The difunctionalization of alkenes and alkynes is a simple and powerful strategy for the synthesis of various organic compounds and has been used to synthesize various important natural products, drug molecules and fine chemical products.The different effects of halo anions, substrates, solvents, temperature and reaction time to the stereospecific and reactivities of 1,1-carboborations of alkynes and B(C6F5)s were studied, meanwhile the corresponding catalytic mechanisum has been expoled.A convenient large-scale preparation method for the stereoselective (E)-1,1-carboboration products has been developed.The catalytic reactivities of ring-opening polymerization of cyclohexene oxide (CHO) have also been explored with different stereo-carboboranes isolated from 1,1-carboboration reaction, and it is noted that the stereospecificity E-or Z-has shown ambiguously different activities.To develop a stereo-specific approach in the synthesis of vinylboranes will not only be very important for the difunctionalization of alkenes and alkynes, but also for the novel stereospecificity organoborons.

Over the decade after the pioneering work of frustrated Lewis pair(FLP)chemistry, this research area has achieved tremendous success as novel transition-metal-free system in organic synthesis, enzymatic models, and material sciences. The popularly accepted mechanism of FLP reactivity involves the polarization and heterolytic cleavages of a substrate molecular. Whiles there are also few work showing differing reaction mechanisms for special kinds of Frustrated radical pairs(FRPs), which suggests a homolytic cleavage via one-electron processes. This work studied the Si-H bond activation by B(C6F5)(3) and enamines. In the presence of B(C6F5)(3) enamines did not undergo the expected hydrosilyation with silanes. The dominated hydrogenation products could not match the classic heterolytic cleavages mechanism by B(C6F5)(3) activating R3Si-H and transferring of R3Si+ to a nucleophile. The isotopic experiment results supported a mechanism that proceeds via the highly reactive radical anion [B(C6F5)(3)](-) as the reported FRP behaviors. Understanding the reaction mechanisms is not only crucial to progress in fundamental chemical research but also for further broadens the potential reactivity of FLP systems.

Recently, the research work concerning B(C6F5)(3) catalyzed reduction of carbonyl compounds revealed that this Lewis acid B(C6F5)(3) presents, actually, a rather water-tolerant system. This fact considerably broadens the scope of the water/base tolerant frustrated Lewis pairs (FLP) chemistry. In this research, an efficient chemoselective reduction of aldehydes and ketones to alcohols catalyzed by the Lewis acid B(C6F5)(3) has been developed. It is the first report about the chemoselective reduction of carbonyl compounds under aqueous conditions catalyzed by FLPs with hydridosilanes as reducing agents. The selectivity and activity of different hydridosilanes and the influence of substituents in carbonyl compounds have been studied. The effect of water concentration on the chemoselectivity of the reaction has also been investigated. It has been found that a 2 similar to 3 fold excess of water relatively to hydridosilanes usually exhibits better selectivity and overall yields than in the equimolar case. The reduction reaction can even be successfully performed with pure water as a solvent without any loss of the reactivity. Such a procedure has been successfully applied to reduce 14 differently substituted aldehydes and ketones into alcohols with up to 100% yields under mild conditions, but failed in case of the diaryl substituted ketones. Both experimental and computational methods have been performed to confirm the possibility of the water mediated mechanism and the effects of different Lewis bases on the LB-H-OH-LA three-component aggregates. These mechanistic studies have revealed that such water mediation between a carbonyl compound and a catalyst advantageously (i) activates the C=O group by protonation and (ii) fixes the catalytic borane moiety by formation of a B-O bond, which to some extent prevents the direct hydrolysis of hydridosilane and makes the reaction possible under moist conditions. Detailed clarification of the actual role of water in the reduction reaction of question will promote the further development of FLP-catalyzed and related reactions in the "green" chemistry field.

