41446-63-3

Neutral and cationic tungsten imido alkylidene complexes of the general formulas W(NtBu)(CHR1)(OR2)Cl(NHC), W(N-2,6-bis(2,4,6-tri-iPr-C6H4)phenyl)(CHR1)Cl2(NHC), [W(NtBu)(CHR1)(OR2)(NHC)][B(ArF)4] and [W(N-2,6-bis(2,4,6-tri-iPr-C6H4)phenyl)(CHR1)Cl(NHC)][B(ArF)4] (R1= CMe3, CMe2Ph; R2= sterically demanding alkoxide; B(ArF)4= tetrakis(3,5-(CF3)2-C6H3)borate; NHC = N-heterocyclic carbene) were prepared. Two electronically different NHCs, namely 1,3-dimethylimidazol-2-ylidene (IMe) and 1,3-dimethyl-4,5-dichloroimidazol-2-ylidene (IMeCl), as well as a variety of terphenolates and a chiral biphenolate were employed.Z-selective homometathesis (HM) of unfunctionalized olefins was achieved with a selectivity of up to 90% and decent turnover numbers (TON) of up to 480 in the HM of 1-dodecene. Additionally, the reactivity of the cationic tungstentert-butylimido complexes in the reaction with vinyltrimethylsilane and ethylene was investigated, which yielded the corresponding silyl-alkylidene complex and, for the first time, a fully characterized cationic tungsten(IV) NHC ethylene complex.

Disclosed herein are methods for synthesizing fatty olefin metathesis products of high Z-isomeric purity from olefin feedstocks of low Z-isomeric purity. The methods include contacting a contacting an olefin metathesis reaction partner, such as acylated alkenol or an alkenal acetal, with an internal olefin in the presence of a Z-selective metathesis catalyst to form the fatty olefin metathesis product. In various embodiments, the fatty olefin metathesis products are insect pheromones. Pheromone compositions and methods of using them are also described.

Ru-alkylidenes bearing sterically demanding arylthiolate ligands (SAr) constitute one of only two classes of catalyst that are Z-selective in metathesis of 1-alkenes. Of particular interest are complexes bearing pyridine as a stabilizing donor ligand, [RuCl(SAr)(a? CHR)(NHC)(py)] (R = phenyl or 2-thienyl, NHC = N-heterocyclic carbene, py = pyridine), which initiate catalysis rapidly and give appreciable yields combined with moderate to high Z-selectivity within minutes at room temperature. Here, we extend this chemistry by synthesizing and testing the first two such complexes (5a and 5b) bearing 3-phenylindenylidene, a ligand known to promote stability in other ruthenium-based olefin metathesis catalysts. The steric pressure resulting from the three bulky ligands (the NHC, the arylthiolate, and the indenylidene) forces the thiolate ligand to position itself trans to the NHC ligand, a configuration different from that of the corresponding alkylidenes. Surprisingly, although this configuration is incompatible with Z-selectivity and slows down pyridine dissociation, the two new complexes initiate readily at room temperature. Although their thermal stability is lower than that of typical indenylidene-bearing catalysts, 5a and 5b are fairly stable in catalysis (TONs up to 2200) and offer up to ca. 80% of the Z-isomer in prototypical metathesis homocoupling reactions. Density functional theory (DFT) calculations confirm the energetic cost of dissociating pyridine from 5a (= M1-Py) to generate 14-electron complex M1. Whereas the latter isomer does not give a metathesis-potent allylbenzene ?-complex, it may isomerize to M1-trans and M2, which both form ?-complexes in which the olefin is correctly oriented for cycloaddition. The olefin orientation in these complexes is also indicative of Z-selectivity.

We report here the first step by step anchoring of a W(≡CtBu)(CH2tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using a Surface Organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT?IR spectroscopy revealed the presence of a W=O moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well-defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of W=O alkyl complexes from their W carbyne analogues.

Second-generation ruthenium olefin metathesis catalysts were investigated with systematic variation of the unsymmetrical uNHC ligands. Depending on the uNHC steric bulk, the catalysts exhibited different activity and selectivity in metathesis reactions. DFT calculations and X-ray crystallographic data were used to understand the influence of uNHC ligand structure on the catalyst properties. Furthermore, the catalysts were examined in the context of reactions that are problematic for general-purpose Ru catalysts, including industrially important self-cross metathesis of α-olefins and ethenolysis of ethyl oleate.

