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How can high enantioselectivity be achieved when the racemic background reaction proceeds at a rate comparable to that of the catalytic asymmetric reaction? We attempted to rationalize this counterintuitive observation by studying the effect of (1) catalyst structure, (2) temperature and addition sequence of components, (3) catalyst loading, and (4) Brønsted acid additives. In the course of our investigation, it was found that increasing the amount of catalyst used led to inhibition of the stoichiometric reaction. Olefinic 1,3-diol 1 , 5 mol % of catalyst 3a , 1 equiv of MsOH, and NBS were added at low temperature in a specific sequence to provide the best performance for the enantioselective bromoetherification. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) investigations revealed that 4-cyanopyridine was capable of homolytically cleaving the B−B σ bond of diborane via the cooperative coordination to the two boron atoms of the diborane to generate pyridine boryl radicals. Our experimental verification provides supportive evidence for this new B−B activation mode. With this novel activation strategy, we have experimentally realized the catalytic reduction of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones with B2(pin)2 at mild conditions. [ABSTRACT FROM AUTHOR]

Using a spectroscopic complex designed for studying the kinetics of chemical reactions, the rate constant for the gas-phase reaction between a Lewis base and a Lewis acid-CHOH + BCl → CHOBCl + HCl-at at room temperature and pressures of 1.5-27.9 Torr has been derived for the first time. The complex comprises a reactor embedded in the optical system of a commercial AF-3 Fourier transform IR spectrometer capable of recording the spectra of reactants during the process. The reaction mechanism has been analyzed. [ABSTRACT FROM AUTHOR]

The Lewis base-promoted alkynylation of fluorobenzenes using trimethylsilylacetylenes studying the reactivity as a function of the number of fluoride groups is described. The reaction of 1-(pentafluorophenyl)- and 1-(3,4,5-trifluorophenyl)-2-phenylacetylenes and 1-(4-methoxyphenyl)-2-trimethylsilylacetylene with CsF/18-crown-6 in DMSO gave the alkynylated products in moderate to good yields with high regioselectivity under mild conditions. However, the 3,4-difluorophenyl derivative showed low reactivity. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of acetylene to ethylene is very important for removing a trace amount of acetylene from ethylene. Tuning catalyst acidity is critical for hydrogenation reaction to prevent oligomerization. In this work, NaN 3 was introduced to Pd catalyst serving as Lewis base sites. NaN 3 -Pd/SAC catalysts with different N 3 − loadings (0–15 wt.%) were prepared by impregnation method and analyzed with BET, temperature-programmed reduction (TPR), Fourier-transferred Infrared (FTIR) spectroscopy, CO pulse chemisorption, temperature-programmed desorption (TPD) of hydrogen and acetylene. The results showed NaN 3 covered some Pd species and increased the reduction temperatures of catalysts. Also NaN 3 addition decreased the catalyst surface areas due to blocking some pores on the support. N 3 − on the catalysts lowered hydrogen adsorption capacity but showed superior adsorption capability for acetylene, the selectivity and conversion of the acetylene hydrogenation was negatively affected by N 3 − species under the current operation conditions. The amount of the adsorbed hydrogen and the types of acetylene adsorption played important roles for the hydrogenation reaction. This work provides insights on how to prepare an effective catalyst for removing acetylene impurity from ethylene. [ABSTRACT FROM AUTHOR]

In the Baylis-Hillman reaction of aryl aldehydes with phenyl vinyl ketone we have observed exclusive formation of diadducts 4, and that the yields of diadduct can reach 80% with increasing amounts of phenyl vinyl ketone. On the other hand, for phenyl acrylate and phenyl thioacrylate, only the normal Baylis-Hillman adduct was obtained. The effects of substituents were also examined and a plausible reaction mechanism is proposed for the formation of compounds 4.

Halogen bonding has emerged at the forefront of advances in improving ligand: receptor interactions. In particular the newfound ability of this extant non-covalent-bonding phenomena has revolutionized computational approaches to drug discovery while simultaneously reenergizing synthetic approaches to the field. Here we survey, via examples of classical applications involving halogen atoms in pharmaceutical compounds and their biological hosts, the unique advantages that halogen atoms offer as both Lewis acids and Lewis bases.

