Synthesis of Nonsymmetrically N,N′‐Diaryl‐Substituted 4,4′‐Bipyridinium Salts with Redox‐Tunable and Titanium Dioxide (TiO2)‐Anchoring Properties

A general method for the synthesis of so far unknown nonsymmetrically substituted N‐aryl‐N′‐aryl′‐4,4′‐bipyridinium salts is presented (Scheme 1). The common intermediate in all procedures is N‐(2,4‐dinitrophenyl)‐4,4′‐bipyridinium hexafluorophosphate ( 1 ⋅ ). For the synthesis of nonsymmetric arylviologens, 1 ⋅ was arenamine‐exchanged by the Zincke reaction, and then activated at the second bipyridine N‐atom with 2,4‐dinitrophenyl 4‐methylbenzenesulfonate. The detailed preparation of the six N‐aryl‐N′‐aryl′‐viologens 21 – 26 is discussed (Scheme 2). The generality of the procedure is further exemplified by the synthesis of two nonsymmetrically substituted N‐aryl‐N′‐benzyl‐ (see 11 and 12 ), and seven N‐aryl‐N′‐alkyl‐4,4′‐bipyridinium salts (see 28 – 34 ) including substituents with metal oxide anchoring and redox tuning properties. The need for these compounds and their usage as electrochromic materials, in dendrimer synthesis, in molecular electronics, and in tunable‐redox mediators is briefly discussed. The latter adjustable property is demonstrated by the reduction potential measured by cyclic voltammetry on selected compounds (Table).     

The photochromic behaviour of two viologen salts modulated by the distances between the halide anions and the cationic N atoms of viologen

In recent years, viologens and their derivatives have received much attention due to their various potential applications, ranging from electro‐ or photochromic devices to clean energy. Generally, viologen compounds exhibit a colour change upon being subjected to an external stimulus. However, the chromic mechanism is still ambiguous, because there are many electron‐transfer pathways for a chromic compound that need to be considered. Thus, exploring new chromic viologen‐based compounds with one pathway should be important and meaningful. In this article, two new viologen‐based derivatives, namely 1‐(2‐cyanobenzyl)‐4,4′‐bipyridinium chloride (o‐CBbpy·Cl), C₁₈H₁₄N₃⁺·Cl^? ( 1 ), and 1‐(2‐cyanobenzyl)‐4,4′‐bipyridinium bromide (o‐CBbpy·Br), C₁₈H₁₄N₃⁺·Br^? ( 2 ), have been synthesized and characterized. Interestingly, both isomorphic compounds possess only one electron‐transfer pathway, in which 1‐(2‐cyanobenzyl)‐4,4′‐bipyridinium cations (o‐CBbpy) and halide anions are employed as electron donors and acceptors, respectively. Salts 1 and 2 consist of o‐CBbpy cations involved in π–π interactions and hydrogen‐bond interactions, and halide anions weakly hydrogen bonded to the viologen cations. The salts show different photoresponsive characteristics under identical conditions, which should be mainly related to the distances between the halide cations and the cationic N atoms of o‐CBbpy but not the electronegativities of the halogen atoms. These results should not only help in understanding that the distance of the electron‐transfer pathway plays an important role in viologen‐based photochromism, but should also guide the design and synthesis of additional photochromic materials.     

Side‐chain polypseudorotaxanes by threading cucurbit[7]uril onto poly‐N‐n‐butyl‐N′‐(4‐vinylbenzyl)‐4,4′‐bipyridinium bromide chloride: Synthesis,characterization, and properties

