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71.
An Efficient Enantioselective Synthesis of Natural Gingerols,the Active Principles of Ginger 下载免费PDF全文
A. Ramesh Reddy Sachin B. Wadavrao J. S. Yadav A. Venkat Narsaiah 《Helvetica chimica acta》2015,98(7):1009-1017
A straightforward synthesis of (S)‐gingerols 1 – 3 has been described. The requisite stereogenic center in the target molecules was introduced by Sharpless asymmetric dihydroxylation using a chiral complex, AD‐mix β. This route is simple and efficient to prepare the products in very good yields. 相似文献
72.
Atisane‐type diterpenoids are the principal constituent of tetracyclic C20‐diterpenoids, widely isolated from the plant kingdom with varying degrees of structural complexity and pharmacological activity. The tetracarbocyclic system with the unique bicyclo[2.2.2]octane skeleton of this natural product family has generated interest within the synthetic community. Divergent total synthesis is an effective tactic to synthesize several atisane‐type diterpenoids using structural interconversion from a common intermediate. This account summarizes the divergent total synthesis of atisane‐type diterpenoids. 相似文献
73.
A dinuclear organometallic acceptor 4,4'-bis[trans-Pt(PEt(3))(2)(O(3)SCF(3))(ethynyl)]biphenyl (1) containing Pt-ethynyl functionality is synthesized. Multinuclear NMR ((1)H, (31)P, and (13)C), infrared (IR), and electrospray ionization mass spectrometry (ESI-MS) including single-crystal X-ray diffraction analysis established the formation of 1. Equimolar treatment of acceptor 1 separately with three different "clip" type ditopic donors (L(a)-L(c)) yielded [2 + 2] self-assembled three metallamacrocycles 2a-2c, respectively. These macrocycles were characterized by various spectroscopic techniques, and their sizes/shapes were obtained through geometry optimization using molecular mechanics universal force field (MMUFF) simulations. Attachment of unsaturated ethynyl functionality to biphenyl building unit helped to make the macrocycles (2a-2c) π-electron rich and thereby fluorescent in nature. Furthermore, 2c in solution has been examined to be suitable for sensing electron-deficient nitroaromatic like picric acid, which is often considered as a secondary chemical explosive. The fluorescence study of 2c showed a marked quenching of initial emission intensity upon titrating with picric acid (PA), and it exhibited the largest fluorescence quenching response with high selectivity among various other electron deficient aromatic compounds tested. 相似文献
74.
Mehta VP Sharma Ak Modha SG Sharma S Meganathan T Parmar VS Van der Eycken E 《The Journal of organic chemistry》2011,76(8):2920-2925
The N-heterocyclic carbene catalyzed chemoselective C3-aroylation of 3,5-dichloro-2(1H)-pyrazinones with various aldehydes is reported. We herein describe results of this remarkable mild and efficient procedure. 相似文献
75.
We demonstrate a photoactivated surface coupling scheme for achieving spatial overlap between biomolecules of interest and optical near field excitation. Using aluminium nanoapertures, we obtained increased coupling efficiency of biotinylated capture probe oligos to the photoactivated surface due to ~3× nanoaperture enhancement of UV light. We further validate DNA sensor functionality via the hybridization of Cy-5 labeled target oligos, with up to 8× fluorescence enhancement obtained from a commercial microarray scanner. This generic photoimmobilization strategy is an essential step to realizing miniaturized plasmon enhanced detection arrays by virtue of localizing capture molecules to the region of plasmonic enhancement. 相似文献
76.
Doiphode Vidya Vairale Priti Sharma Vidhika Waghmare Ashish Punde Ashvini Shinde Pratibha Shah Shruti Pandharkar Subhash Hase Yogesh Aher Rahul Nair Shruthi Jadkar Vijaya Bade Bharat Prasad Mohit Rondiya Sachin Jadkar Sandesh 《Journal of Solid State Electrochemistry》2021,25(6):1835-1846
Journal of Solid State Electrochemistry - Herein, we report the synthesis of ZnO nanorod films onto FTO (fluorine-doped tin oxide) substrates using the solution-processed electrodeposition method.... 相似文献
77.
78.
Q. Feng G. Gallego S. P. Sethi H. Yan H. Zhang 《Journal of Optimization Theory and Applications》2005,124(1):137-155
This paper is concerned with a periodic-review inventory system with three consecutive delivery modes (fast, medium, and slow) and demand forecast updates. At the beginning of each period, the inventory level and demand information are updated and decisions on how much to order using each of the three delivery modes are made. It is shown that there is a base-stock policy for fast and medium modes which is optimal. Furthermore, the optimal policy for the slow mode may not be a base-stock policy in general.This research was supported in part by a Faculty Research Grant from the University of Texas at Dallas, a RGC (Hong Kong) Competitive Earmarked Research Grant,
a Distinguished Young Investigator Grant from the National Natural Sciences Foundation of China, and a Grant from the Hundred Talents Program of the Chinese Academy of Sciences. 相似文献
79.
Bhahwal A. Shah Vijay K. Sethi Samar S. Andotra Ghulam N. Qazi 《Tetrahedron letters》2007,48(6):955-960
The Baylis-Hillman reaction of a sesquiterpene lactone parthenin with various aldehydes gave unexpected products containing a 1,3-dioxolane moiety. Both small aliphatic and aromatic aldehydes produced 1,3-dioxolanes, whereas higher aliphatic aldehydes produced normal Baylis-Hillman products. 相似文献
80.
Yumei Hou Suresh P. Sethi Hanqin Zhang 《Journal of Mathematical Analysis and Applications》2006,317(2):398-428
We consider a production planning problem for a jobshop with unreliable machines producing a number of products. There are upper and lower bounds on intermediate parts and an upper bound on finished parts. The machine capacities are modelled as finite state Markov chains. The objective is to choose the rate of production so as to minimize the total discounted cost of inventory and production. Finding an optimal control policy for this problem is difficult. Instead, we derive an asymptotic approximation by letting the rates of change of the machine states approach infinity. The asymptotic analysis leads to a limiting problem in which the stochastic machine capacities are replaced by their equilibrium mean capacities. The value function for the original problem is shown to converge to the value function of the limiting problem. The convergence rate of the value function together with the error estimate for the constructed asymptotic optimal production policies are established. 相似文献