Palladium(II)‐Komplexe des 1,1,3,3,5,5‐Hexakis(dimethylamino)‐λ5‐[1,3,5]triphosphinins

Palladium(II) Complexes of 1,1,3,3,5,5‐Hexakis(dimethylamino)‐λ⁵‐[1,3,5]triphosphinine 1,1,3,3,5,5‐Hexakis(dimethylamino)‐1λ⁵‐3λ⁵‐5λ⁵‐[1,3,5]triphosphinine ( 5 ) reacts with (benzonitrile)₂PdCl₂ to give the chelate complex dichloro(dodeca‐N‐methyl‐1λ⁵,3λ⁵,5λ⁵‐1,3,5‐triphosphinine‐1,1,3,3,5,5‐hexaamin‐C²,C⁴)palladium ( 6 ). In a pyridine‐d₅ solution of 6 the complex dichloro(dodeca‐N‐methyl‐1λ⁵,3λ⁵,5λ⁵‐1,3,5‐triphosphinine‐1,1,3,3,5,5‐hexaamin‐C²)((²H₅)pyridine‐N)palladium ( 7 ) is formed. The solute 7 could not be isolated as a solid, because elimination of the solvent regenerates 6 quantitatively. Properties, nmr and ir spectra of 6 and 7 are reported. 6 is characterized by the results of an X‐ray structural analysis.     

Reaktionen von 1,1,3,3‐Tetrakis(dimethylamino)‐1 λ5, 3 λ5‐diphosphet mit 5‐Cyano‐1‐pentin und mit 2‐(Cyanmethyl)‐1‐methylpyrrol

Diphosphabenzenes. VII. Reactions of 1,1,3,3‐Tetrakis(dimethylamino)‐1 λ⁵, 3 λ⁵‐diphosphete with 5‐Cyano‐1‐pentine and 2‐(Cyanomethyl)‐1‐methylpyrrol 5‐Cyano‐1‐pentine reacts with the equimolar amount of the λ⁵‐diphosphete 1 to give the λ⁵‐diphosphinine (λ⁵‐diphosphabenzene) ( 3 ), while reaction with the double equimolar amount of 1 yields the λ⁵‐diphosphinine ( 4 ). The acyclic compount 6 is the main product of the reaction between 1 and 2‐(cyanomethyl)‐1‐methylpyrrol, 5 . Melting points of 4 · CH₃CN and 6 , and mass, nmr and ir spectra of 3 , 4 , and 6 are reported. The crystal structure of 4 · CH₃CN shows an open‐chain ylidic CPCP‐sequence, which is linked to a λ⁵‐diphosphinine via an ethylene bridge. The X‐ray structure analysis of 6 confirms the existence as an acyclic conjugated double ylid.     

New Approaches to the Synthesis of 4‐(2‐Aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones and 3‐Ureidoindoles and a Study of Their Interconversion

3‐Alkyl/aryl‐3‐ureido‐1H,3H‐quinoline‐2,4‐diones ( 2 ) and 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 3 ) react in boiling concentrated HCl to give 5‐alkyl/aryl‐4‐(2‐aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones ( 6 ). The same compounds were prepared by the same procedure from 2‐alkyl/aryl‐3‐ureido‐1H‐indoles ( 4 ), which were obtained from the reaction of 3‐alkyl/aryl‐3‐aminoquinoline‐2,4(1H,3H)‐diones ( 1 ) with 1,3‐diphenylurea or by the transformation of 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 3 ) and 5‐alkyl/aryl‐4‐(2‐aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones ( 6 ) in boiling AcOH. The latter were converted into 1,3‐bis[2‐(2‐oxo‐2,3‐dihydro‐1H‐imidazol‐4‐yl)phenyl]ureas ( 5 ) by treatment with triphosgene. All compounds were characterized by ¹H‐ and ¹³C‐NMR and IR spectroscopy, as well as atmospheric pressure chemical‐ionisation mass spectra.     