A novel side‐chain polypseudorotaxanes P4VBVBu/CB[7] was synthesized from poly‐N‐n‐butyl‐N′‐(4‐vinylbenzyl)‐4,4′‐bipyridinium bromide chloride (P4VBVBu) and cucurbit [7]uril (CB[7]) in water by simple stirring at room temperature. CB[7] beads are localized on viologen units in side chains of polypseudorotaxanes as shown by ¹H NMR, IR, XRD, and UV–vis studies, and it is considered that the hydrophobic and charge‐dipole interactions are the driving forces. TGA data show that thermal stability of the polypseudorotaxanes increases with the adding of CB[7] threaded. DLS data show that P4VBVBu and CB[7] could form polypseudorotaxanes, and the average hydrodynamic radius of the polypseudorotaxanes increases with increasing the concentration of CB[7]. The typical cyclic voltammograms indicate that the oxidation reduction characteristic of P4VBVBu is remarkably affected by the addition of CB[7] because of the formation of polypseudorotaxanes and the shielding effects of CB[7] threaded on the viologen units of polypseudorotaxanes. With the increase of the concentration of KBr or K₂SO₄, the formation of the polypseudorotaxanes was inhibited due to the shielding effects of both Br^? or SO to viologen ion and K⁺ to CB[7] by UV–vis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2135–2142, 2010     

Sesquiterpenoids and 2‐(2‐Phenylethyl)‐4H‐chromen‐4‐one (=2‐(2‐Phenylethyl)‐4H‐1‐benzopyran‐4‐one) Derivatives from Aquilaria malaccensis Agarwood

The four new sesquiterpenoids 1 – 4 , and the new 2‐(2‐phenylethyl)‐4H‐chromen‐4‐one (=2‐(2‐phenylethyl)‐4H‐1‐benzopyran‐4‐one) derivative 5 , together with the two known sesquiterpenoids 6 and 7 , the five known chromenones 8 – 12 , and 1‐hydroxy‐1,5‐diphenylpentan‐3‐one ( 13 ), were isolated from a 70% MeOH extract of Aquilaria malaccensis agarwood chips. Their structures were elucidated on the basis of comprehensive spectral analyses and comparison with literature data.     

Cyclotris(paraquat‐p‐phenylenes)

Reported here is the synthesis, solid‐state characterization, and redox properties of new triangular, threefold symmetric, viologen‐containing macrocycles. Cyclotris(paraquat‐p‐phenylene) ( CTPQT⁶⁺ ) and cyclotris(paraquat‐p‐1,4‐dimethoxyphenylene) ( MCTPQT⁶⁺ ) were prepared and their X‐ray single‐crystal (super)structures reveal intricate three‐dimensional packing. MCTPQT⁶⁺ results in nanometer‐sized channels, in contrast with its parent counterpart CTPQT⁶⁺ which crystallizes as a couple of polymorphs in the form of intercalated assemblies. In the solid state, MCTPQT^3(.+) exhibits stacks between the 1,4‐dimethoxyphenylene and bipyridinium radical cations, providing new opportunities for the manipulation and control of the recognition motif associated with viologen radical cations. These redox‐active cyclophanes demonstrate that geometry‐matching and weak intermolecular interactions are of paramount importance in dictating the formation of their intricate solid‐state superstructures.     

Novel Approach for Rapid and Efficient Synthesis of 2‐(3‐(4‐Aryl)‐1‐isonicotinoyl‐4,5‐dihydro‐1H‐pyrazol‐4‐yl)‐3‐phenylthiazolidin‐4‐one Derivatives and Screened Their Antimicrobial Activity

A series of compounds, viz. 2‐(3‐(4‐aryl)‐1‐isonicotinoyl‐4,5‐dihydro‐1H‐pyrazol‐4‐yl)‐3‐phenylthiazolidin‐4‐one 4 ( a – n ), have been synthesized by reaction of 3 ( a – n ) with thioglycolic acid in the presence of zinc chloride. Compounds 3 ( a – n ) have been synthesized by amination of formylated pyrazoles 2 ( A – B ), which were synthesized by formylation of 1 ( A – B ) by Vilsmeier–Haack reagent (POCl₃/DMF). Compounds 1 ( A – B ) were synthesized by condensation of hydrazide and substituted acetophenones under conventional method and microwave irradiation method. These compounds were identified on the basis of melting point range, Rf values, infrared, ¹H NMR, and mass spectral analysis. These compounds were evaluated for their in vitro antimicrobial activity, and their minimum inhibitory concentration was determined. Among them, compound 4b and compound 4l possess appreciable antimicrobial and antifungal activities. Antibacterial activity results showed that compounds containing electron‐withdrawing groups were more active than compounds containing electron‐releasing groups.     

