- Short eight-steps total synthesis of racemic asteriscunolide C
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A concise total synthesis of racemic asteriscunolide C in eight steps has been described starting from neopentane diol involving an efficient Yamaguchi esterification using an aldehyde-acid, intramolecular Horner–Wittig–Emmons olefination, and a late stage ring-closing metathesis to construct the strained 11-membered ring with one Z- and two E-double bonds.
- Fernandes, Rodney A.,Chavan, Vijay P.,Panja, Arpita
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- Synthesis and character of new bis(isoxazoline) ligands
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Synthesis of two kinds of new bis(isoxazoline) ligand, achiral 2,2'bis(isoxazolinyl)propane and (R)-2,2'-bis(isoxazolinyl)-1,1'-binaphthyl bearing an axial chirality is described. Both of the bis(isoxazoline) ligands accelerated the Pd(II)-catalyzed Wacker-type cyclization of alkenyl alcohol. The isoxazoline ligands were found to be essential to promote the cyclization.
- Shinohara, Toshio,Wakita, Kazuhiko,Arai, Midori A.,Arai, Takayoshi,Sasai, Hiroaki
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- Synthesis of the macrocyclic core of rhizopodin
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Rhizing star: A stereoselective synthesis of the fully functionalized macrocyclic core of rhizopodin, a cytotoxic 38-membered macrolide, has been disclosed. The key steps involve Sharpless epoxidation, Robinson-Gabriel oxazole synthesis, olefin cross-metathesis, Suzuki coupling, Yamaguchi esterificationn, and Shiina macrolactonization. Copyright
- Song, Liankai,Liu, Junyang,Gui, Honggang,Hui, Chunngai,Zhou, Jingjing,Guo, Yian,Zhang, Pengpeng,Xu, Zhengshuang,Ye, Tao
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- Synthesis of Tc-D,D-HMPAO and Tc-L,L-HMPAO and their comparison of chemical and biological properties
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Tc-D,D- and Tc-L,L-HMPAO were synthesized. The stability of Tc-D,D- and Tc-L,L-HMPAO in vitro is similar to that of d,l-isomers by the spectrophotometric and three strips methods. Cerebral uptake (%D in brain) for the L,L-isomer is higher than the D,D- and d,l-isomer in rats. Delayed studies shows that Tc-L,L-HMPAO reveals less washout and reflects a higher cerebral deposition properties than the D,D- and d,l-isomer.
- Ding, Hueisch-Jy,Huang, Ying-Fong,Tzeng, Cherng-Chyi,Wei, Li-Mei,Yeh, Si-Jung
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- The smallest cucurbituril analogue with high affinity for Ag+
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A new host, Me8TD[4], was prepared for the first time from propanediurea-formaldehyde condensation in the presence of CaCl2 as the template and it is the smallest cucurbituril analogue reported so far. Measurements of the thermodynamic quantities (log K, ΔH, and ΔS values) of the interactions of Me8TD[4] with a series of cations by isothermal titration calorimetry indicated that Me8TD[4] binds selectively towards Ag+ with a high binding constant, K ~ 1.3 × 106 M-1.
- Wu, Yufan,Xu, Lixi,Shen, Yenan,Wang, Yang,Zou, Lei,Wang, Qiaochun,Jiang, Xiaoqing,Liu, Jiansen,Tian, He
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- Development of chiral bis-hydrazone ligands for the enantioselective cross-coupling reactions of aryldimethylsilanolates
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A palladium-catalyzed, enantioselective, aryl-aryl cross-coupling reaction using 1-naphthyldimethylsilanolates and chiral bis-hydrazone ligands has been developed. A family of glyoxal bis-hydrazone ligands containing various 2,5-diarylpyrrolidine groups was prepared to evaluate the influence of ligand structure on the rate and enantioselectivity of the cross-coupling. New synthetic routes to the 1-amino-2,5-diarylpyrrolidines were developed to enable the structure/reactivity-selectivity studies. Role reversal experiments of aryldimethylsilanolates and aryl bromides result in biaryl products with the same configuration and similar enantioselectivities implying that reductive elimination is the stereodetermining step. The origin of stereoselectivity is rationalized through computational modeling of diarylpalldium(II) complex which occurs through a conrotatory motion for the two aryl groups undergoing C-C bond formation.
- Denmark, Scott E.,Chang, Wen-Tau T.,Houk,Liu, Peng
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supporting information
p. 313 - 366
(2016/09/09)
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- A mechanistic model for the selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid
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The selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid occurs by a rate-limiting carbonyl-forming elimination pathway in which the carbinol proton is abstracted internally via a six-atom cyclic arrangement, which explains the observed selectivity.
- Corey,Palani, Anandan
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p. 7945 - 7948
(2007/10/02)
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- Synthesis of the Tetrahydrofuran Ring Part of a Marine Toxin Polycavernoside-A
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Construction of the tetrahydrofuran ring part of polycavernoside A, which has been isolated as one of toxic principles from the red alga Polycavernosa tsudai, is described starting from 2,2-dimethylpropane-1,3-diol.The synthesis involves the Sharpless epoxidation and the Evans procedure for introduction of the three chiral centers.
- Hayashi, Nobuyuki,Mine, Takaaki,Fujiwara, Kenshu,Murai, Akio
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p. 2143 - 2146
(2007/10/02)
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