(±)-Nuevamine,an isoindoloisoquinoline alkaloid,and (±)-lennoxamine,an isoindolobenzazepine

$\text{Berberis darwinii}$ Hook (Berberidaceae) has yielded the lactams (±)-nuevamine (7) and (±)-lennoxamine (8). Nuevamine is the first known isoindoloisoquinoline alkaloid, while lennoxamine is an isoindolobenzazepine structurally related to (±)-chilenine (3).     

Synthesis, characterization, and isomerization of an iridabenzvalene

Metal- halogen exchange of vinylcyclopropene 4 followed by addition of [(Me3P)2Ir(CO)Cl] produced iridabenzvalene 5. The metallabenzene valence isomer was characterized by NMR and IR spectroscopy and by X-ray crystallography. Isomerization of complex 5 to iridabenzene derivatives 6 and 13 was accomplished by thermolysis and by Ag+ ions, respectively. The former transformation was a clean and quantitative process that displayed first-order kinetics.     

Lenalidomide,an antineoplastic drug,and its hemihydrate

The crystal structures of lenalidomide [systematic name: (RS)‐3‐(4‐amino‐1‐oxoisoindolin‐2‐yl)piperidine‐2,6‐dione], C₁₃H₁₃N₃O₃, (I), an antineoplastic drug, and its hemihydrate, C₁₃H₁₃N₃O₃·0.5H₂O, (II), have been determined by single‐crystal X‐ray diffraction analysis. The overall conformation of the molecule defined by the orientation of the two ring portions, viz. pyridinedione and isoindolinone, is twisted in both structures. The influence of the self‐complementary pyridinedione ring is seen in the crystal packing of both structures through its involvement in forming hydrogen‐bonded dimers, although alternate dione O atoms are utilized. An extensive series of N—H...O hydrogen bonds link the dimers into two‐dimensional supramolecular arrays built up from infinite chains. The water molecule in (II) has a cohesive function, connecting three lenalidomide molecules by hydrogen bonds. The significance of this study lies in the analysis of the interactions in these structures and the aggregations occurring via hydrogen bonds in the hydrated and dehydrated crystalline forms of the title compound.     

A one-pot synthesis of beta-C-glucopyranosides from exo-glucal,p-tolylsulfenyl chloride,an alpha-methoxyalkene,and an external nucleophile

[formula: see text] beta-C-Glycosides were synthesized in one-pot experiments using the following sequence of four reactions: (i) addition of p-TolSCl to an alpha-methoxyalkene, (ii) generation of the episulfonium ion from a beta-(arylsulfanyl)alkyl chloride, (iii) reaction of the episulfonium intermediate with benzylated exo-D-glucal to form a cyclic five-membered sulfonium salt, and (iv) quenching of the sulfonium salt with the external nucleophile: H2O, CH3OH, or NaCNBH3.     

Fluoreszenzuntersuchungen an Monomethin-zyanin-Farbstoffen,insbesondere an reversibel polymeren Monomethin-zyaninen,I

Ohne Zusammenfassung     

InBr3 catalyzed three-component reactions of an aryldiazoacetate,an alcohol,and a carbonyl compound

InBr₃ promoted three-component reactions of an aryldiazoacetate, an alcohol, and an electron deficient carbonyl compound gave α,β-dihydroxyl acid derivatives in good yield with high diastereoselectivity. The reaction is proposed through a protic oxonium ylide trapping process. The reaction mechanism for the formation of the protic oxonium ylide via Lewis acid InBr₃ catalyzed diazo decomposition is suggested through a vinyl cationic intermediate.     

Microwave-assisted decarboxylative three-component coupling of a 2-oxoacetic acid, an amine, and an alkyne

A novel and efficient microwave-assisted decarboxylative three-component coupling of a 2-oxoacetic acid, an amine, and an alkyne (OA(2)-coulpling) has been developed. This new multicomponent coupling constitutes an efficient approach for the synthesis of polysubstituted propargylamines in the presence of a catalytic amount of copper(I) catalyst.     

Polymerization and reptation,an analytical treatment

Free-radical polymerization without crosslinking is considered. By taking the chain length as a continuous variable the reaction kinetics is treated in a simple way for the stationary state. Equations for instantaneous average degrees of polymerization and related quantities are generalized to allow for chain-length dependence of the termination rate constant. For the Ito model, which treats reptation-controlled termination, approximate versions of these equations are derived in the limits of low and high conversion. The observed structure in the peak of the gel permeation chromatograms is shown not to be related to the bimodality in the instantaneous molecular weight distribution. None of the results is very sensitive to the precise reptation behavior.     

