683-60-3Relevant articles and documents
Unprecedented formation of cis- and trans-di[(3-chloropropyl) isopropoxysilyl]-bridged double-decker octaphenylsilsesquioxanes
Ervithayasuporn, Vuthichai,Sodkhomkhum, Rapheepraew,Teerawatananond, Thapong,Phurat, Chuttree,Phinyocheep, Pranee,Somsook, Ekasith,Osotchan, Tanakorn
, p. 3292 - 3296 (2013)
Silsesquioxane formation competing with the deprotonation of alcohol solvents in the presence of a strong base to form alkoxides is reported for the first time. Evidently, sodium isopropoxide is formed during the synthesis of the sodium salt of a double-decker octaphenylsilsesquioxane tetrasilanolate in 2-propanol as the solvent, which leads to the formation of unexpected cis- and trans-di[(3-chloropropyl)isopropoxysilyl]-bridged double-decker octaphenylsilsesquioxanes after in situ coupling with 3- chloropropyltrichlorosilane. The desired products were characterized by 1H NMR, 13C NMR, and 29Si NMR spectroscopy; ESI-MS; and single-crystal X-ray diffraction. During the synthesis of the sodium salt of double-decker octaphenylsilsesquioxane tetrasilanolate in 2-propanol, sodium isopropoxide is formed, which leads to the formation of unexpected cis- and trans-di[(3-chloropropyl)isopropoxysilyl]-bridged double-decker octaphenylsilsesquioxanes after in situ coupling with 3- chloropropyltrichlorosilane. Copyright
Catalytic Regioselective Olefin Hydroarylation(alkenylation) by Sequential Carbonickelation-Hydride Transfer
Liu, Chen-Fei,Luo, Xiaohua,Wang, Hongyu,Koh, Ming Joo
supporting information, p. 9498 - 9506 (2021/07/19)
Alkene hydrocarbofunctionalization represents one of the most important classes of chemical transformations, but related branched-selective examples with unactivated olefins are scarce. Here, we report that catalytic amounts of a dimeric Ni(I) complex and an exogenous alkoxide base promote Markovnikov-selective hydroarylation(alkenylation) of unactivated and activated olefins using organo bromides or triflates derived from widely available phenols and ketones. Products bearing aryl- and alkenyl-substituted tertiary and quaternary centers could be isolated in up to 95% yield and >99:1 regioisomeric ratios. Contrary to previous dual-catalytic methods that rely on metal-hydride atom transfer (MHAT) to the olefin prior to carbofunctionalization with a cocatalyst, our mechanistic evidence points toward a nonradical reaction pathway that begins with site-selective carbonickelation across the C═C bond followed by hydride transfer using alkoxide as the hydride source. Utility of the single-catalyst protocol is highlighted through the synthesis of medicinally relevant scaffolds.
NHC-CDI Betaine Adducts and Their Cationic Derivatives as Catalyst Precursors for Dichloromethane Valorization
Sánchez-Roa, David,Mosquera, Marta E. G.,Cámpora, Juan
, p. 16725 - 16735 (2021/11/18)
Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(p-Tol) betaine adduct (1a) and its cationic derivatives2aand3aas catalyst precursors for the dichloromethane valorization via transformation into high added value products CH2Z2(Z = OR, SR or NR2). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles Na+Z-(preformed or generatedin situfrom HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity. The reactions are conducted in a multigram-scale under very mild conditions, using dichloromethane both as a reagent and solvent, and very low catalyst loading (0.01 mol %). The CH2Z2derivatives were isolated in quantitative yields after filtration and evaporation, which facilitates recycling the dichloromethane excess. Mechanistic studies for the synthesis of methylal CH2(OMe)2rule out organocatalysis as being responsible for the CH2transfer, and a phase-transfer catalysis mechanism is proposed instead. Furthermore, we observed that1aand2areact with NaOMe to form unusual isoureate ethers, which are the actual phase-transfer catalysts, with a strong preference for sodium over other alkali metal nucleophiles.
