The implementation of gold catalysis into large-scale processes suffers from the fact that most reactions still require high catalyst loadings to achieve efficient catalysis thus making upscaling impractial. Here, we...
An unusual germole-to-silole transformation is described. As key intermediates hetero-fulvenes are formed which rearrange to more stable bicyclic carbene analogues. The so-formed germylenes undergo a reductive elimination yielding elemental germanium and siloles. In contrast, the analogous silylenes are stable at ambient conditions and were identified by MS spectrometry and NMR spectroscopy supported by the results of quantum mechanical calculations. These bicyclic silylenes are stable derivatives of the global minimum of the C Si H potential energy surface.
Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions.H owever,t heir direct use in the formation of C À Cbonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp 2 ÀCsp 3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents.P alladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with avariety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry.Furthermore,the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.
Studies of the reactivity and coordination properties of the diamino-carbodiphosphorane 1 revealed that 1 is a weak N donor, but strongly coordinates via the carbon atom thus allowing the isolation of low-valent metal species.
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