In recent years, all-inorganic perovskite cells (PSCs) have been widely studied by researchers because of their excellent thermal and optical stability. Among them, the CsPbIBr 2 PSCs with carbon electrode have attracted extensive attention because of its excellent stability, low preparation difficulty, easy commercialization and low cost. However, the crystal quality of CsPbIBr 2 film is poor. There are a large number of pinholes and surface defects (Pb2+ exposure), which will lead to internal short circuit and a large number of nonradiative recombination, thus affecting the photoelectric conversion efficiency (PCE). Although these problems can be improved by antisolvent engineering, the traditional antisolvent chlorobenzene (CB) and toluene (TL) are highly toxic and harmful to the environment. In this paper, isopropanol (IPA) is used as a green antisolvent to improve the quality of CsPbIBr 2 films, and S2− with strong reducibility and passivation defects are successfully introduced into the CsPbIBr 2 film surface by further adding thiourea as Lewis base to IPA (IPA-S). After the CsPbIBr 2 films were treatment by IPA-S antisolvent, we successfully obtained high-quality CsPbIBr 2 films with large grain size and no pinholes. Moreover, through XPS, PL, EIS and other tests, it is found that the S2− introduced by IPA-S can combine with the exposed Pb2+ on the CsPbIBr 2 surface to passivate the defects, it is beneficial to reduce the non-radiative recombination and improve the transport capacity of carriers. Finally, the results of this paper prove that that the champion PCE of carbon based CsPbIBr 2 PSCs treated with IPA-S antisolvent was 6.79%, which was nearly 30% higher than the original carbon based CsPbIBr 2 PSCs. In addition, due to the strong reducibility of S2−, the carbon based CsPbIBr 2 PSCs treated with isopropanol antisolvent added with thiourea can continue to work in air with 40% relative humidity, and the efficiency can remain 85% within 10 days. In order to improve the performance and stability of the all-inorganic PSCs, this paper provides a non-toxic, environmentally friendly and effective scheme. [ABSTRACT FROM AUTHOR]

The Baylis-Hillman reactions of various aryl aldehydes with methyl vinyl ketone at temperatures below -20oC using Lewis acids such as titanium (IV) chloride, boron (III) chloride or zirconium (IV) chloride in the presence of a catalytic amount of selected amines used as a Lewis bases afford the chlorinated compounds 1 as the major product in very high yields. Acrylonitrile can also undergo the same reaction to give the corresponding chlorinated product in moderate yield. A plausible reaction mechanism is proposed. However, if the reaction was carried out at room temperature (ca. 20oC), then the Z-configuration of the elimination product 3, derived from 1, was formed as the major product.

Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butylphosphane as the µ-bridged dimer is formed, viz. di-µ-chlorido-bis[chloridobis(tri-tert-butylphosphane)zinc], [ZnCl4(C12H27P)2], (1), which features a nearly square-shaped (ZnCl)2 cyclic core and whose Cl atoms interact weakly with C--H groups on the phosphane ligand. In the presence of THF, monomeric dichlorido(tetrahydrofuran-κO)-(tri-terf-butylphosphane-κP)zinc, [ZnCl2(C4H8O)(C12H27P)] or [P(tBu3)(THF)-ZnCl2], (2), is formed. This slightly distorted tetrahedral Zn complex has weak C--H⋯Cl interactions between the Cl atoms and phosphane and THF C--H groups. Under ambient conditions, the hydrolysed complex tri-tert-butyl-phosphonium aquatrichloridozincate 1,2-dichloroethane monosolvate, (C12H28P)[ZnCl3(H2O)]⋅C2H4Cl2 or [HPtBu3]+ [(H2O)ZnCl3]--C2H4Cl2, (3), is formed. This complex forms chains of [(H2O)ZnCl3]- anions from hydrogen-bonding interactions between the water H atoms and Cl atoms that propagate along the b axis. [ABSTRACT FROM AUTHOR]

The N-heterocyclic carbene (NHC) catalyzed redox formal [2+2] cycloaddition between a-aroyloxyalde-hydes and perfluoroketones, followed by ring-opening in situ delivers a variety of perfluorinated β-hydroxycarbonyl compounds in good yield, and excellent diastereo- and enantioselectivity. Through a reductive work-up and subsequent cyclization, this protocol offers access to highly substituted fluorinated oxetanes in two steps and in high ee. [ABSTRACT FROM AUTHOR]

The reaction of the functionalized cyclo-tetraphosphane [ClP(µ-PMes*)]2 (Mes*=2,4,6-tri-tert-butylphenyl) with different Lewis bases led to the formation of an unprecedented tricyclic hexaphosphane, Mes*P6Mes*. The formation of this compound was investigated by spectroscopic and theoretical methods, revealing an unusual ring expansion reaction. The title compound was fully characterized by experimental and computational methods. [ABSTRACT FROM AUTHOR]

