- STIMULI - OR BIO- RESPONSIVE COPOLYMERS, THE POLYMERSOMES COMPRISING THE SAME AND THEIR USE IN DRUG DELIVERY
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The present invention concerns amphiphilic copolymers that may be photo- or redox-cleavable and that may assemble into polymersomes. It also concerns their process of preparation and their use as drug carriers.
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Page/Page column 23
(2021/06/22)
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- Hydroaminoalkylation of Allenes
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The first examples of early-transition-metal-catalyzed hydroaminoalkylation reactions of allenes are reported. Initial studies performed with secondary aminoallenes led to the identification of a suitable titanium catalyst and revealed that under the reaction conditions, the initially formed hydroaminoalkylation products undergo an unexpected titanium-catalyzed rearrangement to form the thermodynamically more stable allylamines. The assumption that this rearrangement involves a reactive allylic cation intermediate provides a simple explanation of the fact that no successful early-transition-metal-catalyzed hydroaminoalkylations of allenes have previously been reported. As a result of the generation of the corresponding cation, the titanium-catalyzed intermolecular hydroaminoalkylation of propa-1,2-diene unexpectedly gives an aminocyclopentane product formed by incorporation of two equivalents of propa-1,2-diene.
- Bielefeld, Jens,Mannhaupt, Steffen,Schmidtmann, Marc,Doye, Sven
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supporting information
p. 967 - 971
(2019/05/10)
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- Product-oriented chemical surface modification of a levansucrase (SacB): Via an ene-type reaction
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Carbohydrate processing enzymes are sophisticated tools of living systems that have evolved to execute specific reactions on sugars. Here we present for the first time the site-selective chemical modification of exposed tyrosine residues in SacB, a levansucrase from Bacillus megaterium (Bm-LS) for enzyme engineering purposes via an ene-type reaction. Bm-LS is unable to sustain the synthesis of high molecular weight (HMW) levan (a fructose polymer) due to protein-oligosaccharide dissociation events occurring at an early stage during polymer elongation. We switched the catalyst from levan-like oligosaccharide synthesis to the efficient production of a HMW fructan polymer through the covalent addition of a flexible chemical side-chain that fluctuates over the central binding cavity of the enzyme preventing premature oligosaccharide disengagement.
- Ortiz-Soto, Maria Elena,Ertl, Julia,Mut, Jürgen,Adelmann, Juliane,Le, Thien Anh,Shan, Junwen,Te?mar, J?rg,Schlosser, Andreas,Engels, Bernd,Seibel, Jürgen
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p. 5312 - 5321
(2018/06/27)
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- Enantiomerically enriched tris(boronates): Readily accessible conjunctive reagents for asymmetric synthesis
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The catalytic enantioselective diboration of vinyl boronate esters furnishes chiral tris(boronates) in a selective fashion. Subsequent deborylative alkylation occurs in a diastereoselective fashion, both for intermolecular and intramolecular processes.
- Coombs, John R.,Zhang, Liang,Morken, James P.
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supporting information
p. 16140 - 16143
(2015/01/09)
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- 4-alkyloxyimino derivatives of uridine-5′-triphosphate: Distal modification of potent agonists as a strategy for molecular probes of P2Y 2, P2Y4, and P2Y6 receptors
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Extended N4-(3-arylpropyl)oxy derivatives of uridine-5′-triphosphate were synthesized and potently stimulated phospholipase C stimulation in astrocytoma cells expressing G protein-coupled human (h) P2Y receptors (P2YRs) activated by UTP (P2Y2/4R) or UDP (P2Y6R). The potent P2Y4R-selective N4-(3- phenylpropyl)oxy agonist was phenyl ring-substituted or replaced with terminal heterocyclic or naphthyl rings with retention of P2YR potency. This broad tolerance for steric bulk in a distal region was not observed for dinucleoside tetraphosphate agonists with both nucleobases substituted. The potent N 4-(3-(4-methoxyphenyl)-propyl)oxy analogue 19 (EC50: P2Y2R, 47 nM; P2Y4R, 23 nM) was functionalized for chain extension using click tethering of fluorophores as prosthetic groups. The BODIPY 630/650 conjugate 28 (MRS4162) exhibited EC50 values of 70, 66, and 23 nM at the hP2Y2/4/6Rs, respectively, and specifically labeled cells expressing the P2Y6R. Thus, an extended N4-(3- arylpropyl)oxy group accessed a structurally permissive region on three G q-coupled P2YRs, and potency and selectivity were modulated by distal structural changes. This freedom of substitution was utilized to design of a pan-agonist fluorescent probe of a subset of uracil nucleotide-activated hP2YRs.
- Jayasekara, P. Suresh,Barrett, Matthew O.,Ball, Christopher B.,Brown, Kyle A.,Hammes, Eva,Balasubramanian, Ramachandran,Harden, T. Kendall,Jacobson, Kenneth A.
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p. 3874 - 3883
(2014/05/20)
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- BIVALENT INHIBITORS OF AKT PROTEIN KINASE
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The present disclosure describes compounds which are Akt kinase inhibitors useful for the treatment of cancer. The compounds disclosed herein are bivalent ligands capable of binding with both the kinase enzyme ATP binding domain and the kinase enzyme subs
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Page/Page column 49
(2008/12/08)
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- Vinyl sulfoxides as stereochemical controllers in intermolecular Pauson-Khand reactions: Applications to the enantioselective synthesis of natural cyclopentanoids
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The use of sulfoxides as chiral auxiliaries in asymmetric intermolecular Pauson-Khand reactions is described. After screening a wide variety of substituents on the sulfur atom in α,β-unsaturated sulfoxides, the readily available o-(N,N-dimethylamino)phenyl vinyl sulfoxide (1i) has proved to be highly reactive with substituted terminal alkynes under N-oxide-promoted conditions (CH3CN, 0°C). In addition, these Pauson-Khand reactions occurred with complete regioselectivity and very high diastereoselectivity (de = 86→96%, (S,RS) diastereomer). Experimental studies suggest that the high reactivity exhibited by the vinyl sulfoxide 1i relies on the ability of the amine group to act as a soft ligand on the alkyne dicobalt complex prior to the generation of the cobaltacycle intermediate. On the other hand, both theoretical and experimental studies show that the high stereoselectivity of the process is due to the easy thermodynamic epimerization at the C5 center in the resulting 5-sulfinyl-2- cyclopentenone adducts. When it is taken into account that the known asymmetric intermolecular Pauson-Khand reactions are limited to the use of highly reactive bicyclic alkenes, mainly norbornene and norbornadiene, this novel procedure constitutes the first asymmetric version with unstrained acyclic alkenes. As a demonstration of the synthetic interest of this sulfoxide-based methodology in the enantioselective preparation of stereochemically complex cyclopentanoids, we have developed very short and efficient syntheses of the antibiotic (-)-pentenomycin I and the (-)-aminocyclopentitol moiety of a hopane triterpenoid.
- Rodriguez Rivero, Marta,Alonso, Ines,Carretero, Juan C.
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p. 5443 - 5459
(2007/10/03)
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- Palladium-Catalyzed Cyclizations of Bromodialkenyl Ethers and Amines
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A variety of vinylic bromoalkenyl alkenyl ethers were reacted with piperidine and a palladium acetate-tri-o-tolylphosphine catalyst.Intramolecular vinylic substitution occurred in many cases.Five-membered rings formed most easily, followed by six and then
- Shi, L.,Narula, C. K.,Mak, K. T.,Kao, L.,Xu, Y.,Heck, R. F.
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p. 3894 - 3900
(2007/10/02)
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