13388-93-7Relevant academic research and scientific papers
A new efficient and selective synthesis of ketones from alkanes or cycloalkanes, CO, and silanes in the presence of aprotic superacids
Akhrem,Churilova,Orlinkov,Afanas'eva,Vitt,Petrovskii
, p. 918 - 923 (1998)
A new approach to the direct synthesis of ketones from alkanes or cycloalkanes (RH), CO, and silanes is proposed. Ketones were obtained in 50-97% yields from propane, butane, cyclopentane, cyclohexane, and methylcyclopentane on treatment with CO and silanes (Me4Si, Et4Si, or m-and p-XC6H4SiMe3, where X = Cl, Me, OMe) in the presence of CX4 · 2AlBr3 (X = Br, Cl) superacids at 0 °C. The reactions with m-and p-XC6H4SiMe3 (X = Cl, Me) occur regioselectively to give m-ketones from m-silanes and p-ketones from p-silanes. However, the only product, p-MeOC6H4COR, is formed both from m-and p-MeOC6H4SiMe3. The reaction of Cyclo-C5H9CO+ with BzSiMe3 results in an organosilicon ketone, Me3SiCH2QH4COC5H9, while in the presence of an excess of an acylating system (after alcoholysis), Me2Si(OR′)CH2C6H4COR is formed.
Synthesis of Vicinal Quaternary All-Carbon Centers via Acid-catalyzed Cycloisomerization of Neopentylic Epoxides
Schmid, Matthias,Sokol, Kevin R.,Wein, Lukas A.,Torres Venegas, Sofia,Meisenbichler, Christina,Wurst, Klaus,Podewitz, Maren,Magauer, Thomas
supporting information, p. 6526 - 6531 (2020/09/02)
We report our studies on the development of a catalytic cycloisomerization of 2,2-disubstituted neopentylic epoxides to produce highly substituted tetralins and chromanes. Termination of the sequence occurs via Friedel-Crafts-type alkylation of the remote (hetero)arene linker. The transformation is efficiently promoted by sulfuric acid and proceeds best in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as the solvent. Variation of the substitution pattern provided detailed insights into the migration tendencies and revealed a competing disproportionation pathway of dihydronaphthalenes.
Polymer-mediated pinacol rearrangements
Pavlik, Christopher,Morton, Martha D.,Smith, Michael B.
experimental part, p. 2191 - 2194 (2011/11/06)
Both poly(3,4-ethylenedioxythiophene) and poly(pyrrole) mediate a pinacol rearrangement of 1,2-diols. The yields of ketone or aldehyde products are comparable to those observed for treatment with mineral acids or Lewis acids. The advantage of this protocol is a two-phase reaction medium in hydrocarbon solvents that allows facile recovery of the products by simple filtration of the polymer and removal of solvents. Both the polymer and the hydrocarbon solvent may be recovered and used in subsequent reactions. Georg Thieme Verlag Stuttgart · New York.
Stereochemical Effects in the Gas-Phase Pinacol Rearrangement. 2. Ring Contraction versus Methyl Migration in cis- and trans-1,2-Dimethylcyclohexane-1,2-diol
Petris, Giulia de,Giacomello, Pierluigi,Pizzabiocca, Adriano,Renzi, Gabriele,Speranza, Maurizio
, p. 1098 - 1103 (2007/10/02)
The gas-phase pinacol rearrangement of cis- and trans-1,2-dimethylcyclohexane-1,2-diols, promoted by D3+, CH5+/C2H5+ and t-C4H9+ ions, was studied by mass spectrometric and radiolytic methods in the pressure range 0.5-760 Torr.When product isomerization is inhibited, by using N(CH3)3 as a trapping reagent at high pressure, mixtures of 2,2-dimethylcyclohexanone and 1-acetyl-1-methylcyclopentane were recovered from the reaction.In methane, the trend of measured relative rates for ring contraction (k5), methyl or hydroxyl group migration (k6) versus the rearrangement rate of pinacol itself (kp), is k6(trans) = k5(trans) > k5(cis) > k6(cis) > kp.No evidence for the formation of an intermediate carbenium ion was found.Stereochemical aspects of the mechanism are discussed and compared with solution data.