2-Acylated 2,3,1-benzodiazaborines can display unusual structures and reactivities. The crystal structure analysis of the boron heterocycle obtained by condensing 2-formylphenylboronic acid and picolinohydrazide reveals it to be an N→B-chelated zwitterionic tetracycle (systematic name: 1-hydroxy-11-oxo-9,10,17λ5-triaza-1λ4-boratetracyclo[8.7.0.02,7.012,17]heptadeca-3,5,7,12,14,16-hexaen-17-ylium-1-uide), C13H10BN3O2, produced by the intramolecular addition of the Lewis basic picolinoyl N atom of 1-hydroxy-2-(pyridin-2-ylcarbonyl)benzo[ d][1,2,3]diazaborinine to the boron heterocycle B atom acting as a Lewis acid. Neither of the other two pyridinylcarbonyl isomers ( viz. nicotinoyl and isonicotinoyl) are able to adopt such a structure for geometric reasons. A favored yet reversible chelation equilibrium provides an explanation for the slow D2O exchange observed for the OH resonance in the 1H NMR spectrum, as well as for its unusual upfield chemical shift. Deuterium exchange may take place solely in the minor open (unchelated) species present in solution. [ABSTRACT FROM AUTHOR]

The reactions of Cd(OAc) 2 ·2H 2 O with variously substituted pyridines in methanol afforded unique one-dimensional coordination polymers (1D CPs), [Cd 2 ( μ 2 - κ 2 : κ 1 -OAc) 2 ( μ 2 - κ 1 : κ 1 -OAc) 2 L 2 ] (L = NC 5 H 5 ( 1 ), NC 5 H 4 Me-3 ( 2 ), and NC 5 H 3 Me 2 -3,5 ( 3 )) and [Cd 3 ( μ 3 - κ 1 : κ 2 -OAc) 3 ( μ 2 - κ 2 -OAc)( μ 2 - κ 2 : κ 1 -OAc) 2 (NC 5 H 3 Me 2 -3,4) 2 ] ( 4 ), and discrete and bimolecular complexes, [(Cd(OAc) 2 (NC 5 H 3 Me 2 -3,4) 2 (H 2 O) 2 ] ( 5 ), [Cd( κ 2 -OAc) 2 (NC 5 H 4 Me-4) 2 (H 2 O)]·[Cd( κ 2 -OAc) 2 (H 2 O) 2 )] ( 6 ), [Cd( κ 2 -OAc) 2 L 2 L′]· x H 2 O ( x = 0, L′ = H 2 O, L = NC 5 H 4 (OMe)-4 ( 7 ); NC 5 H 4 t Bu-4 ( 8 ); x = 2, L = L′ = NC 5 H 4 (NMe 2 )-4 ( 9 ·2H 2 O)). The products were characterised by elemental analysis, IR, solution NMR ( 1 H and 13 C), solid-state CP-MAS 13 C{ 1 H} and 113 Cd NMR, TGA/DTA analyses, and single crystal X-ray diffraction. Phase purity of 1 – 4 was verified by powder X-ray diffraction (PXRD). Plausible mechanisms of formation of the products are proposed based on a point zero charge model. 4 represents the first cadmium containing 1D CP that possesses a tridentate bridging ( μ 3 - κ 1 : κ 2 ) acetate coordination mode and 6 represents the first structurally characterised bimolecular cadmium(II) complex containing two different neutral cadmium(II) coordination species per formula unit. 9 ·2H 2 O was calcined at 500 °C to afford CdO as confirmed by PXRD and the morphology of CdO was studied by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

A highly enantioselective Lewis base-catalysed formal [3+2] cycloaddition of ammonium enolates and oxaziridines to give stereodefined oxazolidin-4-ones in high yield is described. Employing an enantioenriched oxaziridine in this process leads to a matched/mis-matched effect with the isothiourea catalyst and allowed the synthesis of either syn- or anti-stereodefined oxazolidin-4-ones in high d.r., yield and ee. Additionally, the oxazolidin-4-one products have been derivatised to afford functionalised enantioenriched building blocks. [ABSTRACT FROM AUTHOR]

