Abstract
The phototransformation of some 2-(3-methoxyphenyl)-4H-chromen-4-ones bearing a propynyloxy moiety at the 3-position has been described. On photolysis with pyrex-filtered UV light from a Hg lamp (125 W), these chromenones produced a major amount of 5-ethynyl-2-methoxy-6-oxa-benzo[5,6-c]xanthen-7-ones consisting of an exotic tetracyclic scaffold. These photoproducts have been envisioned to be produced through regioselective ring closure at the 6’-position of the 2-(3’-methoxy)phenyl moiety of the initially formed 1,4-biradical via a γ-H abstraction mechanism. No product whatsoever was observed through ring closure at the 2’-position. This behaviour has been found to be in accordance with the directive influence observed in free radical aromatic substitutions. This regioselective photocyclisation is further supported by calculations made from 3D structures (MM2 program). In addition, during the irradiation of these substrates, 2-(3-methoxyphenyl)-4H-chromen-4-ones were also realised through dealkoxylation. The structures of the substrates and photoproduct(s) have been determined by their spectroscopic (IR, NMR, mass spectrometry) studies.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Photochemistry in Organic Synthesis, Carbonyl compounds: H-abstractions, ed. J. D. Coyle, Royal Soc. Chem., London, 1986, pp. 61–69.>
P. J. Wagner, 1,5-Biradicals and 5-membered rings generated by d-Hydrogen abstraction in photoexcited ketones, Acc. Chem. Res., 1989, 22, 83–91.
H. A. J. Carless and S. Mwesigye-Kibende, Intramolecular hydrogen abstraction in ketone photochemistry: the first examples of zeta-hydrogen abstraction, J. Chem. Soc., Chem. Commun., 1987, 1673–1674.
G. A. Kraus, W. Zhang and Y. Wu, 1,12-Hydrogen atom abstraction reactions of a-keto esters, Chem. Commun., 1996, 2439–2440.
G. A. Kraus and Y. S. Wu, 1,5- and 1,9-Hydrogen atom abstractions. Photochemical strategies for radical cyclizations, J. Am. Chem. Soc., 1992, 114, 8705–8707.
K. K. Park, I. K. Han and J. W. Park, Photochemical synthesis of cyclophanes containing tethered benzofuran rings, J. Org. Chem., 2001, 66, 6800–6802.
T. Sumathi and K. K. Balasubramanian, A photochemical route to 2-alkenyl and 2-ethynylbenzo-furans, Tetrahedron Lett., 1990, 31, 3775–3778.
T. Sumathi and K. K. Balasubramanian, A photochemical entry to spirobenzofurans, Tetrahedron Lett., 1992, 33, 2213–2226.
K. R. Henery-Logan and C. G. Chen, Synthesis of oxygen analogs of the penicillins. I. Photocyclization of 2-oxoamides to 3-carbomethoxy-6-hydroxypenams, Tetrahedron Lett., 1973, 14, 1103–1104.
M. J. Jorgenson and S. Patumtevapibal, Ring size and conformational effects on photodeconjugation of cycloalkylidene esters, Tetrahedron Lett., 1970, 11, 489–492.
N. C. Yang and C. Rivas, A new photochemical primary process. Enolization of o-substituted benzophenones, J. Am. Chem. Soc., 1961, 83, 2213.
V. B. Rao, S. Wolff and W. C. Agosta, Novel cyclisation of type-II biradical from alpha, beta and acetylenic ketones, J. Am. Chem. Soc., 1985, 107, 521–522.
W. C. Agosta, R. A. Caldwell, J. Jay, L. J. Johnston, B. R. Venepalli, J. C. Scaiano, M. Singh and S. Wolff, Photochemistry of 4,4-dimethyl-1-mesityl-2-pentyn-1-one, J. Am. Chem. Soc., 1987, 109, 3050–3057.
W. C. Agosta and P. Margaretha, Exploring the cyclisation of propargyl 1,4-biradical, Acc. Chem. Res., 1996, 29, 179.
P. Jindal, R. Bhatia, S. Khullar, S. K. Mandal and R. C. Kamboj, One-shot photochemical synthesis of 5-(thiophen-3-yl)pyrano[2,3-c]chromen-2(3H)-ones from 3-propynyloxy-chromenones: A case of an intramolecular Paterno–Buchi reaction, Photochem. Photobiol. Sci., 2014, 13, 488–491, DOI: 10.1039/C3PP50396H.
R. C. Kamboj, P. Jindal, D. Kumar, S. Khullar and S. K. Mandal, Synthesis of some benzofurooxepines’ derivatives via, [3+2] cycloaddition of epoxide with tethered alkyne: A photochemical approach, J. Photochem. Photobiol., A, 2014, 278, 31–38, DOI: 10.1016/j.jphotochem.2013.12.017.
P. Jindal, R. Bhatia, S. Khullar, S. K. Mandal and R. C. Kamboj, A green synthesis of thieno[2,3-c]xanthen-6-ones through the tandem photochemical sigmatropic shifts and cyclisation, Green Chem. Lett. Rev., 2014, 7, 126–130.