Synthesis and Characterization of New 7‐Substituted 6,14‐Ethenomorphinane Derivatives: N‐{5‐[(5α,7α)‐4,5‐Epoxy‐3,6‐dimethoxy‐17‐methyl‐6,14‐ethenomorphinan‐7‐yl]‐1,3,4‐oxadiazol‐2‐yl}arenamines

In this study, (5α,7α)‐4,5‐epoxy‐3,6‐dimethoxy‐17‐methyl‐6,14‐ethenomorphinan‐7‐carboxylic acid hydrazide ( 5 ) was synthesized by the condensation of methyl (5α,7α)‐4,5‐epoxy‐3,6‐dimethoxy‐17‐methyl‐6,14‐ethenomorphinan‐7‐carboxylate ( 4 ) with NH₂NH₂⋅H₂O. The (5α,7α)‐4,5‐epoxy‐3,6‐dimethoxy‐17‐methyl‐6,14‐ethenomorphinan‐7‐carboxylic acid 2‐[(arylamino)carbonyl]hydrazides 6a – 6q were prepared by the reaction of 5 with corresponding substituted aryl isocyanates, and the N‐{5‐[(5α,7α)‐4,5‐epoxy‐3,6‐dimethoxy‐17‐methyl‐6,14‐ethenomorphinan‐7‐yl]‐1,3,4‐oxadiazol‐2‐yl}arenamines 7a – 7q were obtained via the cyclization reaction of 6a – 6q in the presence of POCl₃. The synthesized compounds have a rigid morphine structure, including the 6,14‐endo‐etheno bridge and the 5‐(arylamino)‐1,3,4‐oxadiazol‐2‐yl residue at C(7) adopting the (S)‐configuration (7α). The structures of the compounds were confirmed by high‐resolution mass spectrometry (HR‐MS) and various spectroscopic methods such as FT‐IR, ¹H‐NMR, ¹³C‐NMR, APT, and 2D‐NMR (HETCOR, COSY, INADEQUATE).     

Four oxoindole‐linked α‐alkoxy‐β‐amino acid derivatives

Four structures of oxoindolyl α‐hydroxy‐β‐amino acid derivatives, namely, methyl 2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐methoxy‐2‐phenylacetate, C₂₄H₂₈N₂O₆, (I), methyl 2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐ethoxy‐2‐phenylacetate, C₂₅H₃₀N₂O₆, (II), methyl 2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐[(4‐methoxybenzyl)oxy]‐2‐phenylacetate, C₃₁H₃₄N₂O₇, (III), and methyl 2‐[(anthracen‐9‐yl)methoxy]‐2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐phenylacetate, C₃₈H₃₆N₂O₆, (IV), have been determined. The diastereoselectivity of the chemical reaction involving α‐diazoesters and isatin imines in the presence of benzyl alcohol is confirmed through the relative configuration of the two stereogenic centres. In esters (I) and (III), the amide group adopts an anti conformation, whereas the conformation is syn in esters (II) and (IV). Nevertheless, the amide group forms intramolecular N—H...O hydrogen bonds with the ester and ether O atoms in all four structures. The ether‐linked substituents are in the extended conformation in all four structures. Ester (II) is dominated by intermolecular N—H...O hydrogen‐bond interactions. In contrast, the remaining three structures are sustained by C—H...O hydrogen‐bond interactions.     

Synthesis of Racemic Δ3‐2‐Hydroxybakuchiol and Its Analogues

The first synthetic approach to (±)‐Δ³‐2‐hydroxybakuchiol (=4‐[(1E,5E)‐3‐ethenyl‐7‐hydroxy‐3,7‐dimethylocta‐1,5‐dien‐1‐yl]phenol; 14 ) and its analogues 13a – 13f was developed by 12 steps (Schemes 2 and 3). The key features of the approach are the construction of the quaternary C‐center bearing the ethenyl group by a Johnson–Claisen rearrangement (→ 6 ); and of an (E)‐alkenyl iodide via a Takai–Utimoto reaction (→ 11 ); and an arylation via a Negishi cross‐coupling reaction (→ 12e – 12f ).     

