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A new family of dienone musks was discovered by alkylation of different aldehydes with but-3-en-1-yn-1-yllithium and subsequent domino reaction of a Saucy–Marbet transfer vinylation–Claisen rearrangement with an intramolecular Diels–Alder reaction, and concluding Lewis acid catalyzed double-bond isomerization. The newly synthesized dienone structures possess pleasant musk odors displaying fatty, slightly fruity and green facets. Although the dienone musks were predicted in silico to bind to the OR5AN1 receptor based on QM/MM calculations, they were found to be inactive in the in vitro assay. The latter results suggest that the OR5AN1 receptor is not the prime musk receptor but primarily responsible for the animalic character of certain macrocyclic ketones and nitro musks.

An atom-economical oxovanadate-catalysed cycloisomerization of hydroxy enynes for the synthesis of bicyclo[4.3.0]non-1(9)-en-2-ones is disclosed, which can be rationalised through a cascade reaction of a dissociative Meyer–Schuster rearrangement to allenyl vanadates, followed by a thermal intramolecular Diels–Alder (IMDA) reaction and hydrolytic regeneration of the catalyst.

The bicyclic 1-aza-2-azoniaallenium salt intermediates, generated from the azoester species upon treatment with a Lewis acid, have been demonstrated to participate in Huisgen-type cycloaddition with nitriles to result in the formation of fused 6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[1,5-d][1,4]diazepinium salts. This transformation is interpreted as a regular [3++2] cycloaddition between intermediates as the reactive 1,3-monopole reactants and nitriles as the nucleophilic reagents followed by spontaneous [1,2]-cationic rearrangement. The azoester precursors were easily accessible via oxidation of the corresponding hydrazones using hypervalent iodine oxidant PhI(OAc)2 under mild conditions. The [1,2,4]triazolodiazepine compounds represent a class of N-containing biologically important heterocycles with a new type of scaffold.

Plocabulin, a marine natural polyketide isolated from the sponge Lithoplocamia lithistoides, is a novel and potent microtubule-destabilizing agent. Guided by the reported binding mode, several new analogs of plocabulin have been designed through removing the right aliphatic chain and further modifying on the carbamate group and the enamide unit. The preliminary results indicate that the right aliphatic chain in plocabulin is allowed to remove with a little loss of activity, the carbamate group plays a role in the activity, and particularly, the enamide unit has an important effect on the activity. This new finding will aid the design of novel potent tubulin-binding agents based on plocabulin.

Production of aromatics from lignin has attracted much attention. Because of the coexistence of C–O and C–C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone (2-PAP), was investigated over several cesium-exchanged polyoxometalate (Cs-POM) catalysts. Decomposition of 2-PAP can follow two different mechanisms: an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox properties of the catalysts. The catalysts of POMs perform the following functions: promoting active hydrogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen liberation and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP (>99%) with excellent selectivities to the desired products (98.6% for phenol and 91.1% for acetophenone) can be achieved.

A novel synthetic approach to (±)- Z -recifeiolide 6, a 12-membered-ring lactone which can be selectively isomerized into ( E )-recifeiolide, a natural antibiotic product isolated from fungus ( Cephalosporium recifei ) is reported. The synthesis is accomplished in five steps starting from readily available cyclooctanone and acetaldehyde based on the Lewis acid-catalyzed TMS-directed oxy-2-oxonia-Cope rearrangement. The work represents a novel strategy to assemble related macrolides.

Novel 1H-pyrazolo[4,3-c]quinolines and 4-anilinoquinoline-3-carbonitriles were prepared from readily accessible 4-chloroquinoline-3-carbaldehyde hydrazones by palladium-catalyzed intramolecular C–N bond formation and concurrent hydrazine N–N bond fission. These two classes of functionalized quinolines were chromatographically separable, and both are of biological interest. The ratio of the two products was found to be temperature-dependent; by changing the reaction temperature, either the pyrazoloquinoline or the anilinoquinolinecarbonitrile can become the dominant product.

