and also between the latter and the more distant external annulene ring proton shifts. These linear correlations are then used to obtain a relationship between the relative aromaticity of benzene and the fused ring in question, such that the aromaticity of the fused ring can be estimated relative to that of a benzene ring simply from a measurement of chemical shift in the fused annulene.
MITCHELL, R. H.;MAHADEVAN, R., TETRAHEDRON LETT., 1981, 22, N 51, 5131-5134
作者:MITCHELL, R. H.、MAHADEVAN, R.
DOI:——
日期:——
Synthesis of diatropic highly benzannelated annulenes.
作者:Reginald H Mitchell、Ramanathan Mahadevan
DOI:10.1016/s0040-4039(01)92439-6
日期:1981.1
The first examples of annelated cis-dihydropyrenes, 16, 18, 19, together with a number of highly annelated trans-dihydropyrenes, 2 - 4 and, 17, are described. All are diatropic and indicate that higher annelation does not remove the delocalisation in a macrocyclic ring.