Hydrosilylation of alkynes generally yield vinylsilanes, which are inert to the further hydrosilylation because of the steric effects. Reported here is the first successful dihydrosilylation of aryl‐ ...and silyl‐substituted internal alkynes enabled by a rare‐earth ate complex to yield geminal bis‐ and tris(silanes), respectively. The lanthanum bis(amido) ate complex supported by an ene‐diamido ligand proved to be the ideal catalyst for this unprecedented transformation, while the same series of yttrium and samarium alkyl and samarium bis(amido) ate complexes exhibited poor activity and selectivity, indicating significant effects of the ionic size and ate structure of the rare‐earth catalysts.
Big metal magic: Dihydrosilylation of aryl‐ and silyl‐substituted internal alkynes is successfully achieved by a lanthanum bis(amido) ate complex to yield geminal bis‐ and tris(silanes), respectively. The high activity could be attributed to the large lanthanum ion and anionic nature of the catalyst.
The incidence of intrahepatic cholangiocarcinoma (iCCA) continues to increase worldwide, however its molecular pathogenesis remains poorly understood. Recent studies have implicated microRNAs in iCCA ...progression. In this study, we demonstrated that miR‐885‐5p was significantly decreased in iCCA tissues. Downregulation of miR‐885‐5p was correlated with vascular invasion, lymph node metastasis, unfavorable overall survival, and shorter disease‐free survival. Silencing or overexpressing miR‐885‐5p by lentiviral approaches significantly influenced iCCA cell proliferation and metastasis in vitro and in vivo. Mechanistically, overexpression of miR‐885‐5p inhibited iCCA metastasis and proliferation by directly inhibiting GALNT3 as well as by indirectly promoting the downregulation of insulin‐like growth factor‐2 mRNA‐binding protein 1 (IGF2BP1). Furthermore, miR‐885‐5p inhibited iCCA metastasis by downregulating the PI3K/AKT/MMPs signaling pathway via targeting GALNT3. Collectively, we demonstrated that miR‐885‐5p was an important mediator of iCCA proliferation and metastasis by regulating GALNT3 and IGF2BP1, thus offering a potential target for iCCA treatment.
The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted ...naphtho1,8-bcpyrans by sequential cleavage of C(sp2)–H/C(sp3)–H and C(sp2)–H/O–H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C(sp2)–H/C(sp3)–H bonds and annulation with alkynes, leading to 1-naphthols as the intermediate products. Subsequently, 1-naphthols react with alkynes by cleavage of C(sp2)–H/O–H bonds, affording the 1:2 coupling products. Moreover, some of the naphtho1,8-bcpyran products exhibit intense fluorescence in the solid state.
A novel and direct approach to synthesize 1-aminoindole derivatives by Rh(iii)-catalyzed cyclization of 2-acetyl-1-arylhydrazines with diazo compounds via aryl C-H activation has been developed. This ...intermolecular annulation involving tandem C-H activation, cyclization and condensation steps proceeds efficiently in water, obviates the need of external oxidants, and displays a broad substituent scope.
Herein we describe an one‐pot protocol for visible light‐induced synthesis of functionalized spirocyclic indolines under mild conditions by means of a process involving sequential difluoromethylative ...dearomatization, hydroxylation, and substitution reactions of indole derivatives. The transformation proceeds via a hydroxylated “acetal pool” intermediate that can react with various nucleophiles. Several of the phosphine‐oxide and indole‐substituted products showed good fungicidal activity, suggesting that this protocol might be useful in the agrochemical field.