Synthesis of Some Novel Phenyl Substituted Oxothiazolidin- 1’’,3’’,4’’-thiadiazolo-[3’,4’-b]thiazoline of 3β-Substituted Cholestane

Three title compounds 4a—4c have been synthesized by the cyclodehydration of 1’-benzylidine-4’-(3β-substituted-5α-cholestane-6-yl)thiosemicarbazones 2a—2c with thioglycolic acid followed by the treatment with cold conc. H2SO4 in dioxane. The compounds 2a—2c were prepared by condensation of 3β-substituted-5α-cholestan- 6-one-thiosemicarbazones 1a—1c with benzaldehyde. These thiosemicarbazones 1a—1c were obtained by the reaction of corresponding 3β-substituted-5α-cholestan-6-ones with thiosemicarbazide in the presence of few drops of conc. HCl in methanol. The structures of the products have been established on the basis of their elemental, analytical and spectral data.     

Synthesis and Structural Characterization of Metal Complexes of 2‐Formylpyrrole‐4N‐ethylthiosemicarbazone (4 EL1) and 2‐Acetylpyrrole‐4N‐ethylthiosemicarbazone (4 EL2)

The reactions of ⁴N‐ethyl‐2‐[1‐(pyrrol‐2‐yl)methylidene(hydrazine carbothioamide ( 4 EL₁ ) and ⁴N‐ethyl‐2[1‐(pyrrol‐2‐yl)ethylidene(hydrazine carbothioamide ( 4 EL₂ ) with Group 12 metal halides afforded complexes of types [M(L)₂X₂] (M = Zn, Cd; L = 4 EL₁, 4 EL₂; X = Cl, Br, I; 1 – 6 , 14 – 19 ) and [M(L)X₂] (M = Hg; L = 4 EL₁, 4 EL₂; X = Cl, Br, I; 7 – 9 , 20 – 22 ). In addition, reaction of 4 EL₁ with salts of Cu^II, Ni^II, Pd^II and Pt^II afforded compounds of type [M(4 EL₁–H)₂] ( 10 – 13 ). The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR and electronic spectroscopy and, for sufficiently soluble compounds, ¹H, ¹³C and, when appropriate, ¹¹³Cd or ¹⁹⁹Hg NMR spectrometry. The spectral data suggest that in their complexes with Group 12 metal cations, both thiosemicarbazones are neutral and S‐monodentate; and for [Zn(4 EL₁)₂I₂] ( 3 ), [Cd(4 EL₁)₂Br₂] ( 5 ) and [Hg(4 EL₁)Cl₂]₂ ( 7 ) this was confirmed by X‐ray diffractometry. By contrast, in its complexes with Cu^II and Group 10 metal cations, 4 EL₁ is monodeprotonated and S,N‐bidentate, as was confirmed by X‐ray diffractometry for [Ni(4 EL₁–H)₂] ( 11 ) and [Pd(4 EL₁–H)₂] ( 12 ).     

Preparation and Structures of 2‐Substituted 5‐Benzyl‐3‐methylimidazolidin‐4‐one‐Derived Iminium Salts,Reactive Intermediates in Organocatalytic Transformations Involving α,β‐Unsaturated Aldehydes

Preparations of the title compounds, 5 – 7 (Scheme 1 and Table 1), of their ammonium salts, 9 – 11 (Scheme 2 and Table 2), and of the corresponding cinnamaldehyde‐derived iminium salts 12 – 14 (Scheme 3 and Table 3) are reported. The X‐ray crystal structures of 15 cinnamyliminium PF₆ salts have been determined (Table 4). Selected ¹H‐NMR data (Table 5) of the ammonium and iminium salts are discussed, and structures in solution are compared with those in the solid state.     

