Using a simple copper(i) catalyst has allowed a high yielding sulfonylative-Suzuki-Miyaura cross-coupling reaction to be developed. The process provides a single step route to diaryl sulfones from ...the direct combination of aryl boronic acids, sulfur dioxide and aryl iodides, and represents the first sulfonylative variant of a classic cross-coupling reaction. Sulfur dioxide is delivered from the surrogate reagent, DABSO. Variation of the reaction conditions allowed interruption of the sulfonylative-Suzuki coupling, resulting in the formation of a presumed Cu-sulfinate intermediate. These sulfinates could be trapped as their sodium salts and treated with electrophiles to allow access to arylalkyl sulfones, β-hydroxyl sulfones, sulfonamides and sulfonyl fluorides.
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IJS, KILJ, NUK, UL, UM, UPUK
Genetically encoding distinct non-canonical amino acids (ncAAs) into proteins synthesized in cells requires mutually orthogonal aminoacyl-tRNA synthetase (aaRS)/tRNA pairs. The pyrrolysyl-tRNA ...synthetase/
tRNA pair from Methanosarcina mazei (Mm) has been engineered to incorporate diverse ncAAs and is commonly considered an ideal pair for genetic code expansion. However, finding new aaRS/tRNA pairs that share the advantages of the MmPylRS/Mm
tRNA pair and are orthogonal to both endogenous aaRS/tRNA pairs and the MmPylRS/Mm
tRNA pair has proved challenging. Here we demonstrate that several ΔNPylRS/
tRNA
pairs, in which PylRS lacks an N-terminal domain, are active, orthogonal and efficiently incorporate ncAAs in Escherichia coli. We create new PylRS/
tRNA pairs that are mutually orthogonal to the MmPylRS/Mm
tRNA pair and show that transplanting mutations that reprogram the ncAA specificity of MmPylRS into the new PylRS reprograms its substrate specificity. Finally, we show that distinct PylRS/
tRNA-derived pairs can function in the same cell, decode distinct codons and incorporate distinct ncAAs.
Expanding and reprogramming the genetic code of cells for the incorporation of multiple distinct non-canonical amino acids (ncAAs), and the encoded biosynthesis of non-canonical biopolymers, requires ...the discovery of multiple orthogonal aminoacyl-transfer RNA synthetase/tRNA pairs. These pairs must be orthogonal to both the host synthetases and tRNAs and to each other. Pyrrolysyl-tRNA synthetase (PylRS)/
tRNA pairs are the most widely used system for genetic code expansion. Here, we reveal that the sequences of ΔNPylRS/
tRNA pairs (which lack N-terminal domains) form two distinct classes. We show that the measured specificities of the ΔNPylRSs and
tRNAs correlate with sequence-based clustering, and most ΔNPylRSs preferentially function with
tRNAs from their class. We then identify 18 mutually orthogonal pairs from the 88 ΔNPylRS/
tRNA combinations tested. Moreover, we generate a set of 12 triply orthogonal pairs, each composed of three new PylRS/
tRNA pairs. Finally, we diverge the ncAA specificity and decoding properties of each pair, within a triply orthogonal set, and direct the incorporation of three distinct non-canonical amino acids into a single polypeptide.
A redox‐neutral palladium(II)‐catalyzed conversion of aryl, heteroaryl, and alkenyl boronic acids into sulfinate intermediates, and onwards to sulfones and sulfonamides, has been realized. A simple ...Pd(OAc)2 catalyst, in combination with the sulfur dioxide surrogate 1,4‐diazabicyclo2.2.2octane bis(sulfur dioxide) (DABSO), is sufficient to achieve rapid and high‐yielding conversion of the boronic acids into the corresponding sulfinates. Addition of C‐ or N‐based electrophiles then allows conversion into sulfones and sulfonamides, respectively, in a one‐pot, two‐step process.
Staying neutral: Pd(OAc)2 promotes the addition of aryl and heteroaryl boronic acids to the sulfur dioxide surrogate 1,4‐diazabicyclo2.2.2octane bis(sulfur dioxide) (DABSO) thus delivering the corresponding sulfinates. When combined with an electrophilic trap, this redox‐neutral system provides a straightforward route for the one‐pot preparation of a broad range of sulfones and sulfonamides.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
David Hume is traditionally seen as a devastating critic of religion. He is widely read as an infidel, a critic of the Christian faith, and an attacker of popular forms of worship. His reputation as ...irreligious is well forged among his readers, and his argument against miracles sits at the heart of the narrative overview of his work that perennially indoctrinates thousands of first-year philosophy students. In Toward a Humean True Religion , Andre Willis succeeds in complicating Hume’s split approach to religion, showing that Hume was not, in fact, dogmatically against religion in all times and places. Hume occupied a “watershed moment,” Willis contends, when old ideas of religion were being replaced by the modern idea of religion as a set of epistemically true but speculative claims. Thus, Willis repositions the relative weight of Hume’s antireligious sentiment, giving significance to the role of both historical and discursive forces instead of simply relying on Hume’s personal animus as its driving force. Willis muses about what a Humean “true religion” might look like and suggests that we think of this as a third way between the classical and modern notions of religion. He argues that the cumulative achievements of Hume’s mild philosophic theism, the aim of his moral rationalism, and the conclusion of his project on the passions provide the best content for this “true religion.”
