Synlett, Table of Contents Synlett 2023; 34(11): 1275-1279DOI: 10.1055/a-2024-4675 letter Synthesis of γ-Aryl Medium-Sized Cyclic Enones by a Domino 4π-Electrocyclic Reaction/Heck–Matsuda Arylation Sequence at Ambient Temperature Authors Tomohiro Ito Nao Takeuchi Yousuke Yamaoka Hiroshi Takikawa Kiyosei Takasu∗ Recommend Article Abstract Buy Article(opens in new window) All articles of this category(opens in new window) Abstract Bicyclo[n.2.0]cyclobutenes were transformed into medium-sized cyclic γ-aryl enones by using a cationic aryl palladium(II) species generated from a diazonium salt. The reaction proceeded at ambient temperature by capturing the cis,trans-cycloalkadiene intermediate generated through a conrotatory 4π-electrocyclic ring-opening reaction, followed by a Heck–Matsuda arylation sequence. Optically pure γ-aryl enones were also synthesized by using a point-to-planar-to-point chirality-transfer process. Key words Key wordsmedium-sized rings - electrocyclic reaction - Heck–Matsuda reaction - arylation - cyclobutenes - chirality transfer Full Text References References and Notes 1 Current address: School of Pharmacy, Hyogo University of Health Sciences, Kobe 650–8530, Japan. For selected reviews, see: 2a Ishmuratov GY, Kharisov RY, Latypova ER, Talipov RF. Chem. Nat. Compd. 2006; 42: 367 2b Conti M. Anticancer Drugs 2006; 17: 1017 2c Das M, Manna K. Curr. Bioact. Compd. 2015; 11: 239 2d Wang Z. Org. Chem. Front. 2020; 7: 3815 3a Chen X, Liu X, Mohr JT. J. Am. Chem. Soc. 2016; 138: 6364 3b Liu X, Chen X, Mohr JT. Org. Lett. 2016; 18: 3182 3c Nambu H, Tamura T, Yakura T. J. Org. Chem. 2019; 84: 15990 3d Christoffers J, Mann A. Eur. J. Org. Chem. 2000; 2000: 1977 3e Hayashi Y, Suga Y, Umekubo N. Org. Lett. 2020; 22: 8603 3f Yuan Q, Prater MB, Sigman MS. Adv. Synth. Catal. 2020; 362: 326 4a Hyde AM, Buchwald SL. Angew. Chem. Int. Ed. 2008; 47: 177 4b Huang DS, Hartwig JF. Angew. Chem. Int. 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Soc. 1984; 106: 1341 For attempts at 4π-electrocyclic reactions of bicyclo[4.2.0]octenes at higher temperatures, see: 9a McConaghy JS. Jr, Bloomfield JJ. Tetrahedron Lett. 1969; 10: 3719 9b Clark RD, Untch KG. J. Org. Chem. 1979; 44: 248 9c Wang X.-N, Krenske EH, Johnston RC, Houk KN, Hsung RP. J. Am. Chem. Soc. 2014; 136: 9802 9d Ralph MJ, Harrowven DC, Gaulier S, Ng S, Booker-Milburn KI. Angew. Chem. Int. Ed. 2014; 54: 1527 9e Murakami M, Matsuda T. In Comprehensive Organic Synthesis, 2nd ed., Vol. 5, Chap. 5.16. Knochel P. Elsevier; Amsterdam: 2014: 732 10a Kikukawa K, Matsuda T. Chem. Lett. 1977; 6: 159 10b Taylor JG, Moro AV, Correia CR. D. Eur. J. Org. Chem. 2011; 2011: 1403 11a van Dijk T, Slootweg JC, Lammertsma K. Org. Biomol. Chem. 2017; 15: 10134 11b Wang H, Xu Q, Shen S, Yu S. J. Org. Chem. 2017; 82: 770 12 Petterson RC, Bennett JT, Lankin DC, Lin GW, Mykytka JP, Troendle TG. J. Org. Chem. 1974; 39: 1841 13 CCDC 2234158 contains the supplementary crystallographic data for compound 5ag. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures 14 Shea KJ, Kim J.-S. J. Am. Chem. Soc. 1992; 114: 3044 15 A related transformation of an η3-1-hydroxyallylpalladium complex into an η2-enone has been reported; see: Ogoshi S, Morita M, Kurosawa H. J. Am. Chem. Soc. 2003; 125: 9020 16 The generation of siloxyallylpalladium species from enones, which corresponds to the retro process of our proposed desilylative reductive elimination, has been reported; see: Ogoshi S, Tomiyasu S, Morita M, Kurosawa H. J. Am. Chem. Soc. 2002; 124: 11598 17 γ-Arylcyclooctenones 5; General Procedure (Conditions A) A test tube was charged with Pd(OAc)2 (0.014 mmol) together with the appropriate diazonium tetrafluoroborate 6 (0.41 mmol) and cyclobutene 1 (0.27 mmol). Ag2CO3 (0.54 mmol) and MeCN (0.20 M) were added to the mixture under argon, and the resulting slurry was vigorously stirred for 38 h. Et2O was added to the mixture, which was then stirred for a further 15 min. The resulting slurry was filtered through Celite, and the filter cake was washed with Et2O. The filtrate was concentrated under reduced pressure to remove the solvent and the residue was dissolved in Et2O. Silica gel was added to the solution and the mixture was stirred for 30 min. The slurry was then filtered and the filter cake was washed with Et2O. Concentration of the filtrate gave a crude product that was dissolved in CHCl3 and purified by column chromatography (silica gel, hexane–EtOAc or hexane–EtOAc). Methyl 3-(4-Methylphenyl)-8-oxocyclooct-1-ene-1-carboxylate (5aa) Colorless oil; yield: 67 mg (90%). Rf = 0.38 (hexane–Et2O, 4:1). IR (ATR): 2928, 2855, 1724, 1697, 1636, 1512, 1454, 1435, 1254, 1223, 1107, 1065 cm–1. 1H NMR (500 MHz, CDCl3): δ = 7.19 (d, J = 5.2 Hz, 1 H), 7.11 (d, J = 7.9 Hz, 2 H), 7.02 (d, J = 11.0 Hz, 2 H), 3.74 (s, 3 H), 3.49 (ddd, J = 10.7, 2.4, 2.4 Hz, 1 H), 2.67 (ddd, J = 16.0, 3.3, 3.3 Hz, 1 H), 2.58 (ddd, J = 14.0, 11.0, 3.0 Hz, 1 H), 2.31 (s, 3 H), 2.10–1.97 (m, 1 H), 1.97–1.86 (m, 2 H), 1.86–1.77 (m, 1 H), 1.77–1.62 (m, 2 H). 13C NMR (126 MHz, CDCl3): δ = 209.2, 164.4, 147.9, 139.4, 136.5, 130.5, 129.4, 127.5, 52.3, 46.9, 44.0, 30.7, 27.9, 22.1, 20.9. HRMS (ESI): m/z [M + H]+ calcd for C17H21O3: 273.1485; found: 273.1484. Supplementary Material Supplementary Material Supporting Information (PDF) (opens in new window)
