102-04-5Relevant articles and documents
Evidence for a 1,4-dioxy diradical as an intermediate in the thermal decomposition of 3,3-dibenzyl-1,2-dioxetane
Adam, Waldemar,Heil, Markus
, p. 8807 - 8809 (1992)
The thermal decomposition of 3,3-dibenzyl-1,2-dioxetane (1) in CDCl3 and CH2Cl2 solutions afforded the expected decomposition product 1,3-diphenyl-2-propanone (2) and the novel rearrangement ketone -(benzyloxy)-3-phenyl-2-propanone (3) in ratios of (73 ± 10):(27 ± 10). A plausible mechanism for the formation of ketone 3 involves homolytic cleavage of the dioxetane peroxide bond with subsequent β cleavage of the benzyl group in the 1,4-dioxy diradical and in-cage combination of the resulting radicals. Moreover, several control experiments render a benzyl radical-induced decomposition of dioxetane 1 unlikely Thus, the ratio of 2 and 3 was found to be essentially independent of the initial dioxetane concentration, and the presence of radical scavengers did not affect the product ratio and reaction rate. With the electron-rich 1,4-dioxene, the dioxetane 1 afforded the cycloadduct cis-3,3-dibenzyl-2,5,7,10-tetraoxabicyclo[4.4.0]decane (4) as major product.
Vapor-phase synthesis of symmetric ketone from alcohol over CeO2-Fe2O3 catalysts
Kamimura, Yoichiro,Sato, Satoshi,Takahashi, Ryoji,Sodesawa, Toshiaki,Fukui, Masahiro
, p. 232 - 233 (2000)
Formation of 3-pentanone via oxidative dimerization of 1-propanol was investigated over CeO2-based solid solution with various metal oxides. An addition of Fe2O3 into CeO2 greatly enhanced the 3-pentanone formation, and both 1-propanol conversion and 3-pentanone selectivity were maximized at Fe content of 20 mol%. It was found that the CeO2-Fe2O3 effectively works as a catalyst for the formation of symmetric ketones such as 3-pentanone, 4-heptanone, 5-nonanone, etc.
Nickel-catalyzed cyanation of aryl halides and triflates using acetonitrile: Via C-CN bond cleavage assisted by 1,4-bis(trimethylsilyl)-2,3,5,6-tetramethyl-1,4-dihydropyrazine
Ueda, Yohei,Tsujimoto, Nagataka,Yurino, Taiga,Tsurugi, Hayato,Mashima, Kazushi
, p. 994 - 999 (2019)
We developed a non-toxic cyanation reaction of various aryl halides and triflates in acetonitrile using a catalyst system of [Ni(MeCN)6](BF4)2, 1,10-phenanthroline, and 1,4-bis(trimethylsilyl)-2,3,5,6-tetramethyl-1,4-dihydropyrazine (Si-Me4-DHP). Si-Me4-DHP was found to function as a reductant for generating nickel(0) species and a silylation reagent to achieve the catalytic cyanation via C-CN bond cleavage.
Iron complexes of a bidentate picolyl-NHC ligand: Synthesis, structure and reactivity
Liang, Qiuming,Janes, Trevor,Gjergji, Xhoana,Song, Datong
, p. 13872 - 13880 (2016)
The synthesis, structure and reactivity of bidentate picolyl N-heterocyclic carbene (NHC) iron compounds were studied. Compounds [FeBr(HL)2]Br (1), [FeBr(HL)(HMDS)] (2) and [FeBr2(HL)] (3) (HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-1-ylidene, HMDS = hexamethyldisilazide) were prepared from H2LBr with suitable amounts of Fe(HMDS)2 or in situ prepared [Fe(HMDS)Br]. The deprotonation of 1 with 2 eq. of LiHMDS gave [FeL2] (4), featuring dearomatized pyridine moieties with exocyclic C-C double bonds. The protonation of 4 with 2 eq. of PPh3·HBr results in the formation of 1. Attempted deprotonation of 3 using benzyl Grignard as the base resulted in transmetalation products [FeBnBr(HL)] (5) and [FeBn2(HL)] (6). Exposure of 6 to CO resulted in the formation of diamagnetic compound [Fe(CO)3(HL)] (7) and dibenzyl ketone. Prolonged exposure of 7 to CO with heating induces pyridine dissociation, affording [Fe(CO)4(HL-κC)] (8). Treatment of compound 6 with an equimolar amount of p-methoxybenzyl bromide yielded homo- and cross-coupling products.
Carbonylative coupling of organozinc reagents in the presence and absence of aryl iodides: Synthesis of unsymmetrical and symmetrical ketones
Jackson, Richard F. W.,Turner, Debra,Block, Michael H.
