1394958-97-4Relevant articles and documents
Functional carbo-butadienes: Nonaromatic conjugation effects through a 14-Carbon, 24-p-electron backbone
Rives, Arnaud,Maraval, Val-Rie,Saffon-Merceron, Nathalie,Chauvin, Remi
, p. 483 - 492 (2014/04/03)
A systematic study of carbo-butadiene motifs not embedded in an aromatic carbo-benzene ring is described. Dibutatrienylacetylene (DBA) targets R 1-C(R)=C=C=C(Ph)- C=C-C(Ph)=C=C=C(R)-R2 are devised, in which R is C=CSiiPr3 and R1 and R2 are R, H, or 4-X-C6H4, with the latter including three known representatives (X: H, NMe 2, or NH2). The synthesis method is based on the SnCl 2-mediated reduction of pentaynediols prepared by early or late divergent strategies; the latter allows access to a OMe-NO2 push-pull diaryl-DBA. If R1 and R2 are H, an over-reduced dialkynylbutatriene (DAB) with two allenyl caps was isolated instead of the unsubstituted DBA. If R1=R2=R, the tetraalkynyl-DBA target was obtained, along with an over-reduced DBA product with a 12-membered 1,2-alkylidene-1H2,2H2-carbo-cyclobutadiene ring. X-ray crystallography shows that all of the acyclic DBAs adopt a planar trans-transoid-trans configuration. The maximum UV/Vis absorption wavelength is found to vary consistently with the overall p-conjugation extent and, more intriguingly, with the p-donor character of the aryl X substituents, which varies consistently with the first (reversible) reduction potential and first (irreversible) oxidation peak, as determined by voltammetry.
