Search results for "CLEAVAGE"
showing 10 items of 281 documents
Signal-Processing and Adaptive Prototissue Formation in Metabolic DNA Protocells
2021
Abstract The fundamental life-defining processes in living cells, such as replication, division, adaptation, and tissue formation, take place via intertwined metabolic reaction networks orchestrating downstream signal processing in a confined, crowded environment with high precision. Hence, it is crucial to understand and reenact some of these functions in wholly synthetic cell-like entities (protocells) to envision designing soft-materials with life-like traits. Herein, we report on a programmable all-DNA protocell (PC) composed of a liquid DNA interior and a hydrogel-like shell, harboring DNAzyme active sites in the interior whose catalytic bond-cleaving activity leads to a downstream phe…
Synthesis of Pillar[6]arenes and Their Host–Guest Complexes
2015
Pillar[n]arenes are a fast-growing research topic in supramolecular chemistry. Originally the focus was predominantly on pillar[5]arenes; however, now more and more studies on pillar[6]arenes are being performed. The ability and selectivity of host–guest complexations depend strongly on the size of the inner cavities of these macrocycles. New results have stimulated us to compile the synthetic entries and the complexations of pillar[6]arenes with large cylindric cavities that offer space for many different guest molecules. 1 Introduction 2 Preparation of Pillar[6]arenes 2.1 Pillar[6]arenes by Macrocyclization Reactions 2.2 Hydroxypillar[6]arenes through Ether Cleavage 2.3 Hydroxypillar[6]ar…
ChemInform Abstract: Synthesis of Pillar[6]arenes and Their Host-Guest Complexes
2015
Pillar[n]arenes are a fast-growing research topic in supramolecular chemistry. Originally the focus was predominantly on pillar[5]arenes; however, now more and more studies on pillar[6]arenes are being performed. The ability and selectivity of host–guest complexations depend strongly on the size of the inner cavities of these macrocycles. New results have stimulated us to compile the synthetic entries and the complexations of pillar[6]arenes with large cylindric cavities that offer space for many different guest molecules. 1 Introduction 2 Preparation of Pillar[6]arenes 2.1 Pillar[6]arenes by Macrocyclization Reactions 2.2 Hydroxypillar[6]arenes through Ether Cleavage 2.3 Hydroxypillar[6]ar…
Palladium-Catalyzed N-Arylation Reactions with Aziridine and Azetidine
2007
Studies on the viability of palladium-catalyzed cross-coupling reactions of aryl- or hetaryl bromides with the parent aziridine or azetidine showed that a wide range of N-arylaziridines and N-arylazetidines are accessible by this method. Ring cleavage of the N-arylaziridines or -azetidines thus produced does not occur under the applied reaction conditions. The synthetic utility of the method is illustrated by examples of double N-arylations with either aziridine or azetidine.
N-Glycosyl Amides as Glycosyl Donors in Stereoselective Glycosylation Reactions
2004
Due to their high stability, N-glycosyl amides have so far not been considered as glycosyl donors for glycosylation reactions. Two new procedures for the cleavage of the anomeric amide functionality under mild reaction conditions and further stereoselective in situ conversions of the activated glycosyl donors with alcohols and amines to give β-configured O- and N-glycosides are described in this article.
Reductive cleavage of 2,2,2-trichloroethyl esters with sodium telluride
1998
Abstract Carboxylic acids are regenerated from their 2,2,2-trichloroethyl esters by treatment with sodium telluride in dimethylformamide in smooth conditions and with good yields. The reaction conditions are compatible with other functional and protective groups such as methyl ester, acetate or tert-butyldimethylsilyl ethers.
ChemInform Abstract: Reductive Cleavage of 2,2,2-Trichloroethyl Esters with Sodium Telluride.
2010
Abstract Carboxylic acids are regenerated from their 2,2,2-trichloroethyl esters by treatment with sodium telluride in dimethylformamide in smooth conditions and with good yields. The reaction conditions are compatible with other functional and protective groups such as methyl ester, acetate or tert-butyldimethylsilyl ethers.
Mechanistic Studies on the Metal-Free Activation of Dihydrogen by Antiaromatic Pentarylboroles
2012
The perfluoro- and perprotiopentaphenylboroles 1 and 2 react with dihydrogen to effect H-H bond cleavage and formation of boracyclopentene products. The mechanism of this reaction has been studied experimentally through evaluation of the kinetic properties of the slower reaction between 2 and H(2). The reaction is first-order in both [borole] and [H(2)] with activation parameters of ΔH(‡) = 34(8) kJ/mol and ΔS(‡) = -146(25) J mol(-1) K(-1). A minimal kinetic isotope effect of 1.10(5) was observed, suggesting an asynchronous geometry for H-H cleavage in the rate-limiting transition state. To explain the stereochemistry of the observed products, a ring-opening/ring-closing mechanism is propos…
Controlled rearrangement of lactam-tethered allenols with brominating reagents: a combined experimental and theoretical study on α- versus β-keto lac…
2011
N-Bromosuccinimide (NBS) smoothly promotes the ring expansion of lactam-tethered allenols to efficiently afford cyclic α- or β-ketoamides with good yields and high chemo-, regio-, and diastereoselectivity, through controlled C-C bond cleavage of the β- or γ-lactam nucleus. Interestingly, in contrast to the rearrangement reactions of 2-azetidinone-tethered allenols, which lead to the corresponding tetramic acid derivatives (β-keto lactam adducts) as the sole products, the reactions of 2-indolinone-tethered allenols under similar conditions give quinoline-2,3-diones (α-keto lactam adducts) as the exclusive or major products. To rationalize the experimental observations, theoretical studies ha…
New sulfonamide complexes with essential metal ions [Cu (II), Co (II), Ni (II) and Zn (II)]. Effect of the geometry and the metal ion on DNA binding …
2019
Abstract Mixed divalent Cu, Co, Ni and Zn complexes containing the new sulfonamide ligand N–(2–(pyridin–2–yl)ethyl)quinoline–8–sulfonamide (HQSEP) were prepared and characterized by physico-chemical techniques. The tetracoordinate [Cu(QSEP)X] [X = Br (1), Cl (2)] compounds present a seesaw geometry (τ4 = 0.56 (1) and 0.50 (2)). The Cu(II) in the [Cu(QSEP)(NO3)(MeOH)] (3) complex is five coordinate with a slightly distorted SP geometry (τ = 0.11). The [M(QSEP)(benz)] [M = Cu(II) (4), Ni(II) (5), Co(II) (6) and Zn(II) (7); benz = benzoate] compounds are configurationally isotypic. The coordination geometries of the M(II) ions can be best described as distorted SP (τ = 0.29, 0.15, 0.34 and 0.1…