Bathocuproine-Enabled Nickel-Catalyzed Selective Ullmann Cross-Coupling of Two sp2-Hybridized Organohalides
Yuqiang Li∗
a
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. of China
,
Guoyin Yin∗
b
The Institute for Advanced Studies, Wuhan University, Wuhan 430072, P. R. of China
› Author AffiliationsThe National Natural Science Foundation of China (21871211) and the Fundamental Research Funds for the Central Universities (2042019kf0208) supported this work.
Cross-coupling reactions are essential for the synthesis of complex organic molecules. Here, we report a nickel-catalyzed Ullmann cross-coupling of two sp2-hybridized organohalides, featuring high cross-selectivity when the two coupling partners are used in a 1:1 ratio. The high chemoselectivity is governed by the bathocuproine ligand. Moreover, the mild reductive reaction conditions allow that a wide range of functional groups are compatible in this Ullmann cross-coupling.
13 Yin, G.; Peng, L.; Zhao, B.; Li, Y. ChemRxiv2020, preprint; doi, 10.26434/chemrxiv.12318398.v1. This content is a preprint and has not been peer–reviewed
14
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Wakabayashi S,
Osakada K.
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18 The general procedure as well as the analytical data of a few typical compounds are summarized as follows. Procedure: To an oven-dried 10 mL reaction tube equipped with a magnetic stir bar was introduced, in an argon-filled glove box, NiI2 (5.0 mol%, 7.8 mg), Bathocuproine (5 mol%, 9.0 mg), n-Bu4NBr (1.0 equiv, 161.2 mg) and zinc dust (1.5 equiv, 49 mg) were added. Then anhydrous DMA (4 mL) was added and the mixture was stirred, at which time aryl bromide (1 equiv, 0.5 mmol), alkenyl bromide (1 equiv, 0.5 mmol) were added to the resulting mixture in this order. The tube was sealed with a rubber stopper and stirred at r.t. for 10 h. After the reaction was complete, EtOAc (50 mL) was added and the mixture was extracted with H2O (20 mL × 3). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The resulting crude product was separated on a silica gel column with petroleum ether and EtOAc as eluent to afford the desired product. 4-(2-Methylprop-1-en-1-yl)phenyl 4-methylbenzenesulfonate (11): The reaction was conducted following the general procedure on a 0.5 mmol scale. The residue was purified by column chromatography on silica gel to afford the product 11 (90% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.72–7.68 (m, 2 H), 7.30–7.28 (m, 2 H), 7.12–7.09 (m, 2 H), 6.92–6.88 (m, 2 H), 6.18 (s, 1 H), 2.43 (s, 3 H), 1.87 (d, J = 1.6 Hz, 3 H), 1.80 (d, J = 1.4 Hz, 3 H). 13C NMR (101 MHz, CDCl3): δ = 147.5, 145.4, 137.7, 136.6, 132.6, 129.83, 129.80, 128.6, 123.9, 122.0, 26.9, 21.8, 19.4. HRMS (ESI): m/z calcd for C17H19O3S ([M + H]+): 303.1049; found: 303.1052.
