51755-56-7Relevant articles and documents
para-Selective Benzylation of Aryl Iodides by the in situ Preparation of ArIF2: a Hypervalent Iodine-Guided Electrophilic Substitution
Chaudhry, Azka,Hyatt, I. F. Dempsey,Im, Haram,Jones, Taro J.,Noorollah, Jennifer,Siddiqi, Fatima,Singh, Nirvanie,Spatola, Nicholas R.
supporting information, (2020/04/16)
Hypervalent iodine-guided electrophilic substitution (HIGES) was described previously for the para-selective benzylation of aryl-λ3-iodane diacetates. One drawback of the method was the synthesis and isolation of hypervalent iodine starting mat
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.
Murahashi Cross-Coupling at ?78 °C: A One-Pot Procedure for Sequential C?C/C?C, C?C/C?N, and C?C/C?S Cross-Coupling of Bromo-Chloro-Arenes
Sinha, Narayan,Heijnen, Dorus,Feringa, Ben L.,Organ, Michael G.
supporting information, p. 9180 - 9184 (2019/07/04)
The coupling of organolithium reagents, including strongly hindered examples, at cryogenic temperatures (as low as ?78 °C) has been achieved with high-reactivity Pd-NHC catalysts. A temperature-dependent chemoselectivity trigger has been developed for the selective coupling of aryl bromides in the presence of chlorides. Building on this, a one-pot, sequential coupling strategy is presented for the rapid construction of advanced building blocks. Importantly, one-shot addition of alkyllithium compounds to Pd cross-coupling reactions has been achieved, eliminating the need for slow addition by syringe pump.
Synthesis of Polysubstituted Iodoarenes Enabled by Iterative Iodine-Directed para and ortho C?H Functionalization
Wu, Yichen,Bouvet, Sébastien,Izquierdo, Susana,Shafir, Alexandr
supporting information, p. 2617 - 2621 (2019/01/04)
Among halogenated aromatics, iodoarenes are unique in their ability to produce the bench-stable halogen(III) form. Earlier, such iodine(III) centers were shown to enable C?H functionalization ortho to iodine via halogen-centered rearrangement. The broader implications of this phenomenon are explored by testing the extent of an unusual iodane-directed para C?H benzylation, as well as by developing an efficient C?H coupling with sulfonyl-substituted allylic silanes. Through the combination of the one-shot nature of the coupling event and the iodine retention, multisubstituted arenes can be prepared by sequentially engaging up to three aromatic C?H sites. This type of iodine-based iterative synthesis will serve as a tool for the formation of value-added aromatic cores.
Palladium-catalyzed C(sp 3)-C(sp 2) cross-coupling of (trimethylsilyl)methyllithium with (hetero)aryl halides
Heijnen, Dorus,Hornillos, Valentín,Corbet, Brian P.,Giannerini, Massimo,Feringa, Ben L.
supporting information, p. 2262 - 2265 (2015/05/13)
The palladium-catalyzed direct cross-coupling of a range of organic chlorides and bromides with the bifunctional C(sp3)-(trimethylsilyl)methyllithium reagent is reported. The use of Pd-PEPPSI-IPent as the catalyst allows for the preparation of structurally diverse and synthetically versatile benzyl- and allylsilanes in high yields under mild conditions (room temperature) with short reaction times.
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.
Methoxy-substituted α, n-didehydrotoluenes. photochemical generation and polar vs diradical reactivity
Raviola, Carlotta,Ravelli, Davide,Protti, Stefano,Fagnoni, Maurizio
supporting information, p. 13874 - 13881 (2015/02/05)
The photoreactivity of differently substituted (chloromethoxybenzyl)trimethylsilanes in alcohols and alcohol/water mixtures has been investigated by means of a combined computational and experimental approach. Subsequent elimination of the chloride anion and the trimethylsilyl cation gives the corresponding methoxy-substituted α,n-didehydrotoluenes (α,n-MeO-DHTs). The rate of desilylation is evaluated through the competition with arylation via phenyl cation (ca. 108s-1). α,2-MeO- and α,4-MeO-DHTs show a purely radical behavior (H abstraction from the solvent, methanol), while α,3-MeO-DHT shows mainly a ionic chemistry, as when the parent α,3-DHT is thermally generated. This is likely due to triplet-singlet surfaces crossing occurring during desilylation.
Synthesis and application of benzyl-TMS derivatives as bench stable benzyl anion equivalents
Das, Manas,O'Shea, Donal F.
, p. 6448 - 6460 (2013/07/26)
The regioselective benzylic metalation of toluenes using BuLi/KO tBu/TMP(H) (LiNK metalation conditions) and subsequent transmetalation to Si by reaction with TMSCl provides a general one-pot procedure for the synthesis of substituted benzyltrimethylsilanes. ArCH 2Si(Me)3 derivatives are bench stable reagents yet can serve as benzyl anion equivalents under mild reaction conditions. Following activation with fluoride they can successfully participate in a wide range of additions to both non-enolizable and enolizable carbonyls. In addition, their use in the synthesis of isochromanones and trifluoromethylated amines is illustrated. The broad synthetic scope and mild practical conditions of use for ArCH2Si(Me)3 reagents demonstrate their general potential as benzyl anion equivalents.
Some evidence in favour of an electron transfer mechanism in the TiO2 photosensitized oxidation of benzyl derivatives in aqueous media
Ranchella, Michele,Rol, Cesare,Sebastiani, Giovanni V.
, p. 311 - 315 (2007/10/03)
The structure and/or distribution of products from the TiO2-sensitized photooxidation of some benzyl derivatives in aerated and/or deaerated aqueous media and in the presence of Ag2SO4 are reported. The results suggest that the single electron transfer process from the substrate to the photogenerated hole, previously proposed in CH3CN, should also be operative on gradually going from aqueous CH3CN to pure water.
