-
Chemical Communications (Cambridge,... Jan 2022We report a modular approach in which a noncovalently cross-linked single chain nanoparticle (SCNP) selectively binds catalyst "cofactors" and substrates to increase...
We report a modular approach in which a noncovalently cross-linked single chain nanoparticle (SCNP) selectively binds catalyst "cofactors" and substrates to increase both the catalytic activity of a Cu-catalyzed alkyne-azide cycloaddition reaction and the Ru-catalyzed cleavage of allylcarbamate groups compared to the free catalysts.
Topics: Alkynes; Allyl Compounds; Azides; Catalysis; Copper; Cycloaddition Reaction; Glutathione; Nanoparticles; Ruthenium; Transition Elements
PubMed: 34935784
DOI: 10.1039/d1cc05578j -
Organic & Biomolecular Chemistry Aug 2018An efficient Rh(iii)-catalyzed dehydrative C-H allylation of indoles with allyl alcohols via β-hydroxide elimination under oxidant-free conditions has been developed....
An efficient Rh(iii)-catalyzed dehydrative C-H allylation of indoles with allyl alcohols via β-hydroxide elimination under oxidant-free conditions has been developed. This method features very mild reaction conditions, excellent regioselectivity and stereoselectivity, and compatibility with various functional groups. In addition, the directing group can be removed under mild reaction conditions, which further underscores the synthetic utility of this method.
Topics: Allyl Compounds; Catalysis; Hydroxides; Indoles; Propanols; Rhodium; Stereoisomerism
PubMed: 30047974
DOI: 10.1039/c8ob01394b -
Molecules (Basel, Switzerland) Nov 2012The rearrangement of allyl a-bromoacetates with Zn dust is known as the Reformatsky-Claisen rearrangement. Whereas the Ireland-Claisen rearrangement has been widely used...
The rearrangement of allyl a-bromoacetates with Zn dust is known as the Reformatsky-Claisen rearrangement. Whereas the Ireland-Claisen rearrangement has been widely used in the synthesis of a diverse range of natural products, the Zn-mediated Reformatsky-Claisen rearrangement has not been utilized so often. In this article, we will provide an overview of recent advances in the Reformatsky-Claisen rearrangement field, including the In-mediated Reformatsky-Claisen rearrangement we have recently developed.
Topics: Acetates; Allyl Compounds; Biological Products; Humans; Molecular Structure; Zinc
PubMed: 23201643
DOI: 10.3390/molecules171214249 -
Organic Letters Aug 2009Allyl esters of 3-carboxylcoumarins undergo facile decarboxylative coupling at just 25-50 degrees C. This represents the first extension of decarboxylative C-C...
Allyl esters of 3-carboxylcoumarins undergo facile decarboxylative coupling at just 25-50 degrees C. This represents the first extension of decarboxylative C-C bond-forming reactions to the coupling of aromatics with sp(3)-hybridized electrophiles. Finally, the same concept can be applied to the sp(2)-sp(3) couplings of pyrones and flavones. Thus, a variety of biologically important heteroaromatics can be readily functionalized without the need for strong bases or stoichiometric organometallics that are typically required for more standard cross-coupling reactions.
Topics: Allyl Compounds; Catalysis; Coumarins; Decarboxylation; Drug Design; Palladium
PubMed: 19588967
DOI: 10.1021/ol901288r -
Journal of the American Chemical Society Dec 2021The Overhauser effect (OE), commonly observed in NMR spectra of liquids and conducting solids, was recently discovered in insulating solids doped with the radical...
The Overhauser effect (OE), commonly observed in NMR spectra of liquids and conducting solids, was recently discovered in insulating solids doped with the radical 1,3-bisdiphenylene-2-phenylallyl (BDPA). However, the mechanism of polarization transfer in OE-DNP in insulators is yet to be established, but hyperfine coupling of the radical to protons in BDPA has been proposed. In this paper we present a study that addresses the role of hyperfine couplings via the EPR and DNP measurements on some selectively deuterated BDPA radicals synthesized for this purpose. Newly developed synthetic routes enable selective deuteration at orthogonal positions or perdeuteration of the fluorene moieties with H incorporation of >93%. The fluorene moieties were subsequently used to synthesize two octadeuterated BDPA radicals, 1,3-[α,γ-]-BDPA and 1,3-[β,δ-]-BDPA, and a BDPA radical with perdeuterated fluorene moieties, 1,3-[α,β,γ,δ-]-BDPA. In contrast to the strong positive OE enhancement observed in degassed samples of fully protonated -BDPA (ε ∼ +70), perdeuteration of the fluorenes results in a negative enhancement (ε ∼ -13), while selective deuteration of α- and γ-positions ( ∼ 5.4 MHz) in BDPA results in a weak negative OE enhancement (ε ∼ -1). Furthermore, deuteration of β- and δ-positions ( ∼ 1.2 MHz) results in a positive OE enhancement (ε ∼ +36), albeit with a reduced magnitude relative to that observed in fully protonated BDPA. Our results clearly show the role of the hyperfine coupled α and γ H spins in the BDPA radical in determining the dominance of the zero and double-quantum cross-relaxation pathways and the polarization-transfer mechanism to the bulk matrix.
