- (±)-cis-4a-alkyl-1,3,4,4a,9,9a-hexahydro-2H-carbazol-2-ones by domino nitro reduction-aza-Michael addition to enones
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A domino nitro reduction-aza-Michael addition sequence has been investigated for α,β-unsaturated ketones and compared with the analogous reaction for conjugated esters. As expected, six-membered ring closures of ketones did not proceed as well as for esters (85%) due to the greater inherent reactivity of the ketones. This problem was minimized by performing the cyclization at lower temperature for a shorter time. The process has been extended to a synthesis of (±)-cis-4a-alkyl-1,3,4,4a,9,9a-hexahydro-2H-carbazol-2-ones with good yields (65%–86%). While the rigidity of the system and closure of the smaller five-membered ring created some strain in the products, yields were acceptable. The cis ring junction resulted from axial attack to give a more stable chair-like enol that tautomerized to the target heterocycle.
- Barrios-Perez, Carlos,Bunce, Richard A.,Embrey, Samuel J.
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- A Singular System with Precise Dosing and Spatiotemporal Control of CRISPR-Cas9
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Several genome engineering applications of CRISPR-Cas9, an RNA-guided DNA endonuclease, require precision control of Cas9 activity over dosage, timing, and targeted site in an organism. While some control of Cas9 activity over dose and time have been achieved using small molecules, and spatial control using light, no singular system with control over all the three attributes exists. Furthermore, the reported small-molecule systems lack wide dynamic range, have background activity in the absence of the small-molecule controller, and are not biologically inert, while the optogenetic systems require prolonged exposure to high-intensity light. We previously reported a small-molecule-controlled Cas9 system with some dosage and temporal control. By photocaging this Cas9 activator to render it biologically inert and photoactivatable, and employing next-generation protein engineering approaches, we have built a system with a wide dynamic range, low background, and fast photoactivation using a low-intensity light while rendering the small-molecule activator biologically inert. We anticipate these precision controls will propel the development of practical applications of Cas9.
- Manna, Debasish,Maji, Basudeb,Gangopadhyay, Soumyashree A.,Cox, Kurt J.,Zhou, Qingxuan,Law, Benjamin K.,Mazitschek, Ralph,Choudhary, Amit
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supporting information
p. 6285 - 6289
(2019/04/08)
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- Photoresponsive cross-linked polymeric particles for phototriggered burst release
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We synthesized a series of cross-linked photoresponsive polymeric particles with photolabile monomers and cross-linkers through miniemulsion polymerization. These particles are quite stable in dark, while light irradiation caused the breakage of particles and the efficient release of encapsulated contents up to 95% based on Nile red fluorescence. Photoswitches of particle systems were confirmed by fluorescence spectroscopy, SEM and colorimetry. Particle uptake and triggered release in RAW264.7 cells were confirmed by fluorescein diacetate loaded particles.
- Wang, Zhen,Yu, Lili,Lv, Cong,Wang, Peng,Chen, Yedong,Tang, Xinjing
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p. 552 - 559
(2013/06/26)
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- Caged glutathione - Triggering protein interaction by light
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Light, GSH, action! Glutathione (GSH) fulfills a universal role as redox factor, scavenger of reactive oxygen species, and as an essential substrate in the conjugation, detoxification, and reduction reactions catalyzed by glutathione S-transferase (GST). A photoactivatable glutathione allows the GSH-GST network to be triggered by light. GST fusion proteins can be assembled in situ at variable density and structures by laser-scanning activation. Copyright
- Gatterdam, Volker,Stoess, Tatjana,Menge, Clara,Heckel, Alexander,Tampe, Robert
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supporting information; experimental part
p. 3960 - 3963
(2012/06/15)
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- Lipase-mediated resolution of substituted 2-aryl-propanols: Application to the enantioselective synthesis of phenolic sesquiterpenes
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A comprehensive study of the lipase-mediated resolution of substituted 2-aryl-propanols is reported. The latter alcohols were submitted to the irreversible acetylation catalyzed either by PPL, CRL, or lipase PS. The enantioselectivity of these transformations was dependent on the type of lipase used. The type of substituents and particularly their position on the aromatic ring strongly affected the selectivity of the reaction. The experiments described prove that PPL is the more versatile lipase catalyzing the acetylation with an enantiomeric ratio (E) value that ranges from 1 up to 144, depending on the substrate used. Conversely, the same transformations were catalyzed by CRL and lipase PS with an enantiomeric ratio value, which is always less than 5. The remarkable behavior of PPL was exploited in the large scale resolution of some substituted 2-aryl-propanols whose enantiomeric forms are relevant building blocks in the enantioselective synthesis of phenolic sesquiterpenes. By these means, the synthesis of (S)-turmeronol B and the formal syntheses of (R)-curcumene, (R)-curcuphenol, (R)-xanthorrhizol, and (R)-curcuhydroquinone were accomplished.