Imidazole substituted hydrogenated amphiphilic ROMP polymers were used as both surfactants and ligand precursors for olefin metathesis reactions in water. Amphiphilic ROMP polymers were synthesized using a two-step procedure. Firstly, dimethyl-5-norbornene-2,3-dicarboxylate was polymerized using ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) in the presence of allyl-PEG5000 methyl ether and a Grubbs 3rd generation (G3) catalyst. Secondly, a one-pot hydrogenation/aminolysis protocol was used for the post-polymerization modification of PEG end-capped polynorbornene derivatives. Hydrogenation reactions were carried out using residual G3 in the presence of formic acid/sodium formate in THF at 70 °C. The aminolysis reaction was carried out without isolation of the hydrogenated polymer, using triazabicyclodecene (TBD) and 1-(3-aminopropyl)-imidazole, forming imidazole substituted hydrogenated amphiphilic ROMP polymers (mod-Amph1) in an efficient manner. G1-mod-Amph1 formed micelle structures in water with an average particle size of 85.95 (±35) nm as determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. The diffusion of Grubbs 1st generation (G1) catalyst into the micelle structure has led to the formation of nano-sized catalysts which exhibited a latent characteristic. The diffusion of hydrophobic olefinic substrates into the nano-reaction spaces, followed by activation of the catalyst with HCl led to a very efficient catalytic system for ring-closing metathesis reactions. RCM reactions of various hydrophobic dienes can run in non-degassed water under an air atmosphere. The catalyst system exhibits similar performance under an air atmosphere even in tap water, reaching a conversion value of 90% for RCM of diethyl diallylmalonate with a catalytic loading of 1% Ru.

The [2+2] cycloaddition is a versatile strategy for the synthesis of strained cyclobutenes of high synthetic value. In this study, two efficient intermolecular [2+2] cycloadditions between two different types of chloroalkynes and unactivated alkene are realized with gold catalysis. Of significance is that the reaction works with challenging monosubstituted unactivated alkenes, which is unprecedented in gold catalysis and scarcely documented in other metal-catalyzed/promoted reactions; moreover, the reaction exhibits excellent regioselectivities, which are much better than those reported in literature. With 1,2-disubstituted unactivated alkenes, the reaction is largely stereospecific. The cyclobutene products can be prepared in nearly gram scale and readily undergo further reactions including various cross-coupling reactions using the C(sp2)-Cl and/or C(sp2)-SPh bond, which in turn substantially broaden the scope of accessible cyclobutenes and enhance the synthetic utility of this bimolecular reaction.

An efficient E-selective semihydrogenation of internal alkynes was developed under low dihydrogen pressure and low reaction temperature from commercially available reagents: Cl2Pd(PPh3)2, Zn0, and ZnI2. Kinetic studies and control experiments underline the significant role of ZnI2 in this process under H2 atmosphere, establishing that the transformation involves syn-hydrogenation followed by isomerization. This simple and easy-to-handle system provides a route to E-alkenes under mild conditions.

The present invention refers to novel ruthenium-based catalysts for olefin metathesis reactions, particularly to fast initiating catalysts having stereoselective properties. In olefin metathesis reactions, the disclosed catalysts provide a high catalytic activity combined with the capability to generate higher yields of the olefin metathesis product.

The invention relates to an N-heterocyclic carbene complex of general formulas I to IV (I) (II) (III) (IV), according to which A1 stands for NR2 or PR2, A2 stands for CR2 R2′, NR2, PR2, 0 or S, A3 stands for N or P, and C stands for a carbene carbon atom, ring B is an unsubstituted or a mono or poly-substituted 5 to 7-membered ring, substituents R2 and R2′ stand, inter alia, for a linear or branched C1-Cw-alkyl group and, if N and N each stand for NR2 or PR2, are the same or different, M in formulas I, II, III or IV stands for Cr, Mo or W, X 1 or X2 in formulas I to IV are the same or different and represent, inter alia, C1-C1s carboxylates and C1-C1s-alkoxides, Y is inter alia oxygen or sulphur, Z is inter alia a linear or branched C1-Cw-alkylenoxy group, and R 1 and R1′ in formulas I to IV are, inter alia, an aliphatic or aromatic group. These compounds are particularly suitable for use as catalysts for olefin metathesis reactions and have the advantage, compared to known Schrock carbene complexes, of displaying clearly increased tolerance to functional groups such as, in particular, aldehydes, secondary amines, nitriles, carboxylic acids and alcohols.