Synthesis of 2,2,5,5‐Tetrasubstituted 1,4‐Dioxa‐2,5‐disilacyclohexanes via Organotin(IV)‐Catalyzed Transesterification of (Acetoxymethyl)alkoxysilanes

(Acetoxymethyl)silanes 2 , 7 a – c , and 10 a – c with at least one alkoxy group, of the general formula (AcOCH₂)Si(OR)_3?n(CH₃)_n (R: Me, Et, iPr; n=0, 1, 2), were synthesized from the corresponding (chloromethyl)silanes 1 , 6 a – c , and 9 a – c by treatment with potassium acetate under phase‐transfer‐catalysis conditions. These compounds were found to provide 2,2,5,5‐organo‐substituted 1,4‐dioxa‐2,5‐disilacyclohexanes 3 , 8 a – c , and 11 a – c if treated with organotin(IV) catalysts such as dioctyltin oxide. The reaction proceeds through transesterification of the acetoxy and alkoxy units followed by ring‐closure to form a dimeric six‐membered ring. The corresponding alkyl acetates are formed as the reaction by‐products. With these mild conditions, the method overcomes the drawbacks of previously reported synthetic routes to furnish 2,2,5,5‐tetramethyl‐1,4‐dioxa‐2,5‐disilacyclohexane ( 3 ) and even allows the synthesis of 1,4‐dioxa‐2,5‐disilacyclohexanes bearing hydrolytically labile alkoxy substituents at the silicon atom in good yields and high purity. These new materials were fully characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and X‐ray analysis (trans‐ 8 a ).     

Well‐defined polymers containing high density of pendant viologen groups

Atom transfer radical polymerization (ATRP) of a viologen‐containing methacrylate, 1‐propyl‐1′‐[2‐(methacryloyloxy)ethyl]‐4,4′‐bipyridinium dihexafluorophosphate, is reported. To achieve good polymerization control, it was essential to use the viologen‐based monomer with a hexafluorophosphate instead of halide counterion, and 2,2′‐bipyridine as the ligand for the Cu‐based ATRP catalyst. The solubility of produced cationic polymers could be tuned by anion metathesis: the polymers with hexafluorophosphate counterions were soluble in organic solvents (e.g., acetone, DMF), and those with chloride counterions were water‐soluble. In aqueous solutions, the polymers (chloride salts) formed large aggregates, the sizes of which ranged from about 200 to about 400 nm (based on dynamic light scattering measurements) depending on the molecular weight. Upon addition of electrolytes (e.g., NaCl), the aggregates underwent dissociation. The apparent diffusion coefficients of the aggregates existing in aqueous solutions and the products of their electrolyte‐induced dissociation were measured by diffusion‐ordered NMR spectroscopy. The association–dissociation processes were also studied by fluorescence spectroscopy: the aqueous polymer solutions, which were originally fluorescent (λ _em = 402 nm at λ _ex = 350 nm), lost their fluorescence in the presence of NaCl. The addition of small amounts of the viologen‐containing polyelectrolytes to solutions of inorganic salts (NaCl) altered the crystal morphology of the salts due to interaction of the multiple charged pendant groups with small ions. In the presence of reducing agents, the pendant viologen groups were converted to viologen radical‐cations, which are prone to dimerize reversibly in aqueous solutions. Indeed, marked dimerization of viologen radical cations (with absorbance maxima at 520 and 870 nm) was observed in relatively dilute aqueous solutions (4 mg mL^?1) upon addition of reducing agents (hydrazine). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55 , 1173–1182     

A zwitterionic viologen disulfonate–hydroquinone charge‐transfer crystal: 2,2′‐(4,4′‐bipyridinium‐1,1′‐diyl)di(ethanesulfonate)–hydroquinone (1/2)

The structure of the title compound, C₁₄H₁₆N₂O₆S₂·2C₆H₆O₂, consists of 2,2′‐(4,4′‐bipyridinium‐1,1′‐diyl)di(ethanesulfon­ate) mol­ecules (with crystallographically imposed twofold symmetry) that are hydrogen bonded to each other, as well as to hydro­quinone mol­ecules, in a complex three‐dimensional motif. The orange color of the crystals is indicative of the donor–acceptor interaction between the electron‐rich hydro­quinone π‐donor and the electron‐deficient bipyridinium π‐acceptor. The dihedral angle between the bipyridyl planes is 38.31 (11)°. The distance from the centroid of one of the hydro­quinone mol­ecules to the center of the bipyridinium group is 3.653 (3) Å, which is within the range typically observed for molecular complexes exhibiting charge‐transfer characteristics.     