Recently the research work concerning B(C6F5)3 catalyzed reductive and amination of aldehydes and ketones revealed that this extremely electron-deficient borane is, actually, a rather water-tolerant catalyst. This fact considerably broadens the scope of the water/base tolerant FLP chemistry. In this project, an efficient one pot reductive amination method has been developed by reaction of aldehydes and alkoxyamines with hydrosilanes as the hydride sources and B(C6F5)3 as catalyst without cleavage of the N—O bond. This protocol can be used to prepare the secondary and tertiary alkoxyamines by starting from the primary and secondary ones, respectively. A special attention has been paid to elucidate the role of water in the reductive amination. When benzaldehyde reacts with benzoxylamine, only the condensation product oxime ether could be observed. Whereas surprisingly when excess amount of water is added, the reductive amination goes successfully like the alkoxyamine hydrochloride works. The detailed NMR data has shown that a transformation of the intermediate oximes ArCH =NOR to the “ammonium borates” [ArCH=NHOR][X-B(C6F5)3] (X=Cl, OH) can take place in the reaction system, while the latter can be converted into the well-known active intermediate “ammonium hydroborates” [ArCH= NHOR][H-B(C6F5)3] to reduce the C=N bond under mild condition in the presence of hydrosilanes. That means the deprotonation reaction of the Lewis acid water adduct H2O-B(C6F5)3 could be a key step for the B(C6F5)3 catalyzed reaction under moist condition. In this case the adduct H2O-B(C6F5)3 acts as a Brønsted acid as HCl does. Meanwhile a simulative experiment under different ratio of water has been fulfilled to prove this speculation. The C=N bond of Benzalaniline (PhCH =NPh) and Benzyloxy oxime ether (PhCH=NOCH2Ph) could be reduced only in presence of 2 equiv. H2O rather than equivalent. Based on this study it has shown that in the frustrated Lewis pair (FLP) chemistry, the Lewis acid B(C6F5)3 is not DOI: 10.6023/A18070281

Although in recent years the frustrated Lewis pairs (FLPs) reactivity towards small molecule activation has been widely concerned, the reports on the FLPs derived from aromatic amines are few. This paper describes a new method of an one-pot hydroamination/reduction reaction of terminal alkynes with aromatic amines catalyzed by the B(C6F5)(3)/aromatic ammonium chloride systems with a hydridosilane as a source of the hydride. We consider that the active intermediate [Ar2NH2](+)[H-B(C6F5)(3)](-) which formed by the aromatic ammonium chloride/B(C6F5)(3) reaction with silanes plays a very important role on the formation and reduction of the mediate product imines. The hydroamination reaction is firstly induced by the trace amount amines produced by the dissociation of the borohydride aromatic amine salt, which then reacts with the alkynes and forms the imines. Then the borohydride intermediate [Ar2NH2](+)[H-B(C6F5)(3)](-) reduces the imines to amines. It has been proved that the borohydride intermediate [Ar2NH2](+)[H-B(C6F5)(3)](-) could successfully reduce the corresponding imines to amines in an in-situ reaction condition. However it has been found that the usually most active mono-substituted hydridosilane, such as PhSiH3 shows the poorest reactivity in this case. And the less active trisubstituted silanes such as Et3SiH or Ph3SiH exhibit the highest reactivity. To explain this abnormal phenomenon the different reaction speeds of the cascade hydroamination/reduction reaction and the dissociation of the borohydride aromatic amine salt should be concerned. Since the dissociation of [Ar2NH2](+)[H-B(C6F5)(3)](-) to H-2 is comparably quicker than the hydroamination reaction. By reacting with the less active trisubstituted silanes could not only slow down the formation and dissociation of [Ar2NH2](+) [H-B(C6F5)(3)](-), but could also let the hydroamination and reduction steps proceeded completely. Moreover by slowly adding the diluted hydrosilanes to the reaction systems could also improve the reaction. The reaction yield is affected by the substituent on the terminal alkynes, too. The alkynes with the electron withdrawn group show comparably higher reactivity than with the electron donating ones.