In our search for more-selective olefin metathesis catalysts, a series of Hoveyda-Grubbs-type second-generation complexes bearing unsymmetrical N-heterocyclic carbene (NHC) ligands were synthesized and tested in model reactions. It was found that the N-benzyl substituent in NHC has a positive influence on the selectivity of the newly obtained catalysts in the self-metathesis reaction of α-olefins. As expected, a typical relationship between activity and selectivity with respect to the N-aryl substituent used was observed. Dipp-containing complexes exhibited higher stability at elevated temperature, while Mes-bearing complexes typically gave better yields than their Dipp analogues.

Pyridine as a stabilizing donor ligand drastically improves the performance of ruthenium monothiolate catalysts for olefin metathesis in comparison with previous versions based on a stabilizing benzylidene ether ligand. The new pyridine-stabilized ruthenium alkylidenes undergo fast initiation and reach appreciable yields combined with moderate to high Z selectivity in self-metathesis of terminal olefins after only a few minutes at room temperature. Moreover, they can be used with a variety of substrates, including acids, and promote self-metathesis of ω-alkenoic acids. The pyridine-stabilized ruthenium monothiolate catalysts are also efficient at the high substrate dilutions of macrocylic ring-closing metathesis and resist temperatures above 100 °C during catalysis.

A method for the synthesis of a homogeneous cationic tungsten(vi)pentamethyl complex [(WMe5)+(C6F5)3BMe-] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [(Si-O-)WMe4+ (C6F5)3BMe-] from a neutral silica supported tungstenpentamethyl complex [(Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)3 reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)+(C6F5)3BMe-] shows moderate activity whereas the supported cationic complex [(Si-O-)WMe4+(C6F5)3BMe-] exhibits good activity in olefin metathesis reactions.

In the interest of preparing molybdenum and tungsten alkylidene complexes for olefin metathesis that are longer-lived at high temperatures (～150 °C or above), we synthesized complexes that contain a phenoxide ligand with a 2-pyridyl in one ortho position and a mesityl (Mes) or 2,4,6-i-Pr3C6H2 (Trip) in the other ortho position ([MesON]- or [TripON]-, respectively). The alkylidene (neophylidene) complexes that were prepared include W(O)(CHCMe2Ph)(Me2Pyr)(RON) (R = Mes or Trip), Mo(NC6F5)(CHCMe2Ph)(RON)Cl, Mo(N-2,6-Me2C6H3)(CHCMe2Ph)(RON)Cl, Mo(N-t-Bu)(CHCMe2Ph)(RON)Cl, and M(N-2,6-i-Pr2C6H3)(CHCMe2Ph)(TripON)(OTf) (M = Mo or W). The reaction between Mo(NAr)(CHCMe2Ph)(TripON)(OTf) and ethylene yielded an ethylene complex, Mo(NAr)(C2H4)(TripON)(OTf)(ether). All neophylidene complexes were essentially unreactive toward terminal olefins at 22 °C and showed modest homocoupling activity (at 80 or 100 °C) and alkane metathesis activity (at 150 and 200 °C). W(O)(CHCMe2Ph)(Me2Pyr)(MesON) also stereoselectively polymerized several substituted norbornadienes at 100 °C.

Herein, we report the successful transformation of a 1st generation Grubbs metathesis catalyst into an asymmetric transfer hydrogenation (ATH) catalyst. Upon addition of a chiral amine ligand, an alcohol and a base, the 1st generation Hoveyda-Grubbs catalyst (HG-I) was found to promote the enantioselective reduction of acetophenone to 1-phenylethanol. After optimizing the order of addition and the reaction conditions, the substrate scope was assessed leading to enantiomeric excesses up to 97% ee. NMR experiments were run in order to get information about the in situ-generated ATH catalyst. Furthermore, the possibility to perform olefin metathesis and ketone transfer hydrogenation sequentially in one pot was demonstrated, and the first tandem olefin metathesis-ketone asymmetric transfer hydrogenation was carried out.

