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Short Note

3,4,5,6,7,8,9-Heptachlorophenaleno[1,9-bc]pyrazole

Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
*
Author to whom correspondence should be addressed.
Molbank 2009, 2009(4), M625; https://doi.org/10.3390/M625
Submission received: 22 September 2009 / Accepted: 7 October 2009 / Published: 7 October 2009

Abstract

:
Treatment of perchloro-7H-cyclopropano[a]acenaphthylene 1 with hydrazine hydrate in DMF at ca. 80 oC gives the new 3,4,5,6,7,8,9-heptachlorophenaleno[1,9-bc]pyrazole 2 in 69% yield. This compound is the first example of a phenalene fused pyrazole.

Graphical Abstract

Phenalene fused heteroles are rare. To date only phenaleno[1,9-bc]furan [1] and phenaleno[1,9-bc]thiophenes [2,3,4] have been reported. During a study on the chemistry of perchloro-7H-cyclopropano[a]acenaphthylene 1 a new phenalene fused heterole 2 was formed. Perchloro-7H-cyclopropano[a]acenaphthylene 1, which can be prepared from perchloroacenaphthylene and dichlorocarbene [5], was a valuable intermediate for the preparation of the stable perchlorophenalenyl radical [6].
The chemistry of cyclopropano[a]acenaphthylene 1 has been little explored; on treatment with mild Lewis acids halogen abstraction led to the formation of perchlorophenalenium cation [5,6]. During these studies traces of the perchlorophenalenone were observed. Interestingly, non substituted cyclopropano[a]acenaphthylene 3 irradiated with oxygen led to the formation of phenalenone 4 [7], which on treatment with hydrazine hydrate in ethylene glycol afforded the phenalenehydrazone 5 [8]. In light of this, we investigated the reaction of perchloro-7H-cyclopropano[a]acenaphthylene 1 with hydrazine hydrate, since in the presence of a peri halogen hydrazone formation should lead to rapid peri cyclisation to afford the fused pyrazole 2.
Molbank 2009 m625 i001
Treatment of perchloro-7H-cyclopropano[a]acenaphthylene 1 with excess hydrazine hydrate (30 equiv) in DMF at ca. 80 oC, led to the formation of a yellow precipitate identified as 3,4,5,6,7,8,9-heptachlorophenaleno[1,9-bc]pyrazole 2. The product gave a correct elemental analysis for a formula C13HCl7N2 and LREI mass spectroscopy afforded a parent ion of m/z 432 Da (100%) supporting the 7 × Cl isotope pattern [m/z 438 Da (16.5%), 436 (53), 434 (95), 432 (100), 430 (45)]. It was not possible to obtain a 1H NMR spectrum owing to the compounds poor solubility, however, a D2SO4 solution gave the 13C NMR spectrum which indicated a symmetrical system with only 8 sp2 carbon resonances between the range of δC 139.5 to 110.8 ppm in agreement with the proposed structure.

Experimental Section

Melting point was determined using a PolyTherm-A, Wagner & Munz, Kofler-Hotstage Microscope apparatus. IR spectrum was recorded on a Shimadzu FTIR-NIR Prestige-21 spectrometer with Pike Miracle Ge ATR accessory and strong, medium and weak peaks are represented by s, m and w respectively. 13C NMR spectrum was recorded on a Bruker Avance 300 NMR spectrometer (at 75 MHz). Deuterated chloroform was used for homonuclear lock and the signals are referenced to the deuterated solvent peak. Low resolution (EI) mass spectrum was recorded on a Shimadzu Q2010 GCMS with direct inlet probe. Microanalysis was performed at London Metropolitan University on a Perkin Elmer 2400 Series II CHN Analyzer.

