Palladium catalysis in cephalosporin chemistry: general methodology for the synthesis of cephem side chains

Synthesis of Carboxyl‐Tethered Symmetric Conjugated Polyenes as Fluorescent Transmembrane Probes of Lipid Bilayers

“…with DI-BAL (2 equiv., 1  solution in THF) in dry THF under an inert gas, according to the Negishi method. [25] The Pd 0 catalysts used under Farina conditions [27] were prepared in situ by treating the Pd 0 complex [tris(dibenzylideneacetone)dipalladium(0)] with trifurylphosphane or triphenylarsane.…”

“…70%) using as cata- 2 ]. The selectivity of the reaction and the yield of tetraene diester were similar when using Pd 0 complexes having the poor electron-donating ligands trifurylphosphane or triphenylarsane (Farina's conditions [27] ), although these complexes strongly increase the cross-coupling rate in Stille reactions, providing a successful route to unsaturated natural products. [28] In all these cases, the selectivity of the coupling 6c and 7 was scarcely improved by changing the reaction time, the catalyst amount (in the range 4Ϫ10 mol % of 7) or the sequence and way of addition of the reactants.…”

Synthesis of 7-Vinylflavone and 7-Aminoflavone by Palladium-Catalyzed Coupling Reactions

“…As calibrant, a mixture of glycerol and polyethylmass spectrometer; ammonia was used as reagent gas; accurate mass measurements were made using a VG-SEQ hybrid mass specene glycol 300 or 600 was used. [35] were distilled from CaH 2 and stored over activated mo-5-Hydroxy-3-methoxy-7-triflyloxyflavone (2b): To a solution of 5,7-lecular sieves (4 Å ). Lithium chloride was dried for about 12 h in dihydroxy-3-methoxyflavone (1b) (0.70 g, 2.5 mmol) in 20 mL of a vacuum oven at 120°C.…”

Cross‐Coupling Reactions to sp Carbon Atoms

“…While Stille proposed the in situ formation of an organozinc intermediate facilitating transmetallation [190a], Farina et al [227] ascribed the acceleration to contained water of hydration, as anhydrous ZnCl 2 did not lead to any enhancement.…”