The present invention refers to novel ruthenium- and osmium-based catalysts for olefin metathesis reactions with high Z-selectivity. The effect is obtained by utilising two monoanionic ligands (X) and (L1) of very different steric requirement. The catalysts selectively provide the Z-isomer even in presence of air or of acids. Claimed are formulae (A) and (B); The anionic ligand "X" is defined as -CN, -N3, -NCO, -CNO, -NCS, and -NCSe. Specific embodiments for these catalysts are:

The present invention relates to compositions comprising 2-phenyl linear alkene benzenes or 2-phenyl linear alkene benzene sulfonates or 2-phenyl linear alkylbenzenes or 2-phenyl linear alkylbenzene sulfonates; where the benzene ring is optionally substituted with one or more groups designated R *, where R * is defined herein and to methods for making the same. This invention also relates to compositions, methods of making, use of, and articles of manufacuture comprising 2-ethoxylated hydroxymethylphenyl linear alkyl benzenes or 2-propoxylated hydroxymethylphenyl linear alkyl benzenes.

The present invention relates generally to catalysts and processes for the Z-selective formation of internal olefin(s) from terminal olefin(s) via homo-metathesis reactions.

The present invention refers to novel ruthenium- and osmium-based catalysts for olefin metathesis reactions, particularly to catalysts having stereoselective properties. Z-selectivity is obtained by utilizing two mono-anionic ligands of very different steric requirement. In olefin metathesis reactions these catalysts selectively provide the Z-isomer of disubstituted olefinic products.

DFT calculations have predicted a new, highly Z-selective ruthenium-based olefin metathesis catalyst that is considerably more robust than the recently reported (SIMes)(Cl)(RS)RuCH(o-OiPrC6H4) (3a, SIMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene, R = 2,4,6-triphenylbenzene) [J. Am. Chem. Soc., 2013, 135, 3331]. Replacing the chloride of 3a by an isocyanate ligand to give 5a was predicted to increase the stability of the complex considerably, at the same time moderately improving the Z-selectivity. Compound 5a is easily prepared in a two-step synthesis starting from the Hoveyda-Grubbs second-generation catalyst 3. In agreement with the calculations, the isocyanate-substituted 5a appears to be somewhat more Z-selective than the chloride analogue 3a. More importantly, 5a can be used in air, with unpurified and non-degassed substrates and solvents, and in the presence of acids. These are traits that are unprecedented among highly Z-selective olefin metathesis catalysts and also very promising with respect to applications of the new catalyst. This journal is the Partner Organisations 2014.

The first instances of ruthenium alkylidene complexes based on chelating phosphine sulfonates are presented. Although these complexes are formally 18-electron complexes bearing cis phosphines and cis one-electron donors (sulfonates and chlorides), they are surprisingly active for ring-closing metathesis, cross-metathesis, and ring-opening metathesis polymerization, thus highlighting the unique potential of the sulfonate ligand in the design of a ruthenium metathesis catalyst.

The present invention provides, among other things, novel compounds and methods for metathesis reactions. In some embodiments, a provided compound has the structure of formula I or II. In some embodiments, the present invention provides compounds and methods for Z-selective olefin metathesis.

(Tetraphenylporphyrin)palladium was developed as a catalyst for the chemoselective and stereoselective hydrogenation of alkynes to cis-alkenes by the syn-addition of hydrogen. Alkynes containing various functional groups were tolerated in the reaction, which gave the corresponding cis-alkenes in good to excellent yields. Georg Thieme Verlag Stuttgart New York.

We report the synthesis of Mo and W MAP complexes that contain O-2,6-(2,5-R2-pyrrolyl)2C6H3 (2,6-dipyrrolylphenoxide or ODPPR) ligands in which R = i-Pr, Ph. W(NAr)(CH-t-Bu)(Pyr)(ODPPPh) (4a; Ar = 2,6-disopropylphenyl, Pyr = pyrrolide) reacts readily with ethylene to yield a metallacyclobutane complex, W(NAr)(C3H6)(Pyr)(ODPPPh) (5). The structure of 5 in the solid state shows that it is approximately a square pyramid with the WC4 ring spanning apical and basal positions. This SP′ structure, which has never been observed as an actual intermediate, must now be regarded as an integral feature of the metathesis reaction.

A one-step substitution of a single chloride anion of the Grubbs-Hoveyda second-generation catalyst with a 2,4,6-triphenylbenzenethiolate ligand resulted in an active olefin metathesis catalyst with remarkable Z selectivity, reaching 96% in metathesis homocoupling of terminal olefins. High turnover numbers (up to 2000 for homocoupling of 1-octene) were obtained along with sustained appreciable Z selectivity (>85%). Apart from the Z selectivity, many properties of the new catalyst, such as robustness toward oxygen and water as well as a tendency to isomerize substrates and react with internal olefin products, resemble those of the parent catalyst.

