Biphenyl-Based Diaminophosphine Oxides as Air-Stable Preligands for the Nickel-Catalyzed Kumada–Tamao–Corriu Coupling of Deactivated Aryl Chlorides, Fluorides, and Tosylates
✍ Scribed by Prof. Dr. Zhong Jin; Yan-Jing Li; Prof. Dr. Yong-Qiang Ma; Ling-Ling Qiu; Prof. Jian-Xin Fang
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 295 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Transition-metal-catalyzed cross-coupling reactions [1] of aryl halides or pseudo-halides with organometallic reagents, such as Grignard reagents, organozinc compounds, boronic acids, organostannanes, and organosiloxanes, are powerful tools for the synthesis of the biaryl motif, which is prevalent in natural products, pharmaceuticals, chiral ligands, liquid crystals, and macromolecular polymers. Over the last decade, transition-metal-catalyzed cross-coupling with aryl chlorides [2] has been elegantly achieved by using well-designed ligands, such as bulky electron-rich tertiary phosphines, [3] N-heterocyclic carbenes (NHCs), [4] secondary phosphine oxides (SPOs), [5] and so on. Relative to the C À Cl bonds, the C À F bonds are more stable and thus inert. To date, only a few protocols are known for cross-coupling with electronically deactivated aryl fluorides. [6, 7] Despite the rather expensive cost, using aryl fluorides as coupling partners contributes to the fundamental conception of the reactivity of the very stable bonds and is, therefore, of great importance in organometallic chemistry. Herein, we report a new class of readily accessible, air-stable SPOs derived from 1,1'-biphenyl-2,2'-diamine (Scheme 1), which show high reactivity in the nickel-catalyzed cross-coupling of electronically deactivated aryl chlorides and fluorides at room tem-perature. Recently, great progress in transition-metal-mediated cross-coupling reactions using the commonly unreactive aryl/alkenyl sulfonylates, [8a, d] carbamates, [9] carboxylates, [10] phenolates, [11] and so on, as the coupling substrates has been made. The present SPO ligands are also found to be very effective on activation of the unreactive C À O bonds in the aryl tosylates. [12] The reactivity of the complexes generated in situ from these diaminophosphine oxides in the nickel-catalyzed Kumada cross-coupling reaction significantly relates to the substituted manner on the heteroatom adjacent to phosphorus atom (Table 1). With diaminophosphine oxides 1, 2, and 3 as a preA C H