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The frustrated Lewis pair (FLP) derived from 2,6-lutidine and B(C6 F5 )3 is shown to mediate the catalytic hydrogenation of CO2 using H2 as the reductant and a silylhalide as an oxophile. The nature of the products can be controlled with the judicious selection of the silylhalide and the solvent. In this fashion, this metal-free catalysis affords avenues to the selective formation of the disilylacetal (R3 SiOCH2 OSiR3 ), methoxysilane (R3 SiOCH3 ), methyliodide (CH3 I) and methane (CH4 ) under mild conditions. DFT studies illuminate the complexities of the mechanism and account for the observed selectivity.

Catalytic hydroarylation reactions of conjugated dienes are achieved using tris(pentafluorophenyl)borane as a Lewis acid catalyst under mild reaction conditions. This new protocol shows a broad substrate scope for the highly regioselective functionalization of sterically hindered aniline derivatives. Experimental and extensive density functional theory mechanistic studies show that the complex of residual water and B(C6F5)3 plays a crucial role in the aryl-assisted protonation of conjugated dienes, forming allyl cation intermediates that induce the facile electrophilic aromatic substitution of aniline substrates.

Synthesis of value-added products from simple C1 feedstocks is an attractive alternative avenue to traditional fossil fuels. Hexa-substituted benzene derivatives are highly useful molecules but are often challenging to prepare. Herein, we report that the lithium complex [(Ph2 P(S))2 CLi2 (THF)]2 1 reacts with CO lead to C-C bond formation and migration of a Ph2 P(S)-fragment affording 2. Subsequent reaction with N2 O results in oxidative cleavage of a P-C bond affording [Ph2 P(S)OLi(THF)2 ]2 4 and the anionic ketene-derivative Ph2 P(S)CCOLi(THF)2 5. Heating 5 prompts cyclotrimerization giving the hexa-substituted benzene derivative [Ph2 P(S)CCOLi(THF)2 ]3 6 regioselectively. This transition metal-free protocol to a hexa-substituted benzene is viable on a gram scale and permits the incorporation of 13 C labels. The mechanisms of these reactions are detailed via extensive DFT computations.

Reactions of benzyl potassium species with CO are shown to proceed via transient carbene-like intermediates that can undergo either dimerization or further CO propagation. In a sterically unhindered case, formal dimerization of the carbene is the dominant reaction pathway, as evidenced by the isolation of ((Ph3 SiO)(PhCH2 )C)2 2 and PhCH2 C(O)CH(OH)CH2 Ph 3. Reactions with increasingly sterically encumbered reagents show competitive reaction pathways involving intermolecular dimerization leading to species analogous to 2 and 3 and those containing newly-formed five-membered rings tBu2 C6 H2 (C(OSiR3 )C(OSiR3 )CH2 ) (R=Me 6, Ph 7). Even further encumbered reagents proceed to either dimerize or react with additional CO to give a ketene-like intermediates, thus affording a 7-membered tropolone derivative 14 or the dione (3,5-tBu2 C6 H3 )3 C6 H2 CH2 C(O))2 15.

N-Benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides, easily obtained from aromatic aldehydes and anilides of dichloroacetic acid under Darzens condensation conditions, proved to be excellent starting compounds for the synthesis of 3-hydroxyindolin-2-ones, cyclohepto[b]pyrrole-2,3-diones, and 1-azaspiro[4.5]deca-3,6,9-triene-2-ones via the C(sp2)-C(sp2) bond formation in the first case and C(sp2)-C(sp3) bond formation in the second and third cases. Under optimized reaction conditions, 3-hydroxyindolin-2-ones are obtained in a one-pot process, which involves the treatment of N-benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides with CF3CO2H or AcOH/H2SO4. In the case of intramolecular cyclization, the detailed reaction channels depend strongly on the substituents present in the anilide component and in the aromatic ring of the aldehyde component of N-benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides, as well as the temperature and duration of the reaction. A combined experimental and DFT mechanistic study of the formation of 1-benzyl-3-hydroxy-4-arylquinolin-2(1H)-ones showed that there are three competing reaction channels: (a) ring-closure via the ipso site, (b) ring-closure via the 1,2-Cl shift, and (c) ring-closure via the ortho site. Such mechanistic insights enabled an effective one-pot gram-scale synthesis of viridicatin from benzaldehyde and 2,2-dichloro-N-(4-methoxybenzyl)-N-phenylacetamide.