Synthesis and Characterization of Enantiomerically Pure cis‐ and trans‐3‐Fluoro‐2,4‐dioxa‐8‐aza‐3‐phosphadecalin 3‐Oxides as γ‐Homoacetylcholine Mimetics and Inhibitors of Acetylcholinesterase

The title compounds, the P(3)‐axially and P(3)‐equatorially substituted cis‐ and trans‐configured 8‐benzyl‐3‐fluoro‐2,4‐dioxa‐8‐aza‐3‐phosphadecalin 3‐oxides (=8‐benzyl‐3‐fluoro‐2,4‐dioxa‐8‐aza‐3‐phosphabicyclo[4.4.0]decane 3‐oxides=2‐fluorohexahydro‐6‐(phenylmethyl)‐4H‐1,3,2‐dioxaphosphorino[5,4‐c]pyridine 2‐oxides) were prepared (ee>98%) and fully characterized (Schemes 2 and 3). The absolute configurations were established from that of their precursors, the enantiomerically pure cis‐ and trans‐1‐benzyl‐4‐hydroxypiperidine‐3‐methanols which were unambiguously assigned. Being configuratively fixed and conformationally constrained phosphorus analogues of acetyl γ‐homocholine (=3‐(acetyloxy)‐N,N,N‐trimethylpropan‐1‐aminium), they are suitable probes for the investigation of molecular interactions with acetylcholinesterase. As determined by kinetic methods, all of the compounds are weak inhibitors of the enzyme.     

Solid‐state conformations of linear depsipeptide amides with an alternating sequence of α,α‐disubstituted α‐amino acid and α‐hydroxy acid

Depsipeptides and cyclodepsipeptides are analogues of the corresponding peptides in which one or more amide groups are replaced by ester functions. Reports of crystal structures of linear depsipeptides are rare. The crystal structures and conformational analyses of four depsipeptides with an alternating sequence of an α,α‐disubstituted α‐amino acid and an α‐hydroxy acid are reported. The molecules in the linear hexadepsipeptide amide in (S)‐Pms‐Acp‐(S)‐Pms‐Acp‐(S)‐Pms‐Acp‐NMe₂ acetonitrile solvate, C₄₇H₅₈N₄O₉·C₂H₃N, ( 3b ), as well as in the related linear tetradepsipeptide amide (S)‐Pms‐Aib‐(S)‐Pms‐Aib‐NMe₂, C₂₈H₃₇N₃O₆, ( 5a ), the diastereoisomeric mixture (S,R)‐Pms‐Acp‐(R,S)‐Pms‐Acp‐NMe₂/(R,S)‐Pms‐Acp‐(R,S)‐Pms‐Acp‐NMe₂ (1:1), C₃₂H₄₁N₃O₆, ( 5b ), and (R,S)‐Mns‐Acp‐(S,R)‐Mns‐Acp‐NMe₂, C₃₀H₃₇N₃O₆, ( 5c ) (Pms is phenyllactic acid, Acp is 1‐aminocyclopentanecarboxylic acid and Mns is mandelic acid), generally adopt a β‐turn conformation in the solid state, which is stabilized by intramolecular N—H…O hydrogen bonds. Whereas β‐turns of type I (or I′) are formed in the cases of ( 3b ), ( 5a ) and ( 5b ), which contain phenyllactic acid, the torsion angles for ( 5c ), which incorporates mandelic acid, indicate a β‐turn in between type I and type III. Intermolecular N—H…O and O—H…O hydrogen bonds link the molecules of ( 3a ) and ( 5b ) into extended chains, and those of ( 5a ) and ( 5c ) into two‐dimensional networks.     

