Fluorous Biphasic Catalysis without Perfluorinated Solvents: Application to Pd-Mediated Suzuki and Sonogashira Couplings

Abstract

, B 8 , and B 9 has not been clarified, but the proposed mechanism would require only a minimal rearrangement of the bonds (one DSD rearrangement and the closing of the cluster after the loss of B 1 ). The loss of B 1 , which is not part of the open face, is surprising. Quantum-mechanical computations might give indications about the feasibility of the proposed pathway, the relative stability of the proposed intermediates, the origin of the H atoms which leave together with B 1 , and the rearrangement of the other H atoms. Experimental Section1, 8±12: Isopropylamine (0.1 g, 1.74 mmol) was added to a solution of (Me 2 S)B 9 H 13 in dry benzene (10 mL, 0.1 g) at room temperature. The mixture was heated to reflux for 3 h. All volatile components were removed under vacuum and the resulting substance was recrystallized from ethanol:water (1:1). Compounds 8 and 9 were purified by TLC by using CH 2 Cl 2 as eluent (R f ¼ 0.31). For further purification the substance was dissolved in CHCl 3 :hexane (1:3) at À20 8C. The solution was filtered and the resulting filtrate was evaporated to dryness to yield the purified product. 1 (DCI): m/z (%) 214 (95)

Microwave-accelerated Mizoroki-Heck and Sonogashira cross- coupling reactions in water using a heterogeneous palladium(II)-precatalyst

“…%) at 100°C for 30 minutes furnished the (2-thienyl)phenylacetylene 28 (100% conversion; 81% isolated yield). Bannwarth and co-workers 31 reported that a perfluorinated Pd-complex was completely poisoned by the thiophene moiety after the first run of cross coupling 3-thienylboronic acid with aryl bromides. However, we could find that our Pd-precatalyst 7 was recyclable for at least five consecutive Sonogashira coupling reactions of 2-iodothiophene with phenylacetylene 23 (Table 5).…”

Microwave-assisted synthesis of 2-acetyl-5-arylthiophenes and 4-(5-arylthiophen-2-yl)thiazoles via Suzuki coupling in water

“…The identity of the resulted coupling products was confirmed from their 1 H and 13 C NMR and MS spectral data. Although, sulfur species are reported as potential catalyst poisons that cause a remarkable decrease in the catalytic activity of palladium catalysts, 42 also the thiophene moiety was mentioned as poison of a perfluorinated Pd-complex, 43 the cross-coupling of 2-acetyl-5-bromothiophene (2) with 3-thienylboronic acid (3e) proceeded straightforward giving excellent yield of 2-acetyl-3`,5-bithiophene (8) after 10 hours of thermal heating and after 9 min of microwave irradiation (Table 1, entry 5). …”

Design of silica-tethered metal complexes for polymerization catalysis

“…While this approach can work quite well, it is limited to use in non-polar media that will not disrupt the ionic interaction between the support and the complex. Another approach is to functionalize the support with an additional phase, for example a grafted fluorous phase [5] or an adsorbed aqueous phase [6]. The metal complex catalyst can then be dissolved/adsorbed in this phase and applied in catalytic reactions in a non-soluble phase (e.g., supported aqueous phase catalysis in non-polar organic solvents).…”