A Halogen‐Bonded Dimeric Resorcinarene Capsule

Iodine (I₂) acts as a bifunctional halogen‐bond donor connecting two macrocyclic molecules of the bowl‐shaped halogen‐bond acceptor, N‐cyclohexyl ammonium resorcinarene chloride 1 , to form the dimeric capsule [(1,4‐dioxane)₃@ 1 ₂(I₂)₂]. The dimeric capsule is constructed solely through halogen bonds and has a single cavity (V=511 ų) large enough to encapsulate three 1,4‐dioxane guest molecules.     

Halogen‐bonded adduct of 1,2‐dibromo‐1,1,2,2‐tetrafluoroethane and 1,4‐diazabicyclo[2.2.2]octane

Halogen bonding is an intermolecular interaction capable of being used to direct extended structures. Typical halogen‐bonding systems involve a noncovalent interaction between a Lewis base, such as an amine, as an acceptor and a halogen atom of a halofluorocarbon as a donor. Vapour‐phase diffusion of 1,4‐diazabicyclo[2.2.2]octane (DABCO) with 1,2‐dibromotetrafluoroethane results in crystals of the 1:1 adduct, C₂Br₂F₄·C₆H₁₂N₂, which crystallizes as an infinite one‐dimensional polymeric structure linked by intermolecular N...Br halogen bonds [2.829 (3) Å], which are 0.57 Å shorter than the sum of the van der Waals radii.     

Crystal structure and photoreactivity of a halogen‐bonded cocrystal based upon 1,2‐diiodoperchlorobenzene and 1,2‐bis(pyridin‐4‐yl)ethylene

The formation of a photoreactive cocrystal based upon 1,2‐diiodoperchlorobenzene ( 1,2‐C₆I₂Cl₄ ) and trans‐1,2‐bis(pyridin‐4‐yl)ethylene ( BPE ) has been achieved. The resulting cocrystal, 2( 1,2‐C₆I₂Cl₄ )·( BPE ) or C₆Cl₄I₂·0.5C₁₂H₁₀N₂, comprises planar sheets of the components held together by the combination of I…N halogen bonds and halogen–halogen contacts. Notably, the 1,2‐C₆I₂Cl₄ molecules π‐stack in a homogeneous and face‐to‐face orientation that results in an infinite column of the halogen‐bond donor. As a consequence of this stacking arrangement and I…N halogen bonds, molecules of BPE also stack in this type of pattern. In particular, neighbouring ethylene groups in BPE are found to be parallel and within the accepted distance for a photoreaction. Upon exposure to ultraviolet light, the cocrystal undergoes a solid‐state [2 + 2] cycloaddition reaction that produces rctt‐tetrakis(pyridin‐4‐yl)cyclobutane ( TPCB ) with an overall yield of 89%. A solvent‐free approach utilizing dry vortex grinding of the components also resulted in a photoreactive material with a similar yield.     

Comparative Study of Halogen‐ and Hydrogen‐Bond Interactions between Benzene Derivatives and Dimethyl Sulfoxide

The halogen bond, similar to the hydrogen bond, is an important noncovalent interaction and plays important roles in diverse chemistry‐related fields. Herein, bromine‐ and iodine‐based halogen‐bonding interactions between two benzene derivatives (C₆F₅Br and C₆F₅I) and dimethyl sulfoxide (DMSO) are investigated by using IR and NMR spectroscopy and ab initio calculations. The results are compared with those of interactions between C₆F₅Cl/C₆F₅H and DMSO. First, the interaction energy of the hydrogen bond is stronger than those of bromine‐ and chlorine‐based halogen bonds, but weaker than iodine‐based halogen bond. Second, attractive energies depend on 1/rⁿ, in which n is between three and four for both hydrogen and halogen bonds, whereas all repulsive energies are found to depend on 1/r^8.5. Third, the directionality of halogen bonds is greater than that of the hydrogen bond. The bromine‐ and iodine‐based halogen bonds are strict in this regard and the chlorine‐based halogen bond only slightly deviates from 180°. The directional order is iodine‐based halogen bond>bromine‐based halogen bond>chlorine‐based halogen bond>hydrogen bond. Fourth, upon the formation of hydrogen and halogen bonds, charge transfers from DMSO to the hydrogen‐ and halogen‐bond donors. The CH₃ group contributes positively to stabilization of the complexes.     

