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Synlett 2010(6): 885-888  
DOI: 10.1055/s-0029-1219546
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Perfluoroalkylated Carboranes by Cross-Metathesis of Allylcarboranes and Perfluoroalkylpropenes

Barbara Eignerováa,b, Zbyněk Janoušekc, Martin Dračínskýb, Martin Kotora*a,b
a Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Praha 2, Czech Republic
Fax: +420(221)951324; e-Mail: kotora@natur.cuni.cz;
b Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
c Institute of Inorganic Chemistry of the Academy of Science, v.v.i., Husinec-Ře˛ 1001, 250 68 Ře˛, Czech Republic
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Publication History

Received 21 December 2009
Publication Date:
23 February 2010 (online)

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Abstract

A ruthenium complex (Hoveyda-Grubbs second-generation) catalyzed cross-metathesis of allylcarboranes with perfluoroalkylpropenes under standard reaction conditions furnished perfluoroalkylated carboranes in good isolated yields (31-53%). The reaction proceeded with various carboranes and carborane sandwich complexes bearing the bridging allylthioether moiety. This method constitutes a simple and versatile procedure for the preparation of fluorophilic carboranes.

Key words

metathesis - perfluoroalkylation - ruthenium - carboranes - metallacarboranes

15

1-(5,5,6,6,7,7,8,8,9,9,10,10,10-Tridecafluorodecen-2-en-1-yl)-1,2-dicarbadodecaborane (7a)
A solution of 2 (90 mg, 0.50 mmol) and 1a (360 mg, 1.00 mmol), Hoveyda-Grubbs second-generation catalyst (32 mg, 0.05 mmol) in CH2Cl2 (4 mL) was stirred at 42 ˚C under Argon atmosphere for 4 h. Column chromatography on silica gel(heptane) afforded 7a (85 mg, 34%) as a colorless oil and the carborane homodimer 12a (20 mg, 23%) as a colorless oil.
Compound 7a: ¹H NMR (600 MHz CDCl3): δ = 1.59-2.81 (m, 10 H, B-H), 2.87 (br td, J 4 ′ ,F = 18.0 Hz, J 4 ′ ,3 ′ = 7.0 Hz, 2 H, H-4′), 2.99 (dm, J 1 ′ ,2 ′ = 7.4 Hz, 2 H, H-1′), 3.52 (br s, 1 H, H-2), 5.55 (dtm, J 3 ′ ,2 ′ = 15.3 Hz, J 3 ′ ,4 ′ = 7.0 Hz, 1 H, H-3′), 5.66 (dtt, J 2 ′ ,3 ′ = 15.3 Hz, J 2 ′ ,1 ′ = 7.4 Hz, J 2 ′ ,4 ′ = 1.1 Hz, 1 H, H-2′). ¹³C NMR (150.9 MHz, CDCl3): δ = 34.77 (t, J 4 ′ ,F = 22.8 Hz, CH2-4′), 40.52 (CH2-1′), 59.69 (CH-2), 73.08 (C-1), 123.21 (t, J 3 ′ ,F = 4.4 Hz, CH-3′), 131.40 (CH-2′). ¹¹B NMR (160.4 MHz, CDCl3, BF3˙OEt2): δ = -1.35 (d, J = 150 Hz, 1 B, B-9), -4.70 (d, J = 150 Hz, 1 B, B-12), -8.23 (d, J = 153 Hz, 2 B, B-8 and B-10), -10.40 (d, J = 160 Hz, 2 B, B-4 and B-5), -11.80 (d, J =  ca. 100 Hz, 2 B, B-7 and B-11), -12.10 (d, J = 155 Hz, 2 B, B-3 and B-6). ¹9F NMR (470.3 MHz, CDCl3, C6F6): δ = -76.99 (m, 3 F), -109.17 (m, 2 F), -118.11 (m, 2 F), -119.07 (m, 2 F), -119.21 (m, 2 F),
-122.33 (m, 2 F). IR (CHCl3): ν = 3068, 2929, 2597, 1362, 1243, 1020, 997 cm-¹. ESI-MS: m/z (%) = 518 (8) [M+], 495 (100), 475 (45), 435 (17), 416 (5). ESI-HRMS: m/z calcd for C12H16B10F13 [M+ - H]: 517.1980; found: 517.1987. R f  = 0.63 (hexane).
Compound 12a: ¹H NMR (600 MHz, CDCl3): δ = 3.15 (m, 4 H, H-1′), 4.61 (br s, 2 H, H-2), 5.66 (m, 2 H, H-2′). ¹³C NMR (150.9 MHz, CDCl3): δ = 40.52 (2 C, CH2-1′), 62.71 (2 C, CH-2), 75.68 (2 C, C-1), 130.45 (2 C, CH-2′). ¹¹B NMR (160.4 MHz, CDCl3, BF3˙OEt2): δ = -2.07 (d, J = 151 Hz, 2 B, B-9), -5.21 (d, J = 150 Hz, 2 B, B-12), -8.71 (d, J = 153 Hz, 4 B, B-8 and B-10), -10.59 (d, J = 160 Hz, 4 B, B-4 and B-5), -11.41 (d, J = ca. 110 Hz, 4 B, B-7 and B-11), -12.21 (d, J = 158 Hz, 4 B, B-3 and B-6). IR (CHCl3): ν = 3067, 2929, 2598, 1433, 1018, 979 cm-¹. MS (EI): m/z (%) = 344 (7) [M+], 181 (47), 153 (15). HRMS (EI): m/z calcd for C8H28B20 [M+]: 344.4052; found: 344.4068. R f  = 0.60 (hexane).