6610-21-5Relevant academic research and scientific papers
Platinum-Catalyzed α,β-Desaturation of Cyclic Ketones through Direct Metal–Enolate Formation
Chen, Ming,Dong, Guangbin
supporting information, p. 7956 - 7961 (2021/03/01)
The development of a platinum-catalyzed desaturation of cyclic ketones to their conjugated α,β-unsaturated counterparts is reported in this full article. A unique diene-platinum complex was identified to be an efficient catalyst, which enables direct metal-enolate formation. The reaction operates under mild conditions without using strong bases or acids. Good to excellent yields can be achieved for diverse and complex scaffolds. A wide range of functional groups, including those sensitive to acids, bases/nucleophiles, or palladium species, are tolerated, which represents a distinct feature from other known desaturation methods. Mechanistically, this platinum catalysis exhibits a fast and reversible α-deprotonation followed by a rate-determining β-hydrogen elimination process, which is different from the prior Pd-catalyzed desaturation method. Promising preliminary enantioselective desaturation using a chiral-diene-platinum complex has also been obtained.
Enantio- and Diastereodivergent Sequential Catalysis Featuring Two Transition-Metal-Catalyzed Asymmetric Reactions
Abel-Snape, Xavier,Lautens, Mark,Masson-Makdissi, Jeanne,Prieto, Liher
supporting information, p. 16932 - 16936 (2021/07/02)
This study demonstrates the feasibility and inherent benefits of combining two distinct asymmetric transition-metal-catalyzed reactions in one pot. The reported transformation features a Pd-catalyzed asymmetric allylic alkylation and a Rh-catalyzed enantioselective 1,4-conjugate addition, effectively converting simple allyl enol carbonate precursors into enantioenriched cyclic ketones with two remote stereocenters. Despite the anticipated challenges associated with controlling stereoselectivity in such a complex system, the products are obtained in enantiomeric excesses ranging up to >99 % ee, exceeding those obtained from either of the individual asymmetric reactions. In addition, since the stereoselectivity of both steps is under catalyst control, this one-pot reaction is enantio- and diastereodivergent, enabling facile access to all stereoisomers from the same set of starting materials.
CeO2-Supported Pd(II)-on-Au Nanoparticle Catalyst for Aerobic Selective α,β-Desaturation of Carbonyl Compounds Applicable to Cyclohexanones
Jin, Xiongjie,Mizuno, Noritaka,Takei, Daisuke,Yabe, Tomohiro,Yamaguchi, Kazuya,Yatabe, Takafumi
, p. 5057 - 5063 (2020/05/27)
Direct selective desaturation of carbonyl compounds to synthesize α,β-unsaturated carbonyl compounds represents an environmentally benign alternative to classical stepwise procedures. In this study, we designed an ideal CeO2-supported Pd(II)-on-Au nanoparticle catalyst (Pd/Au/CeO2) and successfully achieved heterogeneously catalyzed selective desaturation of cyclohexanones to cyclohexenones using O2 in air as the oxidant. Besides cyclohexenones, various bioactive enones can also be synthesized from the corresponding saturated ketones under open air conditions in the presence of Pd/Au/CeO2. Preliminary mechanistic studies revealed that α-C-H bond cleavage in the substrates is the turnover-limiting step of this desaturation reaction.
Total Synthesis of (-)-Xylogranatopyridine B via a Palladium-Catalyzed Oxidative Stannylation of Enones
Schuppe, Alexander W.,Huang, David,Chen, Yifeng,Newhouse, Timothy R.
, p. 2062 - 2066 (2018/02/19)
We report a total synthesis of the pyridine-containing limonoid alkaloid (-)-xylogranatopyridine B in 11 steps from commercially available dihydrocarvone. The central pyridine ring was assembled by a late-stage fragment coupling approach employing a modified Liebeskind pyridine synthesis. One fragment was prepared by an allyl-palladium catalyzed oxidative enone β-stannylation, in which the key bimetallic β-stannyl palladium enolate intermediate undergoes a β-hydride elimination. This methodology also allowed introduction of alkyl and silyl groups to the β-position of enones.
