期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 145, 期 13, 页码 7667-7674出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.3c02301
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The reversible activation of dihydrogen with a molecular zinc anilide complex has been investigated. The mechanism involves the addition of H-2 across the Zn-N bond through a four-membered transition state. The resulting zinc hydride complex is highly effective for the hydrozincation of C=C bonds, particularly alkynes, and this discovery has led to the development of a catalytic system for the semi-hydrogenation of alkynes.
The reversible activation of dihydrogen with a molecular zinc anilide complex is reported. The mechanism of this reaction has been probed through stoichiometric experiments and density functional theory (DFT) calculations. The combined evidence suggests that H-2 activation occurs by addition across the Zn-N bond via a four-membered transition state in which the Zn and N atoms play a dual role of Lewis acid and Lewis base. The zinc hydride complex that results from H-2 addition has been shown to be remarkably effective for the hydrozincation of C=C bonds at modest temperatures. The scope of hydrozincation includes alkynes, alkenes, and a 1,3-butadiyne. For alkynes, the hydrozincation step is stereospecific leading exclusively to the syn-isomer. Competition experiments show that the hydrozincation of alkynes is faster than the equivalent alkene substrates. These new discoveries have been used to develop a catalytic system for the semi-hydrogenation of alkynes. The catalytic scope includes both aryl- and alkylsubstituted internal alkynes and proceeds with high alkene: alkane, Z:E ratios, and modest functional group tolerance. This work offers a first example of selective hydrogenation catalysis using zinc complexes.
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