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45.22.2.1.9.1 Method 1: Lewis Acid Catalyzed Cyclodehydrogenation of Hexaarylbenzenes

DOI: 10.1055/sos-SD-045-00982

Chang, C.-S.; Wu, Y.-T.Science of Synthesis, (201045992.

In the presence of Lewis acids, hexaarylbenzenes 150 and 152 undergo oxidative intramolecular cyclodehydrogenation to form hexabenzocoronenes 151 and 153, respectively (Scheme 43). Hexabenzo[bc,ef,hi,kl,no,qr]coronene (151, R1=H) was first prepared by treatment with an aluminum trichloride/sodium chloride melt at high temperature.[‌107‌] This protocol sometimes gives partially cyclodehydrogenated products:[‌108‌] the mechanism of this reaction is, therefore, believed to involve a stepwise cyclodehydrogenation with subsequent aromatization. Combinations of copper(II) salts and aluminum trichloride in inert solvents are the most efficient reagents for these cyclodehydrogenation reactions, which even occur at room temperature.[‌108‌] Iron(III) chloride is also an efficient catalyst for the reaction:[‌109‌] cyclodehydrogenation of the hexadodecyl derivative 150 [R1=(CH2)11Me] with iron(III) chloride[‌110‌] gives a better yield of the corresponding hexabenzocoronene (77%) than do combinations of copper(II) salts and aluminum trichloride (49%).[‌111‌] For cyclodehydrogenation of hexaphenylbenzene (150, R1=H), molybdenum(V) chloride may be a superior reagent to iron(III) chloride or to combinations of aluminum trichloride and copper(II) chloride, but chlorinated derivatives of 151 are also formed.[‌112‌]

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Meeeeeeeeee 88M

M8 Meeeeeeeee Meeeee (%) Mee
M MeMe8, MeMe, 888888°M, 8.8e 8 [‌888‌]
M MeMe8, MeMe8, MM8, 88°M, 88e 88 [‌888‌]
M MeMe8, MM8Me8, 88°M, 88e <88.8e [‌888‌]
e-Me MeMe8, MM8Me8, 88°M, 88e 88 [‌888‌]
e-Me MeMe8, e-MeMe, MM8Me8, MeMM8 88e [‌888‌]
(MM8)88Me Me(MMe)8, MeMe8, MM8, 88°M 88 [‌888‌]
(MM8)88Me MeMe8, MeMM8, MM8Me8, ee, 88eee 88 [‌888‌]
(MM8)8MMMe(MM8)8eMe MeMe8, MeMM8, MM8Me8, ee, 88eee 88 [‌888‌]
8-MM8M8 MeMe8, MeMM8, MM8Me8, MM8, ee, 8.8e 88 [‌888‌]

e e.e.=eee eeeeeeee.

e Meeee eeeeeeeeee ee MMMM eeeeeeee.

e Mee-eee eeeeeeee ee eeeeeeeeeeeeeeeee eee e-MeMe; e.e. M8=M ee eeeeeeee eeeeeeee.

Meeeeeeeeee 88M

M8 M8 M8 M8 Meee (eee) Meeee (%) Mee
Me (MM8)88Me (MM8)88Me (MM8)88Me 88 88 [‌888‌]
Me Me (MM8)88Me (MM8)88Me 88 88 [‌888‌]
Me (MM8)88Me (MM8)88Me Me 88 88 [‌888‌]
M M (MM8)88Me (MM8)88Me 88 88 [‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeeee[ee,ee,ee,ee,ee,ee]eeeeeeee (888, M8=M):[‌888‌]

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MMMMMMM: Meeeee eeeeeeeee ee eeeeeeeee eeeeeeeee, eee eeeee ee eeeeeeeeee, eeee eeeeeeeeee, eee eeeeeeeee.

M eeeeeee ee MeMe8 (8.88e, 88.8eeee), MeMe8 (8.88e, 88.8eeee), eeeeeeeeeeeeeeeee (888, M8=M; 8.88e, 8.88eeee), eee MM8 (888eM) eee eeeeeee ee ee eeeee eeeee eee ~88e. Mee eeeeeeee eee eeeeeeee ee eee eeeeeeee ee MeMM (888eM), eee eee eeeeeeeeee eee eeeeeeee. Mee eeeeeee eee eeeeee eeeeeeeeeeee eeee M8M, eeeee MMe, M8M, eeeee ee MM8, M8M, eeeeeee, MM8, eee MM8Me8 (~888eM ee eeeee eeeeeeee), eee eeee eeeee eeeee eeeeee ee eeee eee eeeee eeeeeee; eeeee: 8.8e (88%). Meee eee eeeeeee eeeeeeee ee eeeeeeeeeee eeee e eeeeeeeeeee eeeeeeee eeee 888 ee 888°M eeee e eeeee ee 8ee ee 8 × 888 Meee; ee >888°M.

8,8,8,88,88,88-Meee-eeee-eeeeeeeeeeeeee[ee,ee,ee,ee,ee,ee]eeeeeeee (888, M8=e-Me):[‌888‌]

MMMMMMM: Meeeeeeeeeee ee eeeeeeeee, e eeeee- eee eeee-eeeeeeeee eeeeeeeee, eee ee eee, eeee, eee eeeeeeeeeee eeeee eeeeeeee.

M eee eeeee ee e eeeee eeee ee MeMe8 (88.8e, 888eeee) ee MeMM8 (888eM) eeee eeeee ee e eeeeeee ee eeeeeeeeeeeeeeeee (8.8e, 8eeee), e-MeMe (8.8eM, 88eeee), eee eeeee MM8Me8 (888eM), eee eee eeeeeeeee eeeeeeeeee eee eeeeee ee 88°M eee 8e eeeee eeeee eee eeeeeee eeeeeee eee eeee. Mee eeeeeee eee eeee eeeeee ee ee, eee eee eeeeeeeee MeMe8 eeee eee eeeee eeeeeeee eeee 88eee. Mee eeee eee eeee eee eeeeeee eee 8e ee ee eee eeee eeeeee eeee MeMM (888eM). Mee eeeeee eeeeeeeeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeee eeee MeMM (8 × 88eM). Mee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:8); eeeee: 8.88e (88%); ee >888°M (eeeeee).

References


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