In the presence of Re2O7 supported on γ-Al 2O3, the self-metathesis of 1-octene was conveniently carried out under continuous-flow (CF) conditions using supercritical CO 2 (scCO2) as a carrier. This investigation allowed optimization of reaction parameters, the best values of which were found to be 100 °C and 90 bar, operating at flow rates of 0.05 and 1 mL min-1 for 1-octene and scCO2, respectively, the reaction proceeded with very good self-metathesis selectivity (>90%) and an average productivity of ～0.24 mL tetradecene gRe-1 min-1. Although the catalyst was completely deactivated after the first 100-150 min of reaction, it could be recycled for (at least) five subsequent reactions without any loss of performance. The results provided incontrovertible evidence that for the investigated reaction, scCO2was a superior carrier with respect to conventional liquids, such as toluene or n-hexane.

Several new C-H-activated ruthenium catalysts for Z-selective olefin metathesis have been synthesized. Both the carboxylate ligand and the aryl group of the N-heterocyclic carbene have been altered and the resulting catalysts evaluated using a range of metathesis reactions. Substitution of bidentate with monodentate X-type ligands led to a severe attenuation of metathesis activity and selectivity, while minor differences were observed between bidentate ligands within the same family (e.g., carboxylates). The use of nitrato-type ligands in place of carboxylates afforded a significant improvement in metathesis activity and selectivity. With these catalysts, turnover numbers approaching 1000 were possible for a variety of cross-metathesis reactions, including the synthesis of industrially relevant products.

The present invention relates generally to catalysts and processes for the Z-selective formation of internal olefin(s) from terminal olefin(s) via homo-metathesis reactions.

The cross-metathesis of terminal olefins using a novel ruthenium catalyst results in excellent selectivity for the Z-olefin homodimer. The reaction was found to tolerate a large number of functional groups, solvents, and temperatures while maintaining excellent Z-selectivity, even at high reaction conversions.

Addition of LiOHMT (OHMT = O-2,6-dimesitylphenoxide) to W(O)(CH-t-Bu)(PMe2Ph)2Cl2 led to WO(CH-t-Bu)Cl(OHMT)(PMe2Ph) (4). Subsequent addition of Li(2,5-Me2C4H2N) to 4 yielded yellow W(O)(CH-t-Bu)(OHMT)(Me2Pyr)(PMe2Ph) (5). Compound 5 is a highly effective catalyst for the Z-selective coupling of selected terminal olefins (at 0.2% loading) to give product in >75% yield with >99% Z configuration. Addition of 2 equiv of B(C6F5)3 to 5 afforded a catalyst activated at the oxo ligand by B(C6F 5)3. 5·B(C6F5)3 is a highly active catalyst that produces thermodynamic products (～20% Z).

Formamides having 1-arylalkyl groups on nitrogen undergo an unprecedented dehydrogenative [4 + 2] cycloaddition reaction with alkynes via nickel/AlMe 3 cooperative catalysis to give highly substituted dihydropyridone derivatives in good yields. Notably, the transformation proceeds through double functionalization of C(sp2)-H and C(sp3)-H bonds in the formamides.

3,5-Dimethylphenylimido complexes of tungsten can be prepared using procedures analogous to those employed for other tungsten catalysts, as can bispyrrolide species and MonoAryloxide-Pyrrolide (MAP) species. Homocouplings of 1-hexene, 1-octene, and methyl 10-undecenoate are achieved in 45-89% yield and a Z selectivity of >99% with W(Nar″)(C3H6)(pyr) (OHIPT) as a catalyst. Homocoupling of terminal olefins in the presence of (E)-olefins elsewhere in the molecule also was achieved with excellent selectivity.

(Chemical Equation Presented) Mo and W MonoAryloxide-Pyrrolide (MAP) olefin metathesis catalysts can couple terminal olefins to give as high as >98% Z-products in moderate to high yields with as little as 0.2% catalyst. Results are reported for 1-hexene, 1-octene, allylbenzene, allyltrimethylsilane, methyl-10-undecenoate, methyl-9-decenoate, allylB(pinacolate), allylOBenzyl, allylNHTosyl, and allylNHPh. It is proposed that high Z-selectivity is achieved because a large aryloxide only allows metallacyclobutanes to form that contain adjacent cis substituents and because isomerization of Z-product to E-product can be slow in that same steric environment.