Stereoselective hydroboration reaction of alkynes has been considered as one of the most important organic reaction. To date a handful of metal-catalyzed systems have been demonstrated to achieve trans-hydroboration of alkynes. This paper describes the first non-metal-catalyzed systems which could stereoselectively hydroborate the terminal alkynes in a trans-configuration. The Lewis acid B(C6F5)(3) and ammonium chloride have been used as the reaction substrates, and phenylsilane as the hydride source. The hydroboration reaction could be performed in a one-pot procedure by mixing of B(C6F5)(3), ammonium chloride and silane together in an equivalent amount. But this one-pot reaction is not so nice since there is always mixed with the ammonium hydroborate [R2NH2](+)[ H-B(C6F5)(3)](-) intermediates products. A series of ammonium hydroborates prepared from the corresponding primary, secondary, tertiary and quaternary amine hydrochlorides have been isolated, and used in the directly hydroboration with terminal alkynes. To our surprise the ammonium hydroborate [R2NH2](+) [ H-B(C6F5)(3)](-) could not react with the alkynes alone. When using [R2NH2](+)[ H-B(C6F5)(3)](-) to react with alkynes, trace amount of catalytic Lewis acid B(C6F5)(3) is necessary to firstly activate the carbon-carbon triple bonds and form the crucial zwitterionic s-complexes. The mechanism study has shown that different from the typical Lewis acid/Lewis base FLPs system reacted with alkynes, in this B(C6F5)(3)/ammonium chloride system the ammonium chloride plays an important role on the stereoselective control of the reaction. The week interaction between the Cl ion and B(C6F5)(3) in the s-complexes has not only slowed down the unfavorite 1,1-carboboration reaction, but also stabilized the s-complexes which has offer the chance for the nucleophilic reagent to attack the reaction center in a cis-or trans-mode. In our experiment the bulky ion [ H-B(C6F5)(3)] could only attach the active alkynes from the trans-side and form the Z-hydroboration product. This work demonstrates that the combination of the ammonium halides with the Lewis acid B(C6F5)(3) could act as a novel "frustrated Lewis pair" to activate alkynes, and will enable the development of even more sophisticated FLP and related catalyzed reactions.

Development of straightforward and selective approaches to functionalize vinyl groups is an important and continuing goal. A novel convenient route to vinylhalides or enol esters by a Markovnikov regioselective addition of hydrogen chloride or carboxylic acid to the C C bond of alkynes in the presence of an ammonium hydrochloride/B(C6F5)(3) catalytic system is reported. Thus, when treated with catalytic amounts of ammonium hydroborate ([TMPH](+)[ Cl-B(C6F5)(3)](-)), equimolar mixtures of hydrogen chloride and alkynes are converted into a variety of chloroalkenes as monoadducts. The yields of the monoadducts are usually higher than 90% for terminal aromatic alkynes, while for the terminal aliphatic alkynes they are considerably lower, with the worst observed for sterically hindered tert-butylacetylene (only 67%). NMR monitoring of the reaction mixtures reveals that under ambient conditions the main by-products are the corresponding diadducts (gem-dihalides). At higher temperatures (50 degrees C) for equimolar alkyne/HCl mixtures or at ambient temperature for alkyne-enriched mixtures, the diadduct formation can be nearly completely suppressed. Noteworthy, that both ammonium and borane (-ate) components of the catalytic system are essential for the conversion success. In the case of trifuoroacetic acid addition to alkynes, presence of the ammonium component is not required, with the reaction yields usually exceeding 95% for terminal aromatic alkynes and being modest to good for the aliphatic ones. The reported catalytic system presents the first example of the "metal-free" catalysts for the selective addition of acids to alkynes.