A highly enantioselective b-isocupreidine (b-ICD) catalyzed synthesis of dihydropyran-fused benzofurans through [4+2] cycloaddition of allenoates and benzofuranone alkenes was developed. Switchable chirality inversion of cycloaddition products was achieved by replacing the phenolic proton of the catalyst with a methyl, demonstrating an amazing effect of minimal structural variation on inverting enantioselectivity. DFT calculations were utilized to elucidate the origin of the observed phenomena. Computation also provided a clue for a rational design in which the multi-hydrogen bond with the alcohol additive was found to improve the enantioselectivity of the cycloaddition. Finally, the substrate scope was examined, in which a number of functionalized dihydropyran-fused benzofurans could be obtained in high yields (up to 97%) with very good regio- (>20:1) and enantioselectivities (up to 98:2 e.r.). [ABSTRACT FROM AUTHOR]

Allylation, trans- and cis-crotylation of (2 E,4 E)-2,4-dimethylhexadienal, a representative α,β,γ,δ-unsaturated aldehyde, was carried out under different catalytic and stoichiometric conditions. The reactions catalyzed by organocatalysts TRIP-PA and N, N′-dioxides gave the best results with respect to yields, asymmetric induction, and catalyst load in comparison to other procedures. The developed methodology was applied in the enantioselective synthesis of (5 R,6 S)-(+)-pteroenone, a defensive metabolite (ichthyodeterrent) of the Antarctic pteropod Clione antarctica. [ABSTRACT FROM AUTHOR]

The extended π-electronic conjugation system of the (octaethylporphyrin)-(dihexylbithiophene)-(Lewis base) triads [OEP-DHBTh-LB] exhibits the proton-mediated reversible changes in both 1 H NMR and UV–vis spectra via two-step processes, reflecting the structural features of DHBTh and LB constituents. The spectral changes of OEP-DHBTh-LB with trifluoroacetic acid (TFA) were quantitatively examined by means of 1 H NMR spectral measurement and comparatively analyzed in terms of stereo-electronically controlled effects of DHBTh and LB constituents on its reversibly transformable chromatic system. Successively, based on the minimum amount of TFA necessary for completion of spectral changes at respective steps, the sensitivity and stability of OEP-DHBTh-LB to TFA were evaluated, from the viewpoint of the interactive behavior of the lone pair electrons on N atom in LB with the extended OEP constituent. The present study provides a useful guideline of the molecular design for further sophisticated OEP-based chromatic system with proton-sensing functionality. [ABSTRACT FROM AUTHOR]

The proton behaviors and structural evolution of the perovskite film surface upon Lewis base passivation were systematically investigated by using two Lewis base isomers with distinct basicity. By virtue of regulation of roper proton behaviors, boosted power conversion efficiency up to 23.3% and improved operational stability over 1000 h have been achieved. [Display omitted] • Proton behaviors of the perovskite surface induced by Lewis base are investigated. • Basicity dependent structural evolution, carrier kinetics and passivation effects. • Strongly basic Lewis base despoils protons resulting in collapse of perovskite. • Boosted PCE up to 23.3% are achieved by regulating proper proton behavior. Proton behaviors in hybrid perovskites induced by Lewis base upon interfacial passivation have substantial impacts on perovskite lattice structure and the charge transfer kinetics in perovskite solar cells (PSCs). Herein, two Lewis base isomers with distinct basicity are used to investigate the basicity dependent proton behaviors and passivation effects. 2-aminopyridine with gentle basicity can effectively stabilize the superficial organic species of perovskite, whereas 4-aminopyridine (4A) with strong basicity would destructively despoil protons from the organic species in perovskite crystals and uncontrollably form low-dimensional perovskites above a layer of inorganic metal skeleton as a result of hindering the interfacial charge transport seriously. By virtue of regulation of the proton behavior through pre-protonation of 4A, boosted power conversion efficiency up to 23.3% and improved operational stability over 1000 h have been achieved. This work provides new insights into passivation strategy toward Lewis base as well as a basicity guidance for passivator selection. [ABSTRACT FROM AUTHOR]

Preparation of lead halide perovskite polycrystalline films at a low annealing temperature is highly restricted by their intrinsically large crystallization activation energy, which hinders the conversion of the precursors/intermediates to perovskites and yields as-prepared polycrystals with tiny grain sizes and terrible crystal quality. Herein, we demonstrate through in-situ, real-time spectroscopic studies that both the nucleation and crystal growth kinetics can be improved without the need for a high annealing temperature by treating the film with thiourea, as accounted for by the reduced activation energy. As a consequence, the thiourea-treated perovskite polycrystalline film exhibits larger grain sizes and greater crystallinity than the untreated one. More importantly, owing to the synergistic effect of the promoted crystallization kinetics and the passivation of surface defects, the low-temperature prepared films treated with thiourea even present more prominent photophysical properties than those fabricated by using the conventional high-temperature method. The strategy of crystallization kinetics engineering proposed in this work paves the way for fabricating high-quality perovskite polycrystalline films in a low-temperature manner., (© 2022 Wiley-VCH GmbH.)