Background: Floral aroma is an important plant trait and it is one of the main traits of Rhododendron varieties which affect their ornamental value. The volatile compounds of floral aroma are secondary metabolites. In order to reveal the key genes of the phenylpropane pathway, which regulates the fragrance of Rhododendron fortunei, we performed a comprehensive transcriptome and metabolome analysis of the petals of the petals of two alpine rhododendrons from two different varieties: the scented Rhododendron fortunei and the non-scented Rhododendron ‘Nova Zembla’. Results: Transcriptomic and qRT-PCR results showed that nine candidate genes were highly expressed in R. fortunei, but down-regulated in R. ‘Nova Zembla’. The correlation analysis of candidate genes and metabolites revealed nine key genes involved in the regulation of floral aroma in the phenylpropane pathway. Among them, EGS was significantly positively correlated with various volatile benzene/phenylpropane compounds, and significantly negatively correlated with various non-volatile compounds; CCoAOMT, PAL, C4H,and BALDH were significantly negatively correlated with various volatile benzene/phenylpropane compounds, and significantly positively correlated with various non-volatile compounds. CCR, CAD, 4CL, and EGSwere significantly negatively correlated with various benzene/phenylpropane compounds. The validation of RfSAMT proved that RfSAMT gene regulated the synthesis of aromatic substances in R. fortunei. Conclusion: The findings of this study indicated that key candidate genes and metabolites involved in the biosynthetic pathway of phenylpropane may regulate the fragrance of R. fortunei. This lays a foundation for further research on the molecular mechanism of fragrance synthesis in the genus Rhododendron.

Herein is reported the structural characterization and scalable preparation of the elusive iron-phosphido complex FpP(

Primary acyl-phosphines are scarce in the literature. Here we show that the reaction of Ph3 GePCO with the ylide Ph3 PCH2 proceeds to give the species Ph3 PCHC(O)PH(GePh3 ) 1. Deprotonation of 1 with Na[N(SiMe3 )2 ] generates the salt [Na(THF)2 ][Ph3 PCHC(O)P(GePh3 )] 2 which provides subsequent access to the bis-germanylated acylphosphine, Ph3 PCHC(O)P(GePh3 )2 3. Alternatively, treatment of 1 with HCl in dioxane affords the primary acylphosphine Ph3 PCHC(O)PH2 4. Compound 4 is a rare example of an air stable primary acyl-phosphines and the first devoid of a stabilizing heteroatom adjacent to the carbonyl fragment.

The reactions of K[N(SiMe 3 ) 2 ] with 13 CO is shown to proceed in C 6 D 6 or THF affording K 13 CN and O(SiMe 3 ) 2 under mild conditions. This was confirmed by the isolation and crystallographic characterization of K(18-crown-6)CN. In an analogous fashion, reaction of the alkali metal amides, M[N(SiR 3 )R'] (M= Li, K; R = Ph, Me; R' = alkyl, aryl) afford a facile route to the corresponding 13 C labeled isocyanide RN 13 C and MOSiR 3 generally in high yields. In some instances, the use of the sterically bulky Ph 3 Si-substituent is required to preclude 1,2-silyl migration affording the silylcarbamoyl salt M[Me 3 SiC(O)NR']. These reactions have been used to obtain 19 examples of 13 C labelled isocyanides, and several examples of gram scale reactions are reported. The mechanism of the reactions is probed via reliable DFT calculations.

The reactions of FLPs with diazomethanes leads to the rapid loss of N

The continuously arising of SARS-CoV-2 variants has been posting a great threat to public health safety globally, from B.1.17 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta) to B.1.1.529 (Omicron). The emerging or re-emerging of the SARS-CoV-2 variants of concern is calling for the constant monitoring of their epidemics, pathogenicity and immune escape. In this study, we aimed to characterize replication and pathogenicity of the Alpha and Delta variant strains isolated from patients infected in Laos. The amino acid mutations within the spike fragment of the isolates were determined via sequencing. The more efficient replication of the Alpha and Delta isolates was documented than the prototyped SARS-CoV-2 in Calu-3 and Caco-2 ​cells, while such features were not observed in Huh-7, Vero E6 and HPA-3 ​cells. We utilized both animal models of human ACE2 (hACE2) transgenic mice and hamsters to evaluate the pathogenesis of the isolates. The Alpha and Delta can replicate well in multiple organs and cause moderate to severe lung pathology in these animals. In conclusion, the spike protein of the isolated Alpha and Delta variant strains was characterized, and the replication and pathogenicity of the strains in the cells and animal models were also evaluated.

Reactions of PAr

Reactions of the diborane(4) B2(o‐tolyl)4 and monohydridoboranes are shown to give B(o‐tolyl)3 and (o‐tolyl)BR2 (R2=(C8H14) 3, cat 4, pin 5, (C6F5)2 6) as the major products. The corresponding reaction with BH3‐sources gives complex mixtures, resulting from hydride/aryl exchange, dimerization and borane elimination. This led to the isolation of the first tetra‐substituted pentaborane(9) HB[B(o‐tolyl)(μ‐H)]4 8. The reaction pathways are probed experimentally and by computations., The diborane(4) B2(o‐tolyl)4 reacts with species with B−H bonds giving a complex mixture arising from hydride/aryl exchange, dimerization and borane elimination. Use of BH3 sources led to the isolation of the first tetra‐substituted pentaborane(9) HB[B(o‐tolyl)(μ‐H)]4.

Lithium dicyclohexylamide (Cy2NLi) reacts with syn-gas or CO to generate transient intermediates with carbene character, which are capable of reacting further with CO or H2, effecting sequential C-C and C-H bond formations from CO or H2, thus providing a transition-metal-free avenue to the fundamental reactions of the Fischer-Tropsch process. Further experimental and computational data indicate that reactions with CO and H2 are thermodynamically accessible, with a kinetic bias toward CO homologation.