53034-13-2Relevant articles and documents
Direct Wittig Olefination of Alcohols
Li, Qiang-Qiang,Shah, Zaher,Qu, Jian-Ping,Kang, Yan-Biao
, p. 296 - 302 (2018/02/19)
A base-promoted transition metal-free approach to substituted alkenes using alcohols under aerobic conditions using air as the inexpensive and clean oxidant is described. Aldehydes are relatively difficult to handle compared to corresponding alcohols due to their volatility and penchant to polymerize and autoxidize. Wittig ylides are easily oxidized to aldehydes and consequently form homo-olefination products. By the strategy of simultaneously in situ generation of ylides and aldehydes, for the first time, alcohols are directly transferred to olefins with no need of prepreparation of either aldehydes or ylides. Thus, the di/monocontrollable olefination of diols is accomplished. This synthetically practical method has been applied in the gram-scale synthesis of pharmaceuticals, such as DMU-212 and resveratrol from alcohols.
2-Bromo[6]helicene as a Key Intermediate for [6]Helicene Functionalization
Jakubec, Martin,Beránek, Tomá?,Jakubík, Pavel,Sykora, Jan,?ádny, Jaroslav,Církva, Vladimír,Storch, Jan
, p. 3607 - 3616 (2018/04/14)
The synthesis of 2-bromo[6]helicene was revised and improved up to 51% yield. Its reactivity was thoroughly investigated, and a library of 17 different carbon, boron, nitrogen, phosphorus, oxygen and sulfur substituted derivatives was prepared. The racemization barrier for 2-bromo[6]helicene was determined, and the usage of enantiomers in the synthesis of optically pure helicenes was rationalized. The three most energy-demanding reactions using enantiomerically pure 2-bromo[6]helicene were tested in order to confirm the predicted enantiomeric excess.
Surface-assisted diastereoselective Ullmann coupling of bishelicenes
W?ckerlin, Christian,Li, Jingyi,Mairena, Ana?s,Martin, Kévin,Avarvari, Narcis,Ernst, Karl-Heinz
supporting information, p. 12694 - 12697 (2016/11/02)
Ullmann coupling of chiral 2-bromo[4]helicene has been performed on a Cu(100) surface. Only homochiral 2,2′-bis[4]helicene as the product is observed using STM. Such stereoselectivity is based on the fact that the surface will favour a configuration with
Synthesis of stilbene analogues by one-pot oxidation-Wittig and oxidation-Wittig-Heck reaction
Saiyed, Akeel S.,Patel, Krupa N.,Kamath, Bola V.,Bedekar, Ashutosh V.
supporting information; experimental part, p. 4692 - 4696 (2012/09/10)
Synthesis of symmetrical (and unsymmetrical) stilbene derivatives is achieved by a combination of one-pot steps of Kornblum type oxidation of benzyl halide, its simultaneous in situ formation of phosphonium salt, and subsequently their Wittig reaction. In other variant it is oxidized to aldehyde, treated with ylide generated from phosphonium salt (CH3PPh3X) to give styrene, and subjected to Pd catalyzed Heck reaction with arylhalide to give stilbenes as the three-step one-pot sequence.
Synthesis and characterization of a new hexacyclic helicene
Aloui, Faouzi,Moussa, Souad,Hassine, Béchir Ben
scheme or table, p. 3216 - 3219 (2012/08/08)
A new helically chiral hexacyclic system, bearing an acetoxymethyl group, was prepared from a simple naphthalene building block in good yield and purity, via a four-step sequence involving palladium-catalysed Heck couplings and oxidative photocyclizations
Mechanically induced solid-state generation of phosphorus ylides and the solvent-free wittig reaction
Balema, Viktor P.,Wiench, Jerzy W.,Pruski, Marek,Pecharsky, Vitalij K.
, p. 6244 - 6245 (2007/10/03)
We describe the nearly quantitative preparation of phosphorus ylides and the Wittig reaction occurring in the solid sate during high-energy mechanochemical processing. Initial insights into the details of the discovered chemical transformations indicate that high-energy mechanical processing supports the interaction of reacting centers by breaking crystallinity of the reactants and by providing mass transfer without a solvent. Copyright
1,2-shifts of hydrogen atoms in aryl radicals
Brooks, Michele A.,Scott, Lawrence T.
, p. 5444 - 5449 (2007/10/03)
An energy barrier on the order of 60 kcal/mol is predicted for the 1,2- shift of hydrogen atoms in aryl radicals. Such rearrangements are, therefore, not expected to occur under ordinary laboratory conditions, but they should be prevalent in the aryl radicals formed during combustion, flash vacuum pyrolysis, and other high-temperature gas-phase processes. As a demonstration of this rearrangement, the 2-benzo[c]phenanthryl radical (1) was generated by flash vacuum pyrolysis of the corresponding aryl bromide (9). A 1,2-shift of hydrogen out of the sterically congested cove region of 1, followed by cyclization and rearomatization of the resulting radical (Scheme 1), is proposed to explain the observation of benzo[ghi]fluoranthene (4) as the dominant monomeric product formed. Under the same conditions, [ 1,3,4,5- 2H4]-2-bromobenzo[c]phenanthrene (13) gives [ 1,2,3,4-2H4]- benzo[ghi]fluoranthene (15) as the dominant monomeric product (Scheme 6), in accord with the expectation of a deuterium atom 1,2-shift.
