25017-68-9Relevant articles and documents
Selective benzylic C–H monooxygenation mediated by iodine oxides
LaMartina, Kelsey B.,Kuck, Haley K.,Oglesbee, Linda S.,Al-Odaini, Asma,Boaz, Nicholas C.
supporting information, p. 602 - 609 (2019/04/17)
A method for the selective monooxdiation of secondary benzylic C–H bonds is described using an N-oxyl catalyst and a hypervalent iodine species as a terminal oxidant. Combinations of ammonium iodate and catalytic N-hydroxyphthalimide (NHPI) were shown to be effective in the selective oxidation of n-butylbenzene directly to 1-phenylbutyl acetate in high yield (86%). This method shows moderate substrate tolerance in the oxygenation of substrates containing secondary benzylic C–H bonds, yielding the corresponding benzylic acetates in good to moderate yield. Tertiary benzylic C–H bonds were shown to be unreactive under similar conditions, despite the weaker C–H bond. A preliminary mechanistic analysis suggests that this NHPI-iodate system is functioning by a radical-based mechanism where iodine generated in situ captures formed benzylic radicals. The benzylic iodide intermediate then solvolyzes to yield the product ester.
Oxidation of alkylarenes by nitrate catalyzed by polyoxophosphomolybdates: Synthetic applications and mechanistic insights
Khenkin, Alexander M.,Neumann, Ronny
, p. 6356 - 6362 (2007/10/03)
Alkylarenes were catalytically and selectively oxidized to the corresponding benzylic acetates and carbonyl products by nitrate salts in acetic acid in the presence of Keggin type molybdenum-based heteropolyacids, H3+xPVxMo12-xO40 (x = 0-2). H 5PV2Mo10O40 was especially effective. For methylarenes there was no over-oxidation to the carboxylic acid contrary to what was observed for nitric acid as oxidant. The conversion to the aldehyde/ketone could be increased by the addition of water to the reaction mixture. As evidenced by IR and 15N NMR spectroscopy, initially the nitrate salt reacted with H5PV2Mo10O 40 to yield a NVO2+[H 4PV2Mo10O40] intermediate. In an electron-transfer reaction, the proposed NVO2 +[H4PV2Mo10O40] complex reacts with the alkylarene substrate to yield a radical-cation-based donor-acceptor intermediate, NIVO2[H4PV 2Mo10O40]-ArCH2R+.. Concurrent proton transfer yields an alkylarene radical, ArCHR., and NO2. Alternatively, it is possible that the NVO 2+[H4PV2Mo10O 40] complex abstracts a hydrogen atom from alkylarene substrate to directly yield ArCHR. and NO2. The electron transfer-proton transfer and hydrogen abstraction scenarios are supported by the correlation of the reaction rate with the ionization potential and the bond dissociation energy at the benzylic positions of the alkylarene, respectively, the high kinetic isotope effect determined for substrates deuterated at the benzylic position, and the reaction order in the catalyst. Product selectivity in the oxidation of phenylcyclopropane tends to support the electron transfer-proton transfer pathway. The ArCHR. and NO2 radical species undergo heterocoupling to yield a benzylic nitrite, which undergoes hydrolysis or acetolysis and subsequent reactions to yield benzylic acetates and corresponding aldehydes or ketones as final products.
REACTIONS OF TRIALKYL PHOSPHITES WITH KETONES IN THE PRESENCE OF PROTON-DONOR REACTANTS. I. REACTION OF TRIMETHYL PHOSPHITE WITH FLUORENONE IN THE PRESENCE OF ACETIC ACID
Fuzhenkova, A. V.,Tyryshkin, N. I.
, p. 76 - 80 (2007/10/02)
Trimethyl phosphite reacts with fluorenone in the presence of acetic acid to give dimethyl 9-fluorenyl phosphate, 9-fluorenyl acetate, and hydroxyfluorene.The data obtained indicate that ketones react with trialkyl phosphites in the presence of carboxylic acids to give phosphonates and acetonates with a geminal position of the proton and the corresponding group, and also products of ketone reduction.
Benzylic Bromination-Acetoxylation of Toluenes by Bromide Ion Catalyzed Thermal Decomposition of Peroxydisulfate in Acetic Acid in the Presence of Acetate Ions
Citterio, Attilio,Santi, Roberto,Pagani, Anselmo
, p. 4925 - 4927 (2007/10/02)
Side-chain bromination and acetoxylation of alkylaromatics by halide ion induced decomposition of potassium peroxydisulfate in acetic acid have been studied by product analysis techniques.Catalytic amounts of lithium bromide in the presence of sodium acetate were found effective in promoting benzylic bromination, followed by conversion to the corresponding benzyl acetates by reaction with acetate.The reaction is interpreted to take place by the redox and free-radical chain mechanism involving bromine atoms (ρ = -1.38 vs. ? + for substituted toluenes).In competiti ve experiments, benzyl and 4-nitrobenzyl acetates were found lees reactive than the corresponding toluenes in acetic acid with the couple S2O82-/Br- but more reactive in carbon tetrachloride with N-bromosuccinimide.