Ring Contraction of 2-Chlorocyclohexanone with Grignard Reagents
Hori, Mikio,Kataoka, Tadashi,Shimizu, Hiroshi,Imai, Eiji,Iwamura, Tatsunori,Maeda, Kaori
, p. 3599 - 3605 (2007/10/02)
The reaction of 2-chlorocyclohexanone with phenylmagnesium bromide in refluxing tetrahydrofuran unexpectedly afforded the ring-contracted product, cyclopentyl phenyl ketone, as the main product in moderate yield.The reactivities of several cyclic 2-haloketones were examined.Keywords - 2-chlorocyclohexanone; Grignard reaction; ring contraction; cyclopentyl phenyl ketone; solvent effect; THF; conformational isomer
Anodic Behaviour of Epoxides: Conditions for an Electron-transfer Chain Isomerisation induced by the Electrode
Delaunay, Jacques,Lebouc, Alain,Tallec, Andre,Simonet, Jacques
, p. 387 - 388 (2007/10/02)
The electrocatalytic isomerisation of epoxides is observed anodically in acetonitrile free from strong nucleophiles; the electrochemically induced isomerisation and the similar isomerisation caused by strong acids are compared.
Reaction of p-Nitrobenzenesulfonyl Azide with Alkylidenecycloalkanes
McManus, Samuel P.,Ortiz, Margarita,Abramovitch, Rudolph A.
, p. 336 - 342 (2007/10/02)
The 1,3-dipolar addition of p-nitrobenzenesulfonyl azide (PNBSA) to alkylidenecycloalkanes 1-3 was studied, and the products of hydrolysis were isolated and identified.The products from 1 and 2 suggest that these alkenes react to give a single triazoline intermediate.The tetrasubstituted derivatives 3, however, give both possible reaction modes.The products initially derived from 3 were the two sulfonimides expected from ring expansion (4, R=R'=Me) and methyl migration (5).Upon hydrolysis, the respective ketones, 8 and 9, were obtained in excellent overall yields.The ring-expanded sulfonimides 4 (R=R'=Me, n=6-8) were found to be less reactive under hydrolytic conditions than their respective isomers 5.Thus, subjecting the PNBSA adducts to mild hydrolysis conditions allowed the isolation of pure 9 (n=6-8).Also, in two cases (i.e., n=7,8), the pure imides 4 (R=R'=Me, n=7,8) crystallized from the hydrolysis solutions.Dipolar cycloaddition of p-nitrobenzenesulfonyl azide to 2-isopropylidenebicycloheptane followed by acid hydrolysis gives endo-2-acetyl-exo-2-methylbicycloheptane (4.1 percent), exo-2-acetyl-endo-2-methylbicycloheptane (16.3 percent), 2,2-dimethylbicyclooctan-3-one (2.1 percent), and 3,3-dimethylbicyclooctan-2-one (36.8 percent), thus providing evidence that electronic factors are much more important than steric effects in controlling regioselectivity.
Wanderungstendenzen cyclischer, polycyclischer und methylverzweigter Alkylreste bei der Beckmann-Umlagerung
Langhals, Heinz,Ruechardt, Christoph
, p. 3831 - 3854 (2007/10/02)
The migration aptitudes of polycyclic bridgehead groups, cycloalkyl groups as well as of β-, γ- and δ-branched alkyl groups in the Chapman variant of the Beckmann rearrangement were determined.From these data it is concluded that at transition state 2 the migrating group is not resembling a planarised carbenium ion R+, but rather a pentacoordinated carbonium ion structure.Because only small geometrical changes occur in the migrating group vertical stabilisation of charge at transition state is believed to have significant influence on the migration aptitudes.
