3688-24-2Relevant academic research and scientific papers
Total syntheses of (±)-gephyrotoxin and (±)-perhydrogephyrotoxin
Shirokane, Kenji,Tanaka, Yuya,Yoritate, Makoto,Takayama, Nobuaki,Sato, Takaaki,Chida, Noritaka
, p. 522 - 537 (2015)
This article describes the full details of our total syntheses of gephyrotoxin and perhydrogephyrotoxin. Our central strategy toward the total synthesis is based on the use of an N-methoxy group as a reactivity control element. The N-methoxyamide group enabled unique transformations, involving i) the direct coupling reaction of the N-methoxyamide with an aldehyde, and ii) the amide-selective reductive allylation. These reactions were never accomplished without the assistance of the N-methoxy group. The amide-selective reductive allylation of the N-methoxyamide was especially practical, and excluded a number of extra steps including protecting group manipulations and redox reactions in the total syntheses.
Rhodium-Catalyzed Desymmetrization of meso -Glutaric Anhydrides to Access Enantioenriched anti, anti -Polypropionates
Cochran, Brian M.,Henderson, Daniel D.,Thullen, Scott M.,Rovis, Tomislav
supporting information, p. 306 - 309 (2017/10/26)
An expedient desymmetrization of 3,5-dimethyl-4-alkoxyglutaric anhydrides to access anti, anti -polypropionates is described. The previously unknown anhydrides are rapidly assembled from readily available precursors. A Rh(I)· t -BuPHOX catalyst system was found to provide good yield and high selectivities. With these conditions, the trisubstituted anhydrides were desymmetrized with various alkyl zinc reagents to provide synthetically useful enantioenriched anti,anti -2,4-dimethyl-3-hydroxy-δ-ketoacids. An identical catalyst system also affords access to syn, syn -stereotriads as well as a partial kinetic resolution of a chiral anhydride.
Synthesis of tetrahydrobiphenylene via Pd(0)-catalyzed C(sp2)-H functionalization
Tsukano, Chihiro,Suetsugu, Satoshi,Muto, Nobusuke,Takemoto, Yoshiji
, p. 1167 - 1174 (2018/05/02)
Tetrahydrobiphenylene consists of cyclobutene fused with benzene and cyclohexene rings. In this paper, a direct method for synthesizing tetrahydrobiphenylenes based on a palladium (Pd)(0)-catalyzed C(sp2)-H functionalization was investigated. The developed method was applied to the synthesis of several tetrahydrobiphenylenes having an oxygen functionality at the ring juncture. The derivatization of a tetrahydrobiphenylene is also reported.
Stereodivergent synthesis of functionalized tetrahydropyrans accelerated by mechanism-based allylboration and bioinspired oxa-michael cyclization
Yang, Lin,Lin, Zuming,Huang, Sha-Hua,Hong, Ran
supporting information, p. 6280 - 6284 (2016/05/24)
A stereodivergent strategy enabled by bioinspired oxa-Michael cyclization was developed for the synthesis of functionalized tetrahydropyrans on the basis of the inherent symmetry in 1,3-diols, the symmetries of which were tunable by stereoselective hydroboration of an allene with a variety of alkylborane reagents and subsequent allylation of an aldehyde. The mechanism-based utilization of monoalkyl borane in the hydroboration and allylation cascade is unprecedented. Symmetry breakdown: The thermodynamic and kinetic hydroboration of allenes and subsequent allylboration provide a key stereodefinable module with a latent symmetry. Following a deprotection/chain elongation/oxa-Michael cyclization sequence, the stereocogeners of highly functionalized tetrahydropyrans were synthesized for rapid access to structural motifs found in bioactive polyketides.
Polyhomologation based on in situ generated boron-thexyl-silaboracyclic initiating sites: A novel strategy towards the synthesis of polyethylene-based complex architectures
Zhang, Zhen,Zhang, Hefeng,Gnanou, Yves,Hadjichristidis, Nikos
supporting information, p. 9936 - 9939 (2015/06/22)
A novel strategy, based on the in situ generated boron-thexyl-silaboracyclic initiating sites for the polyhomologation of dimethylsulfoxonium methylide, has been developed for the synthesis of complex polyethylene-based architectures. As examples, the synthesis of a 4-arm polyethylene star, three (polystyrene)(polyethylene)2 3-miktoarm stars and a PE-branched double graft copolymer is given.
Total synthesis of (±)-gephyrotoxin by amide-selective reductive nucleophilic addition
Shirokane, Kenji,Wada, Takamasa,Yoritate, Makoto,Minamikawa, Ryo,Takayama, Nobuaki,Sato, Takaaki,Chida, Noritaka
supporting information, p. 512 - 516 (2014/01/23)
A chemoselective approach for the total synthesis of (±)- gephyrotoxin has been developed. The key to success was the utilization of N-methoxyamides, which enabled the direct coupling of the amide with an aldehyde and selective reductive nucleophilic addition to the amide in the presence of a variety of sensitive and electrophilic functional groups, such as a methyl ester. This chemoselective approach minimized the use of protecting-group manipulations and redox reactions, which resulted in the most concise and efficient total synthesis of (±)-gephyrotoxin described to date. Aim for selectivity: A chemoselective approach that utilizes N-methoxyamides has been developed for the total synthesis of (±)-gephyrotoxin. The N-methoxy group enabled the direct coupling of the amide with an aldehyde and amide-selective reductive allylation in the presence of a more electrophilic methyl ester, which resulted in the most concise and efficient total synthesis of (±)-gephyrotoxin described to date.
Total synthesis and complete stereostructure of gambieric acid A
Fuwa, Haruhiko,Ishigai, Kazuya,Hashizume, Keisuke,Sasaki, Makoto
supporting information; experimental part, p. 11984 - 11987 (2012/09/08)
Total synthesis of gambieric acid A, a potent antifungal polycyclic ether metabolite, has been accomplished for the first time, which firmly established the complete stereostructure of this natural product.
Electron paramagnetic resonance and computational studies of radicals derived from boron-substituted N-heterocyclic carbene boranes
Walton, John C.,Brahmi, Malika Makhlouf,Monot, Julien,Fensterbank, Louis,Malacria, Max,Curran, Dennis P.,Lacote, Emmanuel
supporting information; experimental part, p. 10312 - 10321 (2011/08/21)
Fifteen second-generation NHC-ligated boranes with aryl and alkyl substituents on boron were prepared, and their radical chemistry was explored by electron paramagnetic resonance (EPR) spectroscopy and calculations. Hydrogen atom abstraction from NHC - BH
EPR studies of the generation, structure, and reactivity of n-heterocyclic carbene borane radicals
Walton, John C.,Brahmi, Malika Makhlouf,Fensterbank, Louis,Lacote, Emmanuel,Malacria, Max,Chu, Qianli,Ueng, Shau-Hua,Solovyev, Andrey,Curran, Dennis P.
supporting information; experimental part, p. 2350 - 2358 (2010/04/30)
N-Heterocyclic carbene boranes (NHC-boranes) are a new "clean" class of reagents suitable for reductive radical chain transformations. Their structures are well suited for their reactivity to be tuned by inclusion of different NHC ring units and by approp
TRIOXANE MONOMERS AND DIMERS
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Page/Page column 65, (2010/12/18)
Monomeric and dimeric trioxane fluoroaryl amides, 5-carbon-linked, C-10 non-acetal trioxane dimer esters; trioxane silylamides; and trioxane dimer orthoesters and methods of their use for treating subjects infected with malaria or other parasitic infectio
