Cycloacylation of N-phenyl-N′-R-thioureas with 3-aryl-2-propenoyl chlorides

Cycloalkylation of N-phenyl-N′-R-thiourea with 3-aryl-2-propenoyl chlorides in acetone gives as products 6-aryl-3-phenyl-2-(R-imino)-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one and their hydrochlorides. The same reaction carried out in acetone in the presence of K₂CO₃ leads to the formation of 6-aryl-3-phenyl-2-(R-imino)-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-ones, N-(3-aryl-2-propenoyl)-N-phenylthioureas, 3-aryl-2-propenoylanilides, and phenyl isothiocyanate.     

Synthesis and Structural Characterization of the First Europium(III) Pyridylphosphine Complex, [Eu(N,N’,N”-2-Py3P)(NO3)3]

The first europium(iii) pyridylphosphine complex, [Eu(N,N’,N”-2-Py₃P)(NO₃)₃] was prepared by the reaction between Eu(NO₃)₃.6H₂O and tris(2-pyridyl)phosphine; its structure was characterized by single-crystal X-ray diffraction.     

Unexpected course of rearrangement of substituted S-(1(3H)-isobenzofuranone-3-yl)isothiuronium bromides

Three series of S-(1(3H)-isobenzofuranone-3-yl)isothiuronium bromides differing in substitution at the isothiuronium moiety (none, one or two methyl groups) and at the benzene ring were prepared and characterized. These salts were then treated with various bases (acetate, triethylamine, Na₂CO₃) to give either 1-hydroxy-3-oxo-1,3-dihydro-2H-isoindol-2-carbothioamides or the product of S to N isobenzofuranone-3-yl migration, i.e., 1,3-dimethyl-1-(3-oxo-1,3-dihydro-2-benzofuran-1-yl)thioureas. If ammonia was used in reaction with N,N′-dimethyl isothiuronium salts then 3-hydroxy-2,3-dihydro-1H-isoindol-1-ones were formed together with 1,3-dimethyl-1-(3-oxo-1,3-dihydro-2-benzofuran-1-yl)thioureas in parallel reaction with the yields increasing with ammonia concentration. The formation of isoindolones takes place in two steps with an aldehyde intermediate, which can be trapped with N,N-dimethylhydrazine.     

Spin trapping of alkoxyl radicals generated from 5-methyl and 5-aryl-3-alkoxy-4-methylthiazole-2(3H)-thiones in photochemically induced and microwave-initiated reactions

Methoxyl and isopropoxyl radicals were generated from N-alkoxy-4,5-dimethylthiazole-2(3H)-thiones (λ_max∼320 nm) and 5-aryl derivatives (aryl=p-XC₆H₄; X=MeO, H, AcNH, Cl) (λ_max∼335 nm) in photochemically and microwave-induced reactions. Alkoxyl radicals were trapped with dimethylpyrrolidine N-oxide and characterized as spin adducts via EPR. Cumyloxyl radicals were liberated in a similar manner from N-cumyloxy-5-(4-methoxyphenyl)-4-methylthiazole-2(3H)-thione. A noteworthy bathochromic shift was found for the lowest energy transition of N-(hydroxy)indeno[2,1-d]thiazole-2(3H)-thione (λ_max=376 nm), if compared to the UV-vis absorption of N-hydroxy-4-methyl-5-phenylthiazole-2(3H)-thione (λ_max=338 nm). Syntheses of alkoxyl radical precursors and procedures for conducting N,O-homolysis are described in a full account.     

4-Substituted 5-nitroisoquinolin-1-ones from intramolecular Pd-catalysed reaction of N-(2-alkenyl)-2-halo-3-nitrobenzamides

4-Methyl- and 4-benzyl-5-aminoisoquinolin-1-ones are close analogues of the water-soluble PARP-1 inhibitor 5-AIQ. Their synthesis was approached through Pd-catalysed cyclisations of N-(2-alkenyl)-2-iodo-3-nitrobenzamides. Reaction of N,N-diallyl-2-iodo-3-nitrobenzamide with Pd(PPh₃)₄ gave a mixture of 2-allyl-4-methyl-5-nitroisoquinolin-1-one and 2-allyl-4-methylene-5-nitro-3,4-dihydroisoquinolin-1-one. N-Benzhydryl-N-cinnamyl-2-iodo-3-nitrobenzamide similarly gave 2-benzhydryl-4-benzyl-5-nitroisoquinolin-1-one and 2-benzhydryl-4-benzylidene-5-nitro-3,4-dihydroisoquinolin-1-one. The isomeric products are not interconvertible. A deuterium-labelling study indicated that the isomers were formed by different pathways: a π-allyl-Pd route and the classical Heck route. The corresponding secondary amides N-allyl-2-iodo-3-nitrobenzamide and N-((substituted)-cinnamyl)-2-iodo-3-nitrobenzamide gave good yields of the required 4-methyl- and 4-((substituted)-benzyl)-5-nitroisoquinolin-1-ones, respectively, under optimised conditions (Pd(PPh₃)₄, Et₃N, Bu₄NCl, 150 °C, rapid heating). Hydrogenation of the nitro groups gave 4-methyl- and 4-benzyl-5-aminoisoquinolin-1-ones, which were potent inhibitors of PARP-1 activity.     