The catalytic activity of ruthenium alkylidene complexes [RuCl(LX(ON)(=CHPh)] [L = H2IMes and PCy3, ON = 1-(2′-pyridinyl)cyclohexan-1-olate)], bearing a chelating pyridinyl-alcoholate ligand, was investigated for the metathesis of 1-octene in the absence of a solvent. Both systems were active for the metathesis of 1-octene yielding trans-7-tetradecene and ethene as the primary metathesis products. Although the activity of both systems increased with an increase in reaction temperature, the activity of [RuCl(H2IMes)(ON)(=CHPh)] started to decrease at temperatures above 70°C, with a simultaneous exponential increase in the secondary metathesis products due to double-bond isomerisation of the substrate. Although the initiation rates for these systems are slower compared to Grubbs 1 and Grubbs 2 for the metathesis of 1-octene at 60°C, they have a higher activity and longer lifetime.

Effective turnover numbers (TON's) and turnover frequencies (TOF's) of unprecedented magnitude have been obtained for the metathesis of various substrates in the presence of ruthenium-based catalysts, without the use of an additional solvent. For the self

The W(O-2,6-C6H3X2)2Cl 4/Bu4Sn catalytic systems (X = Ph, F, Cl, Br) have a high activity for the metathesis of terminal alkenes and a high selectivity towards primary metathesis products. Tungsten(VI) alkoxide complexes are not nearly as active as the tungsten(VI) aryloxide complexes. Bronsted acids such as HOAc, BuOH and H2O deactivate both the W(O-2,6-C6H 3X2)2Cl4/Bu4Sn (X = Cl and Ph) catalytic systems. The Lewis base (BuOAc) showed no deactivation of the catalytic systems. The Grubbs catalyst, RuCl2(PCy3) 2(=CHPh), is very active for the metathesis of 1-alkenes, even at an alkene/Ru molar ratio = 100,000. Selectivities > 93% were generally obtained. The ruthenium catalyst is active at low temperatures (25°C) and high temperatures (130°C). It shows a high tolerance towards oxygen-containing additives. The polarity of the solvent plays a major role in the activity and also the selectivity of especially the W(O-2,6-C6H3X 2)2Cl4/Bu4Sn catalytic systems.

A process for preparing fatty amines by the cross-metathesis of normal alpha olefins and acrylonitrile to form an intermediate fatty acid nitrile which is hydrogenated to the corresponding fatty amine.

Excellent deoxygenation of ketones and aldehydes is achieved with Keggin-type polyoxometalates in the presence of hydrogen (see Equation (1) for an example). The mixed addenda phosphovanadomolybdate [PV2Mo10O4]5- was found to be the best catalyst. X-ray diffraction and IR studies suggest that the polyoxometalates are structurally stable under the strongly reducing conditions.

Treatment of 2-alkylbenzotriazoles with lithium diisopropylamide (LDA) at -78°C gave, depending on workup conditions, either dimers of the type Bt2CHR-CHRBt2 (2) (Bt2 = benzotriazol-2-yl), or mixtures of symmetrical Z and E olefins (3) (RCH=CHR), in high yields via radical intermediates. The racemic and meso isomers of 2, which differ substantially in properties such as melting points, 1H and 13C NMR, were isolated and characterized (three by X-ray crystallography). Both the meso and racemic dimers of 2 were reduced by Na to give mixtures of Z and E olefins in high yields with the elimination of the benzotriazole anion. 2-Alkylbenzotriazoles (1) were also converted by Na into the corresponding alkanes and benzotriazole. The intermediates were trapped by benzophenone to give, depending on the reaction procedure (see Scheme 2), adducts 6 or adducts 6 with dimers 2, benzotriazol-2-ylalkene 7 and compound 8 (R = H), compound 9 (R = CH3). Several compounds with dibenzotriazol-2-yl groups or benzotriazol-1-yl and benzotriazol-2-yl groups in the same molecule were synthesized and further investigated via lithiation followed by the addition of benzophenone or benzaldehyde. This further indicated that the radical reaction is faster than the nucleophilic reaction. VCH Verlagsgesellschaft mbH, 1996.