In the northern South China Sea, numerous multichannel seismic reflection sections are used to identify internal solitary wave (ISW) packets and extract wave amplitudes and corresponding water ...depths. The analyzed data show that these depression ISWs occur on the upper continental slope at water depths between 263 m and 740 m, with maximum amplitudes ranging from 35 m to 128 m. Our results, in conjunction with previous studies, suggest that the maximum amplitudes of the ISWs on the northern South China Sea continental slope are highly correlated with seafloor depths and that they have a logarithmic function relationship. The maximum amplitudes decrease with decreasing water depths. Interactions between the ISWs and the seafloor play a crucial role in decreasing ISW maximum amplitudes, especially in shallow areas. In addition, we compare the observed vertical amplitude distribution with theoretical results and find that they are concordant. The “bottom depth” (H) in the boundary conditions of eigenfunctions represents the extension depth of the ISW rather than the actual seafloor depth. Here, the ISW extension depth is where the ISW amplitude becomes zero and the seafloor depth is just under the ISW. If the ISW interacts intensely with the seafloor, its observed vertical amplitude distribution may exhibit prominent differences from the theoretical result.
•Fourteen individual internal solitary waves have been identified in the northern South China Sea from multi-channel seismic data..•A logarithmic correlation between maximum amplitude and corresponding depth has been observed.•The individual ISW's amplitude distribution over depth can be best described by the solution of eigenfunctions.
Abstract
Due to their intrinsic high reactivity, isolation of tin(0) complexes remains challenging. Herein, we report the synthesis of a silylene-stabilized ditin(0) complex (
2
) by reduction of a ...silylene-supported dibromostannylene (
1
) with 1 equivalent of magnesium (I) dimer in toluene. The structure of
2
was established by single crystal X-ray diffraction analysis. Density Functional Theory calculations revealed that complex
2
bears a Sn=Sn double bond and one lone pair of electrons on each of the Sn(0) atoms. Remarkably, complex
2
is readily methylated to give a mixed-valent methylditin cation (
4
), which undergoes topomerization in solution though a reversible 1,2-Me migration along a Sn=Sn bond. Computational studies showed that the three-coordinate Sn atom in
4
is the dominant electrophilic center, and allows for facile reaction with KHBBu
s
3
furnishing an unprecedented N-heterocyclic silylenes-stabilized distannavinylidene (
5
). The synthesis of
2
,
4
and
5
demonstrates the exceptional ability of N-heterocyclic silylenes to stabilize low valent tin complexes.
Be economic with your atoms! An efficient Rh‐catalyzed oxidative olefination of indoles and pyrroles with broad substrate scope and tolerance is reported (see scheme). The catalytic reaction proceeds ...with excellent regio‐ and stereoselectivity. The directing group N,N‐dimethylcarbamoyl was crucial for the reaction and could be removed easily.
A new strategy for the highly selective synthesis of tricyclo2,2,0,02,5hexasilanes R6Si6X2 (R = 2,4,6-Me3C6H2; X = H, Cl) and a bridged tricyclic R6Si6 dianion starting from the ...tetrachlorotrisilane RCl2SiSi(H)RSiCl2R (1) was described. Reduction of 1 with lithium naphthalene afforded tricyclohexasilane R6Si6H2 (2), which was halogenated to give the dichloride R6Si6Cl2 (3). Reduction of 3 with four equivalents of potassium graphite in the presence of 18-crown-6 afforded the first R6Si6 dianion (5) paired with K(18-crown-6)+ 2 counterions. The dianion 5 could act as a two-electron reductant toward transition metal halides and a nucleophile toward chlorosilanes. These reactions allowed the efficient and selective access to three types of silicon cages. The structures of the representative cages were confirmed by X-ray diffraction studies. Density functional theory calculations on 5 indicate that the negative charges are localized mainly on the anionic silicon atoms.
A series of trifluoromethyl‐containing heterocycles, like indene and dihydroquinolinone or dihydrocoumarin‐fused tetracyclic compounds have been prepared using copper‐catalyzed cascade reaction of ...benzene‐tethered 1,7‐enynes. A study of the mechanism indicated that radical trifluoromethylation and sequential 6‐exo‐dig/5‐endo‐trig bicyclization processes were involved in this protocol. Moreover, some selected products showed certain fungicidal activities against 14 kinds of plant fungi which means that these functionalized tetracyclic compounds might be used in the agrochemical field.
