Two C-Unsubstituted Enaminals

Diazepines. Part 30.1 A Comparison between the Extent of Delocalisation of Electrons in a Vinamidine and its Protonated Form. Crystal and Molecular Structure of Two 2,3-Dihydro-1,4-diazepines

“…Whereas the vinamidinium systems have bond distances characteristic of a fully delocalised p-electron system, the bonds in the vinamidine systems in the dihydrodiazepine bases alternate in length and are reminiscent of an openchain push-pull conjugated system rather than of a delocalised system. For example, in two enaminals 15 the bond distances of the N±CH= bonds are 1.334(2) and 1.354(2) A Ê and of the CH=CH bonds are 1.363(3) and 1.355(2) A Ê .…”

Synthetic routes to pyrrolizine-1,5-dione derivatives by flash vacuum pyrolysis of amidomethylene derivatives of Meldrum's acid

“…13 The enaminoester unit of 19 is planar (mean deviation from best plane of N1-C1¢-C2¢-C3¢-O3¢-O4¢ 0.0085 A ˚; maximum deviation at C1¢, 0.0215 A ˚); the bond lengths in the propenoate chain show evidence of delocalisation, but less so than in corresponding N,N-disubstituted enaminals. 14 Under FVP conditions, no significant yields of cyclisation products were obtained by pyrolysis of the N-formyl compound 8 or the six-membered lactam derivative 15 or the ureas 16-18 (ESI †). Reasons for this behaviour are unclear, but the high migration aptitude of carbonyl derivatives 15 in potential sigmatropic shifts across the methyleneketene p-system may be involved.…”

“…The amide or lactam used and reflux time for each example are given in parentheses. (14), 155 (18), 128 (29), 127 (30), 99 (26), 84 (21), 83 (100), 82 (81), 81 (13) and 59 (12).…”

3-Dimethylamino-1-(4-methylphenyl)prop-2-en-1-one

“…For the chemical synthesis of enaminones, see: Kantevari et al (2007); Ke et al (2009). For the crystal structures of enaminones, see: Lemmerer et al (2007); Bertolasi et al (1999); Blake et al (1996).…”