Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
作者:Dianhu Zhu、Leiyang Lv、Chen-Chen Li、Sosthene Ung、Jian Gao、Chao-Jun Li
DOI:10.1002/anie.201809112
日期:2018.12.10
carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo‐ and regioselective direct palladium‐catalyzed C‐allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallicreagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not
According to “integrated chemical process”, a novel one-pot process for construction of highly substituted allylic moieties has been achieved. A series of alkylation of allylic sulfones and palladium-catalyzed reductive desulfonylation by use of LiBHEt3 is integrated. The double alkylation furnishes more substituted olefins. Use of arylzinc compounds in place of the hydride enables electrophilic a
Raising the p<i>K</i><sub>a</sub> Limit of “Soft” Nucleophiles in Palladium-Catalyzed Allylic Substitutions: Application of Diarylmethane Pronucleophiles
作者:Sheng-Chun Sha、Jiadi Zhang、Patrick J. Carroll、Patrick J. Walsh
DOI:10.1021/ja409511n
日期:2013.11.20
Tsuji-Trost allylicsubstitution reaction provides a useful and efficient approach to construct C-C bonds between sp(3)-hybridized carbons. The widely accepted paradigm for classifying the mode of attack of nucleophiles on palladium π-allyl intermediates in the Tsuji-Trost reaction is based on the pKa of the pronucleophile: (1) stabilized or "soft" carbonnucleophiles and heteroatom nucleophiles (e.g.,
Palladium-Catalyzed Electrochemical Allylic Alkylation between Alkyl and Allylic Halides in Aqueous Solution
作者:Yin-Long Lai、Jing-Mei Huang
DOI:10.1021/acs.orglett.7b00473
日期:2017.4.21
A new route for the direct cross-coupling of alkyl and allylic halides using electrochemical technique has been developed in aqueous media under air. Catalyzed by Pd(OAc)2, the Zn-mediated allylicalkylations proceed smoothly between a full range of alkyl halides (primary, secondary, and tertiary) and substituted allylic halides. Protection–deprotection of acidic hydrogen in the substrates is avoided
Free Radical Chemistry of β-Lactones. Arrhenius Parameters for the Decarboxylative Cleavage and Ring Expansion of 2-Oxetanon-4-ylcarbinyl Radicals. Facilitation of Chain Propagation by Catalytic Benzeneselenol
作者:David Crich、Xue-Sheng Mo
DOI:10.1021/ja980447w
日期:1998.8.1
loss of carbon dioxide to provide allyl radicals. When the initial radical is generated from a bromolactone with Bu3SnH and AIBN, chainpropagation is poor owing to the relatively slow abstraction of hydrogen from the stannane by the allyl radical. The inclusion of catalytic Ph2Se2, reduced in situ to PhSeH, provides for much smoother cleaner reactions because of the better hydrogen donating capacity