In the presence of a Lewis acid, trimethylsilyl-substituted β,γ-unsaturated ketones and aldehydes (imines) undergo nucleophilic addition to produce zwitterionic intermediates, followed by oxy-2-oxonia(azonia)-Cope rearrangements to give homoallylic esters (amides). In the case of TMS-containing 2-vinylcycloalkanones, the process results in ring-enlargement, providing 10- to 16-membered lactones. This protocol was applied to the total synthesis of (R)-phoracantholide I.

Axially chiral biaryls exist widely in bioactive natural products and auxiliary ligands for homogeneous catalysis. The particular spatial arrangement of the two aromatic rings in the specific space determines their unique properties; therefore, how to effectively control their absolute configuration is the key issue. Within the last decade, the synthesis of axially chiral biaryls has been a research topic of great interest. Asymmetric biaryl coupling controlled by chiral palladium catalysts was first reported in 2000 and has greatly advanced the chemistry of transition-metal-catalyzed cross-coupling reactions. Most notably, some novel chiral auxiliary ligands such as ferrocene- or biaryl backbone-containing monophosphine, bisphosphines, bis-hydrazones, hydrazone–phosphines, diene and NHC ligands have been applied to this reaction. At the same time a broad range of aryl electrophiles such as phenols, aryl ethers, esters, carbonates, carbamates, sulfamates, phosphates, phosphoramides, phosphonium salts, and fluorides can now be coupled efficiently with boron reagents to afford functionalized axially chiral biaryl products with good to excellent yields and enantioselectivities in the presence of chiral palladium catalysts. In this review, we would like to summarize three main categories of chiral catalysts with discussion of their advantages and limitation.

8-Bromo-7-chloro[1,2,4]triazolo[4,3- c ]pyrimidines were prepared by bromine-mediated oxidative cyclization of the aldehyde-derived hydrazones. The structure of one such product was unambiguously confirmed by single-crystal X-ray analysis. While the C-5 unsubstituted 1,2,4-triazolo[4,3- c ]pyrimidine chemotype is extremely susceptible to ring isomerization at ambient conditions, the C-5-substituted analogues were found to be quite stable, permitting isolation in pure form. Nevertheless, they can still be converted into the 1,2,4-triazolo[1,5- c ]pyrimidines by base- or acid-promoted Dimroth rearrangement. The presence of halogen functionalities on the pyrimidine nucleus renders the products useful as versatile synthetic intermediates for the easy diversification, as evidenced by palladium-catalyzed Kumada cross-couplings and Buchwald–Hartwig amination, as well as direct aromatic substitution.

A sequential Diels-Alder reaction/rearrangement sequence was developed for the synthesis of diverse functionalized bicyclo[2.2.1]heptanes as novel floral and woody odorants. The outcome of the rearrangement depended on the substitution pattern of the dienes. 2D NMR analysis has established the correct relative configuration of the bicyclo[2.2.1]heptanone, which was originally misassigned. Furthermore, when the initiating DA reaction was catalyzed by a chiral Lewis acid, the bicyclo[2.2.1]heptane derivatives including (+)-herbanone can be obtained in an enantiomeric ratio (er) up to 96.5:3.5.

A series of fluorinated dendritic chiral ligands have been designed and synthesized. These fluorinated dendrimers are capable of forming a well-defined semi-rigid structure, which was revealed to play a vital role in the ruthenium(II) bifunctional catalyst for asymmetric transfer hydrogenation of prochiral ketone substrates. In contrast to the classical non-fluorinated dendrimer carrier, both NMR and DFT study exhibit that the introduction of fluorine atoms leads to considerable intramolecular weak interactions such as π–π stacking and hydrogen bonding interactions, which make the dendritic backbone exist with a semi-rigid structure in the catalyst. This influences the performance of the catalytic center in terms of the stability and reusability. This concept was employed as a strategy to design a new Ru(II)-complex catalyst Ru-G-2′-F, which demonstrated obviously improved recycling ability up to fifteen times. Significantly enhanced activity, high enantioselectivity and outstanding recycling ability have also been achieved even at high reaction temperature with Ru-G-2-F.

