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Diazaphosphinanes as hydride, hydrogen atom, proton or electron donors under transition-metal-free conditions: thermodynamics, kinetics, and synthetic applications.

ABSTRACT: Exploration of new hydrogen donors is in large demand in hydrogenation chemistry. Herein, we developed a new 1,3,2-diazaphosphinane 1a, which can serve as a hydride, hydrogen atom or proton donor without transition-metal mediation. The thermodynamics and kinetics of these three pathways of 1a, together with those of its analog 1b, were investigated in acetonitrile. It is noteworthy that, the reduction potentials (E _red) of the phosphenium cations 1a-[P]+ and 1b-[P]+ are extremely low, being -1.94 and -2.39 V (vs. Fc^+/0), respectively, enabling corresponding phosphinyl radicals to function as neutral super-electron-donors. Kinetic studies revealed an extraordinarily large kinetic isotope effect KIE(1a) of 31.3 for the hydrogen atom transfer from 1a to the 2,4,6-tri-(tert-butyl)-phenoxyl radical, implying a tunneling effect. Furthermore, successful applications of these diverse P-H bond energetic parameters in organic syntheses were exemplified, shedding light on more exploitations of these versatile and powerful diazaphosphinane reagents in organic chemistry.

SUBMITTER: Zhang J

PROVIDER: S-EPMC8152589 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Diazaphosphinanes as hydride, hydrogen atom, proton or electron donors under transition-metal-free conditions: thermodynamics, kinetics, and synthetic applications.

Zhang Jingjing J Yang Jin-Dong JD Cheng Jin-Pei JP

Chemical science 20200305 14

Exploration of new hydrogen donors is in large demand in hydrogenation chemistry. Herein, we developed a new 1,3,2-diazaphosphinane 1a, which can serve as a hydride, hydrogen atom or proton donor without transition-metal mediation. The thermodynamics and kinetics of these three pathways of 1a, together with those of its analog 1b, were investigated in acetonitrile. It is noteworthy that, the reduction potentials (E red) of the phosphenium cations 1a-[P]+ ...[more]

PMID: 34094055

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Dataset Information

Diazaphosphinanes as hydride, hydrogen atom, proton or electron donors under transition-metal-free conditions: thermodynamics, kinetics, and synthetic applications.

Publications

Diazaphosphinanes as hydride, hydrogen atom, proton or electron donors under transition-metal-free conditions: thermodynamics, kinetics, and synthetic applications.

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