927. Syntheses of coronene and 1 : 2-7 : 8-dibenzocoronene

Liquid‐Crystalline and Electron‐Deficient Coronene Oligocarboxylic Esters and Imides By Twofold Benzogenic Diels–Alder Reactions on Perylenes

“…The first step of this sequence, the oxidative Diels-Alder reaction of perylene with an alkyl acrylate, seemed feasible because of the very high reactivity of perylene towards maleic anhydride (complete reaction occurs within a few minutes at reflux), [9] even though acrylates are known to be far less reactive than maleic anhydride. [10] Indeed, we found that isobutyl acrylate at reflux (132 8C) adds to perylene in the presence of chloranil, but the conversion rate is very slow: a yield of 39 % is isolated after six days, together with 36 % unreacted perylene.…”

“…This offers a straightforward path to coronene tetracarboxylic acid and its derivatives. The reaction of diesters 7 with maleic anhydride is accompanied by saponification of the ester groups due to the acidic reaction conditions (HCl is formed by degradation of chloranil), [9] yielding the unreactive anhydride 4 (Scheme 2). A mixture of coronene tetracarboxylic diester monoanhydride 9 with 5 and 4 is obtained, which, upon reesterification, yields a mixture of esters 7 and 10 that is practically inseparable.…”

“…[9] Unsubstituted benzoA C H T U N G T R E N N U N G [ghi]perylene, on the other hand, is known to react to yield coronene dicarboxylic anhydride 6. [9] Aiming for coronenecarboxylic esters with more than two ester substituents, we found that benzoA C H T U N G T R E N N U N G [ghi]perylene dicarboxylic alkyl esters 7 or imides 8, in contrast to the anhydride, are reactive enough to add maleic anhydride or N-alkyl maleimides in the presence of chloranil. This offers a straightforward path to coronene tetracarboxylic acid and its derivatives.…”

“…H 5.83,N 2.19;found: C 76.68,H 6.04,N 2.16. Perylene 3,4,9,imide (16, R = 4-heptyl): PTCDA 20 (16 g, 41 mmol) was refluxed with 4-heptylamine (17. 5 g, 152 mmol) in DMF (400 mL) overnight.…”

MP2 and DFT Calculations on Circulenes and an Attempt to Prepare the Second Lowest Benzolog, [4]Circulene

“…From this homologous series of compounds only three have been prepared so far: [5]circulene (3, corannulene), [3][4][5] [6]circulene (4, coronene), [5][6][7] and [7]circulene (5, pleiadannulene). [5,[8][9][10] On proceeding from 3 to 5 the geometry of these hydrocarbons changes from a cuplike structure through a flat arrangement to a saddle-shaped geometry.…”