We studied reactions of t Bu 3 M (M = Al, Ga) with 2-mercaptobenzoxazole. In the presence of strong Lewis bases, alkylaluminum o -isotiocyanatophenolates [ t Bu 2 Al(OC 6 H 4 NCS)(THF)] ( 1 ), [ t Bu 2 Al(OC 6 H 4 NCS)(3-picoline)] ( 2 ) were obtained as a result of heterocycle cleavage in the 2-mercaptobenzoxazolate ligand and Al–O phenolate bond formation. The reaction of t Bu 3 Al with 2-mercaptobenzoxazole in OEt 2 as a weak Lewis base produced the stable tetranuclear complex [ t Bu 2 Al(C 7 H 4 NOS)] 4 ( 3 ). The gallium compound [ t Bu 2 Ga(C 7 H 4 NOS)] 4 ( 4 ), isostructural to compound 3 , was formed as a stable complex irrespective of the kind of Lewis base. The molecular structures of 1 , 3 , and 4 were determined by single-crystal X-ray diffraction technique. [ABSTRACT FROM AUTHOR]

The discovery of a novel aerobic oxidative intermolecular azide-zwitterion reaction catalyzed by an organocatalyst is presented. It is demonstrated that the merger of the Lewis base 1,8-diazabicyclo[5.4.0]undec-7-ene and electron-deficient olefins generates reactive zwitterion intermediates, which readily participate in cycloaddition reactions with an array of azides, thus providing facile entry to fully or highly substituted 1,2,3-triazole frameworks. The reaction features an excellent substrate scope, and the products are obtained with high yields and excellent regioselectivities. It is demonstrated that some of these products can be transformed into pharmaceutically important agents. In addition to the experimental results, a detailed mechanistic survey is also provided, including MS studies rationalizing the origin of regioselective control. [ABSTRACT FROM AUTHOR]

From auxiliary to catalyst: Chiral sulfinamides have emerged as versatile organocatalysts showing both Lewis base and Lewis acid activation modes. The reactions highlighted here involve several highly enantioselective transformations, such as reduction of imines, CC‐bond forming reactions, enantioselective protonation, [4+2] cycloadditions etc. [ABSTRACT FROM AUTHOR]

A series of four, five and six-coordinated magnesium derivatives integrating with substituted pyrrole and ketimine ligands are conveniently synthesized. Reaction of two equiv of 2-dimethylaminomethyl pyrrole with Mg[N(SiMe3)2]2 in THF affords the monomeric magnesium complex Mg[C4H3N(2-CH2NMe2)]2 (THF)2 ( 1) in high yield along with elimination of two equiv of HN(SiMe3)2. Similarly, the reaction between two equiv of 2-t-butylaminomethyl pyrrole and Mg[N(SiMe3)2]2 in THF renders the magnesium derivative, Mg[C4H3N(2-CH2NH tBu)]2(THF)22( 2) in good yield. Interestingly, reaction between two equiv of 2-t-butylaminomethyl pyrrole and Mg[N(SiMe3)2]2 in toluene, instead of THF, generates Mg[C4H3N(2-CH2NH tBu)]2 ( 3), also in high yield. Furthermore, the assembly of two equiv of ketimine ligand, HOCMeCHCMeNAr (Ar = C6H3-2,6- iPr2) and Mg[N(SiMe3)2]2, yields five-coordinated magnesium derivatives, Mg(OCMeCHCMeNAr)2(THF) ( 4) and Mg(OCMeCHCMeNAr)2(OEt2) ( 5), using THF and diethyl ether, respectively. All the aforementioned derivatives are characterized by 1H and 13C NMR spectroscopy as well as 1, 3, 4 and 5 are subjected to X-ray diffraction analysis in solid state. [ABSTRACT FROM AUTHOR]