Sulfur dioxide has a rich and varied chemistry that can be traced back to the early 1900s. Despite the potential utility of sulfur dioxide based reactions, delivering products such as sulfones, ...sulfonamides and sulfinic acids, the number of examples of these reactions being exploited in synthesis is arguably lower than would be expected. One significant contributing factor to this is undoubtedly the toxic and gaseous nature of SO2. One strategy to overcome this limitation is to employ an equivalent, or surrogate, so that the gaseous reagent is no longer needed. This strategy has proven to be a success, with a number of methods being described. The reactions reported include variants of traditional reactions in which the gaseous reagent has been replaced with a surrogate, and also new transformations for which no gaseous reaction is known. This Focus Review discusses the origin of sulfur dioxide surrogates and then considers their application to synthetic organic chemistry.
Stunt double: The development of non‐gaseous sulfur dioxide surrogates has stimulated recent interest in sulfur dioxide chemistry. The result has been the invention of new reactions and catalytic processes leading to valuable sulfonyl‐containing molecules. The surrogates, the reactions and applications are all considered in this Focus Review.
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Sulfonyl‐derived functional groups populate a broad range of useful molecules and materials, and despite a variety of preparative methods being available, processes which introduce the most basic ...sulfonyl building block, sulfur dioxide, using catalytic methods, are rare. Described herein is a simple reaction system consisting of the sulfur dioxide surrogate DABSO, triethylamine, and a palladium(0) catalyst for effective convertion of a broad range of aryl and heteroaryl halides into the corresponding ammonium sulfinates. Key features of this gas‐ and reductant‐free reaction include the low loadings of palladium (1 mol %) and ligand (1.5 mol %) which can be employed, and the use of isopropyl alcohol as both a solvent and formal reductant. The ammonium sulfinate products are converted in situ into a variety of sulfonyl‐containing functional groups, including sulfones, sulfonyl chlorides, and sulfonamides.
'SO'2 versatile: The combination of an aryl halide, the SO2 surrogate DABSO, a Pd0 catalyst, isopropyl alcohol, and triethylamine delivers the corresponding ammonium sulfinate salts. Isopropyl alcohol serves as both the solvent and formal reductant, thus allowing the efficient formation of sulfinate intermediates in a process free of gaseous reagents and inorganic reductants. The salts can be converted into sulfones, sulfonamides, and sulfonyl chlorides.
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SO(2) efficient: A three‐component palladium‐catalyzed coupling of aryl lithium compounds; sulfur dioxide (provided by the easy‐to‐handle solid surrogate, DABSO); and aryl, heteroaryl, and alkenyl ...(pseudo)halides yields a diverse library of sulfones. An electron‐poor XantPhos‐type ligand suppresses aryl–aryl exchange and is key to obtaining high yields.
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Species are fundamental units in many biological disciplines, but there is continuing disagreement as to what species are, how to define them, and even whether the concept is useful. While some of ...this debate can be attributed to inadequate data and insufficient statistical frameworks in alpha taxonomy, an equal part results from the ambiguity over what species are expected to represent by the many who use them. Here, mtDNA data, microsatellite data, and sequence data from 17 nuclear loci are used in an integrated and quantitative manner to resolve the presence of evolutionary lineages, their contemporary and historical structure, and their correspondence to species, in a species complex of Amazonian peacock "bass" cichlids (Cichla pinima sensu lato). Results suggest that the historical narrative for these populations is more complex than can be portrayed by recognizing them as one, two, or four species: their history and contemporary dynamics cannot be unambiguously rendered as discrete units (taxa) at any level without both choosing the supremacy of one delimitation criterion and obscuring the very information that provides insight into the diversification process. This calls into question the utility of species as a rank, term, or concept, and suggests that while biologists may have a reasonable grasp of the structure of evolution, our methods of conveying these insights need updating. The lack of correspondence between evolutionary phenomena and discrete species should serve as a null hypothesis, and researchers should focus on quantifying the diversity in nature at whatever hierarchical level it occurs.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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