- Serra, Stefano
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p. 619 - 628
(2011/07/08)
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- METHOD FOR PREPARING DNA FRAGMENT HAVING STICKY END
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The present invention provides a method for preparing a DNA fragment, in which a desired double-stranded DNA fragment having a sticky end is directly and easily obtained from an amplification product (an amplified fragment) after PCR without a restriction
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- Micrometer-and nanometer-scale photopatterning using 2- nitrophenylpropyloxycarbonyl-protected aminosiloxane monolayers
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An approach to nanopatterning is reported in which a scanning near-fieldoptical microscope coupled to a near-UV laser is used to selectively de protect 2-nitrophenylpropyloxycarbonyl (NPPOC)-protected aminosiloxane monolayers on glass. UV deprotection was
- Alang Ahmad, Shahrul A.,Wong, Lu Shin,ul-Haq, Ehtsham,Hobbs, Jamie K.,Leggett, Graham J.,Micklefield, Jason
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experimental part
p. 1513 - 1522
(2009/07/30)
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- Synthesis of a photo-caged aminooxy alkane thiol
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A photo-caged aminooxy alkane thiol synthesized in 7 steps and 15% overall yield was used to form a self-assembled monolayer (SAM). Photo-deprotection on the surface was confirmed by FT-IR spectroscopy and contact angle goniometry. Conjugation of a small molecule ketone, ethyl levulinate, further confirmed the presence of aminooxy groups on the surface. The Royal Society of Chemistry 2009.
- Mancini, Rock J.,Li, Ronald C.,Tolstyka, Zachary P.,Maynard, Heather D.
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experimental part
p. 4954 - 4959
(2010/02/16)
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- Photolabile peptide nucleic acid monomers: Synthesis and photodeprotection
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The photolabile 2-(2-nitrophenyl)propyloxy carbonyl (NPPOC) group has been introduced as an amino protecting group for peptide nucleic acids (PNA) to be used as building blocks in photolithographic solid-phase PNA synthesis. NPPOC-protected PNA derivative
- Bhushan, Kumar R.
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p. 2130 - 2132
(2008/02/05)
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- Photogenerated reagents
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This invention describes reagent precursors and methods for chemical and biochemical reactions. These reagent precursors that can be activated in solution upon irradiation to generate reagents required for the subsequent chemical reactions. Specifically, photogenerated reagents (PGR) are useful for controlling parallel combinatorial synthesis and various chemical and biochemical reactions.
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Page/Page column 16-17
(2008/06/13)
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- Synthesis of photolabile 2-(2-nitrophenyl)propyloxycarbonyl protected amino acids
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The 2-(2-nitrophenyl)propyloxycarbonyl (NPPOC) group has been introduced as a photolabile amino protecting group for amino acids to be used as building blocks in photolithographic solid-phase peptide synthesis. NPPOC-protected amino acids were found to be cleaved in the presence of UV light about twice as fast as the corresponding o-nitroveratryloxycarbonyl (NVOC)-protected amino acids. The protected amino acids are of particular use in the synthesis of peptide arrays.
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- New Types of Very Efficient Photolabile Protecting Groups Based upon the [2-(2-Nitrophenyl)propoxy]carbonyl (NPPOC) Moiety
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Based upon the photolabile [2-(2-nitrophenyl)propoxy]carbonyl group (NPPOC), a large number of modified 2-(2-nitrophenyl)propanol derivatives substituted at the phenyl ring (see 23-34 and 57-76) as well as at the side-chain (see 85-92 and 95-98) were synthesized to improve the photoreactivity of this new type of photolabile entity. The phenyl moiety was also exchanged by the naphthalenyl group (see 102, 103, 105, 108, 110, 113, and 114), the thienyl substituent (see 115, 117, 118, and 120), and the benzothienyl substituent (see 121). The 2-(2-nitroaryl- and heteroaryl) propanols were converted with diphosgene into the corresponding carbonochloridates, which reacted subsequently with thymidine to the thymidine 5′-(protected carbonates) 123-178 as the main reaction products. In several cases, the corresponding 3′-carbonates and 3′,5′ -dicarbonates 179-212 were also isolated and characterized. Photolysis studies under standardized conditions (see Table) indicated that the rate of photocleavage varies in a broad range depending on the substituents. So far, the thymidine 5′-[2-(5-halo-2-nitrophenyl)propyl carbonates] 127-129, 5′-[2-(nitro[1,1′-biphenyl]3-yl)propyl carbonates] 136-139, 5′-{2-[2-nitro-5-(thianthren-1-yl)phenyl]propyl carbonate} (140), 5′-[2-(5-naphthalenyl-2-nitrophenyl)propyl carbonates] 141 and 142, and 5′-[2-(2-nitro-5-thienylphenyl)propyl carbonates] 143 and 144 showed the best properties regarding fast and uniform deprotection. Since the nucleobases of 213-215 do not influence the photocleavage features, in general, the new type of photolabile building blocks allows in form of their 3′ -phosphoramidites the photolithographic formation of high-quality biochips.
