Synthesis of Hexabenzo[a,cd,f,j,lm,o]perylene

Recent Progress in Chemistry of Multiple Helicenes

“…[4] In ar einvestigation in 2004, Ohshima and co-workerss ynthesized 1a by using Clar's methodw ith av ery low yield (1 %), and assigned all of the chemical shifts in the 1 Ha nd 13 CNMR spectra of 1a,t he stereochemistry of which, however,w as not reported. [5] As found by Agranat and co-workersfrom acomputational study, [6] helicene 1a has two minimum-energy conformations, the chiral twisted conformations, (P,P)-1a and (M,M)-1a, at the globalm inimum and the anti-folded meso isomer,( P,M)-1a,a tt he local minimum. In 2012, Miao and co-workers synthesized alkoxylated derivatives of hexbenzo[a,cd,f,j,lm,o]perylene, 1b and 1c,t hrough aS choll (cyclodehydrogenation) reaction, as discussed in the next section.…”

“…[7] As-synthesized 1b was the chiral twisted isomer with torsion angles of 42.1 and 39.28 in the fjordr egions, as revealed by the single-crystal structure. The red twisted isomer of 1c isomerizes at elevated temperature to the yellow anti-folded conformer with an equilibrium constant of 0.35 and an activation free energy of 120 kJ mol À1 ,a sd etermined by kinetic experiments based on 1 HNMR spectroscopy.M üllen et al synthesized tetranaphthoterrylene tetracarboxdiimide 2 ( Figure 1), ad ouble [5]helicene, in 2011t hrough af ourfold palladium-catalyzed benzannulation of the tetrabromoterrylened iimidew ith o-trimethylsilylphenyl triflate as ak ey step. [8] Similar to 1a-c,h elicene 2 has one antifolded meso isomer,( P,M)-2,a nd ap air of chiral twisted isomers, (P,P)-2 and (M,M)-2.A sf ound from theoretical calculations, isomer (P,M)-2 has at orsion angle of 458 in the fjord regions, whereas (P,P)-2 and (M,M)-2 have at orsion angle of 508.…”

“…Compound (P,M)-2 was isolated from am ixture with its diastereomers( P,P)-2 and (M,M)-2 by meanso fs tandard chromatography on silicag el, whereas (P,P)-2 and (M,M)-2 were separated by chiral HPLC. Bock and co-workers synthesized double [5]helicene 3 in 2015 through as equence involving glyoxylic functionalization of chrysene, followed by Perkin reactions, and palladium-catalyzed cyclizations. [9] Compound 3 also exists as two diastereomeric forms,(P,M)-3 and (P,P)/(M,M)-3.U nlike the meso isomerso f1a-c and 2 with ap lane of symmetry,t he meso isomer of 3,( P,M)-3,i sc entrally symmetric.…”

Reinvestigation of the photoreaction of 1,4-bis(2,4,6-triphenylpyridinio)benzene: Synthesis of a diazonia derivative of hexabenzoperylene by multiple photocyclization

“…Comparison of the 1 H NMR chemical shifts (in DMSO-d 6 ) of the photoproduct 2 with the corresponding chemical shifts of a referenced compound 4 [22] revealed that most protons of 2 are shifted to the lower magnetic field, but the signal of the H-7 proton(s) at the "fjord" regions observed at the higher magnetic field ( = -0.30 ppm) caused by a typical shielding effect of the ring current in the overlapping terminal benzene rings [14]. This observation means that the compound 2 has a non-planar double helicene like structure.…”

“…In addition, the latter authors mentioned that HBP showed solid-state thermochromism (yellow to red) at 150°. After that, Fujimaki et al reported in 2004 on the modified synthesis of HBP according to the Halleux's method, but the yield was still around 1% [14]. To the best of our knowledge, there were no other reports about the synthetic research of the parent HBP and their derivatives.…”