Main‐chain viologen polymers with organic counterions exhibiting thermotropic liquid‐crystalline and fluorescent properties*

A series of viologen polymers with bromide, tosylate, and triflimide as counterions were prepared by either the Menshutkin reaction or metathesis reaction in a common organic solvent. Their polyelectrolyte behavior in methanol was determined by solution viscosity measurements, and their chemical structures were determined by Fourier transform infrared and Fourier transform NMR spectroscopy. They were characterized for their thermotropic liquid‐crystalline properties with a number of experimental techniques. Each of the viologen polymers with organic counterions had a low melting transition or fusion temperature above which it formed either a high‐order smectic phase or a low‐order smectic phase. Each of them also exhibited a smectic‐to‐isotropic transition. The ranges of the liquid‐crystalline phase were 80–88 °C for viologen polymers with tosylate as a counterion and 120–146 °C for viologen polymers with triflimide as a counterion. They had excellent thermal stability. The ranges of thermal stability were 288–329 °C for viologen polymers with tosylate as a counterion and 343–350 °C for viologen polymers with triflimide as a counterion. The fluorescence property for all of the viologen polymers in either aqueous or methanol solution was also included in this study. For example, the viologen polymer containing the 4,4′‐bipyridinium and p‐xylyl units along the backbone of the polymer chain with triflimide as a counterion had an absorption spectrum (λ_max = 265 nm), an excitation spectrum (λ_ex values = 357, 443, and 454 with monitoring at 533 nm), and an emission spectrum (λ_em = 536 nm with excitation at 430 and 450 nm) in methanol. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 659–674, 2002; DOI 10.1002/pola.10134     

Synthesis of Glycaro‐1,5‐lactams and Tetrahydrotetrazolopyridine‐5‐carboxylates: Inhibitors of β‐D‐Glucuronidase and α‐L‐Iduronidase

The known glucaro‐1,5‐lactam 8 , its diastereoisomers 9 – 11 , and the tetrahydrotetrazolopyridine‐5‐carboxylates 12 – 14 were synthesised as potential inhibitors of β‐D ‐glucuronidases and α‐L ‐iduronidases. The known 2,3‐di‐O‐benzyl‐4,6‐O‐benzylidene‐D ‐galactose ( 16 ) was transformed into the D ‐galactaro‐ and L ‐altraro‐1,5‐lactams 9 and 11 via the galactono‐1,5‐lactam 21 in twelve steps and in an overall yield of 13 and 2%, respectively. A divergent strategy, starting from the known tartaric anhydride 41 , led to the D ‐glucaro‐1,5‐lactam 8 , D ‐galactaro‐1,5‐lactam 9 , L ‐idaro‐1,5‐lactam 10 , and L ‐altraro‐1,5‐lactam 11 in ten steps and in an overall yield of 4–20%. The anhydride 41 was transformed into the L ‐threuronate 46 . Olefination of 46 to the (E)‐ or (Z)‐alkene 47 or 48 followed by reagent‐ or substrate‐controlled dihydroxylation, lactonisation, azidation, reduction, and deprotection led to the lactams 8 – 11 . The tetrazoles 12 – 14 were prepared in an overall yield of 61–81% from the lactams 54, 28 , and 67 , respectively, by treatment with Tf₂O and NaN₃, followed by saponification, esterification, and hydrogenolysis. The lactams 8 – 11 and 40 and the tetrazoles 12 – 14 are medium‐to‐strong inhibitors of β‐D ‐glucuronidase from bovine liver. Only the L ‐ido‐configured lactam 10 (K_i = 94 μM ) and the tetrazole 14 (K_i = 1.3 mM ) inhibit human α‐L ‐iduronidase.     