Tautomeric behaviour and isotopic multiplets in the 13C NMR spectra of partially deuterated 5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones and 5‐arylazo‐2‐thioxo‐pyrimidine (1H,3H,5H)‐4,6‐diones—evidence for elucidation of tautomeric forms

NMR spectra of the synthesized azo dyes, 5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones (5a–g), 1,3‐dimethyl‐5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones (6a–g), and 5‐arylazo‐2‐thioxo‐pyrimidine (1H,3H,5H)‐4,6‐diones (7a–g) were studied in (CD₃)₂SO (three drops of CD₃OD were added into solutions of the dyes in two different concentrations). All dyes showed intramolecular hydrogen bonding. Dyes 5a–7a showed bifurcated intramolecular hydrogen bonds. Tautomeric behaviours of some of N‐methylated azo dyes (6a‐g) were studied in two different concentrations. The solvent–substrate proton exchange of dyes 5a–d, 6a and 7a–e was examined in presence of three drops of CD₃OD. The dyes which were soluble in (CD₃)₂SO containing CD₃OD showed isotopic splitting (β‐isotope effect) in the ¹³C NMR spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Syntheses,and Crystal Structures of Indium Complexes with η2‐Piperidinyldithiocarbamate and η2‐Pyridine‐2‐Thionate Containing Ligands: Structures of [In(η2‐S2CNC5H10)3] and [In(η2‐pyS)3]

The η²‐thio‐indium complexes [In(η²‐thio)₃] (thio = S₂CNC₅H₁₀, 2 ; SNC₄H₄, (pyridine‐2‐thionate, pyS, 3 ) and [In(η²‐pyS)₂(η²‐acac)], 4 , (acac: acetylacetonate) are prepared by reacting the tris(η²‐acac)indium complex [In(η²‐acac)₃], 1 with HS₂CNC₅H₁₀, pySH, and pySH with ratios of 1:3, 1:3, and 1:2 in dichloromethane at room temperature, respectively. All of these complexes are identified by spectroscopic methods and complexes 2 and 3 are determined by single‐crystal X‐ray diffraction. Crystal data for 2 : space group, C2/c with a = 13.5489(8) Å, b = 12.1821(7) Å, c = 16.0893(10) Å, β = 101.654(1)°, V = 2600.9(3) ų, and Z = 4. The structure was refined to R = 0.033 and Rw = 0.086; Crystal data for 3 : space group, P2₁ with a = 8.8064 (6) Å, b = 11.7047 (8) Å, c = 9.4046 (7) Å, β = 114.78 (1)°, V = 880.13(11) ų, and Z = 2. The structure was refined to R = 0.030 and Rw = 0.061. The geometry around the metal atom of the two complexes is a trigonal prismatic coordination. The piperidinyldithiocarbamate and pyridine‐2‐thionate ligands, respectively, coordinate to the indium metal center through the two sulfur atoms and one sulfur and one nitrogen atoms, respectively. The short C‐N bond length in the range of 1.322(4)–1.381(6) Å in 2 and C‐S bond length in the range of 1.715(2)–1.753(6) Å in 2 and 3 , respectively, indicate considerable partial double bond character.     

A New Monomer for π‐Conjugated Polymers — Synthesis and Characterization of Bis((Z)‐5‐phenyl‐2‐phenylmethylidene‐1, 3‐dithiole‐4‐yl)monosulfane

Bis((Z)‐5‐phenyl‐2‐phenylmethylidene‐1, 3‐dithiole‐4‐yl)monosulfane ( 6 ), a molecule consisting of two diphenyldithiafulvene units connected by a sulfur bridge, was synthesized by the selective lithiation of (Z)‐4‐phenyl‐2‐phenylmethylidene‐1, 3‐dithiole ( 7a ) at the endocyclic double bond and by subsequent reaction of the lithiated intermediate with bis(phenylsulfonyl)sulfane. Since this reaction sequence proceeded with retention of configuration, of three possible isomers (E, E, Z, E, and Z, Z) only the Z, Z form was obtained. On the basis of the X‐ray structure analysis and the NMR‐spectroscopic characterization of 6 supplemented by the NMR parameters of (E)‐ and (Z)‐4‐phenyl‐2‐phenylmethylidene‐1, 3‐dithiole, it was demonstrated that two characteristic ⁵J coupling constants of the proton at the exocyclic double bond indicate the configuration (Z or E) of disubstituted dithiafuvene derivatives.     