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Reaction of aldehydes R2-CHO with the new lithio derivatives of 2-benzothiazoles or pyridines R1-CH2-SO2-Het afforded the corresponding β-hydroxy sulfones which are stable in the pyridine series and generally unstable in the benzothiazole series except for anti derivatives 10a and 20c. t-Butyl-dimethyl silyl ethers of all the heterocyclic β-hydroxy sulfones have been obtained by oxidation of the corresponding anti and syn sulfides, which have been stereoselectively prepared from the epoxides 17, 19, 21 and 23.The lithium or tetrabutylammonium alkoxides of heterocyclic β-hydroxy sulfones undergo an intramolecular addition to the neighboring C=N group followed by an S to O benzothiazole (or pyridine) transfer, and simultaneous extrusion of sulfur dioxide, ejection of benzothiazol-2(3H)-one anion and formation of the corresponding olefins.From the data of twenty cases studied, it can be concluded that the final elimination is entirely antiperiplanar only for the alkoxides of β-hydroxy-BT- or Pyr-sulfones anti or syn bearing saturated aliphatic chains R1 and R2 and for anti derivatives with R1 = R2 = C6H5.Due to their equilibration however, the alkoxides of numerous derivatives of heterocyclic (3-methylbut-2-enyl) or (phenylmethyl) sulfones do not follow entirely the above antiperiplanar elimination. Keywords: heteroaromatic sulfones / intramolecular ipso reaction / organolithium derivatives / stereochemistry / eliminations / olefination

Two-fold extrusion reactions of 1,3,4-thiadiazolines 1 provide a convenient stereoselective route to unhindered Z-olefins.An improved preparation of the thiadiazolines involves reaction of an aldehyde with H2S-hydrazine, followed by in situ oxidation of the intermediate predominantly trans thiadiazolidine 2.Stereospecific extrusion of nitrogen yields the cis-thiirane which upon treatment with triphenylphosphine affords the corresponding Z-alkene in good yields.

Treatment of hydrated RhCl3 and Cu(NO3)2 in THF and H2O with triethoxysilane affords a highly chemo- and stereoselective catalyst system for the reduction of alkynes to Z-alkenes while alkyl-NO2, aryl-NO2, N-carbobenzyloxy, hydroxy, ester, enoate, benzyloxy, alkyl bromide, aryl bromide, and enone moieties remain unaffected.

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The use of the air-stable complexes tetrachlorobis(μ-methoxy)bis(methanolo)dimethoxyditungsten (1) and tetrachlorobis(μ-ethoxy)tetraethoxyditungsten (2) as catalyst precursors for the metathesis of 1-octene is described.Using mild conditions, the latter was converted to 7-tetradecene (4) in fair yields when diethylaluminum chloride (3) was used as a cocatalyst.Product stereoselectivity was 4/1 in favor of the trans isomer.The reaction was also shown to be efficient for the production of 2-nonenes.

A general and stereospecific synthesis of (Z)-disubstituted alkenes using mono- and dihaloboranes is presented.The hydridation of dialkylhaloboranes in the presence of 1-alkynes provides the corresponding dialkylvinylboranes (1), representing the first general synthesis of such derivatives.Treatment with iodine in the presence of sodium methoxide induces the migration of one of the alkyl groups from boron to the adjacent carbon, followed by a rapid deiodoboronation to afford (Z)-disubstituted alkenes (2) in high yields.Similarly, the hydroboration of 1-alkynes with alkyl bromoboranes (R1BHBr*SMe2, 4) followed by iodination in the presence of sodium methoxide in methanol affords (Z)-disubstituted alkenes (2) in good yields.Both procedures constitute a general one-pot synthesis of (Z)- disubstituted alkenes from an alkene and 1-alkyne.A simple synthesis of Muscalure (7), the sex pheromone of the housefly (Musca domestica), is achieved in good yields.An alternative general stereospecific synthesis of (Z)- and (E)-disubstituted alkenes based on alkenylboronic esters is also described.

Alkyltriphenylphosphonium salts react with saturated α,β-ethylenic, α,β-acetylenic, and cyclic aliphatic aldehydes when heated with solid potassium carbonate to form the corresponding alkenes with preparative yields.The reaction is cis-stereoselective with saturated aldehydes and cis-stereospecific with unsaturated aldehydes.

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