Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Tandem silylformylation-crotylsilylation/Tamao oxidation of internal alkynes: a remarkable example of generating complexity from simplicity.

ABSTRACT: The rhodium-catalyzed tandem silylformylation-crotylsilylation reaction has been extended to include internal alkynes. Tamao oxidation of the initial product leads to the production of a substituted enol, which undergoes highly diastereoselective tautomerization. The resulting one-pot procedure fashions three new stereocenters, a ketone, and a terminal alkene from a butenyl group, a propynyl group, a silyl hydride, H2O2, and CO.

SUBMITTER: Spletstoser JT

PROVIDER: S-EPMC2628290 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Tandem silylformylation-crotylsilylation/Tamao oxidation of internal alkynes: a remarkable example of generating complexity from simplicity.

Spletstoser Jared T JT Zacuto Michael J MJ Leighton James L JL

Organic letters 20081201 24

The rhodium-catalyzed tandem silylformylation-crotylsilylation reaction has been extended to include internal alkynes. Tamao oxidation of the initial product leads to the production of a substituted enol, which undergoes highly diastereoselective tautomerization. The resulting one-pot procedure fashions three new stereocenters, a ketone, and a terminal alkene from a butenyl group, a propynyl group, a silyl hydride, H2O2, and CO. ...[more]

PMID: 19007175

Similar Datasets

Small heat shock proteins: Simplicity meets complexity.

Project description:Small heat shock proteins (sHsps) are a ubiquitous and ancient family of ATP-independent molecular chaperones. A key characteristic of sHsps is that they exist in ensembles of iso-energetic oligomeric species differing in size. This property arises from a unique mode of assembly involving several parts of the subunits in a flexible manner. Current evidence suggests that smaller oligomers are more active chaperones. Thus, a shift in the equilibrium of the sHsp ensemble allows regulating the chaperone activity. Different mechanisms have been identified that reversibly change the oligomer equilibrium. The promiscuous interaction with non-native proteins generates complexes that can form aggregate-like structures from which native proteins are restored by ATP-dependent chaperones such as Hsp70 family members. In recent years, this basic paradigm has been expanded, and new roles and new cofactors, as well as variations in structure and regulation of sHsps, have emerged.

| S-EPMC6369295 | biostudies-literature

The Tn antigen-structural simplicity and biological complexity.

Project description:Glycoproteins in animal cells contain a variety of glycan structures that are added co- and/or posttranslationally to proteins. Of over 20 different types of sugar-amino acid linkages known, the two major types are N-glycans (Asn-linked) and O-glycans (Ser/Thr-linked). An abnormal mucin-type O-glycan whose expression is associated with cancer and several human disorders is the Tn antigen. It has a relatively simple structure composed of N-acetyl-D-galactosamine with a glycosidic α linkage to serine/threonine residues in glycoproteins (GalNAcα1-O-Ser/Thr), and was one of the first glycoconjugates to be chemically synthesized. The Tn antigen is normally modified by a specific galactosyltransferase (T-synthase) in the Golgi apparatus of cells. Expression of active T-synthase is uniquely dependent on the molecular chaperone Cosmc, which is encoded by a gene on the X chromosome. Expression of the Tn antigen can arise as a consequence of mutations in the genes for T-synthase or Cosmc, or genes affecting other steps of O-glycosylation pathways. Because of the association of the Tn antigen with disease, there is much interest in the development of Tn-based vaccines and other therapeutic approaches based on Tn expression.

| S-EPMC7159538 | biostudies-literature

Instrumentational complexity of music genres and why simplicity sells.

