770-09-2Relevant articles and documents
Nickel-Mediated Enantiospecific Silylation via Benzylic C-OMe Bond Cleavage
Balakrishnan, Venkadesh,Murugesan, Vetrivelan,Chindan, Bincy,Rasappan, Ramesh
supporting information, p. 1333 - 1338 (2021/02/20)
Benzylic stereocenters are found in bioactive and drug molecules, as enantiopure benzylic alcohols have been used to build such a stereogenic center, but are limited to the construction of a C-C bond. Silylation of alkyl alcohols has the potential to build bioactive molecules and building blocks; however, the development of such a process is challenging and unknown. Herein, we describe an unprecedented AgF-assisted nickel catalysis in the enantiospecific silylation of benzylic ethers.
Divergent Synthesis of Vinyl-, Benzyl-, and Borylsilanes: Aryl to Alkyl 1,5-Palladium Migration/Coupling Sequences
Han, Jie-Lian,Ju, Cheng-Wei,Qin, Ying,Zhao, Dongbing
supporting information, p. 6555 - 6560 (2020/03/03)
Organosilicon compounds have been extensively utilized both in industry and academia. Studies on the syntheses of diverse organosilanes is highly appealing. Through-space metal/hydrogen shifts allow functionalization of C?H bonds at a remote site, which are otherwise difficult to achieve. However, until now, an aryl to alkyl 1,5-palladium migration process seems to have not been presented. Reported herein is the remote olefination, arylation, and borylation of a methyl group on silicon to access diverse vinyl-, benzyl-, and borylsilanes, constituting a unique C(sp3)?H transformation based on a 1,5-palladium migration process.
Fluoroalkylselenolation of Alkyl Silanes/Trifluoroborates under Metal-Free Visible-Light Photoredox Catalysis
Ghiazza, Clément,Khrouz, Lhoussain,Billard, Thierry,Monnereau, Cyrille,Tlili, Anis
supporting information, p. 1559 - 1566 (2019/11/03)
Herein a metal-free fluoroalkylselenolation of alkylsilanes as well as potassium alkyltrifluoroborates under visible light photocatalysis is disclosed. The developed methodologies are performed under mild conditions, room temperature in the presence of an organic photocatalyst and blue LED irradiation. Mechanistic investigations including luminescence and EPR spectroscopy allow us to shed light on both mechanisms.
Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
supporting information, p. 6592 - 6603 (2017/07/15)
The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
Enantioselective Synthesis of Chiral 3-Substituted-3-silylpropionic Esters via Rhodium/Bisphosphine-Thiourea-Catalyzed Asymmetric Hydrogenation
Zhang, Zongpeng,Han, Zhengyu,Gu, Guoxian,Dong, Xiu-Qin,Zhang, Xumu
supporting information, p. 2585 - 2589 (2017/08/16)
We have successfully developed the asymmetric hydrogenation of β-silyl-α,β-unsaturated esters to prepare chiral 3-substituted-3-silylpropionic ester products catalyzed by rhodium/bisphosphine-thiourea (ZhaoPhos) with excellent results (up to 97% yield, >99% ee, 1500 TON). Moreover, our hydrogenation products can be efficiently converted to other important organic molecules, such as chiral ethyl (R)-3-hydroxy-3-phenylpropanoate or (R)-3-[dimethyl(phenyl)silyl]-3-phenylpropanoic acid. (Figure presented.).
Direct oxidation of the C(sp2)-C(sp3) bond from benzyltrimethylsilanes to phenols
Li, Wei,Gao, Guolin,Gao, Yuan,Yang, Chao,Xia, Wujiong
supporting information, p. 5291 - 5293 (2017/07/10)
A novel pathway for direct conversion of benzylsilanes to phenols by oxidation with Na2S2O8 and oxygen is efficiently developed under mild and neutral conditions. The reaction shows good functional group tolerance to afford phenols in moderate yields. The possible mechanism is proposed based on the isotopic labeling trials.
