NMR Spectrum and Fine Structure of 2‐Aryl‐1, 3‐Indandiones

Conjugated donor–acceptor substituted systems involving the 1,3-indandione-derived electron accepting moieties

“…Other known preparation procedures employ refluxing the components in acetic acid containing small amount of sulfuric acid affording the product with the melting point 204 °C (ref. 21 ) and heating in acetic anhydride at 60 °C, 12 the melting point 218–220 °C (from acetic anhydride). The addition of a base as a catalyst gives rise to the formation of several by-products including bindone 11 ( Chart 3 ).…”

Synthesis and study of pseudoaromatic compounds. IX. A reevaluation of the question of aromatic character in tropones based on data derived from dipole moment measurements and CNDO/2[complete neglect of differential overlap/2] calculations

“…However, quite often aromatic character has been assigned to these compounds on the basis of dipole moments and other data without consideration of suitable reference compounds, 40 and therefore these assignments must be considered intuitive at best.…”

Fulvenes and Thermochromic Ethylenes. Part 52 The Fine Structure of 2‐Arylmethylene‐1,3‐Indandiones; their NMR and Infrared Spectra

“…As in the case of l,l-diphenylethylene (of which II is a derivative) [5], the phenyl groups are not coplanar with the remainder of the molecule; thus an interaction of their orthohydrogen atoms with the carbonyl groups is not possible. This is also the obvious reason for the similarity of the NMR spectra of II and 2,2-diphenyl-l,3-indandione in which the phenyl rings are twisted out of the plane of the indandione system [6]. Table I further shows that if one compares two benzylidene derivatives which have the same substituent, once in the 4-, once in the 2-position, the multiplet in the low field appears always in lower field for the latter than for the former.…”