Project description:Listening habits are strongly influenced by two opposing aspects, the desire for variety and the demand for uniformity in music. In this work we quantify these two notions in terms of instrumentation and production technologies that are typically involved in crafting popular music. We assign an 'instrumentational complexity value' to each music style. Styles of low instrumentational complexity tend to have generic instrumentations that can also be found in many other styles. Styles of high complexity, on the other hand, are characterized by a large variety of instruments that can only be found in a small number of other styles. To model these results we propose a simple stochastic model that explicitly takes the capabilities of artists into account. We find empirical evidence that individual styles show dramatic changes in their instrumentational complexity over the last fifty years. 'New wave' or 'disco' quickly climbed towards higher complexity in the 70s and fell back to low complexity levels shortly afterwards, whereas styles like 'folk rock' remained at constant high instrumentational complexity levels. We show that changes in the instrumentational complexity of a style are related to its number of sales and to the number of artists contributing to that style. As a style attracts a growing number of artists, its instrumentational variety usually increases. At the same time the instrumentational uniformity of a style decreases, i.e. a unique stylistic and increasingly complex expression pattern emerges. In contrast, album sales of a given style typically increase with decreasing instrumentational complexity. This can be interpreted as music becoming increasingly formulaic in terms of instrumentation once commercial or mainstream success sets in.

| S-EPMC4281146 | biostudies-literature

Inherent structure length in metallic glasses: simplicity behind complexity.

Project description:One of the central themes in materials science is the structure-property relationship. In conventional crystalline metals, their mechanical behaviour is often dictated by well-defined structural defects such as dislocations, impurities, and twins. However, the structure-property relationship in amorphous alloys is far from being understood, due to great difficulties in characterizing and describing the disordered atomic-level structure. Herein, we report a universal, yet simple, correlation between the macroscopic mechanical properties (i.e., yield strength and shear modulus) and a unique characteristic structural length in metallic glasses (MGs). Our analysis indicates that this characteristic length can incorporate effects of both the inter-atomic distance and valence electron density in MGs, and result in the observed universal correlation. The current findings shed lights on the basic understanding of mechanical properties of MGs from their disordered atomic structures.

| S-EPMC4642538 | biostudies-other

Tandem carbocupration/oxygenation of terminal alkynes.

Project description:[chemical reaction: see text]. A direct and general synthesis of alpha-branched aldehydes and their enol derivatives is described. Carbocupration of terminal alkynes and subsequent oxygenation with lithium tert-butyl peroxide generates a metallo-enolate. Trapping with various electrophiles provides alpha-branched aldehydes or stereo-defined trisubstituted enol esters or silyl ethers. The tandem carbocupration/oxygenation tolerates alkyl and silyl ethers, esters, and tertiary amines. The reaction is effective with organocopper complexes derived from primary, secondary, and tertiary Grignard reagents and from n-butyllithium.

| S-EPMC2519174 | biostudies-literature

Novel Fully Organic Water Oxidation Electrocatalysts: A Quest for Simplicity.

Project description:Despite the growing need for readily available and inexpensive catalysts for the half-reactions involved in water splitting, water oxidation and reduction electrocatalysts are still traditionally based on noble metals. One long-standing challenge has been the development of an oxygen evolution reaction catalyzed by easily available, structurally simple, and purely organic compounds. Herein, we first generalize the performance of the known N-ethyl-flavinium ion to a number of derivatives. Furthermore, we demonstrate an unprecedented application of different pyridinium and related salts as very simple, inexpensive water oxidation organocatalysts consisting of earth-abundant elements (C, H, O, and N) exclusively. The results establish the prospects of heterocyclic aromatics for further design of new organic electrocatalysts for this challenging oxidation reaction.

| S-EPMC5879458 | biostudies-literature

Finding simplicity in complexity: general principles of biological and nonbiological organization.

Project description:What differentiates the living from the nonliving? What is life? These are perennial questions that have occupied minds since the beginning of cultures. The search for a clear demarcation between animate and inanimate is a reflection of the human tendency to create borders, not only physical but also conceptual. It is obvious that what we call a living creature, either bacteria or organism, has distinct properties from those of the normally called nonliving. However, searching beyond dichotomies and from a global, more abstract, perspective on natural laws, a clear partition of matter into animate and inanimate becomes fuzzy. Based on concepts from a variety of fields of research, the emerging notion is that common principles of biological and nonbiological organization indicate that natural phenomena arise and evolve from a central theme captured by the process of information exchange. Thus, a relatively simple universal logic that rules the evolution of natural phenomena can be unveiled from the apparent complexity of the natural world.

| S-EPMC2710456 | biostudies-other

Ant queen egg-marking signals: matching deceptive laboratory simplicity with natural complexity.

