Mendeleev Commun., 2015, 25, 219–220 – 219 – Mendeleev Communications © 2015 Mendeleev Communications. Published by ELSEVIER B.V. on behalf of the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences. The phenanthrene moiety is a part of phenanthroindolizidine alkaloids (tylophorine, deoxytylophorine, tylocrebrine, antofine) known for their high cytotoxic activity. 1,2 Phenanthrene-9-car- boxylic acid and its methyl ester are used in the synthesis of antimalarial agents 3 and compounds active against the tobacco mosaic virus. 4 Phenanthrene derivatives are applied to devise photoconducting, photochemical, electroluminescent and fluore- scent materials. 5–7 Direct synthesis of phenanthrene-9-carboxylic acid by carboxylation of phenanthrene with carbon dioxide (3 MPa) in the presence of Lewis acids, AlBr 3 , and R 3 SiX is known. 8,9 In this study, we found that phenanthrene-9-carboxylic esters 1a–d can be accessed by the reaction of phenanthrene (phen) with CCl 4 and alkanols in the presence of iron catalysts such as FeBr 2 , FeCl 3 ·6H 2 O and Fe(acac) 3 . Among these, iron(III) acetylacetonate Fe(acac) 3 is the catalyst of choice. The conversion of phenanthrene in the cases of FeBr 2 or FeCl 3 ·6H 2 O does not exceed 48%. The optimization was carried out on the example of phenan- threne, n-propanol, CCl 4 and Fe(acac) 3 . The reaction was carried out at the following catalyst and reactant molar ratios: [Fe(acac) 3 ] : [phen] : [PrOH] : [CCl 4 ] = 1–15 : 100 : 500–1000 : 100–1000, at 130–140 °C, and over a period of 6 h. The highest yield of product 1c (96%) was achieved under the following conditions: 130 °C, 6 h, [Fe(acac) 3 ] : [phen] : [PrOH] : [CCl 4 ] = 1 : 10 : 100 : 100 (Table 1, entry 3). † The reaction is general (Scheme 1): under the optimal con- ditions, it can proceed, apart from n-propanol, with methanol, ethanol and n-butanol (Table 1). Synthesis of phenanthrene-9-carboxylic esters by the iron-catalyzed reaction of phenanthrene with CCl 4 and alcohols Ravil I. Khusnutdinov,* Alfiya R. Bayguzina, Kirill Yu. Denisov and Usein M. Dzhemilev Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, 450075 Ufa, Russian Federation. Fax: +7 347 284 2750; e-mail: KhusnutdinovRI47@gmail.com 05.021 DOI: 10.1016/j.mencom.2015. Alkyl phenanthrene-9-carboxylates were synthesized in 74–96% yields by the iron-catalyzed reaction of phenanthrene with tetra- chloromethane and alkanols. Synthesis of alkyl phenanthrene-9-carboxylates by the reaction of Table 1 phenanthrene with CCl 4 and alcohols in the presence of Fe(acac) 3 . a Entry ROH Product Yield (%) 1 Methanol 1a 74 2 Ethanol 1b 80 3 n-Propanol 1c 96 4 n-Butanol 1d 85 a Reaction conditions: 130 °C, 6 h, [Fe(acac) 3 ] : [phen] : [ROH] : [CCl 4 ] = = 1 : 10 : 100 : 100. † Synthesis of compounds 1a–d (general procedure). The reactions were carried out in a 10-ml glass tube placed in a stainless-steel 17 ml