Selective Si?C(sp3) Bond Cleavage in (Aminomethyl)silanes by Carbanionic Nucleophiles and Its Stereochemical Course
Koller, Stephan G.,Bauer, Jonathan O.,Strohmann, Carsten
, p. 7991 - 7994 (2017/06/27)
Selective cleavage of a silicon–carbon bond in tetraorganosilanes is still a great challenge. A new type of Si?C(sp3) bond cleavage in bench-stable (aminomethyl)silanes with common organolithium reagents as nucleophiles has now been identified. Suitable leaving groups are benzyl, allyl, and phenylthiomethyl groups. A β-donor function and polar solvents are essential for the reaction. Simple switching between α-deprotonation and substitution is possible through slight modifications of the reaction conditions. The stereochemical course of the reaction was elucidated by using a silicon-chiral benzylsilane. The new transformation proceeds stereospecifically with inversion of configuration and can be used for the targeted synthesis of enantiomerically pure tetraorganosilanes, which are otherwise difficult to access. Quantum chemical calculations provided insight into the mechanism of the new substitution.
General Ambient Temperature Benzylic Metalations Using Mixed-Metal Li/K-TMP Amide
Manvar, Atul,Fleming, Patricia,O'Shea, Donal F.
, p. 8727 - 8738 (2015/09/15)
Highly regioselective benzylic metalations in hydrocarbon solvent have been achieved at rt and 0 °C using a mixed-metal Li/K-TMP amide comprised of KOtBu, BuLi, and 2,2,6,6,-tetramethylpiperidine (TMP(H)). Mixing of KOtBu, BuLi, and TMP(H) in heptane gave a solution of the base mixture which when used in deuterium labeling experiments confirmed the requirement of the three reagent components for both reactivity and selectivity. The reaction protocol is operationally straightforward and found to be applicable to a broad range of substrates. Upon generation of the metalated products, they are reacted in heptane at ambient temperature in a variety of synthetically useful ways. Illustrated examples include generation of the benzyltrimethylsilanes and α,α-bis(trimethylsilyl)toluenes reagents, which are bench-stable surrogates of benzyl anions and α-silyl carbanions utilized for nucleophilic addition and Peterson olefination reactions. Direct C-C couplings mediated by 1,2-dibromoethane provided entries into bibenzyls and [2.2]metacyclophanes. Comparison of reaction outcomes with the same reactions carried out in THF at -78 °C showed no negative effects for conducting the reactions under these milder more user-friendly conditions.
Stereoselective peterson olefinations from bench-stable reagents and N-phenyl imines
Das, Manas,Manvar, Atul,Jacolot, Ma?wenn,Blangetti, Marco,Jones, Roderick C.,O'Shea, Donal F.
supporting information, p. 8737 - 8740 (2015/06/08)
The synthesis of bench-stable α,α-bis(trimethylsilyl)toluenes and tris(trimethylsilyl)methane is described and their use in stereoselective Peterson olefinations has been achieved with a wide substrate scope. Product stereoselectivity was poor with carbonyl electrophiles (E/Z ～1:1 to 4:1) though this was significantly improved by employing the corresponding substituted N-benzylideneaniline (up to 99:1) as an alternative electrophile. The olefination byproduct was identified as N,N-bis(trimethylsilyl)aniline and could be easily separated from product by aqueous acid extraction. Evidence for an autocatalytic cycle has been obtained.
Benzyllithiums bearing aldehyde carbonyl groups. A flash chemistry approach
Nagaki, Aiichiro,Tsuchihashi, Yuta,Haraki, Suguru,Yoshida, Jun-ichi
supporting information, p. 7140 - 7145 (2015/07/01)
Reductive lithiation of benzyl halides bearing aldehyde carbonyl groups followed by reaction with subsequently added electrophiles was successfully accomplished without affecting the carbonyl groups by taking advantage of short residence times in flow microreactors.
