A novel approach to the Cu-catalyzed cyanation of simple arenes using acetonitrile as an attractive cyano source has been documented. The C-H functionalization of arenes without directing groups involves a sequential iodination/cyanation to give the desired aromatic nitriles in good yields. A highly efficient Cu/TEMPO system for acetonitrile C-CN bond cleavage has been discovered. TEMPO is used as a cheap oxidant and enables the reaction to be catalytic in copper. Moreover, TEMPOCH2CN 6 has been identified as the active cyanating agent and shows high reactivity for forming the -CN moiety.
We report a simple and effective
nickel-based catalytic system,
NiCl2·6H2O/
t
BuOK, for the electrophilically activated hydrosilylation of terminal
alkenes with primary silanes. This protocol provides excellent performance
under mild reaction conditions: exclusive anti-Markovnikov selectivity,
broad functional group tolerance (36 examples), and good scalability
(TON = 5500). However, the secondary and tertiary silanes are not
suitable. Mechanistic studies revealed that this homogeneous catalytic
hydrosilylation includes an electrophilically activated Si–H
bond process without the generation of nickel hydrides.
We report an efficient approach for the direct synthesis of alkenylboronates using copper catalysis. The Cu/ TEMPO catalyst system (where TEMPO = (2,2,6,6tetramethylpiperidin-1-yl)oxyl) exhibits both excellent reactivity and selectivity for the synthesis of alkenylboronates, starting from inexpensive and abundant alkenes and pinacol diboron. This approach allows for the direct functionalization of both aromatic and aliphatic terminal alkenes. Mechanistic experiments suggest that the alkenylboronates arise from oxyboration intermediates.
An efficient protocol for copper-catalyzed aromatic C-H alkoxylation with alcohols has been developed under aerobic conditions. The protocol provides a complementary method to couple arenes and alcohols to furnish aromatic ethers. The advantages of this method are the employment of a cheap Cu(OAc) catalyst, oxygen as the terminal oxidant and alcohol as both an alkoxy reagent and a solvent. Notably, the catalytic amount of benzoic acid plays a significant role in this transformation.
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