Sulfur as hydrogen‐bond acceptor in cocrystals of 2‐thio‐modified thymine

Doubly and triply hydrogen‐bonded supramolecular synthons are of particular interest for the rational design of crystal and cocrystal structures in crystal engineering since they show a high robustness due to their high stability and good reliability. The compound 5‐methyl‐2‐thiouracil (2‐thiothymine) contains an ADA hydrogen‐bonding site (A = acceptor and D = donor) if the S atom is considered as an acceptor. We report herein the results of cocrystallization experiments with the coformers 2,4‐diaminopyrimidine, 2,4‐diamino‐6‐phenyl‐1,3,5‐triazine, 6‐amino‐3H‐isocytosine and melamine, which contain complementary DAD hydrogen‐bonding sites and, therefore, should be capable of forming a mixed ADA–DAD N—H…S/N—H…N/N—H…O synthon (denoted synthon 3s_{N·S;N·N;N·O}), consisting of three different hydrogen bonds with 5‐methyl‐2‐thiouracil. The experiments yielded one cocrystal and five solvated cocrystals, namely 5‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine (1/2), C₅H₆N₂OS·2C₄H₆N₄, (I), 5‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine–N,N‐dimethylformamide (2/2/1), 2C₅H₆N₂OS·2C₄H₆N₄·C₃H₇NO, (II), 5‐methyl‐2‐thiouracil–2,4‐diamino‐6‐phenyl‐1,3,5‐triazine–N,N‐dimethylformamide (2/2/1), 2C₅H₆N₂OS·2C₉H₉N₅·C₃H₇NO, (III), 5‐methyl‐2‐thiouracil–6‐amino‐3H‐isocytosine–N,N‐dimethylformamide (2/2/1), (IV), 2C₅H₆N₂OS·2C₄H₆N₄O·C₃H₇NO, (IV), 5‐methyl‐2‐thiouracil–6‐amino‐3H‐isocytosine–N,N‐dimethylacetamide (2/2/1), 2C₅H₆N₂OS·2C₄H₆N₄O·C₄H₉NO, (V), and 5‐methyl‐2‐thiouracil–melamine (3/2), 3C₅H₆N₂OS·2C₃H₆N₆, (VI). Synthon 3s_{N·S;N·N;N·O} was formed in three structures in which two‐dimensional hydrogen‐bonded networks are observed, while doubly hydrogen‐bonded interactions were formed instead in the remaining three cocrystals whereby three‐dimensional networks are preferred. As desired, the S atoms are involved in hydrogen‐bonding interactions in all six structures, thus illustrating the ability of sulfur to act as a hydrogen‐bond acceptor and, therefore, its value for application in crystal engineering.     

Nucleosides XII.1 Synthesis of 5‐Modified Isoguanosines and Reinvestigation of 5′‐Deoxy‐N3,5′‐cycloisoguanosine

Isoguanosine ( 3 ) underwent a coupling reaction with diaryl disulfides in the presence of tri‐n‐butylphosphine when its 6‐amino group was protected by N,N‐dimethylaminomethylidene. The synthesis of 5′‐deoxy‐N³,5′‐cycloisoguanosine ( 6 ) and its 2′,3′‐O‐isopropylidene derivative ( 11 ) were accomplished in excellent yields from isoguanosines ( 3 & 10 ) in the presence of triphenylphospine and carbon tetrachloride in pyridine. Chlorination at the 5′‐position of isoguanosine ( 3 ) with thionyl chloride followed by the aqueous base‐promoted cyclization afforded the same product 6 . The structures were elucidated by spectroscopic analysis including IR, UV, 1‐D and 2‐D NMR.     

Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one, 3‐hydroxypyridine and 3‐hydroxypyridin‐2‐one ligands: molecular structures and hydrogen‐bonded networks

Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one (pyon), 3‐hydroxypyridine (hpy) and 3‐hydroxypyridin‐2‐one (hpyon) were prepared and the solid‐state structures of (pyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)] or [Cu(tfpb‐κ²O ,O ′)₂(pyon‐κO )], (I), bis(pyridin‐3‐ol‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)₂] or [Cu(tfpb‐κ²O ,O ′)₂(hpy‐κO )₂], (II), and bis(3‐hydroxypyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO₂)₂] or [Cu(tfpb‐κ²O ,O ′)₂(hpyon‐κO )₂], (III), were determined by single‐crystal X‐ray analysis. The coordination of the metal centre is square pyramidal and displays a rare example of a mutual cis arrangement of the β‐diketonate ligands in (I) and a trans‐octahedral arrangement in (II) and (III). Complex (II) presents the first crystallographic evidence of κO‐monodentate hpy ligation to the transition metal enabling the pyridine N atom to participate in a two‐dimensional hydrogen‐bonded network through O—H…N interactions, forming a graph‐set motif R ₂²(7) through a C—H…O interaction. Complex (III) presents the first crystallographic evidence of monodentate coordination of the neutral hpyon ligand to a metal centre and a two‐dimensional hydrogen‐bonded network is formed through N—H…O interactions facilitated by C—H…O interactions, forming the graph‐set motifs R ₂²(8) and R ₂²(7).     

2‐Azido‐2‐deoxycellulose: Synthesis and 1,3‐Dipolar Cycloaddition

Chitosan ( 1 ) was prepared by basic hydrolysis of chitin of an average molecular weight of 70000 Da, ¹H‐NMR spectra indicating almost complete deacetylation. N‐Phthaloylation of 1 yielded the known N‐phthaloylchitosan ( 2 ), which was tritylated to provide 3a and methoxytritylated to 3b . Dephthaloylation of 3a with NH₂NH₂?H₂O gave the 6‐O‐tritylated chitosan 4a . Similarly, 3b gave the 6‐O‐methoxytritylated 4b . CuSO₄‐Catalyzed diazo transfer to 4a yielded 95% of the azide 5a , and uncatalyzed diazo transfer to 4b gave 82% of azide 5b . Further treatment of 5a with CuSO₄ produced 2‐azido‐2‐deoxycellulose ( 7 ). Demethoxytritylation of 5b in HCOOH gave 2‐azido‐2‐deoxy‐3,6‐di‐O‐formylcellulose ( 6 ), which was deformylated to 7 . The 1,3‐dipolar cycloaddition of 7 to a range of phenyl‐, (phenyl)alkyl‐, and alkyl‐monosubstituted alkynes in DMSO in the presence of CuI gave the 1,2,3‐triazoles 8 – 15 in high yields.     

Synthesen und Strukturen von Bis(4,4′‐t‐butyl‐2,2′‐bipyridin)‐Ruthenium(II)‐Komplexen mit funktionellen Derivaten des Tetramethyl‐bibenzimidazols

Syntheses and Structures of Bis(4,4′‐t‐butyl‐2,2′‐bipyridine) Ruthenium(II) Complexes with functional Derivatives of Tetramethyl‐bibenzimidazole [(tbbpy)₂RuCl₂] reacts with dinitro‐tetramethylbibenzimidazole ( A ) in DMF to form the complex [(tbbpy)₂Ru( A )](PF₆)₂ ( 1a ) (tbbpy: bis(4,4′‐t‐butyl)‐2,2′bipyridine). Exchange of the two PF₆^? anions by a mixture of tetrafluor‐terephthalat/tetrafluor‐terephthalic acid results in the formation of 1b in which an extended hydrogen‐bonded network is formed. According to the ¹H NMR spectra and X‐ray analyses of both 1a and 1b , the two nitro groups of the bibenzimidazole ligand are situated at the periphery of the complex in cis position to each other. Reduction of the nitro groups in 1a with SnCl₂/HCl results in the corresponding diamino complex 2 which is a useful starting product for further functionalization reactions. Substitution of the two amino groups in 2 by bromide or iodide via Sandmeyer reaction results in the crystalline complexes [(tbbpy)₂Ru( C )](PF₆)₂ and [(tbbpy)₂Ru( D )](PF₆)₂ ( C : dibromo‐tetrabibenzimidazole, D : diiodo‐tetrabibenzimidazole). Furthermore, 2 readily reacts with 4‐t‐butyl‐salicylaldehyde or pyridine‐2‐carbaldehyde under formation of the corresponding Schiff base Ru^II complexes 5 and 6 . ¹H NMR spectra show that the substituents (NH₂, Br, I, azomethines) in 2 ‐ 6 are also situated in peripheral positions, cis to each other. The solid state structure of both 2 , and 3 , determined by X‐ray analyses confirm this structure. In addition, the X‐ray diffraction analyses of single crystals of the complexes [(tri‐t‐butyl‐terpy)(Cl)Ru( A )] ( 7 ) and [( A )PtCl₂] ( 8 ) display also that the nitro groups in these complexes are in a cis‐arrangement.     

