Reported herein is a visible‐light‐mediated radical approach to the α‐alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2‐based activation of alkyl halides and blue light irradiation. The resulting open‐shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl
FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
作者:Imtiaz Khan、Benjamin G. Reed-Berendt、Rebecca L. Melen、Louis C. Morrill
DOI:10.1002/anie.201808800
日期:2018.9.17
Herein we report the first catalytic transfer hydrogenation of silylenolethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6‐tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ‐terpinene as a dihydrogen surrogate. A variety of silylenolethers undergo efficient hydrogenation, with the reduced products isolated in excellent
Photocatalytic Vicinal Aminopyridylation of Methyl Ketones by a Double Umpolung Strategy
作者:Honggu Im、Wonjun Choi、Sungwoo Hong
DOI:10.1002/anie.202008435
日期:2020.9.28
umpolung strategy for the vicinal aminopyridylation of ketones was developed using pyridinium N−N ylides. The inversion of the polarity of the pyridinium N−N ylides by single‐electron oxidation successfully enables radical‐mediated 1,3‐dipolar cycloadditions with enolsilanes formed in situ from ketones, followed by homolytic cleavage of the N−N bond. Intriguingly, the nucleophilic amino and electrophilic
Intermolecular C–H functionalization versus cyclopropanation of electron rich 1,1-disubstituted and trisubstituted alkenes
作者:Dominic L. Ventura、Zhanjie Li、Michael G. Coleman、Huw M.L. Davies
DOI:10.1016/j.tet.2008.11.059
日期:2009.4
Rhodium(II)-catalyzed reactions of aryldiazoacetates with electron rich 1,1-disubstituted and trisubstituted alkenes were systematically studied. The regio-, diastereo- and enantioselectivity of the chemistry was profoundly influenced by the nature of the substrates and the catalyst. Conditions were developed for either selective cyclopropanation or C–Hinsertion. Both reactions can be achieved with