查看更多>>摘要：Piezofluorochromism (PFC) of crystals of a tert-butyl and [2.2]paracyclophane-containing diaroyl-methanatoboron difluoride (pCP-tBu), which is expected to possess both intermolecular and intramolec-ular pi-pi interactions, was investigated. pCP-tBu crystals were found to exhibit remarkable PFC associated with an over 150-nm redshift of fluorescence (FL) wavelength occurring under increasing isotropic pres-sure applied by using a diamond anvil cell. X-ray crystallographic analysis showed that pCP-tBu mole-cules in the crystal at atmospheric pressure exist in the form of an intermolecular pi-stacking dimer through back-to-back pi-pi interactions. Moreover, the crystallographic data under high pressure showed that increasing isotropic pressure causes a reduction in both the intermolecular pi-stacking distance of the dimer (DINTER) and the intramolecular pi-stacking distance between two benzene rings in the [2.2]-paracyclophane moiety (DINTRA). Density functional theory calculations, using the Cartesian coordinates obtained by X-ray analysis, suggest that the origin of PFC of pCP-tBu crystals is the reduction of the LUMO energy of the pi-stacking dimer and that the intermolecular pi-pi interaction is still the important factor leading to PFC of pCP-tBu crystals. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A simple, efficient, and smooth thiocyanation of indoles, phenols and aniline derivatives using NH4SCN, DMSO and H2SO4 in DMF is introduced. Using this procedure, diverse indoles and N-alkyl indoles are selectively thiocyanated at the C-3 position. para-free anilines, N-alkyl anilines and phenols undergo thiocyanation at the para position selectively. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A method for synthesis of hybrid thiohemicucurbiturils has been developed. With this method, three novel thiohemicucurbiturils have been constructed. Contrary to the acid condition for synthesis of traditional hemicucurbiturls, this method provides a moderate condition which is compatible for more complicated structure in synthesis of novel hybrid hemicucurbiturils. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：In this letter, a new route for the convenient synthesis of selenophene-fused quinoline based heterocycle is described. Iron III chloride and dialkyl diselenides generated intramolecular cascade cyclization of methyl 6-methyl-2-(phenylbuta-1,3-diyn-1-yl)quinoline-3-carboxylate gives selenophene-fused quinoline based heterocycle derivatives in good yields. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：This study reports the development and scope of catalytic enantioselective 5-endo-trig bromocycloetherification of six-membered unactivated alkenes having a hydroxyethyl group. The proposed reaction occurs in a chiral anionic phase-transfer catalytic system using a combination of a binaphthol-based chiral phosphoric acid and a derivative of DABCO bromine complex to provide bicyclic tetrahydrofuranfused 6-membered products, which bear a bromo group at the bridgehead position with complete diastereoselectivity and good to high enantioselectivity. Results show that the enantioselectivity depends on the solvent system and substituents at the 3,3'-position of the catalyst. Thus, the best result can be obtained using a catalyst that has 2,4,6-tricyclohexylphenyl groups at the 3,3'-positions in a mixture of fluorobenzene and n-heptane. In addition, the construction of a quaternary carbon center with the retention of configuration via a radical mediated allylation of the tertiary bromo group in the product was reported.
查看更多>>摘要：We report the total synthesis of jadomycins A, B, and L-digitoxosyl-phenanthroviridin. 2-Aryl-5-hydroxy1,4-naphthoquinones, which were synthesized utilizing a Pd-catalyzed direct arylation of 5-hydroxy-1,4naphthoquinone with aryl iodide, were converted into jadomycin A through introduction of L-isoleucine, followed by oxidative cyclization. Mitsunobu reaction of jadomycin A with 3,4-di-O-acetyl-L-digitoxose, which was prepared from commercially available 3,4-di-O-acetyl-6-deoxy-L-glucal, followed by deacetylation, gave jadomycin B. Additionally, the first total synthesis of L-digitoxosyl-phenanthroviridin was successful via Mitsunobu reaction of phenanthroviridin aglycon with 3,4-di-O-acetyl-L-digitoxose. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Herein we describe a novel lactamization-decarboxylation tandem reaction to form (S)-N-benzyl-prega-balin lactam in solvent-free condensation of benzyl amine with (S)-4-isobutyl a-ethylaceto y-butyrolac-tone, obtained in two steps from commercially available starting material. Triflic acid-mediated debenzylation in the same pot gave (S)-pregabalin lactam, which constitutes a formal synthesis of the anticonvulsant and anxiolytic drug pregabalin. Isolation of the lactamization intermediates indicates that the initially formed kinetic hydroxyamide is in equilibrium with lactone and the formation of amino acid precedes lactamization. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We have developed a novel type of organocatalyst having a 1,8 diarylnaphthalene core, namely, a "Stacked-arene "-type organocatalyst. The key point of the catalyst design is the pi-pi interaction based electron tuning. This through space electron tuning effect is effective enough for the improvement of the catalytic activity (reducing the catalyst loading), and this tendency was evaluated by the Michael addition reaction between nitrostyrene and dimethyl malonate. Additional experiments suggest that the expected improvement of the hydrogen bonding ability plays a critical role in the high performance of the designed catalyst. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：An electrochemical synthesis of N-acylbenzotriazoles has been developed under mild conditions with good to excellent yields using aldehydes and benzotriazole as starting materials. In addition, a one-pot reaction of aldehyde, benzotriazole and phenol has been achieved affording phenolic esters in moderate yields under the combination of electricity-on/off conditions, where N-acyl benzotriazole acted as the benign acylating reagent. It is noteworthy the research provided environmental friendly syntheses in that no superstoichiometric hazardous chemical oxidants were required, corrosive/toxic reagents have been avoided and waste production has significantly been reduced. The key of the electrochemical synthesis involves the oxidation of benzotriazole-aldehyde adduct by phthalimido-N-oxy (PINO), which was generated by N-hydroxyphthalimide (NHPI) as a redox mediator. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Deuteration isa widely used labelling technique. Through a visible-light induced desulfurization and rad-ical addition process in EtOAc-D2O, we were able to develop the direct synthesis of y-deuterated carbonyl compounds from a-sulfide ketones and alkenes. Products with different functionalities were efficiently synthesized with high-deuteration. This mild and metal-free method provides a valuable tool for medic-inal and synthetic chemists. (C) 2022 Elsevier Ltd. All rights reserved.
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