Synthesis and insecticidal activity of O‐aryl O‐(1,2,2,2‐tetrachloroethyl)phosphoramidothioates and their thiophosphoric hydrazides [1]

O‐Aryl O‐(1,2,2,2‐tetrachoroethyl)phos‐ phoramidothioates 3a–h and their thiophosphoric hydrazides 4a–e were synthesized by reactions of O‐aryl O‐(1,2,2,2‐tetrachoroethyl)thiophosphorochloridates 2 with amines and hydrazines, respectively. Their structures were characterized by elemental analysis IR ¹H NMR, ³¹P NMR, and MS. The O‐aryl O‐(1,2,2,2‐tetrachloroethyl)thiophosphoric hydrazides 4a–d (R²=H) can be transformed into 1,3,4,2‐oxadiazaphospholanes 5a–d by the reaction of triethylamine. The results of preliminary bioassays indicated that some of the title compounds have good insecticidal activities against nematodes (Meloidogyne spp.) and pea aphids. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 441–445, 1999     

Highly Selective 1,4‐ and 1,6‐Addition of P(O)?H Compounds to p‐Quinones: A Divergent Method for the Synthesis of C‐ and O‐Phosphoryl Hydroquinone Derivatives

The reaction of P(O)? H compounds with p‐quinones could proceed through either 1,4‐ or 1,6‐addition pathways by employing different additives to selectively give the corresponding C‐ and O‐phosphoryl hydroquinone derivatives in good yields. Oxidative double 1,4‐addition of P(O)? H compounds to p‐quinones was also achieved by tuning the solvent, affording a facile synthesis of bis‐substituted hydroquinones with phosphorus functionality. Further studies on these reactions by using optically active H‐phosphinates showed that all addition reactions took place stereospecifically with retention of configuration at the phosphorus center. The findings lead to the establishment of a divergent method for the synthesis of C‐ and O‐phosphoryl hydroquinone derivatives from easily available P(O)? H compounds.     

Facile synthesis of 2‐alkylthio‐3‐amino‐4 H‐imidazol‐4‐ones and 2H‐imidazo[2,1‐b]‐1,3,4‐thiadiazin‐6(7H)‐ones via N‐vinylic iminophosphorane

2‐Alkylthio‐3‐amino‐4H‐imidazol‐4‐ ones 5 were synthesized by S‐alkylation of 2‐thioxo‐3‐amino‐4‐imidazolidinones 4 , which were obtained via cyclization of isothiocyanates 2 with hydrazine hydrate. 5l–n reacted with Ph₃P, C₂Cl₆, and NEt₃ to give 2H‐imidazo[2,1‐b]‐1,3,4‐thiadiazin‐ 6(7H)‐ones 7a–c in good yields. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:76–80, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20069     

Synthesis of Electron‐Deficient Corona[5]arenes and Their Selective Complexation with Dihydrogen Phosphate: Cooperative Effects of Anion–π Interactions

Reported here are the syntheses, conformational structures, electrochemical properties, and noncovalent anion binding of corona[5]arenes. A (3+2) fragment coupling reaction proceeded efficiently under mild reaction conditions to produce a number of novel heteroatom‐ and methylene‐bridged corona[3]arene[2]tetrazine macrocycles. Selective oxidation of the sulfur atom between two phenylene rings afforded sulfoxide‐ and sulfone‐linked corona[5]arenes in good yields. All corona[5]arenes synthesized adopted similar 1,2,4‐alternate conformational structures, forming pentagonal cavities. The cavity sizes and the electronic properties such as redox potentials, were measured with CV and DPV, and were influenced by the different bridging units. As electron‐deficient macrocycles, the acquired corona[3]arene[2]tetrazines served as highly selective hosts, forming complexes with the hydrogen‐bonded dimer of dihydrogen phosphate through cooperative anion–π interactions.     

