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1.
Daniel C. Steigerwald Bardia Soltanzadeh Aritra Sarkar Cecilia C. Morgenstern Richard J. Staples Babak Borhan 《Chemical science》2021,12(5):1834
Intermolecular asymmetric haloamination reactions are challenging due to the inherently high halenium affinity (HalA) of the nitrogen atom, which often leads to N-halogenated products as a kinetic trap. To circumvent this issue, acetonitrile, possessing a low HalA, was used as the nucleophile in the catalytic asymmetric Ritter-type chloroamidation of allyl-amides. This method is compatible with Z and E alkenes with both alkyl and aromatic substitution. Mild acidic workup reveals the 1,2-chloroamide products with enantiomeric excess greater than 95% for many examples. We also report the successful use of the sulfonamide chlorenium reagent dichloramine-T in this chlorenium-initiated catalytic asymmetric Ritter-type reaction. Facile modifications lead to chiral imidazoline, guanidine, and orthogonally protected 1,2,3 chiral tri-amines.Intermolecular haloamination reactions are challenging due to the high halenium affinity of the nitrogen atom. This is circumvented by using acetonitrile as an attenuated nucleophile, resulting in an enantioselective halo-Ritter reaction. 相似文献
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Increased reliance upon outsourcing has made the issue of vendor selection even more critical to the success of the modern manufacturing organization. The usual performance measure on which selection is based has been the distribution of the vendor’s delivery lead-time (LT), often as characterized by the mean and variance. In this paper, we show that the distribution of demand per unit time (DPUT) must also be considered if an optimal decision is to be made. 相似文献
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Highly Stereoselective Intermolecular Haloetherification and Haloesterification of Allyl Amides 下载免费PDF全文
Bardia Soltanzadeh Dr. Arvind Jaganathan Dr. Richard J. Staples Prof. Dr. Babak Borhan 《Angewandte Chemie (International ed. in English)》2015,54(33):9517-9522
An organocatalytic and highly regio‐, diastereo‐, and enantioselective intermolecular haloetherification and haloesterification reaction of allyl amides is reported. A variety of alkene substituents and substitution patterns are compatible with this chemistry. Notably, electronically unbiased alkene substrates exhibit exquisite regio‐ and diastereoselectivity for the title transformation. We also demonstrate that the same catalytic system can be used in both chlorination and bromination reactions of allyl amides with a variety of nucleophiles with little or no modification. 相似文献
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Yousefi Bardia Sfarra Stefano Ibarra-Castanedo Clemente Avdelidis Nicolas P. Maldague Xavier P. V. 《Journal of Thermal Analysis and Calorimetry》2019,136(2):943-955
Journal of Thermal Analysis and Calorimetry - The application of the thermal and infrared technology in different areas of research is considerably increasing. These applications involve... 相似文献
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Dimerization of Pyramidalized 3,4,8,9‐Tetramethyltetracyclo [4.4.0.03,9.04,8]dec‐1(6)‐ene to a Hydrocarbon Featuring Four Cyclohexane Rings in Boat Conformations 下载免费PDF全文
Matias Rey‐Carrizo Marta Barniol‐Xicota Dr. Mercè Font‐Bardia Prof. Dr. Santiago Vázquez 《Angewandte Chemie (International ed. in English)》2014,53(31):8195-8199
The synthesis, chemical trapping, and dimerization of a highly pyramidalized alkene is reported. Its dimer is a unique nonacycle featuring three planar cyclobutane rings, four cyclopentane rings, and four cyclohexane rings in boat conformations. The X‐ray diffraction analysis showed a H–H distance between the flagpole hydrogen atoms of 1.999 Å and a separation of 2.619 Å between the two flagpole carbon atoms. The three cyclobutane rings of the dimer were thermally stable. 相似文献
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Ángel M. Montaña Juan A. Barcia Gabriele Kociok‐Köhn Mercè Font‐Bardia Xavier Solans 《Helvetica chimica acta》2008,91(2):187-208
The 3‐aminotropones (=3‐aminocyclohepta‐2,4,6‐trien‐1‐ones) 4 were prepared in two steps by i) a [4+3] cycloaddition reaction between a conveniently substituted α,α′‐dihalo ketone 1 and a furan‐2‐amine derivative 2 functionalized at C(2) by a protected amino group (→ 3 ), and ii) a base‐induced molecular rearrangement of the cycloadduct 3 via cleavage of the O‐bridge. A mechanism for the formation of 3‐aminotropones is proposed on the basis of the initial deprotonation of the [(tert‐butoxy)carbonyl]amino (BocNH) group of 3 , followed by O‐bridge opening, an acid–base equilibrium, and finally an alkoxyaluminate elimination to afford the conjugated stable troponoid system (Scheme 7). 相似文献
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Lourdes Urpí Meritxell Martínez‐Palau Merc Font‐Bardia Jordi Puiggalí 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(12):o847-o849
The title compound, C8H12Cl2O4, lies about an inversion centre. The molecular conformation is characterized by a conformation for the butanedioxy moiety and a trans conformation for the ClCH2—C(=O)O bond. The molecular packing is stabilized by a network of weak CH2⋯O=C intermolecular hydrogen bonds, where each molecule interacts with its four closest neighbours. 相似文献
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Short Access to Belt Compounds with Spatially Close CC Bonds and Their Transannular Reactions 下载免费PDF全文
Prof. Dr. Pelayo Camps Dr. Tània Gómez Ane Otermin Dr. Mercè Font‐Bardia Dr. Carolina Estarellas Prof. Dr. Francisco Javier Luque 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14036-14046
Two domino Diels–Alder adducts were obtained from 3,7‐bis(cyclopenta‐2,4‐dien‐1‐ylidene)‐cis‐bicyclo[3.3.0]octane and dimethyl acetylenedicarboxylate or N‐methylmaleimide under microwave irradiation. From the first adduct, a C20H24 diene with C2v symmetry was obtained by Zn/AcOH reduction, hydrolysis, oxidative decarboxylation, and selective hydrogenation. Photochemical [2+2] cycloaddition of this diene gave a thermally unstable cyclobutane derivative, which reverts to the diene. However, both the diene and the cyclobutane derivatives could be identified by X‐ray diffraction analysis upon irradiation of the diene crystal. New six‐membered rings are formed upon the transannular addition of bromine or iodine to the diene. The N‐type selectivity of the addition was examined by theoretical calculations, which revealed the distinct susceptibility of the doubly bonded carbon atoms to the bromine attack. 相似文献