The series of chiral 1,2-cyclohexane-bridged bis-N-heterocyclic carbene ligand precursors H2[(1R,2R)-(1a–i)]Br with different substituent groups and their neutral and cationic diaqua palladium complexes, namely {Pd[(1R,2R)-(1a–i)]Br2} (2a–i), {Pd[(1R,2R)-(1a)]X2} (X = Cl (3), OAc (4-OAc), OC(O)CF3 (4-OCH(O)CF3)), and {Pd[(1R,2R)-(LOMe)](OH2)2}X2 (X = OTf (5-OTf), SbF6 (5-SbF6)) have been prepared in moderate to good yields. These chiral palladium complexes were fully characterized by elemental analysis, high-resolution mass spectra, 1H and 13C NMR, and optical rotation determinations. The crystal structures of the chiral complexes 2a and 5-OTf were further confirmed to adopt a distorted-square-planar coordination geometry around the palladium center. The obtained chiral NHC-Pd compounds were able to catalyze the asymmetric Suzuki–Miyaura couplings of aryl halides with arylboronic acids in good yields (up to 96%) and moderate enantioselectivities (up to 64% ee). The coligand and steric effects were studied...

A general method to synthesize functionalized allyl α-amino acid derivatives through an irreversible oxy-2-azonia-Cope rearrangement is reported. In the presence of AlCl3, the reaction of imino ethyl glyoxalates with various β,γ-unsaturated ketones furnished the corresponding allyl α-amino acid derivatives. The key to the success of this method is the amide bond formation, which makes the rearrangement irreversible. This reaction system constitutes a new strategy for the synthesis of unusual allyl glycine derivatives, which are valuable synthetic intermediates. An efficient and operationally simple three-component version of this reaction was also performed.

Reaction of novel salalen ligands trans-1-(2′-OH-3′,5′-tBu2C6H2CH2N(Me))-2-(2″-OH-3″,5″-R2-C6H2CH N)-cyclohexane (R = tert-Butyl, H2(La); R = Cl, H2(Lb); R = Br, H2(Lc); R = I, H2(Ld)) with appropriate group 4 metal precursors [MCl4(THF)2] (M = Ti, Zr, Hf) gave a family of complexes [Ti(La–d)Cl2] (1a–1d) and [M(La, c)Cl2] (M = Zr, 2a, c; M = Hf, 3a, c). X-ray single crystal analysis revealed that in the solid state these salalen group 4 metal complexes formed as single isomers with fac–mer geometry and the two chlorine groups are cis-oriented. Introducing the trans-1,2-cyclohexylene bridge and the electron-withdrawing effects of halide substituents improved the catalytic prosperity for ethylene polymerization. The titanium complexes 1a–d showed moderate activity of 37.2–110.0 kg/(molTi h atm) in the polymerization of ethylene using MAO as cocatalyst. Zirconium and hafnium complexes were almost inactive except 2a with a low activity of 4.4 kg/(molZr h atm). The high temperature 1H and 13C NMR analysis revealed that these polymers are vinyl-terminated low-molecular-weight linear polyethylene (Mn = 1800–3800 g mol−1; the vinyl selectivity is about 85–91 mol %).

Chelation therapy is a known effective method to increase the excretion of U(VI) from the body. Until now, no any uranium chelator has been approved for emergency medical use worldwide. The present study aimed to evaluate the efficacy of new ligand BPCBG containing two catechol groups and two aminocarboxylic acid groups in decorporation of U(VI) and protection against acute U(VI) nephrotoxicity in rats, and further explored the detoxification mechanism of BPCBG for U(VI)-induced nephrotoxicity in HK-2 cells with comparison to DTPA-CaNa₃. Chelating agents were administered at various times before or after injections of U(VI) in rats. The U(VI) levels in urine, kidneys and femurs were measured 24 h after U(VI) injections. Histopathological changes in the kidney and serum urea and creatinine and urine protein were examined. After treatment of U(VI)-exposed HK-2 cells with chelating agent, the intracellular U(VI) contents, formation of micronuclei, lactate dehydrogenase (LDH) activity and production of reactive oxygen species (ROS) were assessed. It was found that prompt, advanced or delayed injections of BPCBG effectively increased 24 h-urinary U(VI) excretion and decreased the levels of U(VI) in kidney and bone. Meanwhile, BPCBG injection obviously reduced the severity of the U(VI)-induced histological alterations in the kidney, which was in parallel with the amelioration noted in serum indicators, urea and creatinine, and urine protein of U(VI) nephrotoxicity. In U(VI)-exposed HK-2 cells, immediate and delayed treatment with BPCBG significantly decreased the formation of micronuclei and LDH release by inhibiting the cellular U(VI) intake, promoting the intracellular U(VI) release and inhibiting the production of intracellular ROS. Our data suggest that BPCBG is a novel bi-functional U(VI) decorporation agent with a better efficacy than DTPA-CaNa₃.

