18410-58-7Relevant academic research and scientific papers
SOME GROUP IVB DERIVATIVES OF 1,6-METHANOANNULENE. SYNTHESIS, SUBSTITUENT EFFECTS AND REACTIVITY
Kitching, William,Olszowy, Henry A.,Schott, Inge,Adcock, William,Cox, D. P.
, p. 269 - 284 (1986)
Certain Group IVB derivatives of 1,6-methanoannulene have been synthesised, and their 13C nuclear magnetic resonance spectra recorded and assigned, to provide a measure of the substituent effects exerted by metalloid-containing groups in this non-benzenoid aromatic system.Comparisons are made with the corresponding naphthalene and some anthracene derivatives.Protiodemetallations of a number of arylsilanes and -stannanes have been examined, and in protiodestannyletion by CH3CO2H/dioxane at 27 deg C (an electrophilic aromatic substitution) the α- (or 2-) posititon of 1,6-methanoannulene is ca. 35 times as reactive as the α (or 1-) position of naphthalene, whereas in protiodesilylation by CF3CO2H/CH3CO2H at 27 deg C it is ca. 700 times the more reactive.
Nickel(0)-Catalyzed Inert C-O Bond Functionalization: Organo Rare-Earth Metal Complex as the Coupling Partner
Yan, Xiangqian,Yang, Fanzhi,Cai, Guilong,Meng, Qingwei,Li, Xiaofang
, p. 624 - 627 (2018)
An organo rare-earth metal complex has been employed as a highly efficient nucleophile in Ni(0)-catalyzed C-O bond functionalization. The optimized catalytic system which consists of Ni(cod)2, PCy3, and t-BuONa could smoothly convert 1 equiv of naphthyl ethers to alkylated naphthalene analogues with 0.4 equiv of Ln(CH2SiMe3)3(THF)2, delivering good to excellent yields. The reaction system could also activate the ArCH2-O bond with mild base.
Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
supporting information, p. 1799 - 1802 (2019/01/25)
Direct palladium-catalysed cross-couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross-coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E-factor as low as 7.35.
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.
Nickel-Catalyzed Csp2-Csp3 Bond Formation via C-F Bond Activation
Ho, Yee Ann,Leiendecker, Matthias,Liu, Xiangqian,Wang, Chengming,Alandini, Nurtalya,Rueping, Magnus
supporting information, p. 5644 - 5647 (2018/09/12)
A nickel-catalyzed cross coupling of aryl fluorides via C-F bond activation has been developed. The alkylation method allows selective replacement of aryl fluorides by alkyl groups and enables the synthesis of diverse and otherwise difficult to access scaffolds in good yields.
Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
supporting information, p. 3354 - 3359 (2017/03/17)
The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
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.
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.
Metal-catalyzed dealkoxylative Caryl-C sp 3 cross-coupling - Replacement of aromatic methoxy groups of aryl ethers by employing a functionalized nucleophile
Leiendecker, Matthias,Hsiao, Chien-Chi,Guo, Lin,Alandini, Nurtalya,Rueping, Magnus
supporting information, p. 12912 - 12915 (2016/02/18)
The direct replacement of aromatic methoxy groups with activated carbon nucleophiles would give rise to novel synthetic pathways for targeted and diversity-oriented syntheses. We demonstrate here that this transformation can be achieved in a one-step reac
