The first Ni-catalyzed C-O/P-H cross-coupling producing organophosphorus compounds is disclosed. This method features wide generality in regard to both C-O and P-H compounds: for C-O compounds, the ...readily available alcohol derivatives of aryl, alkenyl, benzyl, and allyl are applicable, and for P-H compounds, both >P(V)(O)H compounds (secondary phosphine oxide, H-phosphinate, and H-phosphonate) and hydrogen phosphines (>P(III)H) can be used as the substrates. Thus, a variety of valuable C(sp(2))-P and C(sp(3))-P compounds can be readily obtained in good to excellent yields by this new strategy.
Abstract
Extreme-mass-ratio inspirals (EMRIs) are important gravitational-wave (GW) sources for future space-based detectors. The standard model consists of one stellar-mass black hole spiraling into ...a supermassive one, and such a process emits low-frequency (~10
−3
Hz) GWs, which contain rich information about the space–time geometry around the central massive body. Here we show that the small bodies in EMRIs, in fact, could be binary black holes, which are captured by the massive black holes during earlier close encounters. About 30% of the captured binaries coalesce due to the perturbation by the massive bodies, resulting in a merger rate of 0.03 Gpc
3
yr
−1
in the most optimistic scenario. The coalescence generates also high-frequency (~10
2
Hz) GWs detectable by ground-based observatories, making these binary-EMRIs ideal targets for future multi-band GW observations.
A new inexpensive copper‐catalyzed denitrogenative C−P coupling reaction of pyridotriazoles with P(O)H compounds has been developed. The reaction proceeds via a process of copper‐catalyzed P(O)−H ...insertion into the pyridyl carbene intermediates generated in situ from pyridotriazoles. This reaction provides a new and effective method for the synthesis of a variety of 2‐picolylphosphoryl compounds.
Abstract
It is known that massive black holes (MBHs) of $10^{5-7}\, \mathrm{ M}_\odot$ could capture small compact objects to form extreme-mass-ratio inspirals (EMRIs). Such systems emit ...gravitational waves (GWs) in the band of the Laser Interferometer Space Antenna (LISA) and are ideal probes of the space–time geometry of MBHs. Recently, we have shown that MBHs could also capture stellar-mass binary black holes (about $10\, \mathrm{ M}_\odot$) to form binary-EMRIs (b-EMRIs) and, interestingly, a large fraction of the binaries coalesce due to the tidal perturbation by the MBHs. Here we further show that the coalescence could be detected by LISA as glitches in EMRI signals. We propose an experiment to use the multiband (102 and 10−3 Hz) glitch signals to test gravity theories. Our simulations suggest that the experiment could measure the mass and linear momentum lost via GW radiation, as well as constrain the mass of gravitons, to a precision that is one order of magnitude better than the current limit.
The motion of photons around black holes determines the shape of shadow and match the ringdown properties of a perturbed black hole. Observations of shadows and ringdown waveforms will reveal the ...nature of black holes. In this paper, we study the motion of photons in a general parametrized metric beyond the Kerr hypothesis. We investigated the radius and frequency of the photon circular orbits on the equatorial plane and obtained fitted formula with varied parameters. The Lyapunov exponent which connects to the decay rate of the ringdown amplitude is also calculated. We also analyzed the shape of shadow with full parameters of the generally axisymmetric metric. Our results imply the potential constraint on black hole parameters by combining the Event Horizon Telescope and gravitational wave observations in the future.
Despite the importance of P-chiral organophosphorus compounds in asymmetric catalysis, transition metal-catalyzed methods for accessing P-chiral phosphine derivatives are still limited. Herein, a ...catalytic enantioselective method for the synthesis of P-stereogenic alkenylphosphinates is developed through asymmetric hydrophosphorylation of alkynes. This process is demonstrated for a wide range of racemic phosphinates and leads to diverse P-stereogenic alkenylphosphinates directly.
4‐Methoxy‐3‐(trimethylphosphonio)phenolate was obtained from a regioselective addition of PMe3 to p‐quinone monoacetal. This compound undergoes hydrogen isotope exchange with D2O or CD3CN, and is ...capable of catalyzing H/D exchange of CD3CN with substrates bearing weakly acidic hydrogens. It exhibits similar reactivity to phosphorus ylides for olefinations of aldehydes. A possible tautomerization between the phosphonium phenolate zwitterion and phosphonium ylide is proposed for the first time to rationalize the unique reactivity.
A direct decarbonylative phosphorylation of benzoic acids catalyzed by palladium was disclosed. Under the reaction conditions, a wide range of benzoic acids coupled readily with all the three kinds ...of P(O)–H compounds, i.e. secondary phosphine oxides, H‐phosphinates and H‐phosphonates, producing the corresponding organophosphorus compounds in good to high yields. This reaction could be conducted at a gram scale and applied in the late‐stage phosphorylative modification of carboxylic acids drug molecules. These results well demonstrated the potential synthetic value of this new reaction in organic synthesis.
A direct decarbonylative phosphorylation of benzoic acids catalyzed by palladium was disclosed. Under the reaction conditions, a wide range of carboxylic acids coupled readily with all the three kinds of P(O)–H compounds, i.e. secondary phosphine oxides, H‐phosphinates and H‐phosphonates, producing the corresponding organophosphorus compounds in good to high yields. This reaction could be conducted at a gram scale and applied in the late‐stage phosphorylative modification of carboxylic acids drug molecules. These results well demonstrated the potential synthetic value of this new reaction in organic synthesis.
β-Glucans are a heterogeneous group of glucose polymers with a common structure comprising a main chain of β-(1,3) and/or β-(1,4)-glucopyranosyl units, along with side chains with various branches ...and lengths. β-Glucans initiate immune responses via immune cells, which become activated by the binding of the polymer to specific receptors. However, β-glucans from different sources also differ in their structure, conformation, physical properties, binding affinity to receptors, and thus biological functions. The mechanisms behind this are not fully understood. This mini-review provides a comprehensive and up-to-date commentary on the relationship between β-glucans' structure and function in relation to their use for immunomodulation.
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