Auration, argentation, and mercuration reactions of an iridaphosphirene

The reactions of the iridaphosphirene complex [Ir{=C(tBu)P(Cy)}(CO)(PPh3)2] (Cy = cyclohexyl) with either [AuCl(tht)] (tht = tetrahydrothiophene) or AgCl result in the products [Ir{=C(tBu)P[M(Cl)](Cy)}(CO)(PPh3)2], M = Au or Ag. The aurated product can additionally be obtained on reaction of the iridaphosphirene with [AuCl(CNtBu)], via loss of the isocyanide ligand. Treatment of [Ir{=C(tBu)P(Cy)}(CO)(PPh3)2] with [AuCl(PPh3)] in the presence of silver triflate leads to the isolation of the salt, [Ir{=C(tBu)P[Au(PPh3)](Cy)}(CO)(PPh3)2][SO3CF3]. Reaction of the iridaphosphirene with PhHgCl in the absence or presence of silver triflate affords the mercurated species [Ir{=C(tBu)P[Hg(Ph)](Cy)}(CO)(PPh3)2]X, X = Cl or CF3SO3, respectively. The former exhibits a weakly mercury-coordinated chloride ion. The X-ray crystal structures of all of the complexes are described.     

Almotriptan,an antimigraine agent,and its malate salt

The crystal structures of almotriptan {systematic name: N,N‐dimethyl‐2‐[5‐(pyrrolidin‐1‐ylsulfonylmethyl)‐1H‐indol‐3‐yl]ethanamine}, C₁₇H₂₅N₃O₂S, and almotriptan malate {systematic name: N,N‐dimethyl‐2‐[5‐(pyrrolidin‐1‐ylsulfonylmethyl)‐1H‐indol‐3‐yl]ethanaminium malate, C₁₇H₂₆N₃O₂S⁺·C₄H₅O₅⁻, a novel selective serotonin 1B/D agonist, have been determined in order to gain further insight into the structure–activity relationships of triptans. The two structures differ in the orientation of their sulfonylpyrrolidine side chains. A comparison with other triptans reveals that molecules of almotriptan, sumatriptan, zolmitriptan and rizatriptan can adopt two principal conformations. N—H...N, N—H...O and O—H...O hydrogen bonds are responsible for the molecular packing.     

Preparation,characteristics, and application of an asparaginase tube

Conditions for the preparation of an asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1) tube using polyacrylamide gel were investigated. The apparent yield of activity of the asparaginase tube was about 20%; the activity of the tube was dependent on inner surface area. The optimum pH of the asparaginase tube shifted by 1 pH unit to the acid side in comparison with that of native enzyme. The apparent Michaelis constant of the tube was about 200 times higher than that of the native enzyme. The half-life of the asparaginase tube in continuous operation was estimated to be 16 days at 37°C. The tube was found to be resistant to attack by proteolytic enzyme. The L-asparagine level in blood plasma of a dog was lowered to 1/4 by the performance of an extracorporeal shunt using the asparaginase tube.     

Granisetron,an antiemetic drug,and its cobalt complex

The crystal structures of granisetron [systematic name: 1‐methyl‐N‐(9‐methyl‐9‐azabicyclo[3.3.1]nonan‐7‐yl)indazole‐3‐carboxamide], C₁₈H₂₄N₄O, (I), an antinauseant and antiemetic agent, and its Co^II complex, diaqua[1‐methyl‐N‐(9‐methyl‐9‐azoniabicyclo[3.3.1]nonan‐7‐yl)indazole‐3‐carboxamide]cobalt(II) tetrachloride dodecahydrate, [Co(C₁₈H₂₅N₄O)₂(H₂O)₂]Cl₄·12H₂O, (II), have been determined by X‐ray diffraction. The granisetron molecule is in an extended conformation in both structures. Twisting of the central carboxamide group facilitates the Co^II coordination in (II). The Co^II atom is located on an inversion centre. The azabicyclononane ring adopts a chair–boat conformation in both structures. The molecules in (I) are linked into centrosymmetric dimers and form tetracyclic rings through C—H...O hydrogen‐bonding interactions. The simultaneous presence of free chloride ions in conjunction with a number of hydration water molecules in (II) provides interesting hydrogen‐bond patterns. This study can aid in the investigation of the properties of metal complexes with active pharmaceuticals in which the drug molecules play the role of a ligand.     

Lamotrigine,an antiepileptic drug,and its chloride and nitrate salts

In lamotrigine [systematic name: 6‐(2,3‐dichlorophenyl)‐1,2,4‐triazine‐3,5‐diamine], C₉H₇Cl₂N₅, (I), the asymmetric unit contains one lamotrigine base molecule. In lamotriginium chloride [systematic name: 3,5‐diamino‐6‐(2,3‐dichlorophenyl)‐1,2,4‐triazin‐2‐ium chloride], C₉H₈Cl₂N₅⁺·Cl⁻, (II), the asymmetric unit contains one lamotriginium cation and one chloride anion, while in lamotriginium nitrate, C₉H₈Cl₂N₅⁺·NO₃⁻, (III), the asymmetric unit contains two crystallographically independent lamotriginium cations and two nitrate anions. In all three structures, N—H...N hydrogen bonds form an R₂²(8) dimer. In (I) and (II), hydrophilic layers are sandwiched between hydrophobic layers in the crystal packing. In all three structures, hydrogen bonds lead to the formation of a supramolecular hydrogen‐bonded network. The significance of this study lies in its illustration of the differences between the supramolecular aggregation in the lamotrigine base and in its chloride and nitrate salts.     

