Compound 3c

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Compound data: 1H NMR

Compound data: 13C NMR

Compound data: 19F NMR

Compound data: IR

Compound data: Crystallographic data

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

In a 15-mL scintillation vial, a mixture of 2c (94.7 mg, 40 µmol) and KHMDS (10.0 mg, 50 µmol) was chilled for 1 hour in a glovebox coldwell cooled with dry ice/acetone bath. Then, pre-cooled tert-butyl methyl ether (2.0 mL) was added, and the mixture was stirred with cooling for 10 minutes. The yellow solution was quickly passed through a glass filter and layered by cold heptane (ca. 15 mL). The bi-layered solution was stored at −40 °C overnight, to afford 3c as yellowish crystals (47.2 mg, 22 µmol, 55% yield). Note: Compound 3c gradually decomposes in solution at room temperature or even at −40 °C. The lifetime of 3c was found highly dependent to the solvent used (tert-butyl methyl ether > diethyl ether >> THF). While the decomposition pathways are unclear due to the formation of multiple decomposed products, the formation of the carbene dimer has never been detected by NMR and MALDI-TOF-MS analyses. ¹H NMR (300 MHz, MTBE + C₆D₆) δ 13.81 (s, 1H), 8.01–7.45 (m, 40H); ¹³C NMR (201 MHz, MTBE) δ 320.0 (¹J_C-H = 95.3 Hz, 3°), 147.2 (4°), 145.1 (4°), 143.1 (4°), 142.9 (4°), 142.5 (4°), 140.8 (4°), 140.2 (4°), 139.8 (4°), 133.1 (br m, ²J_C-F could not be determined, 4°), 130.8 (3°), 129.3 (3°), 128.5 (3°), 127.8 (3°), 126.9 (3°), 123.8 (br q, ¹J_C-F = 272 Hz, 4°), 122.4 (3°), 122.3 (3°), 122.1 (3°) (Note: The signals in the aromatic region could not be fully counted, due to the broad and complex spectrum), 89.1 (4°), 86.3 (4°); ¹⁹F NMR (282 MHz, MTBE + C₆D₆) δ −63.1, −63.2; IR (ATR, neat): 2981.8 (w), 1621.0 (w), 1593.0 (w), 1460.7 (w), 1388.6 (w), 1366.2 (s), 1275.0 (s), 1232.3 (s), 1171.0 (w), 1124.7 (s), 987.2 (w), 896.4 (m), 882.3 (m), 844.6 (m), 757.2 (w), 704. 8 (m), 682.0 (m), 668.0 (m), and 638.7 (m) cm⁻¹.