Synthesis of N,N,N-4,4＂-Di-（4-methylphenyl）-2,2＇：6＇,2＂- terpyridine-N,N,N-tris（isothiocyanato） Ruthenium（Ⅱ） and Application to Colorimetric Hg^2＋ Sensor

A terpyridine derivative DPTP [di-（4-methylphenyl）-2,2＇：6＇,2＂-terpyridine] was conveniently synthesized from 2-bromopyridine via halogen-dance reaction, Kharash coupling and Stille coupling reaction. Then its corresponding ruthenium complex Ru-DPTP [N,N,N-4,4＇＇-di-（4-methy,phenyl）-2,2＇：6＇,2＂-terpyridine-N,N,N-tris（is,-thi,cyanat,）- ruthenium（H） ammonium] was obtained and fully characterized by IR, UV-Vis, ESI MS and elemental analysis. The MLCT absorption band of Ru-DPTP was blue-shifted from 570 to 500 nm upon addition of Hg^2＋. Among a series of surveyed metal ions, the complex showed a unique recognition to Hg^2＋, indicating that it can be used as a selective colorimetric sensor for Hg^2＋.     

Rapid and Slow Generation of 1‐Trifluoromethylvinyllithium: Syntheses and Applications of CF3‐Containing Allylic Alcohols,Allylic Amines,and Vinyl Ketones

1‐(Trifluoromethyl)vinylation is accomplished in two protocols by the in situ generation of thermally unstable 3,3,3‐trifluoroprop‐1‐en‐2‐yllithium ( 1 ): 1) a rapid lithium–halogen‐exchange reaction of 2‐bromo‐3,3,3‐trifluoroprop‐1‐ene ( 2 ) takes effect with sec‐BuLi at ?105 °C to generate vinyllithium 1 , which reacts with more reactive electrophiles, such as aldehydes and N‐tosylimines before its decomposition, to afford 2‐(trifluoromethyl)allyl alcohols and N‐[2‐(trifluoromethyl)allyl] sulfoamides in good yield; 2) treatment of 2 with nBuLi at ?100 °C causes a slow lithium–halogen exchange of 2 , which gives rise to a mixture of 1 and nBuLi. Vinyllithium 1 is preferentially trapped with less reactive electrophiles, such as N,N‐dimethylamides in the presence of BF₃?OEt₂, to afford 1‐(trifluoromethyl)vinyl ketones in good yield. Versatility of the products toward syntheses of CF₃‐containing ring‐fused cyclopentenones is also demonstrated by the Pauson–Khand reaction and the Nazarov cyclization.     

The Synthesis of 1,4‐Bis[N‐(4/6‐Substituted Benzothiazole‐2‐yl)‐N′‐Glycosylguanidino]Benzenes

The starting material O‐protected glycosyl isothiocyanate ( 1?3 ) was refluxed with 1,4‐diaminobenzene in CHCl₃ under nitrogen atmosphere to give 1,4‐bis(N‐glycosyl)thioureidobenzene ( 4?6 ). Then 1,4‐bis[N‐(4/6‐substituted benzothiazole‐2‐yl)‐N′‐glycosylguanidino]benzenes ( 8a?8e , 9a?9e , 10a?10e ) were obtained in good yield by reaction of compounds ( 4?6 ) with 2‐amino‐4/6‐benzothizoles ( 7a?7e ) and HgCl₂ in the presence of TEA in DMF. The structures of all 18 new compounds were confirmed by IR, ¹H NMR, LC‐MS and elemental analysis. The bioactivity of anti‐HIV‐1 protease (HIV‐1 PR) and against angiotensin converting enzyme (ACE) have been evaluated.     

Boron as an Electron‐Pair Donor for B⋅⋅⋅Cl Halogen Bonds

MP2/aug′‐cc‐pVTZ calculations were performed to investigate boron as an electron‐pair donor in halogen‐bonded complexes (CO)₂(HB):ClX and (N₂)₂(HB):ClX, for X=F, Cl, OH, NC, CN, CCH, CH₃, and H. Equilibrium halogen‐bonded complexes with boron as the electron‐pair donor are found on all of the potential surfaces, except for (CO)₂(HB):ClCH₃ and (N₂)₂(HB):ClF. The majority of these complexes are stabilized by traditional halogen bonds, except for (CO)₂(HB):ClF, (CO)₂(HB):ClCl, (N₂)₂(HB):ClCl, and (N₂)₂(HB):ClOH, which are stabilized by chlorine‐shared halogen bonds. These complexes have increased binding energies and shorter B?Cl distances. Charge transfer stabilizes all complexes and occurs from the B lone pair to the σ* Cl?A orbital of ClX, in which A is the atom of X directly bonded to Cl. A second reduced charge‐transfer interaction occurs in (CO)₂(HB):ClX complexes from the Cl lone pair to the π* C≡O orbitals. Equation‐of‐motion coupled cluster singles and doubles (EOM‐CCSD) spin–spin coupling constants, ^1xJ(B‐Cl), across the halogen bonds are also indicative of the changing nature of this bond. ^1xJ(B‐Cl) values for both series of complexes are positive at long distances, increase as the distance decreases, and then decrease as the halogen bonds change from traditional to chlorine‐shared bonds, and begin to approach the values for the covalent bonds in the corresponding ions [(CO)₂(HB)?Cl]⁺ and [(N₂)₂(HB)?Cl]⁺. Changes in ¹¹B chemical shieldings upon complexation correlate with changes in the charges on B.     