Abstract In presence of 2,2,6,6-tetramethylpiperidinium ([TMPH]+) chlorotris(pentafluorophenyl)borate ([TMPH]+[ClB(C6F5)3]−, 3), phenylacetylene undergoes an unusual cyclotrimerization-rearrangement leading to tris(pentafluorophenyl)(3,4,5-triphenylphenyl)borate anion (1) as a minor product which can be isolated and purified in a form of salts [1·(TMPH) n ·Cl ( n –1)] (n=3 or 5). A variable temperature and concentration NMR spectroscopy study of 3 in CDCl3 unambiguously demonstrated its ability to liberate free B(C6F5)3, which initiates cyclotrimerization and guides rearrangements towards formation of the tetraarylborate anion 1. For the previously studied “spectator” reaction between phenylacetylene and B(C6F5)3 in CDCl3, 1H, 19F, and 11B NMR-spectral evidence of the (C6F5)3B−–C(H)=C+Ph zwitterionic intermediate of the 1,1-carboboration reaction has been demonstrated. The crystal structures of [1·(TMPH) 3 ·Cl 2], the salt 3, and a 1:1 adduct of 1,3,5-tris(4-fluorophenyl)benzene and 2,4,6-tris(pentafluorophenyl)-1,3,5,2,4,6-trioxatriborinane (2) have been established by X-ray diffraction analysis.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

C14H15N5O2, orthorhombic, Pbca (no. 61), a = 7.1378(3) Å, b = 12.0046(4) Å, c = 32.1450(13) Å, V = 2754.4 Å3, Z = 8, Rgt(F) = 0.0452, wRref(F2) = 0.1009, T = 120 K.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

文章以碳酸二甲酯和己二胺为原料反应,制得己二氨基甲酸甲酯,得出了反应的较佳合成工艺:HDA和催化剂的摩尔比为1:0.04,DMC和HDA的摩尔比为6:1,反应温度65℃,反应冷凝回流2h.冷却室温,经醇洗得到产物己二氨基甲酸甲酯,产率56％.产物结构通过1H-NMR和13C-NMR进行了表征.

In modern practice, frustrated Lewis pairs (FLPs) are well-known to exhibit unique chemical properties in respect to H-2 activation. Additionally, CO2 catalytic reduction and related catalytic hydrogenations of unsaturated bonds have also been widely concerned. This paper describes designation and studies of a novel FLP catalyst system, in which the Lewis base component is introduced as an amine hydrochloride (not a free amine), while the Lewis acid component is retained [tris(pentafluorophenyl)borane, B(C6F5)(3) (BCF)]. With a hydridosilane as a source of the hydride, this novel system, at first, presents a new facile synthetic approach to ammonium hydridoborates [R3NH](+)[HBCF](-). Remarkably, that irrespective of the bulkiness of the ammonium component, various primary, secondary and tertiary ammonium salts with HBCF- anion can all be prepared by the suggested procedure under mild conditions and in high yields. At the same time this system may serve as a powerful tool for selective and exhaustive reduction of organic carbonyl compounds and even CO2 down to alkanes and methane, respectively. Comparison of the H-1 NMR spectra of the starting hydrochlorides, the intermediate ammonium chloroborates [R3NH](+)[ClBCF](-), and [R3NH](+) [HBCF](-) reveals that the appearance of the NH signals is strongly dependent upon the nature of the counterion. While in the parent chlorides signals of these protons are observed as broad singlets or multiplets due to the quadrupolar relaxation on the adjacent N-14 nucleus, in the spectra of their [HBCF](-) analogues these signals exhibit distinct fine structure due to the spin-spin coupling with the N-14 [(1)J(N-14-H)approximate to 50 Hz; 1: 1 : 1 triplets]. The latter is indicative of the increase of the symmetry of the electric field at the N-14 nucleus location along with the decrease of the degree of ammonium/anoin interaction. The chemical reactivity of these [HBCF](-) analogues is interesting matched with their NH signals.

Although in recent years the frustrated Lewis pairs (FLPs) reactivity towards small molecule activation has been widely concerned, the reports on the FLPs derived from aromatic amines are few.This paper describes a new facile route to the aromatic amine based FLPs starting from aromatic amine hydrochloride/tri(pentafluorophenyl)borane (BCF) as a combined active couple and hydridosilane as a source of the hydride.The reaction characteristics have been studied for a set of the stoichiometrical reactions.The difference between the alkyl amine hydrochloride/BCF and aromatic amine hydrochloride/BCF systems is that after reacting with the silanes the formed aromatic ammonium hydridoborates [Ar 2 NH 2 ]＋ [HBCF]are not thermally stable and immediately release H 2 with formation of the corresponding amine and BCF.However, it is precisely because of this fact making this system applicable for a catalytic reaction-a novel efficient chlorination reaction of hydridosilanes, which could be considered as the first example of the nonmetal catalytic reactions of the type, with the aromatic amine hydrochloride as a function of the chlorination reagent and BCF as a catalytic activator.The chlorination products and reaction mechanism have been also explored in detail under different ratios of silanes and aromatic amine hydrochlorides.Remarkably, if required, the initial aromatic amine hydrochloride can be regenerated and recycled by a simple reaction with gaseous HCl.This makes the reaction rather attractive from the viewpoint of "green chemistry".

