查看更多>>摘要：Electrochemical oxidative bromination and cyclization sequences of unsaturated carboxylic acids were developed in this study. This approach is environmentally-friendly, using bromide anion as bromine radical precursor without external oxidizing reagents. The electrochemical protocol offers a facile way to prepare bromomethylated y-lactones derivatives in moderate to high yields. (c) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A simple and fast method of preparation of non-natural nicotinamide adenine dinucleotide (NAD) analog nicotinamide cytosine dinucleotide (NCD) was developed. NCD synthetase (NcdS-1) was developed from nicotinic acid mononucleotide adenylyltransferase (NadD) with higher catalytic efficiency towards nicotinamide mononucleotide (NMN) and cytidine triphosphate (CTP). Reaction composition was optimized with inorganic pyrophosphatase (PPase) from E. coli to achieve near quantitative conversion of substrates. A Scalable purification procedure was determined to achieve a fast 4.19 g NCD preparation of 96 % purity. (c) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Ru-catalyzed direct C-H amidation of pyrrolo[2,3-d]pyrimidine derivatives was developed using sulfonyl azides as the amino source in a mild, efficient and highly chemoselective manner. The promising protocol has good compatibility with diverse functional groups and high regioselectivity, providing various structurally versatile monoamidated pyrrolo[2,3-d]pyrimidines in good to excellent yields with potential biological and therapeutic activity. (c) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：An environmentally friendly aerobic oxidation of benzyl C(sp(3))-H bonds to ketones via selective oxidation catalysis was developed. Fluorescein is an efficient photocatalyst with excellent chemical selectivity. The reaction has a wide substrate scope, and a successful gram-scale experiment demonstrated its potential industrial utility. (C) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：One uncommon sesquiterpenoid dimer (1), a new nardosinane-type sesquiterpenoid (3), along with two known sesquiterpenoids (2 and 4) were isolated from soft coral Litophyton nigrum using a structure-oriented HR-MS/MS approach. The configurations of the isolates were determined by spectroscopic data analyses, including HR-ESI-MS, 1D/2D NMR, single crystal X-ray diffraction, and DP4+ statistical analyses. Compound 3 exhibited potent PTP1B inhibitory activity (IC50 = 10.67 +/- 1.81 mu g/mL) compared to the positive control. (C) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Catalysts based on the combination of Pd(OAc)(2) and the electron-deficient phosphatrioxa-adamantane ligands are described for borylation of aryl bromides and chlorides. Catalytic evaluation of a small library of phosphatrioxa-adamantane ligands provided some insights on the preferred ligand steric profile for borylation reactions. The corresponding aryl boronate esters were accessed under mild conditions (25-70 degrees C) and isolated in high yields (up to 96%). (C) 2021 Elsevier Ltd. All rights reserved.
Kelley, Amber M.Frost, Joshua A.Baber, Tylisha M.Youngblood, Kala C....
4页
查看更多>>摘要：Nitriles are important organic functional groups, allowing for installation of nitrogen in organic synthesis. The Pinner reaction transforms nitriles into esters via the imidate group, but in general has previously necessitated harsh acid conditions. This work builds on the utility of the Pinner reaction through a stereoselective desymmetrization of dinitriles to form gamma- and delta-lactones in good yields and diastereoselectivites. (C) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Herein, we disclose our efforts directed toward the synthesis of the kavalactone-based natural product penstyrylpyrone and other related 4-OMe-2-pyrones possessing diverse substituents at the 3-, 5-, and 7-positions. Further, a facile approach to access 6-styrylpyrones via the KHMDS-mediated regioselective aldol condensation of 2-pyrones is described with moderate substrate scope and good to high yields (58- 80%). The utility of this methodology was exemplified by the stereoselective construction of desmethoxyyangonin, asnipyrone A, and asnipyrone B. (c) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We have developed a method to synthesize alpha,alpha-dihaloketones under electrochemical conditions. In this reaction, the Cl- or Br- is oxidized to Cl-2 or Br-2 at the anode, which undergoes two-step addition reactions with the N,N-dimethyl enaminone, and finally breaks C=C of the N,N-dimethyl enaminone to generate alpha,alpha-dihaloketones. The electrosynthesis reaction can be conveniently carried out in an undivided electrolytic cell at room temperature. In addition, various functional groups are compatible with this green protocol which can be applied simultaneously to the gram scale without significantly lower yield. (C) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A mild, practical, eco-friendly and environmentally friendly electrochemical synthesis method of p-aminovinyl sulfone and carbonyl sulfones from sulfonyl hydrazide and enamides has been developed. This transformation only requires electrolytes and solvent, thus avoids transition metal catalysts, stoichiometric oxidant and base. Two different types of sulfone derivatives can be obtained only by changing the reaction solvent. This transformation also features mild conditions (room temperature, air), broad substrate scopes, and excellent stereoselectivities in mild to good yield. (c) 2021 Elsevier Ltd. All rights reserved.
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Elsevier