64781-40-4Relevant academic research and scientific papers
Catalytic Intermolecular C(sp3)-H Amination: Selective Functionalization of Tertiary C-H Bonds vs Activated Benzylic C-H Bonds
Brunard, Erwan,Boquet, Vincent,Van Elslande, Elsa,Saget, Tanguy,Dauban, Philippe
supporting information, p. 6407 - 6412 (2021/05/29)
A catalytic intermolecular amination of nonactivated tertiary C(sp3)-H bonds (BDE of 96 kcal·mol-1) is reported for substrates displaying an activated benzylic site (BDE of 85 kcal·mol-1). The tertiary C(sp3)-H bond is selectively functionalized to afford α,α,α-Trisubstituted amides in high yields. This unusual site-selectivity results from the synergistic combination of Rh2(S-Tfpttl)4, a rhodium(II) complex with a well-defined catalytic pocket, with tert-butylphenol sulfamate (TBPhsNH2), which leads to a discriminating rhodium-bound nitrene species under mild oxidative conditions. This catalytic system is very robust, and the reaction was performed on a 50 mmol scale with only 0.01 mol % of catalyst. The TBPhs group can be removed under mild conditions to afford the corresponding NH-free amines.
Distinction between polar and electron-transfer routes. A mechanistic study on the wittig reactions of nonstabilized ylides
Yamataka, Hiroshi,Nagareda, Katsushi,Takatsuka, Tsutomu,Ando, Katsuhiro,Hanafusa, Terukiyo,Nagase, Shigeru
, p. 8570 - 8576 (2007/10/02)
The Wittig reaction of nonstabilized ylides with benzaldehyde and benzophenone was investigated in detail by means of carbonyl-14C kinetic isotope effects, substituent effects, and isotope-scrambling and probe experiments. The reaction with benzophenone gave the carbon isotope effects and the Hammett ρ values of considerable magnitude both in Li salt-free and salt-present conditions. In contrast, they are quite small for the reaction with benzaldehyde. Enone-isomerization and dehalogenation probe experiments indicated that the nonstabilized ylide has enough ability to transfer an electron to benzaldehyde and benzophenone. These results were interpreted in a self-consistent manner by the mechanism that the Wittig reaction of nonstabilized ylides proceeds via initial electron transfer from the ylide to the carbonyl compounds. The electron-transfer step is rate-determining for benzaldehyde, while radical coupling following the electron-transfer step is rate determining for benzophenone. From the probe experiments together with the isotope effects and the substituent effects reported previously, the reaction of semistabilized ylides was concluded to proceed through a polar nucleophilic addition mechanism.