Synthesis of Phosphanes Bearing 2‐Imino‐1,3‐thiazolidine Ligands – X‐Ray Analyses and NMR Spectroscopy

Pseudo‐ephedrine derived 2‐imino‐1,3‐thiazolidine 1 reacts with tris(diethylamino)phosphane by stepwise replacement of the diethylamino group to give the mono‐, bis‐ and tris(imino)phosphanes 2 , 3 and 4 , respectively, of which 4 could be isolated in pure state. The analogous reaction with diethylamino‐diphenylphosphane affords the imino‐diphenylphosphane 5 . The iminophosphanes react with sulfur or selenium to give the corresponding phosphorus(V) compounds. In contrast, the reaction of the iminophosphanes with oxygen is very slow; anhydrous trimethylamine N‐oxide reacts in the melt with the phosphanes to give the oxides 4(O) and 5(O) . The molecular structures of 4(O) (in mixture with 4 ), 4(Se) , 5(S) and 5(Se) were determined by X‐ray analysis. In all cases the ring‐sulfur and the phosphorus atoms are in cis‐positions at the C=N bonds. The analogous solution structures were determined by ¹H, ¹³C, ¹⁵N, ³¹P and ⁷⁷Se NMR spectroscopy. In the case of the compounds 5 , 5(O) , 5(S) and 5(Se) the isotope‐induced chemical shifts ¹δ^14/15N(³¹P) were determined, using INEPT‐HEED experiments.     

Gadolinium‐Catalyzed Regio‐ and Enantioselective Aminolysis of Aromatic trans‐2,3‐Epoxy Sulfonamides

The first enantioselective aminolysis of aromatic trans‐2,3‐epoxy sulfonamides has been accomplished, which was efficiently catalyzed by a Gd‐N,N′‐dioxide complex. Under the directing effect of the sulfonamide moiety the ring‐opening reaction proceeded selectively at the C‐3 position in a highly enantioselective manner furnishing various Ts‐ and SES‐protected 3‐amino‐3‐phenylpropan‐2‐olamines as products.     

Efficient Synthesis of 1,4‐Bis‐heteroatom‐substituted Tetraselanylbenzenes via 1,4‐Dilithiation of Hexaselanylbenzene and Investigation on Their Electronic Properties

We successfully synthesized mono‐ and bis‐substituted polyselanylbenzenes 3 and 5 via mono‐ and dilithiation of hexakis(phenylselanyl)benzene ( 1 ), respectively. Introduction of various heteroatom functionalities into hexaselanylbenzene changed the electronic properties dependent on the σ‐symmetric circular orbitals that were formed by the interactions between neighboring heteroatoms. In the cyclic voltammetry and theoretical studies on bis‐heteroatom‐substituted benzenes 5 , the extent of the interactions in the circular orbitals with σ‐symmetry affected the stability of the cationic species of 5 . This study would give insight into the molecular design for new σ‐delocalized systems and inspire the development of tuning electronic properties of benzene derivatives by σ‐type orbital interactions derived from heteroatom functionalities.     

Derivatives of α‐ and β‐S‐thiophosphates of 2‐bromo‐2‐deoxy‐D‐hexopyranose

The first examples of S‐thiophosphate derivatives of 2‐bromo‐2‐deoxy sugars 7–12 were synthesized by reacting alkyl ammonium salts 1–4 of thiophosphoric acids with α‐1,2‐cis (5) or α‐1,2‐trans dibromo sugars (6) and addition of free thiophosphoric acids 1a or 2a to 2‐bromo‐D‐glucal (13). It was observed that the solvent determines formation of either the O‐ or S‐glycosyl compound. β‐Thiophosphates can be transformed to the α‐configuration in the presence of acid in quantitative yield. The structures of the synthesized derivatives of 7–12 were confirmed by spectroscopic methods. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 465–470, 1999     

Solvent‐Controlled C2/C5‐Regiodivergent Alkenylation of Pyrroles

A solvent‐controlled C2/C5‐selective alkenylation of 3,4‐disubstituted pyrroles has been developed. The C3 substituent of pyrroles proved crucial to the regioselectivity. Substrates bearing directing groups at the C3 position exhibited excellent C2‐selectivities in chelation‐assisted C?H activation in toluene or 1,4‐dioxane. However, a DMSO/DMF solvent system could override the chelation effect of weak directing groups, such as carboxylate and carbonyl groups, favoring instead regioselectivity towards the more electron‐rich C5 position. A series of 3‐carboxylate and 3‐carbonyl pyrroles were tested and showed moderate to good yields with good regioselectivities for both C2‐ and C5‐alkenylation process.     