7‐Halogenated 7‐Deazapurine 2′‐Deoxyribonucleosides Related to 2′‐Deoxyadenosine, 2′‐Deoxyxanthosine,and 2′‐Deoxyisoguanosine: Syntheses and Properties

A series of 7‐fluorinated 7‐deazapurine 2′‐deoxyribonucleosides related to 2′‐deoxyadenosine, 2′‐deoxyxanthosine, and 2′‐deoxyisoguanosine as well as intermediates 4b – 7b, 8, 9b, 10b , and 17b were synthesized. The 7‐fluoro substituent was introduced in 2,6‐dichloro‐7‐deaza‐9H‐purine ( 11a ) with Selectfluor (Scheme 1). Apart from 2,6‐dichloro‐7‐fluoro‐7‐deaza‐9H‐purine ( 11b ), the 7‐chloro compound 11c was formed as by‐product. The mixture 11b / 11c was used for the glycosylation reaction; the separation of the 7‐fluoro from the 7‐chloro compound was performed on the level of the unprotected nucleosides. Other halogen substituents were introduced with N‐halogenosuccinimides ( 11a → 11c – 11e ). Nucleobase‐anion glycosylation afforded the nucleoside intermediates 13a – 13e (Scheme 2). The 7‐fluoro‐ and the 7‐chloro‐7‐deaza‐2′‐deoxyxanthosines, 5b and 5c , respectively, were obtained from the corresponding MeO compounds 17b and 17c , or 18 (Scheme 6). The 2′‐deoxyisoguanosine derivative 4b was prepared from 2‐chloro‐7‐fluoro‐7‐deaza‐2′‐deoxyadenosine 6b via a photochemically induced nucleophilic displacement reaction (Scheme 5). The pK_a values of the halogenated nucleosides were determined (Table 3). ¹³C‐NMR Chemical‐shift dependencies of C(7), C(5), and C(8) were related to the electronegativity of the 7‐halogen substituents (Fig. 3). In aqueous solution, 7‐halogenated 2′‐deoxyribonucleosides show an approximately 70% S population (Fig. 2 and Table 1).     

Ethyl 1,4‐Dihydro‐4‐oxo‐1,8‐naphthyridine‐3‐carboxylates by a Tandem SNAr‐Addition‐Elimination Reaction

A series of N‐substituted 1,4‐dihydro‐4‐oxo‐1,8‐naphthyridine‐3‐carboxylate esters has been prepared in two steps from ethyl 2‐(2‐chloronicotinoyl)acetate. Treatment of the β‐ketoester with N,N‐dimethylformamide dimethyl acetal in N,N‐dimethylformamide (DMF) gave a 95% yield of the 2‐dimethylaminomethylene derivative. Subsequent reaction of this β‐enaminone with primary amines in DMF at 120^oC for 24 h then afforded the target compounds in 47–82% yields by a tandem S_NAr‐addition‐elimination reaction. Synthetic and procedural details as well as a mechanistic rationale are presented.     

Diels–Alder Additions,Ene Reactions,and Condensations of 4‐(Acylamino)‐5‐nitrosopyrimidines – Synthesis of 8‐Substituted Guanines and of 6‐Substituted Pteridinones