Topics: Allyl Compounds; Deuterium; Fluorenes; Free Radicals; Magnetic Resonance Spectroscopy
PubMed: 34813311
DOI: 10.1021/jacs.1c09406 -
The Journal of Organic Chemistry Aug 2018The spontaneous rearrangement of allylic azides is thought to be a sigmatropic reaction. Presented herein is a detailed investigation into the rearrangement of several...
The spontaneous rearrangement of allylic azides is thought to be a sigmatropic reaction. Presented herein is a detailed investigation into the rearrangement of several allylic azides. A combination of experiments including equilibrium studies, kinetic analysis, density functional theory calculations, and selective N-isotopic labeling are included. We conclude that the Winstein rearrangement occurs by the assumed sigmatropic pathway under most conditions. However, racemization was observed for some cyclic allylic azides. A kinetic analysis of this process is provided, which supports a previously undescribed ionic pathway.
Topics: Allyl Compounds; Azides; Catalysis; Stereoisomerism
PubMed: 29870252
DOI: 10.1021/acs.joc.8b00961 -
The Journal of Physical Chemistry. A Jun 2013The recombination and disproportionation of allyl radicals has been studied in a single pulse shock tube with gas chromatographic measurements at 1-10 bar, 650-1300 K,...
The recombination and disproportionation of allyl radicals has been studied in a single pulse shock tube with gas chromatographic measurements at 1-10 bar, 650-1300 K, and 1.4-2 ms reaction times. 1,5-Hexadiene and allyl iodide were used as precursors. Simulation of the results using derived rate expressions from a complementary diaphragmless shock tube/laser schlieren densitometry study provided excellent agreement with precursor consumption and formation of all major stable intermediates. No significant pressure dependence was observed at the present conditions. It was found that under the conditions of these experiments, reactions of allyl radicals in the cooling wave had to be accounted for to accurately simulate the experimental results, and this unusual situation is discussed. In the allyl iodide experiments, higher amounts of allene, propene, and benzene were found at lower temperatures than expected. Possible mechanisms are discussed and suggest that iodine containing species are responsible for the low temperature formation of allene, propene, and benzene.
Topics: Allyl Compounds; Chromatography, Gas; Free Radicals; Temperature
PubMed: 23679206
DOI: 10.1021/jp402391n -
Chemical Reviews Jun 2008
Review
Topics: Alkynes; Allyl Compounds; Hydrocarbons, Fluorinated; Models, Chemical; Molecular Conformation; Stereoisomerism
PubMed: 18543877
DOI: 10.1021/cr068410e -
Angewandte Chemie (International Ed. in... Jul 2019Herein, we report a modular synthetic route to linear and branched homoallylic amines that operates through a sequential one-pot Lewis base/transition-metal catalyzed... (Review)
Review
Herein, we report a modular synthetic route to linear and branched homoallylic amines that operates through a sequential one-pot Lewis base/transition-metal catalyzed allylic alkylation/Hofmann rearrangement strategy. This protocol is operationally trivial, proceeds from simple and easily prepared substrates and catalysts, and enables all aspects of regio- and stereoselectivity to be controlled through a conserved experimental protocol. Overall, the high levels of enantio-, regio-, and diastereoselectivity obtained, in concert with the ability to access orthogonally protected or free amines, render this a straightforward and effective approach for the preparation of useful enantioenriched homoallylic amines. We have also demonstrated the utility of the products in the context of pharmaceutical synthesis.
Topics: Alkylation; Allyl Compounds; Amines; Catalysis; Metals, Heavy; Molecular Structure; Stereoisomerism
PubMed: 31132203
DOI: 10.1002/anie.201905426 -
Journal of the American Chemical Society Jun 2009The isolation and structural characterization of metallacyclic allyl (2a) and crotyl (2b) iridium complexes are reported. Complexes 2a and 2b are rare examples of...
The isolation and structural characterization of metallacyclic allyl (2a) and crotyl (2b) iridium complexes are reported. Complexes 2a and 2b are rare examples of iriduim allyl complexes that undergo nucleophilic attack at terminal position, rather than the central position, of the allyl unit. Structures of 2a and 2b were obtained by X-ray diffraction. Nucleophilic attack was observed at the carbon that is bound to iridium trans to phosphorus through a longer Ir-C bond. However, the effect of the trans phosphine ligand on the Ir-C bond lengths was smaller than the effect of the substituent on the allyl group in 2b. The competence of complexes 2a and 2b to be intermediates in the catalytic asymmetric allylic substitutions was evaluated by studying their reactivity toward stabilized carbon and heteroatom nucleophiles and comparing the rates and selectivities to those of the catalytic reactions. The stereoselectivity and regioselectivity of stoichiometric reactions of 2b were similar to those of reactions catalyzed by the previously reported iridium catalysts, supporting their intermediacy in the catalytic reactions. On the basis of the structural data, a model is proposed for the origin of stereoselectivity in iridium-catalyzed asymmetric allylic substitution reactions.
Topics: Allyl Compounds; Catalysis; Chemical Phenomena; Iridium; Molecular Structure
PubMed: 19432473
DOI: 10.1021/ja902609g