Synthesis of novel 1,3‐substituted 1H‐[1,2,4]‐triazole‐3‐thiol derivatives

By means of regioselective S‐alkylation of 1H‐1,2,4‐triazole‐3‐thiol ( 1 ), a series of S‐substituted derivatives 2a‐j were synthesized. In certain conditions, the reaction of 2 with arylsulfochlorides, arylisocyanates, and quaternary ammonium salts of azines corresponding compounds were obtained 1‐arylsulfonyl‐ (3a‐d) , 1‐arylcarbonamido‐ ( 4a,b ), and 1‐azinyl‐1,2,4‐ ( 6a‐p ) triazoles. Structures of compounds were confirmed by ¹H NMR and elemental analyses. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:405–410, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20565     

Synthesis of Dibenzo[c,e]oxepin‐5(7H)‐ones from Benzyl Thioethers and Carboxylic Acids: Rhodium‐Catalyzed Double CH Activation Controlled by Different Directing Groups

A rhodium(III)‐catalyzed cross‐coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C? H, C? S, O? H) and the formation of two bonds (C? C, C? O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C? H activation, the first of such examples in cross‐oxidative coupling.     

Pd‐Catalyzed C−H Alkylation of Arenes Using PyrDipSi,a Transformable and Removable Silicon‐Tethered Directing Group

An efficient Pd‐catalyzed ortho‐C?H alkylation reaction of arenes using a transformable and removable Si‐tethered pyridyldiisopropylsilyl (PyrDipSi) directing group has been developed. In addition, the PyrDipSi directing group allows for an efficient sequential double‐fold C?H alkylation/oxygenation of arenes to produce meta‐alkylated phenols. This directing group can easily be removed or converted into valuable functionalities, such as aryl, iodo, boronic ester, or phenol.     

Synthesis of Dibenzo[c,e]oxepin‐5(7H)‐ones from Benzyl Thioethers and Carboxylic Acids: Rhodium‐Catalyzed Double C?H Activation Controlled by Different Directing Groups

A rhodium(III)‐catalyzed cross‐coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C H, C S, O H) and the formation of two bonds (C C, C O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C H activation, the first of such examples in cross‐oxidative coupling.     

3‐[(Diphenylphosphinothioyl)oxy]‐N‐methylpropan‐1‐aminium diphenylphosphanylthioate

The title salt, C₁₆H₂₁NOPS⁺·C₁₂H₁₀OPS, was synthesized from the reaction between 3‐(methylamino)propan‐1‐ol and PPh₂(S)Cl in the presence of Et₃N. Its structure has been identified using spectroscopic methods and X‐ray analysis. Single crystals were obtained from ethanol by slow evaporation. In the asymmetric unit, a cation–anion pair is formed through an intermolecular N—H...O [N...O = 2.6974 (18) Å] hydrogen bond. The molecules are packed through N—H...O and N—H...S hydrogen bonds in the crystal and these hydrogen bonds are responsible for the high melting point. The P atoms of the anion and cation both have distorted tetrahedral environments.     