Tridentate ligands 4-R1-6-R2-2-{[trans-2-(isoindolin-2-yl)-1,2-diphenylethylimino]methyl}phenol [R1 = R2 = H, H(La); R1 = R2 = tert-butyl, H(Lb); R1 = Ph, R2 = H, H(Lc)] in which a substituted salicylaldimine moiety and an isoindoline are linked by a trans-1,2-diphenylethylene moiety have been prepared. Deprotonation of these tridentate ligands H(La)–H(Lc) by NaH at room temperature in tetrahydrofuran (THF), followed by treatment with 1 equiv. of [(PPh3)2NiX2] (X = Cl, Br, I) at room temperature afforded the desired nickel complexes [(L)NiX] (X = Cl, L = La, 1; X = Cl, L = Lb, 2; X = Cl, L = Lc, 3; X = Br, L = Lb, 4; X = I, L = Lb, 5) in moderate yields. The structures of 2 and 4 were unequivocally confirmed by single-crystal X-ray diffraction in the solid state. The metal atom has a distorted square-planar coordination geometry and is coordinated to the two nitrogen atoms and one oxygen atom from the tridentate ligand and one halide atom. Dehydrogenation of the chelate tridentate ligand (Lb) in the presence of oxygen afforded the corresponding nickel complexes [(Lb*)NiX] (X = Br, 6; X = I, 7). X-ray analysis showed that in these complexes the two bridged benzylic carbon atoms of (Lb)– were oxidized and a cis-stilbene moiety, which includes a C=C double bond (1.205–1.268 A) was formed. These nickel complexes with such trans-1,2-diphenylethylene bridged tridentate ligands proved to be active catalysts for ethylene oligomerization in the presence of methylaluminoxane (MAO) and produced butene and hexene with catalytic activities of 0.49 × 105–3.25 × 105 g mol–1 Ni h–1 at 30 °C, under 20 bar of ethylene, and with an MAO/Ni ratio of 250. They were also active catalysts for the homopolymerization of norbornene and styrene and displayed activities of up to 1.89 × 105 and 7.36 × 105 g mol–1 Ni h–1, respectively.

The tridentate ligands, 4-R 1 -6-R 2 -2-{( trans -2-(isoindolin-2-yl)-1,2–diphenylethylimino) methyl}phenol (R 1 = R 2 = tert -butyl, 3a ; R 1 = Ph, R 2 = H, 3b ; R 1 = R 2 = H, 3c ; R 1 = R 2 = Cl, 3d ; R 1 = R 2 = Br, 3e ; R 1 = R 2 = I, 3f ) in which a substituted salicylaldiminato moiety and an isoindoline are linked by trans -1,2-diphenylethylene moiety have been prepared. Ligand 4-R 1 -6-R 2 -2-{( trans -2-(isoindolin-2-yl)-1,2–diphenylethylamino)methyl}phenol (R 1 = R 2 = tert -butyl, 4a ; R 1 = R 2 = I, 4f ) was obtained from the reduction of 3a and 3f with NaBH 4 in methanol/THF solution at low temperature. Deprotonation of these tridentate ligands 3a – f , 4a and 4f by NaH at −78 °C in THF, followed by treating with 1.2 equiv of TiCl 4 in toluene at room temperature, afforded the desired dark red titanium complexes[Ti(L)Cl 3 ] ( 5a – f , 6a and 6f ) in moderate to good yields. The structures of 5a and 6a were confirmed by single-crystal X-ray diffraction in the solid state. The metal atom has a distorted octahedral coordination geometry through the two nitrogen and one oxygen atoms from the tridentate ligand and three chlorides. These titanium complexes with such trans -1,2-diphenylethylene bridged tridentate ligands proved to be active to catalyze ethylene (co)polymerization with activity of 12.4–232.0 kg-polymer/mol(Ti)⋅h. The 13 C NMR analysis of the polymer produced revealed that the polymer is highly linear polyethylene with no detectable branches and only very low amount of 1-hexene was incorporated into the main chain of the polyethylene.