4‐(Acylamino)‐5‐nitrosopyrimidines react either by a reductive condensation to provide 8‐substituted guanines, or by a Diels–Alder cycloaddition, or an ene reaction, to provide 6‐substituted pteridinones, depending on the nature of the acyl group and the reaction conditions. Experimental details are provided for the transformation of (acylamino)‐nitrosopyrimidines to 8‐substituted guanines, and the scope of the reaction is further demonstrated by transforming the trifluoro acetamide 25 to the 8‐(trifluoromethyl)guanine ( 27 ), and the N,N′‐bis(nitrosopyrimidinyl)‐dicarboxamide 29 to the (R,R)‐1,2‐di(guan‐8‐yl)ethane‐1,2‐diol ( 32 ). An intramolecular Diels–Alder reaction of the N‐sorbyl (=N‐hexa‐2,4‐dienoyl) nitrosopyrimidine 10 , followed by a spontaneous elimination to cleave the N,O bond of the initial cycloaddition product provided the pteridinones 14 or 15 , characterized by a (Z)‐ or (E)‐3‐hydroxyprop‐1‐enyl group at C(6). Treatment of 10 with Ph₃P led to the C(8)‐penta‐1,3‐dienyl‐guanine 18 . The ene reaction of the N‐crotonyl (=N‐but‐2‐enoyl) nitrosopyrimidine 19 provided the 6‐vinyl‐pteridinone 20a that dimerized readily to 21a , while treatment of 19 with Ph₃P led in high yield to 8‐(prop‐1‐enyl)guanine ( 23 ). The structure of the dimer 21 was established by X‐ray analysis of its bis(N,N‐dimethylformamidine) derivative 21b . The crystal structure of the nitroso amide 10 is characterized by two molecules in the centrosymmetric unit cell. Intermolecular H‐bonds connect the amino group to the amide carbonyl and to N(1). The crystalline bis(purine) 30 forms a left‐handed helix with four molecules per turn and a pitch of 30.2 Å.     

Supramolecular architectures in cytosinium 6‐chloronicotinate monohydrate and 5‐bromo‐6‐methylisocytosinium hydrogen sulfate

Aminopyrimidine derivatives are biologically important as they are components of nucleic acids and drugs. The crystals of two new salts, namely cytosinium 6‐chloronicotinate monohydrate, C₄H₆N₃O⁺·C₆H₃ClNO₂⁻·H₂O, ( I ), and 5‐bromo‐6‐methylisocytosinium hydrogen sulfate (or 2‐amino‐5‐bromo‐4‐oxo‐6‐methylpyrimidinium hydrogen sulfate), C₅H₇BrN₃O⁺·HSO₄⁻, ( II ), have been prepared and characterized by single‐crystal X‐ray diffraction. The pyrimidine ring of both compounds is protonated at the imine N atom. In hydrated salt ( I ), the primary R₂²(8) ring motif (supramolecular heterosynthon) is formed via a pair of N—H…O(carboxylate) hydrogen bonds. The cations, anions and water molecule are hydrogen bonded through N—H…O, N—H…N, O—H…O and C—H…O hydrogen bonds, forming R₂²(8), R₃²(7) and R₅⁵(21) motifs, leading to a hydrogen‐bonded supramolecular sheet structure. The supramolecular double sheet structure is formed via water–carboxylate O—H…O hydrogen bonds and π–π interactions between the anions and the cations. In salt ( II ), the hydrogen sulfate ions are linked via O—H…O hydrogen bonds to generate zigzag chains. The aminopyrimidinium cations are embedded between these zigzag chains. Each hydrogen sulfate ion bridges two cations via pairs of N—H…O hydrogen bonds and vice versa, generating two R₂²(8) ring motifs (supramolecular heterosynthon). The cations also interact with one another via halogen–halogen (Br…Br) and halogen–oxygen (Br…O) interactions.     

Ultrasound‐Assisted Synthesis of 6‐Methyl‐1,2,3,4‐tetrahydro‐N‐aryl‐2‐oxo/thio‐4‐arylpyrimidine‐5‐carboxamides Catalyzed by Uranyl Nitrate Hexahydrate

An efficient and simple method developed for the synthesis of 6‐methyl‐1,2,3,4‐tetrahydro‐N‐aryl‐2‐oxo/thio‐4‐arylpyrimidine‐5‐carboxamide derivatives ( 4a‐o ) using UO₂(NO₃)₂.6H₂O catalyst under conventional and ultrasonic conditions. The ultrasound irradiation synthesis had shown several advantages such as milder conditions, shorter reaction times and higher yields. The structures of all the newly synthesized compounds have been confirmed by FT‐IR, ¹H NMR, ¹³C NMR and mass spectra.     

