Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Carboalumination of Seven-Membered-Ring trans-Alkenes.

ABSTRACT: Seven-membered-ring trans-alkenes undergo rapid hydro- and carboalumination reactions in the absence of a catalyst with complete regio- and diastereoselectivity. Control experiments, including deuterium labeling, adding radical inhibitors, and using a radical clock, suggest that these reactions proceed by a concerted mechanism. The products of the reaction possess a new carbon-aluminum bond that can then undergo subsequent transformations, particularly oxidation, providing functionalized products as single stereoisomers.

SUBMITTER: Greene MA

PROVIDER: S-EPMC7541770 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Carboalumination of Seven-Membered-Ring <i>trans</i>-Alkenes.

Greene Margaret A MA Liu Yudong Y Sanzone Jillian R JR Woerpel K A KA

Organic letters 20200917 19

Seven-membered-ring <i>trans</i>-alkenes undergo rapid hydro- and carboalumination reactions in the absence of a catalyst with complete regio- and diastereoselectivity. Control experiments, including deuterium labeling, adding radical inhibitors, and using a radical clock, suggest that these reactions proceed by a concerted mechanism. The products of the reaction possess a new carbon-aluminum bond that can then undergo subsequent transformations, particularly oxidation, providing functionalized ...[more]

PMID: 32942861

Similar Datasets

Diastereoselective synthesis of seven-membered-ring trans-alkenes from dienes and aldehydes by silylene transfer.

Project description:Silver-catalyzed silylene transfer to alkenes forms vinylsilacyclopropanes regioselectively. These allylic silanes undergo additions to aldehydes to form seven-membered-ring trans-alkenes with high diastereoselectivity. The high reactivity of the trans-alkenes is evidenced by their formal [1,3]-sigmatropic rearrangement reactions and the rapid additions of oxygen-hydrogen bonds across the carbon-carbon double bonds.

| S-EPMC3437758 | biostudies-literature

Origin of High Diastereoselectivity in Reactions of Seven-Membered-Ring Enolates.

Project description:Unlike many reactions of their six-membered-ring counterparts, the reactions of chiral seven-membered-ring enolates are highly diastereoselective. Diastereoselectivity was observed for a range of substrates, including lactam, lactone, and cyclic ketone derivatives. The stereoselectivity arises from torsional and steric interactions that develop when electrophiles approach the diastereotopic π-faces of the enolates, which are distinguished by subtle differences in the orientation of nearby atoms of the ring.

| S-EPMC8940697 | biostudies-literature

Seven-membered ring nucleobases as inhibitors of human cytidine deaminase and APOBEC3A.

Project description:The APOBEC3 (APOBEC3A-H) enzyme family as a part of the human innate immune system deaminates cytosine to uracil in single-stranded DNA (ssDNA) and thereby prevents the spread of pathogenic genetic information. However, APOBEC3-induced mutagenesis promotes viral and cancer evolution, thus enabling the progression of diseases and development of drug resistance. Therefore, APOBEC3 inhibition offers a possibility to complement existing antiviral and anticancer therapies and prevent the emergence of drug resistance, thus making such therapies effective for longer periods of time. Here, we synthesised nucleosides containing seven-membered nucleobases based on azepinone and compared their inhibitory potential against human cytidine deaminase (hCDA) and APOBEC3A with previously described 2'-deoxyzebularine (dZ) and 5-fluoro-2'-deoxyzebularine (FdZ). The nanomolar inhibitor of wild-type APOBEC3A was obtained by the incorporation of 1,3,4,7-tetrahydro-2H-1,3-diazepin-2-one in the TTC loop of a DNA hairpin instead of the target 2'-deoxycytidine providing a Ki of 290 ± 40 nM, which is only slightly weaker than the Ki of the FdZ-containing inhibitor (117 ± 15 nM). A less potent but notably different inhibition of human cytidine deaminase (CDA) and engineered C-terminal domain of APOBEC3B was observed for 2'-deoxyribosides of the S and R isomers of hexahydro-5-hydroxy-azepin-2-one: the S-isomer was more active than the R-isomer. The S-isomer shows resemblance in the position of the OH-group observed recently for the hydrated dZ and FdZ in the crystal structures with APOBEC3G and APOBEC3A, respectively. This shows that 7-membered ring analogues of pyrimidine nucleosides can serve as a platform for further development of modified ssDNAs as powerful A3 inhibitors.

| S-EPMC10282898 | biostudies-literature

Lewis acid-assisted Ir(iii) reductive elimination enables construction of seven-membered-ring sulfoxides.

Project description:Iridium has played an important role in the evolution of C-H activation chemistry over the last half century owing to its high reactivity towards stoichiometric C-H bond cleavage; however, the use of Ir(iii) complexes in catalytic C-H functionalization/C-C bond formation appears to have fallen off significantly. The main problem lies in the reductive elimination step, as iridium has a tendency to form stable and catalytically inactive Ir(iii) species. Herein, with a rationally designed Lewis acid assisted oxidatively induced strategy, the sluggish Ir(iii) reductive elimination is successfully facilitated, enabling the facile C-C bond formation. The X-ray crystal structure of a silver salt adduct of iridacycle and DFT calculations demonstrate that the sulfoxide group acts as a key bridge connecting the Ir(iii) metal centre with the silver Lewis acid, which facilitates the reductive elimination of the Ir(iii) metallacycle. Further identification of oxidants was carried out by performing stoichiometric reactions, which enables the development of catalytic construction of various highly functionalized seven-membered-ring sulfoxides, that are of great interest in medicinal chemistry and materials science.

| S-EPMC8162422 | biostudies-literature

Stereoelectronic Model To Explain Highly Stereoselective Reactions of Seven-Membered-Ring Oxocarbenium-Ion Intermediates.

