75144-61-5Relevant academic research and scientific papers
Enantioselective Synthesis of γ-Oxycarbonyl Motifs by Conjugate Addition of Photogenerated α-Alkoxy Radicals
Dong, Xiao,Li, Qi Yukki,Yoon, Tehshik P.
supporting information, p. 5703 - 5708 (2021/08/16)
Enantioselective catalytic Giese addition of photogenerated α-alkoxy radicals to acyl pyrazolidinones can be accomplished using a tandem Sc(III) Lewis acid/photoredox catalyst system. Surprisingly, the excited-state oxidation potential was not the only important variable, and the optimal photocatalyst was not the strongest oxidant screened. Our results show that both the oxidation and reduction potentials of the photocatalyst can be important for the reaction outcome, highlighting the importance of holistic considerations in designing photochemical reactions.
Visible-Light Photoredox-Catalyzed Hydroalkoxymethylation of Activated Alkenes Using α-Silyl Ethers as Alkoxymethyl Radical Equivalents
Khatun, Nilufa,Kim, Myeong Jun,Woo, Sang Kook
supporting information, p. 6239 - 6243 (2018/09/27)
A new neutral silicon-based traceless activation group (TAG) for visible-light photoredox-catalyzed hydroalkoxymethylation of alkenes is presented. This reaction involves in-situ-generated alkoxymethyl radical via single electron oxidation (SET) of α-TMS-substituted ethers, followed by subsequent conjugate addition to activated alkenes. Various functional groups were tolerated both under mild metal and metal-free conditions to provide good to excellent yields. Furthermore, the addition products were transformed to valuable synthetic building blocks, such as carboxylic acids,-butyrolactones, and complex aryl alkyl ethers.
Pentacoordinate silicon intermediates in relay substitution reactions of organosilanes: successive nucleophilic attack at silicon and its adjacent carbon
Eisch, John J.,Chiu, Chingchen S.
, p. C1 - C5 (2007/10/02)
Chloromethylsilyl chlorides of the type, ClCH2R2SiCl, have been shown to undergo kinetically controlled nucleophilic attack at silicon, with either phenols or amines (PhEH, with E=O or NMe), to yield products of the type, PhESiR2CH2Cl.Subsequent treatment of the latter products with KF in acetonitrile causes the nucleophile to be shifted from silicon to carbon with the formation of FSiR2CH2EPh.Alternatively, treatment of ClCH2R2SiCl simultaneously with PhEH and KF yields the same thermodynamically controlled product directly, FSiR2CH2EPh.This possibility of directing nucleophilic attack toward silicon or its adjacent carbon has great importance in the synthesis of substituted organosilanes.The mechanism of these so-called relay nucleophilic substitutions is proposed as involving pentacoordinate silicon intermediates.The concept of initial nucleophilic attack at silicon and the subsequent relaying of the nucleophile from the pentacoordinate silicon to the adjacent carbon is also shown to be applicable to the unusual reactions of α,β-epoxyalkylsilanes.
Rearrangement and Cleavage of silanes by Organolithium Reagents: Conversion of Phenols into Benzylic Alcohols
Eisch, John J.,Galle, James E.,Piotrowski, Andrzej,Tsai, Miin-Rong
, p. 5051 - 5056 (2007/10/02)
The feasibility of converting phenols into their corresponding benzylic alcohols by means of novel Wittig rearrangement has been investigated.The method consists of (a) treating the phenol with (chloromethyl)trimethylsilane and base to produce the aryl (trimethylsilyl)methyl ether, (b) using sec- or n-BuLi in THF transform this ether into the α-(trimethylsilyl)benzylic alcohol, and (c) removing the silyl group with alcoholic KOH to yield the benzylic alcohol.With phenols, such as phenol itself, 2-naphthol, and 9-phenanthrol, benzylic alcohols were obtained in 50-80percent yields.Ring substituents of a nitro or methoxy type tend to favor α elimination in step b, at the expense of the Wittig rearrangement.The competitive nature of these latter two processes was examined as a function of substituents on the aryloxy groups or on the silicon, as well as a function of the lithium reagent and solvent employed.The independent synthesis and the thermal study of (phenoxymethyl)lithium demonstrated that in THF it undergoes an α elimination almost to the complete exclusion of any Wittig rearrangement.The relative importance of these two processes is discussed in terms of the locoselectivity of lithiation and an electron-transfer view of the Wittig aryl ether rearrangement.