Synthesis,Characterization, and Crystal Structure of 1,3‐Dipentafluorophenyl‐2,2,2,4,4,4‐hexazido‐1,3‐diaza‐2,4‐diphosphetidine

1,3‐Dipentafluorophenyl‐2,2,2,4,4,4‐hexazido‐1,3‐diaza‐2,4‐diphosphetidine ( 1 ) was synthesized by the reaction of [(C₆F₅)NPCl₃]₂ with trimethylsilyl azide in CH₂Cl₂ and characterized by multinuclear NMR and vibrational spectroscopy. The molecular structure of the compound was determined by single‐crystal X‐ray structure analysis. [(C₆F₅)NP(N₃)₃]₂ crystallizes in the monoclinic space group P2₁/n with a = 9.6414(2), b = 7.4170(1) and c = 15.9447(4) Å, β = 94.4374(9)°, with 2 formula units per unit cell. The bond situation in [(C₆F₅)NP(N₃)₃]₂ has been studied on the basis of NBO analysis. The antisymmetric stretching vibration of the azide groups is discussed. The structural diversity of 1 and 1,3‐diphenyl‐2,2,2,4,4,4‐hexazido‐1,3‐diaza‐2,4‐diphosphetidine in solution and in the solid state depending on the aryl substituent at the nitrogen atom is discussed.     

Superfluorinated Ionic Liquid Crystals Based on Supramolecular,Halogen‐Bonded Anions

Unconventional ionic liquid crystals in which the liquid crystallinity is enabled by halogen‐bonded supramolecular anions [C_nF_{2 n+1}‐I⋅⋅⋅I⋅⋅⋅I‐C_nF_{2 n+1}]⁻ are reported. The material system is unique in many ways, demonstrating for the first time 1) ionic, halogen‐bonded liquid crystals, and 2) imidazolium‐based ionic liquid crystals in which the occurrence of liquid crystallinity is not driven by the alkyl chains of the cation.     

Superfluorinated Ionic Liquid Crystals Based on Supramolecular,Halogen‐Bonded Anions

Unconventional ionic liquid crystals in which the liquid crystallinity is enabled by halogen‐bonded supramolecular anions [C_nF_{2 n+1}‐I???I???I‐C_nF_{2 n+1}]^? are reported. The material system is unique in many ways, demonstrating for the first time 1) ionic, halogen‐bonded liquid crystals, and 2) imidazolium‐based ionic liquid crystals in which the occurrence of liquid crystallinity is not driven by the alkyl chains of the cation.     

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.     

An Exceedingly Mild,Green Synthesis of Substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amine Derivatives and Their Antimicrobial Activity

An exceedingly and highly efficient procedure has been described for the synthesis of substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amines by the reaction of 2‐chloro‐3‐aryl‐1,8‐naphthyridines with various anilines in the presence of N‐methyl‐2‐pyrrolidone and K₂CO₃ under thermal green solvent‐free conditions. The significant features of this green reaction include very good yields in purity, simple experimental, short reaction time, easy workability, and avoidance of toxic solvents. All synthesized compounds have been evaluated for their antibacterial activity.     

Synthesis of 4‐Aryl‐4,6‐dihydropyrimido[4,5‐d]pyridazine‐2,5(1H,3H)‐diones from Biginelli Compounds

Biginelli compounds 1 were first brominated at Me? C(6) with 2,4,4,6‐tetrabromocyclohex‐2,5‐dien‐1‐one to give Br₂CH? C(6) derivatives 2 . The hydrolysis of the 6‐(dibromomethyl) group of 2c to give the 6‐formyl derivative 3c in the presence of an expensive Ag salt followed by reaction with N₂H₄?H₂O yielded tetrahydropyrimido[4,5‐d]pyridazine‐2,5(1H,3H)‐dione ( 4c ; Scheme 1). However, treatment of the 6‐(dibromomethyl) derivatives 2 directly with N₂H₄?H₂O led to the fused heterocycles 4 in better overall yield (Schemes 1 and 2; Table).     

Facile Synthesis of N‐(Benzyl‐1H‐1,2,3‐Triazol‐5‐yl) Methyl)‐4‐(6‐Methoxybenzo [d] Thiazol‐2‐yl)‐2‐Nitrobenzamides via Click Chemistry

A series of novel N‐((l‐benzyl‐lH‐l,2,3‐triazol‐5‐yl) methyl)‐4‐(6‐methoxy benzo[d ]thiazol‐2‐yl)‐2‐nitrobenzamide derivatives were prepared from 4‐(6‐methoxybenzo[d ]thiazol‐2‐yl)‐2‐nitro‐N‐(prop‐2‐ynyl) benzamide with benzyl azides by using click reaction (copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction) in the presence of CuSO₄.5H₂O and sodium ascaorbate. All the newly synthesized compounds were evaluated further in vitro antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus and Bacillus subtillis ), Gram‐negative bacteria (Echerichia coli and Pseudomonas aeuroginosa ), and fungi (Aspergillus niger and Aspergillusfumigatus ) strains. The new compounds were characterized based on spectroscopic evidence. Among them compounds 10a , 10h , and 10i were showed promising activity when compared with standard drugs Ciprofloxacin and Miconazole.