Project description:Nucleophilic attack on seven-membered-ring oxocarbenium ions is generally highly stereoselective. The preferred mode of nucleophilic attack forms the product in a conformation that minimizes transannular interactions, thus leading to different stereoselectivity as compared to that of reactions involving six-membered-ring oxocarbenium ions.

| S-EPMC4811184 | biostudies-literature

Rhodium-catalyzed ring expansion of cyclopropanes to seven-membered rings by 1,5 C-C bond migration.

Project description: Not available

| S-EPMC3329940 | biostudies-literature

Seven-Membered Cyclic Potassium Diamidoalumanyls.

Project description:The seven-membered cyclic potassium alumanyl species, [{SiNMes }AlK]2 [{SiNMes }={CH2 SiMe2 N(Mes)}2 ; Mes=2,4,6-Me3 C6 H2 ], which adopts a dimeric structure supported by flanking K-aryl interactions, has been isolated either by direct reduction of the iodide precursor, [{SiNMes }AlI], or in a stepwise manner via the intermediate dialumane, [{SiNMes }Al]2 . Although the intermediate dialumane has not been observed by reduction of a Dipp-substituted analogue (Dipp=2,6-i-Pr2 C6 H3 ), partial oxidation of the potassium alumanyl species, [{SiNDipp }AlK]2 , where {SiNDipp }={CH2 SiMe2 N(Dipp)}2 , provided the extremely encumbered dialumane [{SiNDipp }Al]2 . [{SiNDipp }AlK]2 reacts with toluene by reductive activation of a methyl C(sp3 )-H bond to provide the benzyl hydridoaluminate, [{SiNDipp }AlH(CH2 Ph)]K, and as a nucleophile with BPh3 and RN=C=NR (R=i-Pr, Cy) to yield the respective Al-B- and Al-C-bonded potassium aluminaborate and alumina-amidinate products. The dimeric structure of [{SiNDipp }AlK]2 can be disrupted by partial or complete sequestration of potassium. Equimolar reactions with 18-crown-6 result in the corresponding monomeric potassium alumanyl, [{SiNDipp }Al-K(18-cr-6)], which provides a rare example of a direct Al-K contact. In contrast, complete encapsulation of the potassium cation of [{SiNDipp }AlK]2 , either by an excess of 18-cr-6 or 2,2,2-cryptand, allows the respective isolation of bright orange charge-separated species comprising the 'free' [{SiNDipp }Al]- alumanyl anion. Density functional theory (DFT) calculations performed on this moiety indicate HOMO-LUMO energy gaps in the of order 200-250 kJ mol-1 .

| S-EPMC8596455 | biostudies-literature

Novel β-Benzyloxy-Substituted Copolymers of Seven-Membered Cyclic Carbonate: Ring-Opening Polymerization with L-Lactide, ε-Caprolactone and Trimethylenecarbonate.

Project description:To prepare novel biodegradable copolymers with functional substituents that are distributed statistically or randomly over the macromolecule chain and have improved characteristics compared to homopolymers, we conducted a series of synthetic experiments with a novel cyclic monomer, 5-(benzyloxy)-1,3-dioxepan-2-one (4). This compound was synthesized, and its homopolymer, as well as its copolymers with L-lactide, ε-caprolactone and trimethylene carbonate, were prepared in a polymerization solution with stannous octoate as the initiator. The formation of the copolymers was confirmed using NMR spectroscopy and DSC data. The distribution of the monomeric units of the substituted 7CC in the copolymers with L-lactide and ε-caprolactone is random, as it is close to a statistical distribution. The copolymer with TMC is a gradient copolymer due to the different rates of monomer polymerization. The copolymer with a composition of 10(ε-CL):1(carbonate 4) can be considered a promising polymer after the deprotection of the hydroxy group for the inoculation of the functional substituents due to its convenience of preparation and properties similar to those of poly(ε-caprolactone).

| S-EPMC11644486 | biostudies-literature

Fully reagent-controlled asymmetric synthesis of (-)-spongidepsin via the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction).

Project description:The ZACA reaction has been shown to proceed satisfactorily with internally OH-substituted 1-alkenes, provided that the OH group is unprotected and non-allylic. This reaction was used for reagent-controlled asymmetric construction of 3. Allylic alcohol was converted to 2 in seven steps via iterative ZACA processes and simple chromatography. (-)-Spongidepsin (1) was synthesized by using 2 and 3 through application of the esterification-amidation-ring-closing metathesis protocol previously reported.

| S-EPMC3891660 | biostudies-literature

Chemical Bonding in Three-Membered Ring Systems.

Project description:The formation of the four 3-ring systems c-(CH2)3-k(SiH2)k (k=0: cyclopropane, k=1: silirane, k=2: disilirane, k=3: cyclotrisilane) by addition of methylene and silylene to the double bond in ethene, disilene, and silaethene, as well as the elimination of the carbene analogs from the 3-rings, was studied with CAS(4,4) wave functions in both C2v and Cs symmetry. To reveal the charge and spin redistribution during these reactions the CAS(4,4) wave functions were analyzed using the orthogonal valence bond method (OVB). The potential energy curves, different internal coordinates, and the results of the OVB analysis show that, frequently, the addition and elimination reactions follow different minimum energy paths, because they are indeed diabatic reactions. In these cases, there are no energy barriers corresponding to saddle points on the potential energy surfaces but the energy increases during one diabatic reaction until, at a certain point, the system jumps to the other diabatic state and, in the following, the energy decreases. This happens for reactions in C2v symmetry; as soon as the system can change to the lower symmetry, the diabatic states combine to an adiabatic one and the reaction follows a single minimum energy path.

| S-EPMC11820764 | 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