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991.
Robin M. Bär Dr. Patrick J. Gross Dr. Martin Nieger Prof. Dr. Stefan Bräse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4242-4245
Herein, we present the synthesis of the bench-stable sodium bicyclo[1.1.1]pentanesulfinate (BCP-SO2Na) and its application in the synthesis of bicyclo[1.1.1]pentyl (BCP) sulfones and sulfonamides. The salt can be obtained in a four-step procedure from commercially available precursors in multigram scale without the need for column chromatography or crystallization. Sulfinates are known to be useful precursors in radical and nucleophilic reactions and are widely used in medicinal chemistry. This building block enables access to BCP sulfones and sulfonamides avoiding the volatile [1.1.1]propellane which is favorable for the extension of SAR studies. Further, BCP-SO2Na enables the synthesis of products that were not available with previous methods. A chlorination of BCP-SO2Na and subsequent reaction with a Grignard reagent provides a new route to BCP sulfoxides. Several products were analyzed by single-crystal X-ray diffraction. 相似文献
992.
993.
994.
Rapid Generation and Safe Use of Carbenes Enabled by a Novel Flow Protocol with In‐line IR spectroscopy 下载免费PDF全文
Simon T. R. Müller Aurélien Murat Delphine Maillos Dr. Patrick Lesimple Dr. Paul Hellier Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7016-7020
A powerful new continuous process for the formation and use of donor/acceptor‐substituted carbenes is described. The safety profile of diazo group transfer on methyl phenylacetate was determined including kinetic studies in batch and in flow using in‐line IR analysis. Batch work‐up and liquid chromatography were circumvented by developing an optimized liquid/liquid flow separation method providing aryl diazoacetates in high purity. Fast screening of reaction conditions in flow with in‐line IR analysis allowed rapid reaction optimization. Finally, a multistep process of diazo group transfer, extraction, separation and subsequent diazo decomposition combined with multiple X?H insertion reactions was established. 相似文献
995.
996.
Mazhar-ul-Haque Patrick Pollet Jamil Ahmed William Horne 《Journal of chemical crystallography》1984,14(5):495-503
The title compound crystallizes in the monoclinic space groupP21/n (No. 14),a=14.923(2),b=4.165(2),c=18.097(2) Å,=106.40(1)°,Z=4. The structure was solved by direct methods, and refined by full-matrix least squares toR=0.048 for 1313 observed reflections. Inter- and intramolecular hydrogen bonding is observed, the latter resulting in the formation of dimers. 相似文献
997.
High‐Frequency Fe–H Vibrations in a Bridging Hydride Complex Characterized by NRVS and DFT 下载免费PDF全文
Dr. Vladimir Pelmenschikov Dr. Leland B. Gee Dr. Hongxin Wang Dr. K. Cory MacLeod Sean F. McWilliams Dr. Kazimer L. Skubi Prof. Dr. Stephen P. Cramer Prof. Dr. Patrick L. Holland 《Angewandte Chemie (International ed. in English)》2018,57(30):9367-9371
High‐spin iron species with bridging hydrides have been detected in species trapped during nitrogenase catalysis, but there are few general methods of evaluating Fe?H bonds in high‐spin multinuclear iron systems. An 57Fe nuclear resonance vibrational spectroscopy (NRVS) study on an Fe(μ‐H)2Fe model complex reveals Fe?H stretching vibrations for bridging hydrides at frequencies greater than 1200 cm?1. These isotope‐sensitive vibrational bands are not evident in infrared (IR) spectra, showing the power of NRVS for identifying hydrides in this high‐spin iron system. Complementary density functional theory (DFT) calculations elucidate the normal modes of the rhomboidal iron hydride core. 相似文献
998.
Patrick Headley 《Journal of Algebraic Combinatorics》1997,6(4):331-338
Let be an irreducible crystallographic rootsystem in a Euclidean space V, with + theset of positive roots. For ,
, let
be the hyperplane
. We define a set of hyperplanes
. This hyperplane arrangement is significant inthe study of the affine Weyl groups. In this paper it is shown that thePoincaré polynomial of
is
, where n is the rank of and h is the Coxeter number of the finiteCoxeter group corresponding to . 相似文献
999.
Patrick Chiu 《Proceedings of the American Mathematical Society》1997,125(3):723-730
Relations between the height and the determinant of the Laplacian on the space of -dimensional flat tori and the classical formulas of Kronecker and Epstein are established. Extrema of the height are shown to exist, and results for a global minimum for 2-d tori and a local minimum for 3-d tori are given, along with more general conjectures of Sarnak and Rankin.
1000.
The matrix elements of the exponential of a finite difference realization of the one-dimensional Laplacian are found exactly. This matrix is used to formulate an efficient algorithm for the numerical solution to the time-dependent quantum mechanical scattering of a single particle from a time-independent potential in one-space and one-time dimension. The method generalizes to higher spatial dimensions, as well as to multiparticle problems. 相似文献