, p. 865 - 870 (1997)
The utility of the palladium(o) catalysed reaction of the iodoalanine-derived organozinc reagent 6a with functionalised aryl iodides, under a carbon monoxide atmosphere, to give protected 4-aryl-4-oxo α-amino acids 8, is illustrated by a short synthesis of L-kynurenine 4. Treatment of functionalised organozinc reagents with catalytic tetrakis(triphenylphosphine)palladium(0) under an atmosphere of carbon monoxide in the absence of any electrophile leads to the formation of symmetrical functionalised ketones 9 in good yields. This reaction is illustrated by a one-step synthesis of protected (2S,6S)-4-oxo-2,6-diaminopimelic acid 9a from commercially available compounds. It has been established that adventitious molecular oxygen plays a key role in the formation of the symmetrical ketones 9, and that rigorous exclusion of oxygen can result in substantially higher yields of ketones 8 in the cross-coupling with some aromatic iodides.
Bismuth compounds in organic synthesis. Deprotection of ketoximes using bismuth bromide-bismuth triflate
Arnold, Joshua N.,Hayes, Patrick D.,Kohaus, Robert L.,Mohan, Ram S.
, p. 9173 - 9176 (2003)
Ketoximes undergo deprotection in CH3CN/acetone/H2O (3:6:1) in the presence of 20-40 mol percent BiBr3/5 mol percent Bi(OTf)3. Bismuth(III) salts are relatively non-toxic, insensitive to air and inexpensive. These features coupled with the use of a relatively non-toxic solvent system make this method an attractive alternative to existing routes for deprotection of ketoximes.
ELCTROCHEMICAL PREPARATION AND REACTIONS OF UNMASKED ACYL-ANION SYNTHONS
Yoshida, Kunihisa,Kunugita, Ei-ichi,Kobayashi, Masaru,Amano, Sei-ichi
, p. 6371 - 6374 (1989)
Organic halides can be converted into carbonyl compounds by electroreducing a mixture of them and Fe(CO)5 in acetonitrile first and adding an electrophile to this mixture.
Cathodic carbonylation. Synthesis of aliphatic aldehydes using an electroreductively generated iron-carbonyl anion
Yoshida, Kunihisa,Kuwata, Hideki
, p. 1873 - 1877 (1996)
Alkyl halides are electroreductively coupled with pentacarbonyliron to generate the acyliron complexes. After hydrolytic work-up, these anionic acyl compounds produce aldehydes in good yields. The best results were obtained with the bromide as starting halide. The first step in the formation of acyliron complexes is the direct cathodic reduction of [Fe(CO)5] to the anionic species. Synthetic and mechanistic aspects of the reaction are discussed.
Mechanism of the nickel-catalyzed electrosynthesis of ketones by heterocoupling of acyl and benzyl halides
Amatore, Christian,Jutand, Anny,Perichon, Jacques,Rollin, Yolande
, p. 1293 - 1304 (2000)
The mechanism of the nickel-catalyzed electrosynthesis of ketones by heterocoupling of phenacyl chloride and benzyl bromide has been investigated by fast scan rate cyclic voltammetry with [Ni(bpy)2+3](BF-4)2 as the catalytic precursor (bpy = 2,2′-bipyridine). The key step is an oxidative addition of Ni0(bpy) (electrogenerated by reduction of the Ni(II) precursor) to PhCH2Br whose rate constant is found to be 10 times higher than that of PhCH2COCl. The complex PhCH2NiIIBr(bpy) formed in the oxidative addition is reduced at the potential of the NiII/Ni0 reduction by a two-electron process which affords an anionic complex PhCH2Ni0(bpy)- able to react with PhCH2COCl to generate eventually the homocoupling product PhCH2COCH2Ph. The formation of the homocoupling product PhCH2COCOCH2Ph is prevented because of the too slow oxidative addition of Ni0(bpy) to PhCH2COCl compared to PhCH2Br. The formation of the homocoupling product PhCH2CH2Ph is also prevented because PhCH2Ni0(bpy)- does not react with PhCH2Br. This explains why the electrosynthesis of the ketone can be performed selectively in a one-pot procedure, starting from an equal mixture of PhCH2COCl and PhCH2Br and a nickel catalyst ligated by the bpy ligand.
A mechanistic model for the selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid
Corey,Palani, Anandan
, p. 7945 - 7948 (1995)
The selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid occurs by a rate-limiting carbonyl-forming elimination pathway in which the carbinol proton is abstracted internally via a six-atom cyclic arrangement, which explains the observed selectivity.