Synthesis and crystal structure of 2‐phosphonoalkyl‐1, 2‐benzisoselenazol‐3(2H)‐ones and their antitumor activities

The title compounds were synthesized in good yields by the condensation reaction of diphenyl α‐aminoalkylphosphonates with 2‐(chloroseleno)‐benzoyl chloride. Their structures were confirmed by spectroscopic methods and microanalyses. The X‐ray analyses showed that the selenium‐containing fused ring has a planar structure and that, by the molecular packing of the unit cells, two adjacent molecules are symmetrically linked to each other through Se(1c) … O=P(1) bonding interactions with an intermolecular Se(1c) … O distance of 2.797 Å. The results of bioassay indicated that some of these compounds possess potent antitumor activities against some human carcinoma cells in vitro. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10:247–254, 1999     

A Computational and Experimental Study of Thieno[3,4‐b]thiophene as a Proaromatic π‐Bridge in Dye‐Sensitized Solar Cells

Four D ‐π‐A dyes (D=donor, A=accpetor) based on a 3,4‐thienothiophene π‐bridge were synthesized for use in dye‐sensitized solar cells (DSCs). The proaromatic building block 3,4‐thienothiophene is incorporated to stabilize dye excited‐state oxidation potentials. This lowering of the excited‐state energy levels allows for deeper absorption into the NIR region with relatively low molecular weight dyes. The influence of proaromatic functionality is probed through a computational analysis of optimized bond lengths and nucleus independent chemical shifts (NICS) for both the ground‐ and excited‐ states. To avoid a necessary lowering of the TiO₂ semiconductor conduction band (CB) to promote efficient dye–TiO₂ electron injection, strong donor functionalities based on triaryl‐ and diarylamines are employed in the dye designs to raise both the ground‐ and excited‐state oxidation potentials of the dyes. Solubility, aggregation, and TiO₂ surface protection are addressed by examining an ethylhexyl alkyl chain in comparison to a simple ethyl chain on the 3,4‐thienothiophene bridge. Power conversion efficiencies of up to 7.8 % are observed.     

Rhodium‐Catalyzed Highly Diastereo‐ and Enantioselective Synthesis of a Configurationally Stable S‐Shaped Double Helicene‐Like Molecule

An S‐shaped double helicene‐like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex‐catalyzed highly diastereo‐ and enantioselective intramolecular double [2+2+2] cycloaddition of a 2‐naphthol‐ and benzene‐linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S‐shaped double helicene‐like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S‐shaped double helicene‐like molecule forms a trimer through the multiple C?H???π and C?H???O interactions in the solid‐state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S‐shaped double helicene‐like molecule enhanced the chiroptical properties.     

Visible‐Light‐Induced Direct Photocatalytic Carboxylation of Indoles with CBr4/MeOH

Photocatalysis enables the cascade reactions of indoles and CBr₄ in MeOH through a C(sp²)?H functionalization/methanolysis sequence. The title reaction provides an efficient access to indole 2‐ and 3‐carboxylates in a single operation (no preinstallation of protecting as well as directing groups was required) with good yields under mild reaction conditions.     

Ruthenium‐Catalyzed O‐ to S‐Alkyl Migration: A Pseudoreversible Barton–McCombie Pathway

A practical ruthenium‐catalyzed O‐ to S‐alkyl migration affords structurally diverse thiooxazolidinones in excellent yields. Our studies suggest this catalytic transformation proceeds through a pseudoreversible radical pathway drawing mechanistic parallels to the classic Barton–McCombie reaction.     

Straightforward Solvent‐Free Synthesis of Tertiary Phosphine Chalcogenides from Secondary Phosphines,Electron‐Rich Alkenes,and Elemental Sulfur or Selenium

A series of tertiary phosphine sulfides and selenides have been synthesized in excellent yields (88‐99%) via a three‐component reaction between secondary phosphines, electron‐rich alkenes (styrene, vinyl chalcogenides), and elemental sulfur or selenium, proceeding under solvent‐free conditions (80‐82°C, 4–44 h). The interaction occurs via initial oxidation of secondary phosphines with elemental sulfur or selenium followed by noncatalyzed anti‐Markovnikov addition of the generated R₂P(E)H (E = S, Se) species to alkenes to afford the corresponding adducts with high chemo‐ and regioselectivity.