The cleavage of a lignin model compound of 2-phenoxyacetophenone (2-PAP) was studied in an anhydrous ethanol solvent. A high conversion of 2-PAP (> 99%) to the desired products (> 80% for phenol) with impressive selectivity was achieved in a stainless steel (T316SS) autoclave without any added catalyst. The stainless steel was analyzed as being effective at catalyzing the decomposition of 2-PAP because of its hydrogen transfer activity and stabilization of reaction intermediates, while anhydrous ethanol served as both a solvent and hydrogen donator. An active hydrogen-promoted reaction network was proposed to explain these results. Further investigation demonstrated that the co-catalyst, Cs2.5H0.5PMo12O40, enhanced the cleavage efficiency, which resulted in high yields of the desired products (> 98% of phenol and > 91% of acetophenone). The proposed method in this study based on the stainless steel-promoted hydrogen transfer reaction, which had the merits of a high conversion efficiency and easy handling, can be expected to develop a promising process for further transformation of lignin to valuable multi-substituted aromatics.

A new Lewis acid-catalyzed endo-selective Prins bicyclization of γ,δ-unsaturated aldehydes or ketones with a broad range of aldehydes to dioxabicyclo[2.2.2]octanes is disclosed. When using a chiral BINOL-derived N-triflylphosphoramide (NTPA) as catalyst and glyoxylate esters as substrates, the cross-dimerization afford functionalized bicyclic acetals with excellent diastereo- and enantioselectivities.

A new Lewis acid-catalyzed endo-selective Prins bicyclization of γ,δ-unsaturated aldehydes or ketones with a broad range of aldehydes to dioxabicyclo[2.2.2]octanes is disclosed. When using a chiral BINOL-derived N-triflylphosphoramide (NTPA) as catalyst and glyoxylate esters as substrates, the cross-dimerization afford functionalized bicyclic acetals with excellent diastereo- and enantioselectivities.

Novel 1H-pyrazolo[4,3-c]quinolines and 4-anilinoquinoline-3-carbonitriles were prepared from readily accessible 4-chloroquinoline-3-carbaldehyde hydrazones by palladium-catalyzed intramolecular C–N bond formation and concurrent hydrazine N–N bond fission. These two classes of functionalized quinolines were chromatographically separable, and both are of biological interest. The ratio of the two products was found to be temperature-dependent; by changing the reaction temperature, either the pyrazoloquinoline or the anilinoquinolinecarbonitrile can become the dominant product.

The platinum-encapsulated zeolitically microcapsular catalyst, associated with the immobilized Candida antartica lipase B (Novozyme®435), is successfully employed in the dynamic kinetic resolution of phenylethylamine. A conversion of 80% and a selectivity of 95% are achieved, and negligible loss of activity is detected even after reaction of 5 runs. It is found that the existence of the silicalite-1 shell not only effectively prevents the deactivation of both enzyme and Pt by isolating them in different regions of reaction system, but also significantly reduces the formation of by-products on the Pt nanoparticles within the protected space of zeolitic microcapsule. Such features of zeolitic shell should further promote the designing of various catalysts for multistep reaction network.