Three one‐dimensional coordination polymers based on 1,1′‐bis(pyridin‐4‐ylmethyl)‐2,2′‐bi‐1H‐benzimidazole and HgX2 (X = Cl,Br and I)

A new 2,2′‐bi‐1H‐benzimidazole bridging organic ligand, namely 1,1′‐bis(pyridin‐4‐ylmethyl)‐2,2′‐bi‐1H‐benzimidazole, C₂₆H₂₀N₆, L or (I), has been synthesized and used to create three new one‐dimensional coordination polymers, viz.catena‐poly[[dichloridomercury(II)]‐μ‐1,1′‐bis(pyridin‐4‐ylmethyl)‐2,2′‐bi‐1H‐benzimidazole], [HgCl₂(C₂₆H₂₀N₆)]_n, (II), and the bromido, [HgBr₂(C₂₆H₂₀N₆)]_n, (III), and iodido, [HgI₂(C₂₆H₂₀N₆)]_n, (IV), analogues. Free ligand L crystallizes with two symmetry‐independent half‐molecules in the asymmetric unit and each L molecule resides on a crytallographic inversion centre. In structures (II)–(IV), the L ligand is also positioned on a crystallographic inversion centre, whereas the Hg centre resides on a crystallographic twofold axis. Compound (I) adopts an anti conformation in the solid state and forms a two‐dimensional network in the crystallographic bc plane viaπ–π and C—H...π interactions. The three Hg^II coordination complexes, (II)–(IV), have one‐dimensional zigzag chains composed of L and HgX₂ (X = Cl, Br and I), and the Hg^II centres are in a distorted tetrahedral [HgX₂N₂] coordination geometry. Complexes (III) and (IV) are isomorphous, whereas complex (II) displays an interesting conformational difference from the others, i.e. a twist in the flexible bridging ligand.     

A Novel,One‐Pot Four‐Component Route to 2′‐Thioxo‐2′,3′‐dihydrospiro[indole‐3,6′‐[1,3]thiazin]‐2‐one Derivatives

An efficient route to 2′,3′‐dihydro‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives is described. It involves the reaction of isatine, 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one, and different amines in the presence of CS₂ in dry MeOH at reflux (Scheme 1). The alkyl carbamodithioate, which results from the addition of the amine to CS₂, is added to the α,β‐unsaturated ketone, resulting from the reaction between 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one and isatine, to produce the 3′‐alkyl‐2′,3′‐dihydro‐4′‐phenyl‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives in excellent yields (Scheme 2). Their structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses.     

Analogues of α‐Campholenal (= (1R)‐2,2,3‐Trimethylcyclopent‐3‐ene‐1‐acetaldehyde) as Building Blocks for (+)‐β‐Necrodol (= (1S,3S)‐2,2,3‐Trimethyl‐4‐methylenecyclopentanemethanol) and Sandalwood‐like Alcohols