micro autoclave with continuous stirring and controlled heating. The tube was charged under argon with Fe(acac) 3 (0.059 mmol), phenanthrene (0.59 mmol), tetrachloromethane (5.9 mmol), and appropriate alkanol (5.9 mmol). The sealed tube was placed into an autoclave, the autoclave was tightly closed and heated at 130 °C for 6 h with continuous stirring. After completion of the reaction, the autoclave was cooled to room temperature, the tube was opened, and the reaction mixture was filtered through a paper filter and refluxed with absorbent carbon. The volatiles were distilled off. The target ester 1 was separated from remaining phenanthrene by column chromatography on silica gel using a light petroleum : ethyl acetate (5:1) mixture as the eluent (column, l = 21 cm, d = 1.2 cm). The physicochemical and spectral characteristics of com- pounds 1a,b correspond to published data. 10–13 n-Propyl phenanthrene-9-carboxylate 1c. White crystals, yield 96%, mp 46–47 °C. 1 H NMR (400.13 MHz, CDCl 3 ) d: 7.96 (d, 1H, C 1 H, J 8 Hz), 7.71 (m, 1H, C 2 H), 7.63 (t, 1H, C 3 H, J 8 Hz), 8.65 (d, 1H, C 4 H, J 8Hz), 8.71 (m, 1H, C 5 H), 7.71 (m, 1H, C 6 H), 7.71 (m, 1H, C 7 H), 8.98 (m, 1H, C 8 H), 8.48 (s, 1H, C 10 H), 4.45 (t, 2 H, CH 2 ), 1.93 (m, 2 H, CH 2 ), 1.15 (t, 3 H, Me). 13 C NMR (100.62 MHz, CDCl 3 ) d: 129.91 (C 1 ), 128.81 (C 2 ), 126.98 (C 3 ), 122.64 (C 4 ), 130.10 (C 4a ), 130.70 (C 4b ), 122.83 (C 5 ), 126.87 (C 6 ), 127.37 (C 7 ), 126.67 (C 8 ), 126.60 (C 8a ), 132.10 (C 9 ), 132.13 (C 10 ), 129.12 (C 10a ), 167.74 (COO), 66.84 (CH 2 Et), 22.26 (CH 2 Me), 10.73 (Me). MS (EI, 70 eV), m/z (%): 264 [M] + (93), 222 (90), 205 (100), 177 (70), 151 (20), 88 (35). Found (%): C, 81.68; H, 6.16; O, 12.16. Calc. for C 18 H 16 O 2 (%): C, 81.79; H, 6.10; O, 12.11. n-Butyl phenanthrene-9-carboxylate 1d. White crystals, yield 85%, mp 56–57 °C. 1 H NMR (400.13 MHz, CDCl 3 ) d: 7.99 (d, 1H, C 1 H, J 8 Hz), 7.69 (t, 1H, C 2 H, J 8 Hz), 7.76 (t, 1H, C 3 H, J 8 Hz), 8.70 (d, 1H, C 4 H, J 8 Hz), 8.74 (m, 1H, C 5 H), 7.71 (m, 1H, C 6 H), 7.71 (m, 1H, C 7 H), 8.94 (m, 1H, C 8 H), 8.47 (s, 1H, C 10 H), 4.49 (t, 2 H, CH 2 ), 1.89 (m, 2 H, CH 2 ), 1.57 (m, 2 H, CH 2 ), 1.06 (t, 3 H, Me). 13 C NMR (100.62 MHz, CDCl 3 ) d: 129.92 (C 1 ), 127.82 (C 2 ), 126.99 (C 3 ), 122.64 (C 4 ), 130.12 (C 4a ), 130.70 (C 4b ), 122.81 (C 5 ), 127.36 (C 6 ), 126.88 (C 7 ), 126.65 (C 8 ), 126.69 (C 8a ), 134.42 (C 9 ), 132.08 (C 10 ), 129.10 (C 10a ), 167.77 (COO), 65.12 (CH 2 Pr), 30.89 (CH 2 Et), 19.41 (CH 2 Me), 13.83 (Me). MS (EI, 70 eV), m/z (%): 278 [M] + (60), 222 (100), 205 (65), 177 (70), 151 (20), 88 (10). Found (%): C, 81.89; H, 6.66; O, 11.45. Calc. for C 19 H 18 O 2 (%): C, 81.98; H, 6.52; O, 11.50. CO 2 R CCl 3 Fe(acac) 3 + CCl 4 – 3 HCl – ROR – HCl – Fe(acac) 3 ROH + HCl RCl + H 2 O [Fe(acac) 3 Cl] [CCl 3 ] [Fe(acac) 3 Cl] [CCl 3 ] 1a R = Me 1b R = Et 1c R = Pr 1d R = Bu 2 3 ROH Scheme 1