Bismuth-substituted "sandwich" type polyoxometalate catalyst for activation of peroxide: Umpolung of the peroxo intermediate and change of chemoselectivity
Amanchi, Srinivasa Rao,Khenkin, Alexander M.,Diskin-Posner, Yael,Neumann, Ronny
, p. 3336 - 3341 (2015/06/16)
The epoxidation of alkenes with peroxides by WVI, MoVI, VV, and TiIV compounds is well established, and it is well accepted that the active intermediate peroxo species are electrophilic toward nucleophilic substrates. Polyoxotungstates, for example, those of the "sandwich" structure, [WZn(TM-L)2(ZnW9O34)2]q- in which TM = transition metal and L = H2O, have in the past been found to be excellent epoxidation catalysts. It has now been found that substituting the Lewis basic BiIII into the terminal position of the "sandwich" polyoxometalate structure to yield [Zn2BiIII2(ZnW9O34)2]14- leads to an apparent umpolung of the peroxo species and formation of a nucleophilic peroxo intermediate. There are two lines of evidence that support the formation of a reactive nucleophilic peroxo intermediate: (1) More electrophilic sulfoxides are more reactive than more nucleophilic sulfides, and (2) nonfunctionalized aliphatic alkenes and dienes showed ene type reactivity rather than epoxidation pointing toward "dark" formation of singlet oxygen from the nucleophilic intermediate peroxo species. Allylic alcohols reacted much faster than alkenes but showed chemoselectivity toward C-H bond activation of the alcohol and formation of aldehydes or ketones rather than epoxidation. This explained via alkoxide formation at the BiIII center followed by oxidative β-elimination.
2-Quinoxalinol diamine Cu(II) complex: Facilitating catalytic oxidation through dual mechanisms
Li, Yuancheng,Lee, Taebum,Weerasiri, Kushan,Wang, Tanyu,Buss, Emily E.,McKee, Michael L.,Gorden, Anne E. V.
, p. 13578 - 13583 (2014/11/08)
The Cu(II) complex 1, Cu(II)-6-N-3,5-di-tert-butylsalicylidene-6,7- quinoxalinol-diamine, has been developed to address problems with current methods of catalytic oxidation using tert-butyl hydroperoxide (TBHP). Complex 1 demonstrated an increased capability to utilize TBHP while limiting interference from free radical reactions and was demonstrated to be highly effective in the oxidations of a variety of olefins. the Partner Organisations 2014.
Structure confirmation of a bioactive lactone isolated from Otoba parvifolia through the synthesis of a model compound
Marques, Francisco A.,Lenz, Cesar A.,Simonelli, Fabio,Noronha Sales Maia, Beatriz Helena L.,Vellasco, Adriana P.,Eberlin, Marcos N.
, p. 1939 - 1941 (2008/04/18)
Synthesis of a model compound 4 structurally related to a bioactive lactone 3 isolated from Otoba parvifolia has been accomplished. The good match between the NMR data of both compounds suggests they have identical bicyclic [3.3.1] carbon skeletons.
Synthetic Applications in Radical/Radical Cationic Cascade Reactions
Rinderhagen, Heiko,Mattay, Jochen
, p. 851 - 874 (2007/10/03)
Oxidative photoinduced electron transfer (PET) reactions have been performed with various cyclic cyclopropyl(vinyl) silyl ethers bearing an olefinic or acetylenic side chain. The reactions result in bi- to tetracyclic ring systems via a fragmentation-radical/radical cationic addition reaction pathway with well defined ring juncture. The mode of cyclisation (endo/exo) can be partially controlled by addition of nucleophiles due to the suppression of radical cationic reaction pathways. Quantum chemical calculation of the cyclisation transition states underline the experimentally found selectivities. Additional mechanistic studies concerning the saturation step reveal that the final radical is saturated mostly by the solvent and traces of water in the solvent.
Synthesis of α,β-unsaturated ketones and esters using polymer-supported selenium bromide
Sheng, Shou-Ri,Liu, Xiao-Ling,Wang, Xing-Cong
, p. 279 - 281 (2007/10/03)
Treatment of the polymer-supported α-phenylseleno ketones and esters prepared from polymer-supported selenium bromide with ketone and ester enolates with hydrogen peroxide afford α,β-unsaturated ketones and esters in good yields and high purities.
Oxidation of silyl enol ethers by using IBX and IBX·N-oxide complexes: A mild and selective reaction for the synthesis of enones
Nicolaou,Gray, David L. F.,Montagnon, Tamsyn,Harrison, Scott T.
, p. 996 - 1000 (2007/10/03)
α,β-Unsaturated carbonyl compounds can be prepared by the oxidation of trimethylsilyl enol ethers with IBX (1) or IBX·MPO (2). A diverse set of carbonyl compounds can be dehydrogenated with ease by using this method. Trimethylsilyl enol ethers such as 4, which are formed in situ by the addition of an organometallic species to an enone, can be dehydrogenated with 1 or 2 to give a functionalized enone (e. g. 3 → 5). IBX = iodoxybenzoic acid; MPO = 4-methoxypyridine-N-oxide.