C11H12N4O3, monoclinic, P21/c (no. 14), a = 12.0039(6) Å, b = 9.5916(4) Å, c = 10.5824(5) Å, β = 109.429(3)°, V = 1149.1 Å3, Z = 4, Rgt(F) = 0.0456, wRref(F2) = 0.1032, T = 120 K.

A straightforward reaction between 1,3-dimethyl-1 H -imidazolium iodide ( 1 ) and AgF in acetonitrile (molar ratio 2: 3) results in bis[1,3-dimethyl-2,3-dihydro-1 H -imidazol-2-ylidene-κ C 2 ]silver(1+) hydrofluorides ( 2 ) and AgI in an almost quantitative yield. Hydrofluorides 2 , namely, [(C 5 H 8 N 2 ) 2 Ag] + [HF 2 ] - ( 2a ) and [(C 5 H 8 N 2 ) 2 Ag] + [H 2 F 3 ] - ( 2b ), were isolated under different crystallization conditions. Crystal and molecular structures of hydrofluorides 2a and 2b as well as that of the initial salt 1 were established by X-ray diffraction analysis.

Thermolytic decomposition of 3,3’-(ethan-1,2-diyl)bis(1-methyl-1H-imidazolium) bis-(hexafluorophosphate) (1) under reduced pressure results in a 1: 1 mixture of pentafluo-ro(1-ethenyl-3-methyl-2,3-dihydro-1H-imidazole-2-ylidene-κC 2)phosphorous (2) and penta- fluoro(3-methyl-1H-imidazole-κN 3)phosphorous (3) in an almost quantitate yield. Products 2 and 3 were isolated as individual compounds by fractional recrystallization from hot methanol. Direct observation of a 1: 1 co-crystallite of 2-pentafluorophosphanyl-1-ethenyl-3-methyl-1H-imidazolium hexafluorophosphate and adduct 2 (compound 5) as a minor coproduct of this reaction reveals a complicated path of the thermolysis. Crystal and molecular structures of compounds 2, 3, and 5 were established by X-ray diffraction analysis. Compound 2 presents the first example of an N-alkenyl substituted Arduengo carbene adduct with a main Group element Lewis acid. Compound 3 presents the second known organic base N-adduct with PF5.

The title compound, 2C5H9N2 (+)·SiF6 (2-), (I), crystallized as a new polymorph, different from the previously reported one (Ia) [Light et al. (2007 ▶) private communication (refcode: NIQFAV). CCDC, Cambridge, England]. The symmetry [space groups P21/n for (I) and C2/c for(Ia)] and crystal packing patterns are markedly different for this pair of polymorphs. In (I), all imidazolium cations in the lattice are nearly parallel to each other, whereas a herringbone arrangement can be found in (Ia). In (I), each SiF6 (2-) dianion forms four short C-H⋯F contacts with adjacent C5H9N2 (+) cations, resulting in the formation of layers parallel to the ac plane. In (Ia), the C-H⋯F contacts are generally longer and result in the formation of layers along the bc plane.

This article studied mainly the activities of two kind of novel Zirconocenes as catalyst for norbornene polymerization.The activities were determined under different conditions.The reaction temperature and the ratio of Al/Zr have shown great effect on the catalyst activities,and the optimal temperature is 70 ℃,the best ratio of Al/Zr is 700∶1.The polynorbornene measured by FT-IR spectra and NMR analysis was mainly in addition polymerization.