3,4,5,6,7,8,9-Heptachlorophenaleno[1,9-bc]pyrazole (2)

To a stirred mixture of perchloro-7H-cyclopropano[a]acenaphthylene 1 (0.58 g, 1.14 mmol) in DMF (30 mL) at ca. 30 oC, was added hydrazine hydrate (1.65 mL, 34.2 mmol). The mixture was then warmed to ca. 80 oC for 1 h and then allowed to cool to ca. 20 oC. On cooling a yellow precipitate formed which was isolated by filtration, washed first with EtOH and then with DCM, and finally recrystallised to afford the title compound 2 (342 mg, 69%) as colourless cotton fibers, mp > 295 oC (from PhMe); (Found: C, 36.16; H, 0.20; N, 6.38. C13HCl7N2 requires: C, 36.03; H, 0.23; N, 6.46%); νmax/cm-1 3200w (NH), 1532m, 1506m, 1482m, 1477m, 1331w, 1244s, 1198w, 1111s, 1090s, 1063s, 1010m, 930s, 862m, 845m, 755m, 746s; δC (75 MHz, D2SO4/CDCl3) 139.5, 139.2, 136.4, 134.9, 122.8, 120.3, 118.1, 110.8; m/z (EI) 438 (16.5%), 436 (53), 434 (95), 432 (M+, 100), 430 (45), 400 (12), 398 (15), 396 (8), 373 (10), 372 (12), 371 (23), 370 (16), 369 (28), 367 (15), 362 (9), 335 (12), 333 (11), 327 (9), 301 (8), 300 (13), 299 (13), 298 (12), 297 (9), 255 (9), 228 (9), 217 (16), 216 (17), 185 (11), 184 (11), 181 (9), 167.4 (12), 166.35 (16), 156 (9), 149 (9).

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3

Acknowledgments

The authors wish to thank the Cyprus Research Promotion Foundation and the following organisations in Cyprus for generous donations of chemicals and glassware: the State General Laboratory, the Agricultural Research Institute and the Ministry of Agriculture. Furthermore we thank the A.G. Leventis Foundation for helping to establish the NMR facility in the University of Cyprus.

References and Notes

  1. Weeratunga, G.; Austrup, M.; Rodrigo, R. Preparation, properties, and some chemical reactions of phenaleno[1,9-bc]furan. J. Chem. Soc., Perkin Trans. 1 1988, 3169–3174. [Google Scholar]
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  5. Haddon, R.C.; Chichester, S.V.; Stein, S.M.; Marshall, J.H.; Mujsce, A.M. Perchloro-7H-cycloprop[a]acenaphthylene and the perchlorophenalenyl system. J. Org. Chem. 1987, 52, 711–712. [Google Scholar] [CrossRef]
  6. Koutentis, P.A.; Chen, Y.; Cao, Y.; Best, T.P.; Itkis, M.E.; Beer, L.; Oakley, R.T.; Cordes, A.W.; Brock, C.P.; Haddon, R.C. Perchlorophenalenyl radical. J. Am. Chem. Soc. 2001, 123, 3864–3871. [Google Scholar] [CrossRef] [PubMed]
  7. Pagni, R.M.; Burnett, M.N.; Hassaneen, H.M. The behavior of the singlet and triplet spin states of methylene-bridged 1,8-naphthoquinodimethane with O2. Tetrahedron 1982, 38, 843–851. [Google Scholar] [CrossRef]
  8. Lock, G.; Gergely, G. Über Perinaphthinden. Chem. Ber. 1944, 77, 461–465. [Google Scholar] [CrossRef]
  • Sample Availability: Samples of the compounds are available from the corresponding author.

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MDPI and ACS Style

Demetriadou, P.K.; Koutentis, P.A. 3,4,5,6,7,8,9-Heptachlorophenaleno[1,9-bc]pyrazole. Molbank 2009, 2009, M625. https://doi.org/10.3390/M625

AMA Style

Demetriadou PK, Koutentis PA. 3,4,5,6,7,8,9-Heptachlorophenaleno[1,9-bc]pyrazole. Molbank. 2009; 2009(4):M625. https://doi.org/10.3390/M625

Chicago/Turabian Style

Demetriadou, Polina K., and Panayiotis A. Koutentis. 2009. "3,4,5,6,7,8,9-Heptachlorophenaleno[1,9-bc]pyrazole" Molbank 2009, no. 4: M625. https://doi.org/10.3390/M625

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