Transition metal-catalyzed carbonylation with carbon nucleophiles is one of the most prominent methods to construct ketones, which are highly versatile motifs prevalent in a variety of organic compounds. In comparison to the well-established palladium catalytic system, the nickel-catalyzed carbonylative coupling is much underdeveloped due to the strong binding affinity of CO to nickel. By leveraging easily accessible tert-butyl isocyanide as the CO surrogate, we present a nickel-catalyzed allylic carbonylative coupling with alkyl zinc reagent, allowing for the practical and straightforward preparation of synthetically important β,γunsaturated ketones in a linear-selective fashion with excellent trans-selectivity under mild conditions. Moreover, the undesired polycarbonylation process which is often encountered in palladium chemistry could be completely suppressed. This nickel-based method features excellent functional group tolerance, even including the active aryl iodide functionality to allow the orthogonal derivatization of β,γ-unsaturated ketones. Preliminary mechanistic studies suggest that the reaction proceeds via a π-allylnickel intermediate.
Herein, we disclose
a Ni-catalyzed formal aminocarbonylation of
primary and secondary unactivated aliphatic iodides with isocyanides
to afford alkyl amide, which proceeds via the selective monomigratory
insertion of isocyanides with alkyl iodides, subsequent β-hydride
elimination, and hydrolysis process. The reaction features wide functional
group tolerance under mild conditions. Additionally, the selective,
one-pot hydrolysis of reaction mixture under acid conditions allows
for expedient synthesis of the corresponding alkyl carboxylic acid.
The distribution of pores and the mechanical properties of materials are the key factors in preparing satisfactory low-k films. In the present study, a kind of silsesquioxane-polyethylene glycol (SSQ-PEG) was synthesized and used as a template to make the distribution of pores more even in the low-k films. The crosslinking density of films could be adjusted by the sol-gel of tetramethoxysilane/dimethoxydimethylsilane with various proportions. The porosity of films could also be adjusted with different proportions of pendant PEG chains introduced. A dielectric constant as low as 2.1 had been achieved for nanoporous polyorganosilicate films with good tenacity.
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