Synthesis, characterization, and interfacial properties of an oligomeric, cationic fluorooxetane

The synthesis and characterization of a cationic oligo(fluorooxetane) surfactant with pendant -C4F9 groups are reported. Molecular area demand at saturation was determined to be 55.6 +/- 0.3 angstroms2/molecule and characteristic of an oligomer. The adsorption of the cationic oligo(fluorooxetane) to the air-water interface appears to be diffusion-limited, and dilational rheological properties of the adsorbed molecules are representative of a "soluble" monolayer. Adsorption dynamics have been measured yielding diffusion coefficients that are dependent on concentration and in the 10(-7)-10(-8) cm2/s range. Complex moduli from dilational interfacial rheological measurements as a function of oscillation frequency were well fitted to the Lucassen-van den Tempel equation, providing an estimate of the Gibbs elasticity. The combination of the oligomeric nature of the fluorosurfactant, short perfluoroalkyl chain and its interfacial properties suggests that this synthetic approach is an attractive route to the development of fluorinated surfactants that avoid the environmental concerns of small-molecule, long perfluoroalkyl-chain surfactants.     

Nitric oxide as an electron donor, an atom donor, an atom acceptor, and a ligand in reactions with atomic transition-metal and main-group cations in the gas phase

The room-temperature reactions of nitric oxide with 46 atomic cations have been surveyed systematically across and down the periodic table using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. Rate coefficients and product distributions were measured for the reactions of first-row cations from K+ to Se+, of second-row cations from Rb+ to Te+ (excluding Tc+), and of third-row cations from Cs+ to Bi+. Reactions both first and second order in NO were identified. The observed bimolecular reactions were thermodynamically controlled. Efficient exothermic electron transfer was observed with Zn+, As+, Se+, Au+, and Hg+. Bimolecular O-atom transfer was observed with Sc+, Ti+, Y+, Zr+, Nb+, La+, Hf+, Ta+, and W+. Of the remaining 32 atomic ions, all but 8 react in novel termolecular reactions second order in NO to produce NO+ and the metal-nitrosyl molecule, the metal-monoxide cation and nitrous oxide, and/or the metal-nitrosyl cation. K+, Rb+, Cs+, Ga+, In+, Tl+, Pb+, and Bi+ are totally unreactive. Further reactions with NO produce the dioxide cations CaO2+, TiO2+, VO2+, CrO2+, SrO2+, ZrO2+, NbO2+, RuO2+, BaO2+, HfO2+, TaO2+, WO2+, ReO2+, and OsO2+ and the still higher order oxides WO3+, ReO3+, and ReO4+. NO ligation was observed in the formation of CaO+(NO), ScO+(NO), TiO+(NO), VO+(NO)(1-3), VO2+(NO)(1-3), SrO+(NO), SrO2+(NO)1,2, RuO+(NO)(1-3), RuO2+(NO)1,2, OsO+(NO)(1-3), and IrO+(NO). The reported reactivities for bare atomic ions provide a benchmark for reactivities of ligated atomic ions and point to possible second-order NO chemistry in biometallic and metal-surface environments leading to the conversion of NO to N2O and the production of metal-nitrosyl molecules.     

Dithiolopyranthione Synthesis,Spectroscopy, and an Unusual Reactivity with DDQ

The bicyclic pyran thiolone tetrahydro‐3αH‐[1,3]dithiolo[4,5‐β]pyran‐2‐thione ( 3a ) engages in a highly unusual fragmentation in the presence of DDQ. The pyran thiolone, 3a , was synthesized by chlorination of 3,4‐dihydro‐2H‐pyran ( 1 ) followed by condensing with CS₂ and NaSH. Reaction of 3a with DDQ generates the isomerized pyran thiolone tetrahydro‐3αH‐[1,3]dithiolo[4,5‐β]pyran‐2‐thione ( 3b ) and 4‐benzyl‐5‐(3‐hydroxypropyl)‐1,3‐dithiole‐2‐thione ( 4 ) via a deep‐seated rearrangement. The identity of 3b was confirmed by single crystal X‐ray analysis: P2₁/c, a = 5.807(9) Å, b = 12.99(2) Å, c = 11.445(15), β = 113.23(6)°. Mechanistic experiments and computational insight is used to explain the likely sequence of events in the highly unusual formation of 4 . Collectively, these results establish fundamental reactivity patterns for further research in this area.