The fused 2-vinyl or 2-phenyl substituted cyclobutanones 4 undergo stereoselective ring openings by the action of alkoxide ions (t-BuO− or MeO−) to produce novel vicinally disubstituted cycloalkene derivatives 5 and 6 in moderate to high yields. The ring cleavage usually occurs with complete regioselectivity. The accessibility of γ,δ-unsaturated ester or acid derivatives makes this transformation a good supplementary method for the well-established Johnson–Claisen rearrangement.

A pair of novel palladium complexes {[(1S,2S)-L]PdBr2} and {[(1R,2R)-L]PdBr2} of chiral di-N-heterocyclic carbene ligands derived from chiral 1,2-cyclohexanediamine have been prepared in moderate to good yields and characterized by NMR, HRMS and X-ray single crystal diffraction studies. The obtained chiral NHC–Pd compound was able to catalyze the asymmetric Suzuki–Miyaura couplings of aryl bromides with arylboronic acids in good yields and moderate enantioselectivities (up to 61% ee).

The mechanisms of the title reactions between 1-aza-2-azoniaallene cations and carbodiimides in the gas phase have been examined using the Becke-3-parameter-Lee-Yang-Parr (B3LYP) at 6-31++G** level. The theoretical results revealed that the reaction is a domino reaction that comprises two consecutive reactions: an ionic [3+2] cycloaddition reaction between 1-aza-2-azoniallene cation and carbodiimide to yield the cycloadduct 3 and then a [1,2]-shift to yield the thermodynamically more stable adduct 4. Both stepwise and concerted pathways are accessible in the first cycloaddition in the model reaction. The activation barriers of them are almost equivalent. For the [1,2]-shift reactions, both of the electron-withdrawing chlorine substituent and the electron-releasing methyl substituent on the 1-aza-2-azoniaallene cation can facilitate the reaction but have little effects when substituted in the carbodiimide moiety. The model reaction has also been investigated at the QCISD (quadratic configuration interaction using single and double substitutions)/6-31++G** and CCSD(T) (coupled cluster calculations with single and double excitations and a perturbative estimate of triple contributions calculations)/6-31++G** levels as well as by the density functional theory. In addition, solvent effects with the isodensity-surface polarized continuum model are also reported for all the reactions. In solvent dichloromethane, the cycloadducts of all the reactions, except model reaction and reaction d, were obtained from reactants directly as the result of the solvent effect. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Simple allenyl ethers have been shown to be efficiently activated by cationic gold(I) catalysts to form reactive dienophiles in intermolecular Diels-Alder reactions. A range of different dienes give the cycloaddition products in moderate to excellent yields and good selectivity.

A novel pentaheterocyclic ring system derived from (5α)-cholestan-3-one, i.e. [1R-[1α(R*),3aβ,3bα,5aβ,12aα,12bβ,14aα]]-1-(1,5-dimethylhexyl)-1,2,3,3a,3b,4,5,11,12,12a,12b,13,14,14a-tetradecahydro-8,12a,14a-trimethyl-9-(2,4,6-trichlorophenyl)-cyclopenta[5,6]naphtho[2,1-d][1,2,4]triazolo[1,5-a]azepinium hexachloroantimonate (6) has been synthesized via the reverse-electron-demand 1,3-dipolar cycloaddition of the 1-aza-2-azoniaallene cation 4 to the triple bond of acetonitrile followed by ring enlargement. The structure of 6 was determined by NMR, IR and high-resolution mass spectra, and unequivocally confirmed by X-ray crystallographic analysis. The title compound crystallizes in monoclinic class under the space group P2-1 with a = 8.163(3) A, b = 11.214(4) A, c = 24.191(9) A, α = 90°, β = 97.740(5)°, and γ = 90°. The five-membered triazole ring is essentially planar and aromatic, while the seven-membered azepine ring is not planar, but adopts a chair-like conformation. [1R-[1α(R*),3aβ,3bα,5aβ,12aα,12bβ,14aα]]-1-(1,5-dimethylhexyl)-1,2,3,3a,3b,4,5,11,12,12a,12b,13,14,14a-tetradecahydro-8,12a,14a-trimethyl-9-(2,4,6-trichlorophenyl)-cyclopenta[5,6]naphtho[2,1-d][1,2,4]triazolo[1,5-a]azepinium hexachloroantimonate (6) has been synthesized and unequivocally confirmed by X-ray crystallographic analysis.