Synthesis of Some New 2‐Oxo‐N‐[(10H‐phenothiazin‐10‐yl)alkyl] Derivatives of Azetidine‐1‐carboxamides

The synthesis of a new series of 4‐aryl‐3‐chloro‐2‐oxo‐N‐[3‐(10H‐phenothiazin‐10‐yl)propyl]azetidine‐1‐carboxamides, 4a – 4m , is described. Phenothiazine on reaction with Cl(CH₂)₃Br at room temperature gave 10‐(3‐chloropropyl)‐10H‐phenothiazine ( 1 ), and the latter reacted with urea to yield 1‐[3‐(10H‐phenothiazin‐10‐yl)propyl]urea ( 2 ). Further reaction of 2 with several substituted aromatic aldehydes led to N‐(arylmethylidene)‐N′‐[3‐(phenothiazin‐10‐yl)propyl]ureas 3a – 3m , which, on treatment with ClCH₂COCl in the presence of Et₃N, furnished the desired racemic trans‐2‐oxoazetidin‐1‐carboxamide derivatives 4a – 4m . The structures of all new compounds were confirmed by IR, and ¹H‐ and ¹³C‐NMR spectroscopy, FAB mass spectrometry, and chemical methods.     

Synthesis and Characterization of New Thebaine Derivatives as Potential Opioid Agonists and Antagonists: 2‐[N‐(1H‐Tetrazol‐5‐yl)‐6,14‐endo‐etheno‐6,7,8,14‐tetrahydrothebaine‐7α‐yl]‐5‐phenyl‐1,3,4‐oxadiazoles

In this study, we report the synthesis a series of novel 2‐[N‐(1H‐tetrazol‐5‐yl)‐6,14‐endo‐etheno‐6,7,8,14‐tetrahydrothebaine‐7α‐yl]‐5‐phenyl‐1,3,4‐oxadiazole derivatives ( 7a – e ) which have potential opioid antagonist and agonist. The substitution reaction of 6,14‐endo‐ethenotetrahydrothebaine‐7α‐carbohydrazide with corresponding benzoyl chlorides gave diacylhydrazine compounds 4a – e in good yields. The treatment of compounds 4a – e with POCl₃ caused the conversion of side‐chain of compounds 5a – e into 1,3,4‐oxadiazole ring at C(7) position; thus, compounds 5a – e were obtained. Subsequently, cyanamides ( 6a – e ) were prepared from compounds 5a – e and then compounds 7a – e were synthesized by the azidation of 6a – e with NaN₃. The structures of the compounds were established on the basis of their IR, ¹H NMR, ¹³C APT, 2D‐NMR (COSY, NOESY, HMQC, HMBC) and high‐resolution mass spectral data.     

Synthesis of 9‐Halogenated 9‐Deazaguanine N7‐(2′‐Deoxyribonucleosides)

The syntheses of N⁷‐glycosylated 9‐deazaguanine 1a as well as of its 9‐bromo and 9‐iodo derivatives 1b , c are described. The regioselective 9‐halogenation with N‐bromosuccinimide (NBS) and N‐iodosuccinimide (NIS) was accomplished at the protected nucleobase 4a (2‐{[(dimethylamino)methylidene]amino}‐3,5‐dihydro‐3‐[(pivaloyloxy)methyl]‐4H‐pyrrolo[3,2‐d]pyrimidin‐4‐one). Nucleobase‐anion glycosylation of 4a – c with 2‐deoxy‐3,5‐di‐O‐(p‐toluoyl)‐α‐D ‐erythro‐pentofuranosyl chloride ( 5 ) furnished the fully protected intermediates 6a – c (Scheme 2). They were deprotected with 0.01M NaOMe yielding the sugar‐deprotected derivatives 8a – c (Scheme 3). At higher concentrations (0.1M NaOMe), also the pivaloyloxymethyl group was removed to give 7a – c , while conc. aq. NH₃ solution furnished the nucleosides 1a – c . In D₂O, the sugar conformation was always biased towards S (67–61%).     

