‘Oligomere' Kondensationsprodukte von (1E,3E,5E)‐1,6‐Di(2‐furyl)hexa‐1,3,5‐trien mit Acetaldehyd: Tetrahydro‐tetramethyl‐octaepoxy[60]annulen(6.1.6.1.6.1.6.1)

Oligomeric Condensation Products of (1E,3E,5E)-1,6-Di(2-furyl)hexa-1,3,5-triene with Acetaldehyde: Tetrahydro-tetramethyl-octaepoxy[60]annulene(6.1.6.1.6.1.6.1) The Ca(NO3)2-induced condensation of (1E,3E,5E)-1,6-di(2-furyl)hexa-1,3,5-triene (6) with acetaldehyde yields the linear ‘oligomers' 7–11 with 2–6 1,6-di(2-furyl)hexa-1,3,5-triene units and 1–4 acetaldehyde units, besides a cyclic condensation product 12 obtained from 4 equiv. of 6 with 4 equiv. of acetaldehyde. According to spectroscopic studies, 12 is the tetrahydro-tetramethyl-octaepoxy[60]annulene(6.1.6.1.6.1.6.1) as the most expanded annulene system known so far. While the dehydrogenation of 12 to give the tetramethyl-octaepoxy[60]annulene(6.1.6.1.6.1.6.1) cannot be achieved, the oxidation of 12 with Br2 yields a black, in all organic solvents nearly insoluble solid 14, which possibly is the tetramethyl-octaepoxy[58]annulene(6.1.6.1.6.1.6.1) dication. Because of the insolubility of 14, unfortunately most of its spectroscopic data are not available. However, the λmax values in the UV/VIS/NIR spectrum of 14 (Soret and Q bands) are in line with the values of the tetraepoxy[26]annulene(4.2.4.2) dication, the tetraepoxy[30]annulene(4.4.4.4) dication, and the tetraepoxy[34]annulene(6.4.6.4) dication.