Compound 4b

(E)-1,2-bis(1,1,3,3-tetrakis(1,1':3',1''-terphen-5'-yl)isoindolin-2yl)ethylene

From: A crystalline monosubstituted carbene

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Compound data: 1H NMR

Compound data: 13C NMR

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 2b (64.1 mg, 50 µmol) and KHMDS (12.0 mg, 60 µmol) was chilled for 1 hour in a glovebox coldwell cooled with dry ice/acetone bath. Then, pre-cooled toluene-d8 (2.0 mL) was added, and the mixture was stirred with cooling for 10 minutes. 1H NMR monitoring of the blue-green suspension suggested the existence of free carbene 3b at low temperature but also concomitant formation of dimer 4b (See Supplementary Figure 19). After further stirring at room temperature for 3 hours, the bright yellow solution was passed through a glass filter, and evaporated to dryness. The obtained solid was dissolved into THF, passed through a plug of Florisil, dried in vacuo at 120 °C overnight, to afford 4b as a yellow powder (50.2 mg, 48 µmol, 96% yield). Recrystallization from toluene/hexane (bi-layering) at room temperature afforded single crystals suitable for X-ray crystallographic analysis. NOTE: Compound 4b is sensitive to oxygen. The highly broad nature of the NMR spectra of 4a can be attributed to slow rotation of hindered terphenyl substituents (See also the X-ray structure in Supplementary Figure 59). 1H NMR (300 MHz, C6D6) δ 8.61–6.47 (m, 112H), 6.04 (br s, 2H, NCH=CHN); 13C NMR (126 MHz, 1,2-dichloroethane) δ 146.8 (4°), 141.0 (4°), 139.7 (4°), 138.4 (4°), 130.7 (3°), 128.8 (3°), 127.2 (3°), 124.5 (3°), (Note: The signals in the aromatic region could not be fully counted, due to the highly broad spectrum) 111.5 (NCH=CHN), 82.8 (4°); HRMS (m/z): [M+H]+ calcd. for C162H115N2, 2087.9055; found, 2087.9098.