- Buehler, Sigrid,Lagoja, Irene,Giegrich, Heiner,Stengele, Klaus-Peter,Pfleiderer, Wolfgang
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p. 620 - 659
(2007/10/03)
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- Synthesis of photolabile 2-(2-nitrophenyl)propyloxycarbonyl protected amino acids
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The 2-(2-nitrophenyl)propyloxycarbonyl (NPPOC) group has been introduced as a photolabile amino protecting group for amino acids to be used as building blocks in photolithographic solid-phase peptide synthesis. NPPOC-protected amino acids were found to be cleaved in the presence of UV light about twice as fast as the corresponding o-nitroveratryloxycarbonyl (NVOC)-protected amino acids.
- Bhushan, Kumar R.,DeLisi, Charles,Laursen, Richard A.
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p. 8585 - 8588
(2007/10/03)
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- New photolabile protecting groups in nucleoside and nucleotide chemistry - Synthesis, cleavage mechanisms and applications
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New photolabile protecting groups have been found in the 2-(2- nitrophenyl)ethoxycarbonyl and the 2-(2-nitrophenyl)ethylsulfonyl group, respectively. The influence of substituents at the phenyl ring as well as the side-chain has been investigated regarding the photolysis rates on irradiation at 365 mn. β-Branching in the side-chain leads to highly increased rates of photodeprotection. A new type of photocleavage mechanism consisting of a photoinduced β-elimination process is proposed.
- Giegrich,Eisele-Buehler,Hermann,Kvasyuk,Charubala,Pfleiderer
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p. 1987 - 1996
(2007/10/03)
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- Nucleoside derivatives with photolabile protective groups
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The invention relates to nucleoside derivatives having photolabile protective groups of the general formula (I) STR1 in which R1 =H, NO2, CN, OCH3, halogen or alkyl or alkoxyalkyl having 1 to 4 C atoms R2 =H, OCH3 R3 =H, F, Cl, Br, NO2 R4 =H, halogen, OCH3, or an alkyl radical having 1 to 4 C atoms R5 =H or a usual functional group for preparing oligonucleotides R6 =H, OH, halogen or XR8, where X=O or S and R8 represents a protective group usual in nucleotide chemistry, B=adenine, cytosine, guanine, thymine, uracil, 2,6-diaminopurin-9-yl, hypoxanthin-9-yl, 5-methylcytosin-1-yl, 5-amino-4-imidazolcarboxamid-1-yl, or 5-amino-4-imidazolcarboxamid-3-yl, where in the case of B=adenine, cytosine or guanine, the primary amino function optionally exhibits a permanent protective group. These derivatives may be used for the light-controlled synthesis of oligonucleotides on a DNA chip.
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- Ruthenium-Catalyzed Dehydrogenative N-Heterocyclization: Indoles from 2-Aminophenethyl Alcohols and 2-Nitrophenethyl Alcohols
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Indole derivatives 3 were readily obtained from 2-aminophenethyl alcohols 1 in the presence of 2 mol percent (based on 1) of RuCl2(PPh3)3 under reflux in toluene.Indole (3a) was afforded from 2-aminophenethyl alcohol (1a) quantitatively.Other indoles (3) were also obtained in 73-99percent isolated yields from the corresponding 1, which were easily prepared by condensation between the corresponding 2-nitrotoluenes and aldehydes followed by reduction.During the reaction, a stoichiometric amount of hydrogen was spontaneously evolved into the gas phase.With a heterogeneous and homogeneous binary catalyst system, indoles were afforded in one pot from 2-nitrophenethyl alcohols 2 under a hydrogen atmosphere.
- Tsuji, Yasushi,Kotachi, Shinji,Huh, Keun-Tae,Watanabe, Yoshihisa
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p. 580 - 584
(2007/10/02)
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- Electrogenerated Base (EG Base) Induced Hydroxymethylation of the Side Chain of Nitroalkylbenzenes with Paraformaldehyde
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Hydroxymethylation of nitroalkylbenzenes with paraformaldehyde was accomplished by electrolysis in a (CH2O)n-DMF-Et4NOTs-(Pt electrode) system.The reaction was found to be catalytic (0.25 faraday/mol) and dependent on the electroreduction of formaldehyde and/or nitroalkylbenzene.A variety of nitroalkylbenzenes were transformed to their corresponding mono- and/or bishydroxymethylated derivatives in good yield.The product yield and selectivity were shown to depend on the order of reagent addition, solvent, supporting electrolyte, and structure of the starting nitroalkylbenzenes.A plausible mechanism of the generation of base catalysts (EG base) in electroreductive media is discussed.
- Torii, Sigeru,Murakami, Yasuo,Tanaka, Hideo,Okamoto, Koichi
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p. 3143 - 3147
(2007/10/02)
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