An Easy and Multigram-Scale Synthesis of Pillar[5]quinone by the Hypervalent Iodine Oxidation of 1,4-Dimethoxypillar[5]arene

Dedicated to Prof. K. N. Ganesh on the occasion of his 60^th birthday

Abstract

Pillar[5]quinone (P[5]Q), a potential molecule for anion recognition and supramolecular host-guest chemistry, has not as yet been used for practical purposes, presumably due to the synthetic difficulties in obtaining it in large amounts. Herein, we reveal an easy-to-operate and chromatography-free synthetic strategy that can furnish P[5]Q on a multigram scale; its success relies on the utility of hypervalent iodine, generated in situ from Oxone/iodobenzene, as an efficient oxidant. Pillar[5]quinone was obtained in multigram quantities by oxidation of 1,4-dimethoxypillar[5]arene with Oxone/iodobenzene and simple purification by crystallization from 1,1,2,2-tetrachloroethane, thus opening up the opportunity to explore the properties of this interesting macrocyclic quinone.

Key words

supramolecular chemistry - macromolecules - pillar­arenes - hypervalent iodine oxidation

• References

• 1 Ogoshi T, Kanai S, Fujinami S, Yamagishi T, Nakamoto Y. J. Am. Chem. Soc. 2008; 130: 5022
• 2a Cragg PJ, Sharma K. Chem. Soc. Rev. 2012; 41: 597
• 2b Xue M, Yang Y, Chi X, Zhang Z, Huang F. Acc. Chem. Res. 2012; 45: 1294
• 3 Strutt NJ, Forgan RS, Spruell JM, Botros YY, Stoddart JF. J. Am. Chem. Soc. 2011; 133: 5668
• 4 Ogoshi T, Shiga R, Hashizume M, Yamagishi T. Chem. Commun. 2011; 47: 6927
• 5 Strutt NL, Zhang H, Giesener MA, Lei J, Stoddart JF. Chem. Commun. 2012; 48: 1647
• 6 Lao K.-N, Yu C.-I. J. Comput. Chem. 2011; 32: 2716
• 7 Yu G, Zhang Z, Han C, Xue M, Zhou Q, Huang F. Chem. Commun. 2012; 48: 2958
• 8 Si W, Hu X.-B, Liu X.-H, Fan R, Chen Z, Weng L, Hou J.-L. Tetrahedron Lett. 2011; 52: 2484
• 9 Aoki T, Ogoshi T, Yamagishi T. Chem. Lett. 2011; 40: 795
• 10 Ogoshi T, Shiga R, Yamagishi T. J. Am. Chem. Soc. 2012; 134: 4577
• 11 Zhang Z, Xia B, Han C, Yu Y, Huang F. Org. Lett. 2010; 12: 3285
• 12 Han C, Ma F, Zhang Z, Xia B, Yu Y, Huang F. Org. Lett. 2010; 12: 4360
• 13a Li C, Zhao L, Li J, Ding X, Chen S, Zhang Q, Yu Y, Jia X. Chem. Commun. 2010; 46: 9016
• 13b Yu G, Han C, Zhang Z, Chen J, Yan X, Zheng B, Liu S, Huang F. J. Am. Chem. Soc. 2012; 134: 8711
• 13c Yu G, Xue M, Zhang Z, Li J, Han C, Huang F. J. Am. Chem. Soc. 2012; 134: 13348
• 14 Zhang Z, Luo Y, Chen J, Dong S, Yu Y, Ma Z, Huang F. Angew. Chem. Int. Ed. 2011; 50: 1397

The Isaacs group pioneered in developing cucurbituril-based molecular sensors. See;
• 15a Kim C, Agasti SS, Zhu Z, Isaacs L, Rotello VM. Nature Chem. 2010; 2: 962
• 15b Lagona J, Mukhopadhyay P, Chakrabarti S, Isaacs L. Angew. Chem. Int. Ed. 2005; 44: 4844
• 16 Gomez-Kaifer M, Reddy PA, Gutsche CD, Echegoyen L. J. Am. Chem. Soc. 1994; 116: 3580
• 17 Pochorovski I, Boudon C, Gisselbrecht J.-P, Ebert M.-O, Schweizer WB, Diederich F. Angew. Chem. Int. Ed. 2012; 51: 262
• 18 P[5]Q was found to be yellow-colored fluffy microcrystalline material when freshly crystallized from 1,1,2,2-tetrachloroethane (see photograph, Figure 1).
• 19 Ogoshi T, Aoki T, Kitajima K, Fujinama S, Yamagishi TA, Nakamoto Y. J. Org. Chem. 2011; 76: 328
• 20 Cao D, Kou Y, Liang J, Chen Z, Wang L, Meier H. Angew. Chem. Int. Ed. 2009; 48: 9721
• 21a Yakura T, Yamauchi Y, Tian Y, Omoto M. Chem. Pharm. Bull. 2008; 56: 1632
• 21b Yakura T, Konishi T. Synlett 2007; 765
• 21c Yusubov MS, Nemykin VN, Zhdankin VV. Tetrahedron 2010; 66: 5745
• 22 We have used 1,4-dimethoxypillar[5]arene, crystallized from boiling chlorobenzene. We have found that chlorobenzene is a very good solvent for crystallizing large quantities of 1,4-dimethoxypillar[5]arene, since a substantial amount of 1,4-dimethoxypillar[5]arene can be dissolved in boiling chlorobenzene, from which it crystallizes out on cooling.
• 23 It is our observation that efficient stirring is essential for the success of the oxidative de-aromatization reaction, since the starting materials have been always found to remain as a suspension due to its poor solubility in the reaction solvent. In fact, trials using 1 equiv of iodobenzene on a smaller scale with 1 day reaction time did not have appreciable effect on the product yield.
• 24 We have observed that if MeOH washing is avoided, about 2.5 equiv of 1,1,2,2-tetrachloroethane is adsorbed onto P[5]Q, as evident from its ¹H NMR integration (see ¹H NMR spectrum). However, MeOH washing helps in removing adsorbed 1,1,2,2-tetrachloroethane.
• 25 TLC pattern, ¹H NMR, and mass spectra suggest that the recovered off-white compound is the starting material (1,4-dimethoxypillar[5]arene).