transannular cyclization of dehydrobenzo 12 annulene induced by nucleophilic attack
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Transannular Cyclization of Dehydrobenzo [12] annulene Induced by Nucleophilic Attack. Tobe Lab Ayumi Yoshizaki. Contents. Introduction - π-Conjugated compounds Application Frame-work Dibenzoindacene Motivation Experiments & Results Future Work Summary. π-Conjugated compounds.

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transannular cyclization of dehydrobenzo 12 annulene induced by nucleophilic attack

TransannularCyclization of Dehydrobenzo[12]annulene Induced by Nucleophilic Attack

TobeLab

AyumiYoshizaki

contents
Contents
  • Introduction - π-Conjugated compounds

Application

Frame-work

Dibenzoindacene

  • Motivation
  • Experiments & Results
  • Future Work
  • Summary
conjugated compounds
π-Conjugated compounds

2D π-conjugated compounds have attracted attention as organic semiconductors.

E

・・・

N=1

N=2

N=3

N=4

N=5

N→∞

Pentadienyl Radical

Ethylene

AllylRadical

Butadiene

Energy bands of olefins

application
Application

Pentacenehas already been put to practical use in thin-film transistor. But, it unfortunately is prone toward oxidative degradation.

There is demand for alternative, acene-like topologies.

Pentacene

frame work
Frame-work
  • Acenes

condensed benzene ring in a line

  • Dibenzopentalene
  • Dibenzoindacene

Pentalene

Attractive Structural Motifs

Indacene

dibenzoindacene
Dibenzoindacene
  • Antiaromatic (20 π-electorons)
  • p-Xylylenecore
  • More resistant to degrade acenes

It does not possess any internal s-cisdiene linkage.

Fully conjugated dibenzoindacenesare extremely rare.

p-Xylylene

s-cisdiene

the h ckel rule
The HückelRule
  • Aromatic

(4n+2) π-electrons (n = 0, 1, 2, 3, …)

  • Antiaromatic

(4n) π-electrons (n = 0, 1, 2, 3, …)

E

x

Cyclic π-Conjugated Polyene

1,3-Cyclobutadiene

(4n) π

Benzene

(4n+2) π

example of dibenzoindacene
Example1of Dibenzoindacene
  • TransannularCyclization is induced by Iodine, electrophilic.
  • Tetraiodides

These rapidly oxidized to the corresponding diones upon exposure to air.

R = H, Decane, Dodecane

Tetraiodides

T. M. Swager, et al. J. Org. Chem. 1994, 59, 1294-1301.

example 2 of dibenzoindacene
Example 2 of Dibenzoindacene
  • The Synthesis of StableDibenzoindacenes

MultipleSteps

2 or 3 months

1: R = H

2 : R = Decane

M. M. Haley, et al. Angew. Chem. Int. Ed.ASAP

electronic absorption spectra
Electronic Absorption Spectra

pentacene

2

1

M. M. Haley, et al. Angew. Chem. Int. Ed.ASAP

motivation
Motivation
  • The dibenzoindacene (tetraiodides) synthesized in a single step is unstable.
  • Multiple steps are required to synthesize the stable one.
  • For easy synthesis, a short-stepsynthesis rout is required.
  • I have studied to synthesize a dibenzoindacenewith transannularcyclization.
transannular cyclization
TransannularCyclization

J.Otera, et al. Chem. Lett. 2008, 37, 1296-1297.

transannular cyclization of dehydrobenzo 12 annulene
TransannularCyclization of Dehydrobenzo[12]annulene

3

Various reaction conditions were investigated.

(concentration of material, equivalent of BuLi, reaction time, reaction temperature)

Reaction conditions were optimized.

future work 1
Future Work 1
  • I will study reaction conditions for the next transannularcyclization.
  • Then I will mesure its physical properties, and tune them by using other reagents instead of BuLi and BuI.
future work
Future Work 2
  • Bergman Cycloaromatization

W. M. Dai, et al. J. Am. Chem. Soc. 1992, 114, 7360-7371.

future work1
Future Work 2
  • Bergman Cycloaromatizationof 3
summary
Summary
  • Dibenzoindacene are rare fully conjugated species.
  • The reaction conditions for transannularcyclizationof dehydrobenzo[12]annulene were optimized.
  • Future works are transannularcyclization of the next step and bergmancycloaromatization to synthesize π-conjugated compounds with short-steps.
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