28449-86-7Relevant academic research and scientific papers
Transition-Metal-Free Valorization of Biomass-derived Levulinic Acid Derivatives: Synthesis of Curcumene and Xanthorrhizol
Fu, Yao,Gong, Tian-Jun,Xu, Wen-Yan,Zhuo, Kai-Feng
, p. 884 - 891 (2020/12/13)
Levulinic acid (LA) is acknowledged one of the most promising biomass-derived platform molecules and can be transformed into various value-added chemicals. Here, we report a new reaction process for the valorization of LA derivatives under transition-meta
Catalytic activation of carbon-carbon bonds in cyclopentanones
Xia, Ying,Lu, Gang,Liu, Peng,Dong, Guangbin
, p. 546 - 550 (2017/04/01)
In the chemical industry, molecules of interest are based primarily on carbon skeletons. When synthesizing such molecules, the activation of carbon-carbon single bonds (C-C bonds) in simple substrates is strategically important: it offers a way of disconnecting such inert bonds, forming more active linkages (for example, between carbon and a transition metal) and eventually producing more versatile scaffolds. The challenge in achieving such activation is the kinetic inertness of C-C bonds and the relative weakness of newly formed carbon-metal bonds. The most common tactic starts with a three- or four-membered carbon-ring system, in which strain release provides a crucial thermodynamic driving force. However, broadly useful methods that are based on catalytic activation of unstrained C-C bonds have proven elusive, because the cleavage process is much less energetically favourable. Here we report a general approach to the catalytic activation of C-C bonds in simple cyclopentanones and some cyclohexanones. The key to our success is the combination of a rhodium pre-catalyst, an N-heterocyclic carbene ligand and an amino-pyridine co-catalyst. When an aryl group is present in the C3 position of cyclopentanone, the less strained C-C bond can be activated; this is followed by activation of a carbon-hydrogen bond in the aryl group, leading to efficient synthesis of functionalized α-tetralones - a common structural motif and versatile building block in organic synthesis. Furthermore, this method can substantially enhance the efficiency of the enantioselective synthesis of some natural products of terpenoids. Density functional theory calculations reveal a mechanism involving an intriguing rhodium-bridged bicyclic intermediate.
Heteroatom-directed Wacker oxidations. A protection-free synthesis of (-)-heliophenanthrone
Mukherjee, Parag,Sarkar, Tarun K.
supporting information; experimental part, p. 3060 - 3065 (2012/05/07)
The first enantioselective six-step synthesis of (-)-heliophenanthrone has been achieved without any protection-deprotection protocol at an overall yield of 28%. Key features of this synthesis comprise a heteroatom-directed Wacker oxidation of an internal cyclic olefin in addition to asymmetric Brown allylation and ring closing metathesis (RCM). The Royal Society of Chemistry 2012.
Erogorgiaene congeners and methods and intermediates useful in the preparation of same
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Page/Page column 29, (2010/04/30)
Disclosed are compounds having the formula: wherein R21 is an alkyl, aryl, alkoxy, hydroxy, or amino group or a halogen atom; wherein R2 is hydrogen or an alkyl, aryl, alkoxy, or amino group; wherein R23 and R24 are independently selected from hydrogen, an alkyl, aryl, alkoxy, hydroxy, or amino group, and a halogen atom or wherein R23 and R24, taken together with the carbon atom to which they are bound, form a ring; wherein R25 is hydrogen, an alkyl, aryl, alkoxy, hydroxy, or O-silyl group or a halogen atom; wherein Z, taken together with the carbons to which it is bonded, forms a 5-12 membered ring; and wherein Y is an electron withdrawing group. These compounds can be used to prepare erogorgiaene congeners, such as erogorgiaene, pseudopterosin A, helioporin E, pseudopteroxazole, colombiasin A, elisapoterosin B, elisabethadione, p-benzoquinone natural products, ileabethin, sinulobtain B, sinulobtain C, and sinulobtain D.
Activation of 1,1-difluoro-1-alkenes with a transition-metal complex: Palladium(II)-catalyzed friedel - crafts-type cyclization of 4,4-(difluorohomoallyl)arenes
Yokota, Misaki,Fujita, Daishi,Ichikawa, Junji
, p. 4639 - 4642 (2008/03/15)
(Chemical Equation Presented) Cationic palladium(II) ([Pd(MeCN) 4](BF4)2) provides the first transition-metal-catalyzed method for electrophilic activation of electron-deficient 1,1-difluoro-1-alkenes, which allows their Friedel-Crafts-type cyclization with an intramolecular aryl group via a Wacker-type process. By using BF3·OEt2, the cyclization was effected by a catalytic amount of the palladium without its reoxidation.
Direct synthesis of (+)-erogorgiaene through a kinetic enantiodifferentiating step
Davies, Huw M. L.,Walji, Abbas M.
, p. 1733 - 1735 (2007/10/03)
(Chemical Equation Presented) The combined approach of C-H activation and a Cope rearrangement catalyzed by a rhodium catalyst [Rh2(R-dosp) 4] (dosp = (N-dodecylbenzenesulfonyl)prolinate) is shown to be a very effective method for the construction of the three stereogenic centers (marked in red, see scheme) present in the diterpene erogorgiaene (1).