Project description:BACKGROUND: Experiments under controlled laboratory conditions can produce decisive evidence for testing biological hypotheses, provided they are representative of the more complex natural conditions. However, whether this requirement is fulfilled is seldom tested explicitly. Here we provide a lab/field comparison to investigate the identity of an egg-marking signal of ant queens. Our study was based on ant workers resolving conflict over male production by destroying each other's eggs, but leaving queen eggs unharmed. For this, the workers need a proximate cue to discriminate between the two egg types. Earlier correlative evidence indicated that, in the ant Pachycondyla inversa, the hydrocarbon 3,11-dimethylheptacosane (3,11-diMeC(27)) is more abundant on the surface of queen-laid eggs. METHODOLOGY: We first tested the hypothesis that 3,11-diMeC(27) functions as a queen egg-marking pheromone using laboratory-maintained colonies. We treated worker-laid eggs with synthetic 3,11-diMeC(27) and found that they were significantly more accepted than sham-treated worker-laid eggs. However, we repeated the experiment with freshly collected field colonies and observed no effect of treating worker-laid eggs with 3,11-diMeC(27), showing that this compound by itself is not the natural queen egg-marking pheromone. We subsequently investigated the overall differences of entire chemical profiles of eggs, and found that queen-laid eggs in field colonies are more distinct from worker-laid eggs than in lab colonies, have more variation in profiles, and have an excess of longer-chain hydrocarbons. CONCLUSIONS: Our results suggest that queen egg-marking signals are significantly affected by transfer to the laboratory, and that this change is possibly connected to reduced queen fertility as predicted by honest signaling theory. This change is reflected in the worker egg policing response under field and laboratory conditions.

| S-EPMC2648039 | biostudies-other

Remarkable NO oxidation on single supported platinum atoms.

Project description:Our first-principles density functional theoretical modeling suggests that NO oxidation is feasible on fully oxidized single θ-Al2O3 supported platinum atoms via a modified Langmuir-Hinshelwood pathway. This is in contrast to the known decrease in NO oxidation activity of supported platinum with decreasing Pt particle size believed to be due to increased platinum oxidation. In order to validate our theoretical study, we evaluated single θ-Al2O3 supported platinum atoms and found them to exhibit remarkable NO oxidation activity. A comparison of turnover frequencies (TOF) of single supported Pt atoms with those of platinum particles for NO oxidation shows that single supported Pt atoms are as active as fully formed platinum particles. Thus, the overall picture of NO oxidation on supported Pt is that NO oxidation activity decreases with decreasing Pt particle size but accelerates when Pt is present only as single atoms.

| S-EPMC4246204 | biostudies-literature

Diastereodivergent Reductive Cross Coupling of Alkynes through Tandem Catalysis: Z- and E-Selective Hydroarylation of Terminal Alkynes.

Project description:A diastereodivergent hydroarylation of terminal alkynes is accomplished using tandem catalysis. The hydroarylation allows highly selective synthesis of both E and Z diastereoisomers of aryl alkenes, from the same set of starting materials, using the same combination of palladium and copper catalysts. The selectivity is controlled by simple changes in the stoichiometry of the alcohol additive. The hydroarylation has excellent substrate scope and can be accomplished in the presence of various classes of compounds, including esters, nitriles, alkyl halides, epoxides, carbamates, acetals, ethers, silyl ethers, and thioethers. The Z-selective hydroarylation is accomplished using a new approach based on tandem Sonogashira coupling and catalytic semireduction. The E-selective hydroarylation involves an additional catalytic isomerization of the Z-alkene. Our explorations of the reaction mechanism explain the role of individual reaction components and how the subtle changes in the reaction conditions influence the rates of specific steps of the hydroarylation. Our studies also show that, although the Z- and E-selective hydroarylation reactions are mechanistically closely related, the roles of the palladium and copper catalysts in the two reactions are different.

| S-EPMC6693874 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data