2H-1,2,3-Diazaphospholes 3a—3h were prepared from various ketone acylhydrazones and phosphorus trichloride in the presence of triethylamine. Compounds 3 underwent feasible hetero-Diels-Alder reactions with cyclopentadiene to afford the respective anellated [1,2,3]diazaphospholes 4a–4d as well as 4a'—d.″ in moderate yields. The endo rule in the reaction was observed under kinetic control conditions.

A practical procedure for palladium catalyzed Suzuki cross-coupling reaction of arylboronic acids with aryl halides, including aryl chlorides in molten tetra-n-butylammonium bromide (TBAB) was developed. The reaction exhibits high efficiency and functional group tolerance. The recovery of the catalyst and molten n-Bu4NBr was also investigated.

Reactions of easily accessible chloropyrimidinyl hydrazones with bromine were investigated. Oxidative cyclization followed by concomitant bromination led to the formation of [1,2,4]triazolo[4,3-c]pyrimidines, which then underwent the Dimroth rearrangement to afford highly functionalized 2-substituted [1,2,4]triazolo[1,5-c]pyrimidines.

The Diels-Alder reactions of ethyl α-bromoacrylate 1 with open-chain dienes 2 were conducted under thermal or Lewis acid-catalysis conditions. In most cases, the cyclic adducts of 1-bromocyclohex-3-enecarboxylates 3 were formed in high yields with good regio- and stereoselectivity. Subsequent E2-elimination by treatment with DBU provided the corresponding 1,3- or 1,4-cyclohexadienecarboxylates depending on the relative configuration of the products. Starting from myrcene (7-methyl-3-methyleneocta-1,6-diene) the reaction sequence afforded the ester precursor of Georgywood with good yields.

Ru-TsDPEN (TsDPEN = N -( p -tolylsulfonyl)-1,2-diphenylethylenediamine) catalyzed asymmetric transfer hydrogenation of ketones in emulsions is reported for the first time. The new protocol provides markedly enhanced activity and enantioselectivities (up to 99% ee) as compared with results when performed either in an aqueous medium or in common organic solvents.

A novel construction of 2-benzazepine derivatives based on TiCl4-mediated tandem Mannich reaction of electron-rich benzyl iminium ions with alkenyl ethers and Friedel–Crafts-type alkylation is described. The protocol is amenable to provide the tricyclic furo[3,2-d][2]benzazepine and pyrano[3,2-d][2]benzazepine derivatives, respectively, with 2,3-dihydrofuran or 3,4-dihydro-2H-pyran as the substrates.

An efficient palladium-catalyzed amination of aryl halides with amines, using rac-P-Phos as the ancillary ligand and Pd(OAc)2 as the palladium source is developed. The ligand and all of the synthetic intermediates are stable to air and moisture, allowing the easy handling. The catalyst system performed well for a large number of different substrate combinations in 80–110°C to furnish aromatic amines in high yields.

An unprecedented nucleophilic ring opening of cyclopropanecarbaldehydes with benzenethiols proceeds regioselectively under the catalysis of 40 mol% proline to afford fair to good yields of 4-phenylthio-substituted butyraldehydes. If o-thiosalicyl-aldehydes are employed, a tandem homoconjugate addition―aldol reaction occurs, which constitutes an expedient entry to pharmaceutically valuable 2,3-dihydrobenzo[b]thiepine-4-carbaldehydes.

An efficient synthesis of novel O-protected isotetronic acids is described. The method relies on DBU (1,8-diazabicyclo[5.4.0]-undec-7-ene) and triethylamine triggered homo-aldol reactions of 2-oxocarboxylic esters, followed by successful ring closure via lactonization and O-protection with various electrophiles. The unprotected isotetronic acids were also achieved with moderate to high yields if the free-OH group were pre-capped by the silylation agent TMSCl. All the three reaction steps were conducted in a sequential manner, without isolation of any intermediates.