Dalton Transactions
Paper
General procedure for a Mitsunobu reaction at 4 with 1-HO– 100148835). The authors thank Carlotta Taddei for experi-
CH2–C2B10H11.20b The reactions were carried out using either mental support.
PBu3/DIAD (diisopropyl azodicarboxylate) in THF or PBu3/
TMAD (tetramethyl azodicarboxamide) in toluene. 1-Hydroxy-
methyl-1,2-dicarba-closo-dodecaborane(12) (2 eq.) was added
to a solution of 4 (1 eq.) and PBu3 (2 eq.). At 0 °C, DIAD or
Notes and references
TMAD (2 eq.) was added and the reaction mixture was stirred
at 40 °C overnight. The reactions were monitored by TLC.
Sodium 7-{[5-methoxy-2-methyl-3-(methoxycarbonyl-methyl)-
1H-indolyl] methyl}-7,8-dicarba-nido-dodecahydro-undecabo-
rate(−1) (3). NaH (60% suspension in mineral oil; 0.09 g,
2.2 mmol, 2.6 eq.) was added to a solution of 4 (0.49 g,
2.1 mmol, 2.5 eq.) in CH3CN (25 mL) at 0 °C. After stirring for
20 min at 0 °C the suspension was added dropwise to a solu-
tion of 1-bromomethyl-1,2-dicarba-closo-dodecaborane(12)
(0.20 g, 0.8 mmol, 1.0 eq.) in CH3CN (15 mL) at 0 °C. After stir-
ring at room temperature overnight the reaction was quenched
by addition of water (10 mL). The product was extracted with
EtOAc and purified by column chromatography (n-hexane–
EtOAc 6 : 1 → 1 : 10) yielding an orange oil from which colour-
less crystals crystallised over several weeks at room tempera-
ture. The crystals were washed with CH2Cl2, dissolved in
CH3OH and filtered to remove any methyl borates and the
product was precipitated with CH2Cl2 to yield 3 as a pale beige
solid with moderate water solubility (0.11 g, 34%): mp: 190 °C;
1H NMR (400 MHz, CD3OD): δ = −3.2 to −2.6 (br, 1H, endo-H),
0.3−2.5 (br, 9H, B9H9), 1.61 (br s, 1H, CclusterH), 2.36 (s, 3H,
CH3), 3.64 (s, 3H, COOCH3), 3.69 (s, 2H, OOC-CH2), 3.81 (s,
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2
2
3H, OCH3), 4.06 (d, JH,H = 16 Hz, 1H, N-CH2), 4.36 (d, JH,H
16 Hz, 1H, N-CH2), 6.72 (dd, JH,H = 8 Hz, JH,H = 2 Hz, 1H,
=
3
4
4
3
CHind), 6.92 (d, JH,H = 2 Hz, 1H, CHind), 7.22 (d, JH,H = 8 Hz,
1H, CHind) ppm; 11B (128 MHz, CD3OD): δ = −36.7 (d, JB,H
=
=
1
141 Hz, 1B), −33.3 (dd, 1JB,H = 129 Hz, 38 Hz, 1B), −22.8 (d, 1JB,H
1
1
145 Hz, 1B), −19.2 (d, JB,H = 137 Hz, 1B), −18.7 (d, JB,H = 159
Hz, 1B), −17.6 (d, JB,H = 138 Hz, 1B), −15.0 (d, JB,H = 148 Hz,
1
1
1
1
1B), −11.1 (d, JB,H = 133 Hz, 1B), −10.5 (d, JB,H = 126 Hz, 1B)
ppm; 13C{1H} (100 MHz, CD3OD): δ = 11.0 (CH3), 31.3 (CH2),
48.7 (CclusterH), 48.9 (Ccluster), 51.8 (N-CH2), 52.3 ((CO)OCH3),
56.4 (OCH3), 101.2 (CHind), 104.1 (Cind), 110.9 (CHind), 111.6
(CHind), 129.1 (Cind), 133.5 (Cind), 136.7 (Cind), 155.1 (Cind),
174.9 (CO) ppm; IR (KBr): ˜ν = 3450 (s), 2963 (m), 2532 (s), 1718
(s), 1620 (m), 1583 (m), 1485 (s), 1460 (m), 1439 (m), 1342 (m),
1262 (m), 1221 (s), 1179 (m), 1156 (m), 1095 (m), 1030 (s), 893
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(w), 845 (w), 798 (m), 705 (w), 574 (w), 491 (w), 436 (w) cm−1
;
HR-ESI-MS (negative mode, DMSO–CH3OH) m/z [M−Na]−: 10 F. G. Bordwell, G. E. Drucker and H. E. Fried, J. Org. Chem.,
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1981, 46, 632.
isotopic pattern was in agreement with the calculated one.
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Acknowledgements
This research was supported by the Fonds der Chemischen
Industrie (doctoral grant for W.N.), the Graduate School
“Building with Molecules and Nano-objects (BuildMoNa)”
funded by the Deutsche Forschungsgemeinschaft, and the 13 L. I. Zakharkin, V. A. Brattsev and Y. A. Chapovskii, Zh.
European Union, and the Free State of Saxony (ESF-NFG
Obshch. Khim., 1965, 35, 2160.
This journal is © The Royal Society of Chemistry 2015
Dalton Trans.