M. L. Cardona, I. Fernández, J. R. Pedro and A. Serrano, Xanthones from Hypericum reflexum, Phytochemistry, 1990, 29, 3003–3006.
S. M. Menchen, S. C. Benson, J. Y. L. Lam, W. Zhen, D. Sun, B. B. Rosenblum, S. H. Khan and M. Taing, Sulfonated diaryl rhodamine dyes, U. S. Patent, US6583168, 2003, Chem. Abstr., 2003, 139, 54287f.
G. A. Reynolds, S. A. Tuccio, O. G. Peterson and D. P. Specht, Ger Offen DE 2, 109040, 1971, Chem. Abstr., 1971, 71, 81334c.
R. C. Hunter and T. J. Beveridge, Application of a pH-sensitive fluoroprobe (C-SNARF-4) for pH microenvironment analysis in Pseudomonas aeruginosa biofilms, Appl. Environ. Microbiol., 2005, 71, 2501–2510.
M. Ahmad, T. A. King, D. K. Ko, B. H. Cha and J. Lee, Performance and photostability of xanthene and pyrromethene laser dyes in sol–gel phases, J. Phys. D: Appl. Phys., 2002, 35, 1473–1476.
C. S. Konkoy, D. B. Fick, S. X. Cai, N. C. Lan and J. F. W. Keana, Int. Appl, Wo, 2000, 75, 123; Chem. Abstr., 2001, 134, 29313a.
R. A. Finnegan, G. M. Stephani, G. Ganguli and S. K. Bhattacharya, Occurrence of mangiferin in Hiptage madablota geartn, J. Pharm. Sci., 1968, 57, 1039–1040.
P. Da Re, V. Mancini, E. Toth and L. Cima, Xanthones derivatives with centrally stimulating and analeptic activities, Arzneim. Forsch., 1968, 18, 718–720.
P. Da Re, L. Sagramora, V. Mancini, P. Valenti and L. Cima, Central nervous system stimulants of the xanthone series, J. Med. Chem., 1970, 13, 527–531.
B. C. Baquley and L. M. Ching, Immunomodulatory actions of xanthenone anticancer agents, BioDrugs, 1997, 8, 119–127.
K. Asres, F. Bucar, T. Karting, M. Witvrouw, C. Panne Couque, E. De Clercq, Antiviral activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) of ethnobotanically selected Ethiopian medicinal plants, Phytother. Res., 2001, 15, 62–69.
M. M. Pinto, M. E. Sousa, M. S. J. Nascimento, Xanthone Derivatives: New insights in Biological Activities, Curr. Med. Chem., 2005, 12, 2517–2538.
R. C. Kamboj, U. Berar, S. Berar, M. Thakur, S. C. Gupta, R. C. Kamboj, U. Berar, S. Berar, M. Thakur and S. C. Gupta, Photoreorganisation of some 3-alkoxy-2-(alkoxyphenyl) chromones, Indian J. Chem., 2009, 48B, 685–691.
R. C. Kamboj, U. Berar, S. Berar, Z. N. Siddiqui and S. C. Gupta, Photochemistry of 3-alkoxychromones: photocyclisation of 2-aryl-6-chloro-3-(thiophen-2-yl)methoxychromones, J. Braz. Chem. Soc., 2010, 21, 270–278.
R. C. Kamboj, U. Berar, S. Berar, M. Thakur, R. Arora and S. C. Gupta, Photochemistry of 3-alkoxychromones I — Photocyclisation of 6-chloro-3-alkoxy-2-(furan-3-yl)-4H-chromen-4-ones, Can. J. Chem., 2009, 87, 422–429.
T. Oyamada, A new general method for the synthesis of flavonol derivatives, J. Chem. Soc. Jpn., 1934, 55, 1256–1260.
J. Algar and J. P. Flynn, A new method for the synthesis of flavonols, Proc. R. Ir. Acad., Sect. B, 1934, 42, 1–8.
R. C. Kamboj, P. Jindal, R. Arora, A. Chaudhary, S. Khullar and S. K. Mandal, Some novel phototransformations in 4H-chromen-4-ones: Photolysis of 3-propynyloxy-2-(thiophen-3-yl)-4H-chromen-4-ones, Chem. Sci. Rev. Lett., 2014, 3, 231–246.
R. Perez-Ruiz, S. Gil and M. A. Miranda, Stereodifferentiation in the photochemical cycloreversion of diastereomeric methoxynaphthalene-oxetane dyads, J. Org. Chem., 2005, 70, 1376–1381.
R. Raviola, D. Ravelli, S. Protti, A. Albini and M. Fagnoni, Conditions and edges for the photochemical generation of short-lived aryl cations: A computational approach, Synlett, 2015, 471–478.
J. F. Bunnet and J. K. Kim, Evidence for a radical mechanism of aromatic nucleophilic substitution, J. Am. Chem. Soc., 1970, 92, 7463.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Khanna, R., Dalal, A., Kumar, R. et al. Phototransformation of 3-alkoxychromenones: regioselective photocyclisation and dealkoxylation. Photochem Photobiol Sci 14, 2195–2202 (2015). https://doi.org/10.1039/c5pp00318k
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1039/c5pp00318k