A chiral Lewis base organocatalyzed asymmetric hydrosilylation of α-substituted β-enamino esters is presented. The reactions proceeded through dynamic kinetic resolution to afford various enantioenriched β2-amino esters with high yields (up to 98%) in moderate enantioselectivities (up to 77% ee). [ABSTRACT FROM AUTHOR]

Lewis base catalysis by lone pair donation into antibonding porbitals (n-π*) is a growing field with a range of Lewis bases capable of this type of catalysis. In this review, catalysis of the Morita-Baylis-Hillman reaction, the Steglich rearrangement, and the annulation of ɑ,β-unsaturated acyl Lewis adducts are discussed, using N-heterocyclic carbene (NHC), isothiourea, bicyclic tertiary amine and electron-rich pyridyl catalysts. In many cases, each of these popular Lewis base catalysts is viable for the given reaction, with the degree of utility defined by the catalyst's nucleophilicity and Lewis basicity. 1 Introduction to Lewis Base Catalysis 2 Enolates from 1,4-Addition: Morita-Baylis-Hillman Reaction 3 O→C Carboxyl Transfer: Steglich Rearrangement 4 Annulations of a,ß-Unsaturated Acyl Lewis Base Adducts 5 Summary and Outlook [ABSTRACT FROM AUTHOR]

A facile approach was developed for the rapid synthesis of multi-substituted furan-2(5 H)-one derivatives libraries. The synthetic strategy included the selenyl bromide resin-induced electrophilic catalyzed by Lewis base, , and oxidation-elimination of the selenium resins. The advantages of the new method are good yields, high purity, straightforward operations and high diversity of the products, lack of odor, and good stability of the selenium resins. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT The development of a binary catalyst system for bromocycloetherification, consisting of an achiral Lewis base and a chiral Brønsted acid, is described in detail. The results of preliminary kinetic studies are also presented. Chirality 26:343-354, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A facile, efficient, and highly diastereo- and enantioselective bromoetherification of diolefinic diols has been developed using an amino-thiocarbamate catalyst. Further manipulations of the bromoether products enabled entry into a new class of spirocycles which are distinctively lacking in the literature. [ABSTRACT FROM AUTHOR]

Abstract: A divergent isomerization of 5-hydroxyl-2,3-dienoate 1 catalyzed by Lewis base has been developed, the phosphine catalyst leads to 5-oxohex-2(3)-enoates 2 while DABCO catalyst affords 3-ethoxy α,β-unsaturated lactone 3. [Copyright &y& Elsevier]

Highlights: [•] ZrO2 has strong affinity for the deprotonated alkyl methylphosphonic acids. [•] ZrO2 was combined with a reversed phase separation column in on-line SPE–LC–MS. [•] Alkyl methylphosphonic acids were eluted from ZrO2 by 15mM ammonium acetate. [•] Humic compounds were eluted from ZrO2 with H2O/acetonitrile (60/40) at pH 10. [ABSTRACT FROM AUTHOR]

Highlights: [•] Asymmetric bromolactonization of 4,4-disubstituted 3-butenoic acid was achieved. [•] Cinchonine-derived amino-thiocarbamate was used as the catalyst. [•] The γ-butanolide products have two stereogenic centers. [•] The γ-butenolides can be achieved by quenching the reaction under basic condition. [•] The products are fundamental units of many pharmaceutically important molecules. [Copyright &y& Elsevier]

We report herein a new method for the synthesis of densely functionalized chiral allyl SCF 3 , SCF 2 R, SCN and SAr species with a separate CF 3 functionality. The synthetic approach is based on selenium-catalyzed sulfenofunctionalization of chiral α-CF 3 allylboronic acids. The reactions proceeded with remarkably high stereo-, diastereo- and site-selectivity, based on the formation of a stable thiiranium ion followed by rapid deborylative ring opening., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The title compound, alternatively called (4-bromophenyl)dihydrido(triphenylphosphanyl)boron, C 24 H 21 BBrP, crystallizes in the space group P-1 with one symmetry-independent molecule in the asymmetric unit. The B and P atoms both adopt the expected tetrahedral geometry. A possible intramolecular B-H δ- ... δ+ H-C dihydrogen bond exists between an arene group on phosphorus and the borane center. In the solid state, the title molecule is connected to its neighbors by intermolecular C-H...π interactions, with the arene rings on the P atom acting as hydrogen-bond donors and the arene ring of the borane acting as the acceptor. Hirshfeld analysis supports the existence of these interactions, as well as weak Br...Br interactions between neighboring molecules.