Large PAHs by reductive peri-peri "dimerization" of phenalenones

[GRAPHICS] Reactions of phenalenone (2), benzanthrone (3), and naphthanthrone (4) with a low-valent titanium reagent (TiCl4/LiAIH(4)/THF) gave peropyrene (1), te trabenzo[a,cd,j,lm]perylene (6), and dibenzo[ik,uv]dinaphtho[2,1,8,7-defg;2 ',1 ',8',7'-opqr]pentacene (10), respectively. The syntheses of the LPAHs 6 and 10 were regioselective, An unsymmetrical pathway of reductive peri-per i "dimerization" of the phenalenones leading to peropyrene-type LPAHs was p roposed. Ab initio DFT B3LYP/6-311G** calculations indicated that D-2h-1, t he most stable conformation, resembles the Clar picture of 1.