Oxidation vinylic

Indole, l-methyl-2-sulfonamido-tautomerism, 4, 200 Indole, l-methyl-3-sulfonamido-tautomerism, 4, 200 Indole, (methylthio)-synthesis, 4, 368 Indole, 3-(methylthio)-synthesis, 4, 338, 368 Indole, l-methyl-3-vinyl-oxidation, 4, 280 Indole, nitro-rearrangement, 4, 297 Indole, 3-nitro-nitration, 4, 211, 213 reduction, 4, 362 synthesis, 4, 210, 363 Indole, 5-nitro-synthesis, 4, 211, 363 Indole, nitroso-rearrangement, 4, 297 Indole, 1-nitroso-reduction, 4, 362 Indole, 3-nitroso-reduction, 4, 362 Indole, nitrovinyl-... 

Isoxazole, 3,5-dimethyl-4-(p-nitrophenyl)-bromination, 6, 51 Isoxazole, 3,5-dimethyl-4-vinyl-oxidation, 6, 27, 54 Isoxazole, diphenyl-mass spectra, 6, 6-7 Isoxazole, 3,4-diphenyl-... 

It is difficult for them to cover a risk situ on that depends on different parameters since a same risk ievei might cover situations that have nothing in common. So a comparison using physical factors of amyl oxide and vinyl oxide gives code 20 for the first because its autoinflammation temperature is less than 190°C though it has a flashpoint greater than 57°C, and 18 for the second for which the flashpoint is less than 0°C. 

The acidic properties of methanesulphonic acid that have just been mentioned have been responsible for two other accidents. When this acid is contact with methyl and vinyl oxide, this caused the latter to polymerise violently. The electrolysis of methanesulphonic acid with an aqueous solution of hydrogen fluoride gives rise to a violent detonation that was put down to the formation of oxygen difluoride that is explosive. 

Alkenes can be transformed to carbonyl compounds through the oxidation of the vinylic carbon atom. A special case of vinylic oxidation is acetoxylation of alkenes and dienes. 

Palladium-catalyzed allylic oxidations, in contrast, are synthetically useful reactions. Palladium compounds are known to give rise to carbonyl compounds or products of vinylic oxidation via nucleophilic attack on a palladium alkene complex followed by p-hydride elimination (Scheme 9.16, path a see also Section 9.2.4). Allylic oxidation, however, can be expected if C—H bond cleavage precedes nucleophilic attack 694 A poorly coordinating weak base, for instance, may remove a proton, allowing the formation of a palladium rr-allyl complex intermediate (89, path by694-696 Under such conditions, oxidative allylic substitution can compete... 

Vinylic Oxidation. Various alkenes are oxidized to the corresponding ketones using fm-BuOOH in the presence of Pd(II) catalysts bearing perfluorinated ligands in a fluorous biphasic system.1309 The catalyst can be reused, but progressively longer reaction times are required. 

Imidazole, l,2,5-trimethyl-4-nitro-mass spectra, 5, 359 Imidazole, 1-trimethylsilyl-reactions, 5, 454 with acid chlorides, 5, 391 Imidazole, 1-trimethylstannyl-reactions, 5, 454 Imidazole, 2,4,5-trinitro-reactions, 5, 98 synthesis, 5, 395 Imidazole, 1,2,4-triphenyl-UV spectra, 5, 356 Imidazole, 1,2,5-triphenyl-UV spectra, 5, 356 Imidazole, 2,4,5-triphenyl-chemiluminescence, 5, 381, 406 irradiation, 5, 433 oxidation, 5, 376, 406 photochemical addition reactions, 5, 421 synthesis, 5, 467, 483 UV spectra, 5, 356, 357 Imidazole, 1-trityl-rearrangement, 5, 377 Imidazole, vinyl-Michael addition, 5, 437 polymers, 1, 281 Imidazole, 1-vinyl-reactions, 5, 450 thermal rearrangement, 5, 450 Imidazole, 2-vinyl-oxidation, 5, 437 Imidazole, l-(D-xylofuranosyl)-synthesis, 5, 491 277-Imidazole, 2,2-dialkyl-rearrangement, 5, 422 277-Imidazole, 4,5-dicyano-2,2-dimethyl-synthesis, 5, 472... 

Most of the reactions listed in Table 6 involve prior activation of the substrate by coordination to palladium in the form of a v-, a 77-ally lie, a 77-benzylic, or an alkyl or aryl complex. Once coordinated to the metal, the substrate becomes an electron acceptor and can react with a variety of different nucleophiles. The addition of nucleophiles (Nu) to the coordinated substrate may occur in two different ways, as shown by Scheme 9 for 7r-alkene complexes 397"399 (a) external attack leading to trans addition of palladium and nucleophile across the 77-system (path A) or (b) internal addition of the coordinated nucleophile to the complexed alkene resulting in cis addition of palladium and nucleophile to the double bond. The cis and trans adducts (120) and (121) may then undergo /3-hydride elimination (/3-H), producing the vinylic oxidation product... 

The cyclic substrate 32 and other disubstituted olefins such as 35a were oxidized in sc C02 to give the corresponding epoxides with reasonable rates (>95% conversion in less than 18 h) and excellent selectivities (>98%) under otherwise similar reaction conditions (Loeker and Leitner, 2000). It is important to note, however, that no addition of a metal catalyst was required in the supercritical reaction medium. Detailed control experiments revealed that the stainless steel of the reactor walls served as efficient initiator for the epoxidation under these conditions. Terminal olefins 35b,c were oxidized with somewhat reduced rates and either epoxidation or vinylic oxidation occurred as the major reaction pathway depending on the substrate (eq. 5.11). Apart from providing the first examples for efficient and highly selective oxidation with 02 in sc C02 (earlier attempts Birnbaum et al., 1999 Loeker et al., 1998 Wu et ah, 1997), this study points to the possible importance of wall effects during catalytic reactions in this medium (see also Christian et ah, 1999 Suppes et ah, 1989). 

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