448,146 research outputs found
Domino C–H/N–H Allylations of Imidates by Cobalt Catalysis
No full textThe domino C-H/N-H allylation of aryl imidates was accomplished by a versatile cobalt(III) catalyst. In contrast to a tandem rhodium/palladium catalysis approach, an operationally simple cationic cobalt complex proved effective in the step-economical C-H/N-H functionalization of imidates to directly provide expedient access to decorated vinyl isoquinolines by kinetically relevant C-H activation
Air-Stable Manganese(I)-Catalyzed C−H Activation for Decarboxylative C−H/C−O Cleavages in Water
No full textThe decarboxylative C-H/C-O functionalization was accomplished by air-and water-tolerant manganese(I) catalysis. The versatile C-H allylation occurred by facile organometallic C-H metalation on indoles, arenes, amino acids and synthetically meaningful aryl ketimines with ample substrate scope and high levels of chemo-, site- and regioselectivity
ljt-uiuc/H-k-c: H-k-c
No full textH-k-c package:
Generalized H-k after harmonic correction on receiver functions
a modification of H-k method by Zhu and Kanamori (2000)
by Jiangtao Li, Xiaodong Song, Pan Wang, and Lupei Zhu
Reference: Li, J., Song, X., Wang, P., & Zhu, L. (2019). A generalized H-k method with harmonic corrections on Ps and its crustal multiples in receiver functions. J. Geophys. Res. Solid Earth, 124(4), 3782-3801
Contact: [email protected]; [email protected]
Total synthesis of the fumiquinazoline alkaloids: Solid-phase studies
No full textWe have previously described an efficient four-step synthesis of the fumiquinazoline alkaloids (Wang, H.; Ganesan, A. J. Org. Chem. 1998, 63, 2432-2433). Here, we demonstrate that this route is readily adaptable to combinatorial synthesis on solid phase. Linear tripeptides containing a central anthranilate unit were assembled on the Wang resin and subjected to dehydration and cyclative release to yield the pyrazino[2,1-b]quinazoline-3,6-diones in high purity. To demonstrate the scope of this protocol, a small library [ca. 20 compounds] of unnatural analogues was prepared by parallel synthesis
Lydia H. Hart Diary
Full text linkDiary, 1823-1830, 1875 and loose papers 1813, 1831, and undated of Lydia H. Hart of Richmond, Virginia and later Walden, Orange County, New York. The Diary was started by Lydia H. Hart, the wife of Reverend William H. Hart, who was the rector of St. John’s Church in Richmond, VA and later St. Andrews Church in Walden, New York. Diary entries include day-to-day activities and meetings with local neighbors and church patron’s. These neighbors included Elizabeth Van Lew and her parents, which Lydia Hart writes about several times. Most dated entries also include discussion of specific bible verses or Rev. Hart’s sermons. Notable entries include a description of the funeral service for Rev. John Buchanan, former rector of St. John’s Church from 1795 to 1822. Diary entries are chronological and more frequent for 1823 and become less frequent in 1823. In 1828, Lydia Hart moved to New York and eventually to Walden, New York in May 1830.At the end of the diary entries is an entry form another author, possibly by Mary. W. Hart dated 1875. Lydia Hart died in 1831 and could not have made the entry.At the back of the diary and upside down to the diary entries are transcriptions of letters and poems of Lydia Hart’s to various newspapers and and personnel correspondence. Entries include a plea for support to the city of Richmond to take care of its ‘destitute children’, letters to the editor of local newspapers, and poems for the birth of a child or death of a patron.Loose papers include a letter dated Jan 8th 1813, a bequeath request from William H. Hart for the placement of a Tombstone for Lydia Hart, a table of contents for various letters or sermons, a letter from William Hart to a friend from Richmond, and 2 loose undated papers of unknown authorship. The letter from William Hart speaks of the events of Lydia’s death, and inquiries about events taking place in Richmond
Cobalt-Catalyzed Oxidase C-H/N-H Alkyne Annulation:Mechanistic Insights and Access to Anticancer Agents
No full textCp*-free cobalt-catalyzed alkyne annulations by C-H/N-H functionalizations were accomplished with molecular O2 as the sole oxidant. The user-friendly oxidase strategy proved viable with various internal and terminal alkynes through kinetically relevant C-H cobaltation, providing among others step-economical access to the anticancer topoisomerase-I inhibitor 21,22-dimethoxyrosettacin. DFT calculations suggest that electronic effects control the regioselectivity of the alkyne insertion step.</p
Overcoming the Limitations of C−H Activation with Strongly Coordinating N‐Heterocycles by Cobalt Catalysis
No full textStrongly coordinating nitrogen heterocycles, including pyrimidines, oxazolines, pyrazoles, and pyridines, were fully tolerated in cobalt-catalyzed C-H amidations by imidate assistance. Structurally complex quinazolines are thus accessible in a step-economic manner. Our findings also establish the relative powers of directing groups in cobalt(III)-catalyzed C-H functionalization for the first time
H∞ fuzzy control for systems with repeated scalar nonlinearities and random packet losses
No full textCopyright [2009] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.This paper is concerned with the H∞ fuzzy control problem for a class of systems with repeated scalar nonlinearities and random packet losses. A modified Takagi-Sugeno (T-S) fuzzy model is proposed in which the consequent parts are composed of a set of discrete-time state equations containing a repeated scalar nonlinearity. Such a model can describe some well-known nonlinear systems such as recurrent neural networks. The measurement transmission between the plant and controller is assumed to be imperfect and a stochastic variable satisfying the Bernoulli random binary distribution is utilized to represent the phenomenon of random packet losses. Attention is focused on the analysis and design of H∞ fuzzy controllers with the same repeated scalar nonlinearities such that the closed-loop T-S fuzzy control system is stochastically stable and preserves a guaranteed H∞ performance. Sufficient conditions are obtained for the existence of admissible controllers, and the cone complementarity linearization procedure is employed to cast the controller design problem into a sequential minimization one subject to linear matrix inequalities, which can be readily solved by using standard numerical software. Two examples are given to illustrate the effectiveness of the proposed design method
Observer-based H∞ control for systems with repeated scalar nonlinearities and multiple packet losses
No full textThis paper is concerned with the H∞ control problem for a class of systems with repeated scalar nonlinearities and multiple missing measurements. The nonlinear system is described by a discrete-time state equation involving a repeated scalar nonlinearity, which typically appears in recurrent neural networks. The measurement missing phenomenon is assumed to occur, simultaneously, in the communication channels from the sensor to the controller and from the controller to the actuator, where the missing probability for each sensor/actuator is governed by an individual random variable satisfying a certain probabilistic distribution in the interval [0 1]. Attention is focused on the analysis and design of an observer-based feedback controller such that the closed-loop control system is stochastically stable and preserves a guaranteed H∞ performance. Sufficient conditions are obtained for the existence of admissible controllers. It is shown that the controller design problem under consideration is solvable if certain linear matrix inequalities (LMIs) are feasible. Three examples are provided to illustrate the effectiveness of the developed theoretical result
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