To complete our panorama in structure–activity relationships (SARs) of sandalwood‐like alcohols derived from analogues of α‐campholenal (= (1R)‐2,2,3‐trimethylcyclopent‐3‐ene‐1‐acetaldehyde), we isomerized the epoxy‐isopropyl‐apopinene (?)‐ 2d to the corresponding unreported α‐campholenal analogue (+)‐ 4d (Scheme 1). Derived from the known 3‐demethyl‐α‐campholenal (+)‐ 4a , we prepared the saturated analogue (+)‐ 5a by hydrogenation, while the heterocyclic aldehyde (+)‐ 5b was obtained via a Bayer‐Villiger reaction from the known methyl ketone (+)‐ 6 . Oxidative hydroboration of the known α‐campholenal acetal (?)‐ 8b allowed, after subsequent oxidation of alcohol (+)‐ 9b to ketone (+)‐ 10 , and appropriate alkyl Grignard reaction, access to the 3,4‐disubstituted analogues (+)‐ 4f,g following dehydration and deprotection. (Scheme 2). Epoxidation of either (+)‐ 4b or its methyl ketone (+)‐ 4h , afforded stereoselectively the trans‐epoxy derivatives 11a,b , while the minor cis‐stereoisomer (+)‐ 12a was isolated by chromatography (trans/cis of the epoxy moiety relative to the C₂ or C₃ side chain). Alternatively, the corresponding trans‐epoxy alcohol or acetate 13a,b was obtained either by reduction/esterification from trans‐epoxy aldehyde (+)‐ 11a or by stereoselective epoxidation of the α‐campholenol (+)‐ 15a or of its acetate (?)‐ 15b , respectively. Their cis‐analogues were prepared starting from (+)‐ 12a . Either (+)‐ 4h or (?)‐ 11b , was submitted to a Bayer‐Villiger oxidation to afford acetate (?)‐ 16a . Since isomerizations of (?)‐ 16 lead preferentially to β‐campholene isomers, we followed a known procedure for the isomerization of (?)‐epoxyverbenone (?)‐ 2e to the norcampholenal analogue (+)‐ 19a . Reduction and subsequent protection afforded the silyl ether (?)‐ 19c , which was stereoselectively hydroborated under oxidative condition to afford the secondary alcohol (+)‐ 20c . Further oxidation and epimerization furnished the trans‐ketone (?)‐ 17a , a known intermediate of either (+)‐β‐necrodol (= (+)‐(1S,3S)‐2,2,3‐trimethyl‐4‐methylenecyclopentanemethanol; 17c ) or (+)‐(Z)‐lancifolol (= (1S,3R,4Z)‐2,2,3‐trimethyl‐4‐(4‐methylpent‐3‐enylidene)cyclopentanemethanol). Finally, hydrogenation of (+)‐ 4b gave the saturated cis‐aldehyde (+)‐ 21 , readily reduced to its corresponding alcohol (+)‐ 22a . Similarly, hydrogenation of β‐campholenol (= 2,3,3‐trimethylcyclopent‐1‐ene‐1‐ethanol) gave access via the cis‐alcohol rac‐ 23a , to the cis‐aldehyde rac‐ 24 .     

A fourfold interpenetrating cadmium(II) metal–organic framework based on 2,4,6‐tris(pyridin‐4‐yl)‐1,3,5‐triazine with reversible photochromic properties

2,4,6‐Tris(pyridin‐4‐yl)‐1,3,5‐triazine (tpt), as an organic molecule with an electron‐deficient nature, has attracted considerable interest because of its photoinduced electron transfer from neutral organic molecules to form stable anionic radicals. This makes it an excellent candidate as an organic linker in the construction of photochromic complexes. Such a photochromic three‐dimensional (3D) metal–organic framework (MOF) has been prepared using this ligand. Crystallization of tpt with Cd(NO₃)₂·4H₂O in an N,N‐dimethylacetamide–methanol mixed‐solvent system under solvothermal conditions afforded the 3D MOF poly[[bis(nitrato‐κ²O,O′)cadmium(II)]‐μ₃‐2,4,6‐tris(pyridin‐4‐yl)‐1,3,5‐triazine‐κ³N²:N⁴:N⁶], [Cd(NO₃)₂(C₁₈H₁₂N₆)]_n, which was characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis and single‐crystal X‐ray diffraction. The X‐ray diffraction crystal structure analysis reveals that the asymmetric unit contains one independent Cd^II cation, one tpt ligand and two coordinated NO₃^? anions. The Cd^II cations are connected by tpt ligands to generate a 3D framework. The single framework leaves voids that are filled by mutual interpenetration of three independent equivalent frameworks in a fourfold interpenetrating architecture. The compound shows a good thermal stability and exhibits a reversible photochromic behaviour, which may originate from the photoinduced electron‐transfer generation of radicals in the tpt ligand.