2,2‐Difluor‐1,3‐diaza‐2‐sila‐cyclopenten – Synthese und Reaktionen

2,2‐Difluor‐1,3‐diaza‐2‐sila‐cyclopentene – Synthesis and Reactions N,N′‐Di‐tert‐butyl‐1,4‐diaza‐1,3‐butadiene reacts with elemental lithium under reduction to give a dilithium salt, which forms with fluorosilanes the diazasilacyclopentenes 1 – 4 ; (HCNCMe₃)₂SiFR, R = F ( 1 ), Me ( 2 ), Me₃C ( 3 ), N(CMe₃)SiMe₃ ( 4 ). As by‐product in the synthesis of 1 , the tert‐butyl‐amino‐methylene‐tert‐butyliminomethine substituted compound 5 was isolated, R = N(CMe₃)‐CH₂‐CH = NCMe₃. 5 is formed in the reaction of 1 with the monolithium salt of the 1,4‐diaza‐1,3‐butadiene in an enamine‐imine‐tautomerism. 1 reacts with lithium amides to give (HCNCMe₃)₂SiFNHR, 6 – 12 , R = H ( 6 ), Me ( 7 ), Me₂CH ( 8 ), Me₃C ( 9 ), H₅C₆ ( 10 ), 2,6‐Me₂C₆H₃ ( 11 ), 2,6‐(Me₂CH)₂C₆H₃ ( 12 ). The reaction of 12 with LiNH‐2.6‐(Me₂CH)₂C₆H₃ leads to the formation of (HCNCMe₃)₂Si(NHR)₂, ( 13 ). In the presence of n‐BuLi, 12 forms a lithium salt which looses LiF in boiling toluene. Lithiated 12 adds this LiF and generates a spirocyclic tetramer with a central eight‐membered LiF‐ring ( 14 ), [(HCNCMe₃)₂Si(FLiFLiNR)]₄, R = 2,6‐(Me₂CH)₂C₆H₃. ClSiMe₃ reacts with lithiated 12 to yield the substitution product (HCNCMe₃)₂SiFN(SiMe₃) R, ( 15 ). The crystal structures of 1 , 5 , 6 , 9 , 11 , 13 , 14 are reported.     

Novel Synthesis of 2‐Aryl‐4,5,6,7‐tetrahydro‐1,2‐benzisothiazol‐3(2H)‐ones and Their S‐Oxides

2‐Aryl‐4,5,6,7‐tetrahydro‐1,2‐benzisothiazol‐3(2H)‐ones 1a – e were synthesized by cyclocondensation of 2‐(thiocyanato)cyclohexene‐1‐carboxanilides 9 as a convenient new method. Their S‐oxides 10 were prepared by two routes, either by oxidation of 1 or dehydration of rac‐cis‐3‐hydroperoxysultims 11 . Furthermore, compounds 1 have been identified by HPLC? API‐MS‐MS as intermediates in the oxidation process of the salts 6 . The hydroperoxides 12b and rac‐trans‐ 11b have been unambiguously detected by HPLC? MS investigations and in the reaction of rac‐cis‐ 13b with H₂O₂ to the hydroperoxides rac‐trans‐ 11b and rac‐cis‐ 11b .     

Synthesis and Characterization of New (Z)‐5‐((1H‐1,2,4‐Triazol‐1‐yl)methyl)‐3‐arylideneindolin‐2‐ones

Ten compounds of new (Z)‐5‐((1H‐1,24‐triazol‐1‐yl)methyl)‐3‐arylideneindolin‐2‐ones ( 5a – j ) have been synthesized by the Knoevenagel condensation of 5‐((1H‐1,2,4‐triazol‐1‐ylmethyl)indolin‐2‐one ( 3 ) with 4‐substituted aromatic aldehydes ( 4a – j ).