A study of the interaction between polyvinylpyrrolidone and gemini surfactant G12-3-12 by NMR

The interaction between a water-soluble polymer polyvinylpyrrolidone (PVP) and a gemini surfactant N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-propanediyl-diammonium dibromide (G12-3-12) was investigated by means of NMR in a D₂O solution at 298 K. The critical micelle concentration (СMC), critical aggregation concentration (СAC) and adsorption reached the saturated concentration (C2) were confirmed by chemical shift and self-diffusion coefficients, respectively. The results of the relaxation time ratio (T_R = T₂/T₁) of G12-3-12 show that the motion of the ionic head N⁺–CH₃^* proton (G6) is seriously restricted, and thus, it can be proved that the cationic head groups are situated in the hydrophilic layer of the micelle. The size of the mixed-aggregates in the G12-3-12/PVP solution is larger than pure G12-3-12 micelles according to self-diffusion coefficients, indicating that the G12-3-12 and PVP has formed mixed micelles, and ionic heads N⁺–CH₃^* become more tightly packed in the hydrophilic layer of the micelle shell. On the other hand, strong cross peaks, such as G1-P2, G1-P3, and G2-P3, appear in the 2D nuclear Overhauser enhancement spectroscopy (2D NOESY) spectra of the G12-3-12/PVP system, further indicating that the interaction sites are located between the hydrophobic tail of G12-3-12 and PVP ring.     

Reinvestigating the synthesis of N-arylbenzamidines from benzonitriles and anilines in the presence of AlCl3

The preparation of N-phenylbenzamidine 3a from the reaction between benzonitrile 1a and aniline in the presence of AlCl₃ is reinvestigated with respect to mode of reagent addition, reaction temperature and Lewis acid catalysis. Pre-forming the nitrile-Lewis acid complex prior to the addition of aniline allows for milder reaction conditions, allowing for the higher yielding synthesis of N-phenylbenzamidine 3a (83%). Using these modified conditions several N-(4-substituted phenyl)benzamidines can be prepared including the N-(4-methoxyphenyl)benzamidine 3b (93%) and the previously unobtainable 2-amino-N-(4-methoxyphenyl)benzamidine 3l (56%). All new compounds are fully characterised.     

A new route to (±)-erythro-roccellic acid and chaetomellic anhydride C through functional rearrangement, promoted by n-propylamine or CH3ONa/CH3OH, of N-propyl-3-chloro-4-dichloromethyl-3-dodecylpyrrolidin-2-one

The rearrangement of a trichloro-pyrrolidin-2-one, prepared by the CuCl-TMEDA catalyzed atom transfer radical cyclization of N-alkyl-N-(3-chloro-2-propenyl)-2,2-dichloromyristamide, with n-propylamine or CH₃ONa/CH₃OH, is the key step of a new, short and inexpensive route to chaetomellic anhydride C and (±)-erythro-roccellic acid.     

Preparation and properties of dinitrogen complexes of molybdenum and tungsten with trimethylphosphine as coligand : III. Synthesis and properties of cis-[W(N2)2(PMe3)4], trans-[W(C2H4)2(PMe3)4] and [M(N2)(PMe3)5] (M = Mo,W). The crystal and molecular structure of [Mo(N2)(PMe3)5]

The reduction of [WCl₄(PMe₃)₃] with dispersed sodium, under dinitrogen, gives cis-[W(N₂)₂(PMe₃)₄], while under ethylene trans-[W(C₂H₄)₂(PMe₃)₄] is obtained. The ethylene complex can also be prepared by displacement of the dinitrogen molecules in cis-[W(N₂)₂(PMe₃)₄] by ethylene at room temperature and pressure. Interaction of cis-[M(N₂)₂(PMe₃)₄] complexes (M = Mo, W), with PMe₃, under helium or argon, yields [M(N₂)(PMe₃)₅]. The molybdenum complex crystallizes in the orthorhombic space group Pnma, with a 22.063(6), b 12.106(4), c 9.745(4) Å. The Mo—P distance trans to the dinitrogen ligand (2.483(7) Å) is slightly longer than the average of the other four Mo—P bonds (2.460(5) Å).     

Stereoselective synthesis of cis and trans-fused 3a-aryloctahydroindoles using cyclization of N-vinylic α-(methylthio)acetamides: synthesis of (−)-mesembrane

Treatment of N-(2-arylcyclohex-1-en-1-yl)-α-(methylthio)acetamides with N-chlorosuccinimide (NCS) gave 3a-aryl-2,3,3a,4,5,6-hexahydro-3-(methylthio)indol-2-ones. Desulfurization of the cyclization products followed by a catalytic hydrogenation of the resulting hexahydroindol-2-ones gave predominantly or exclusively trans-fused octahydroindol-2-ones. On the other hand, reduction of the desulfurization products with Et₃SiH in CF₃CO₂H exclusively provided cis-fused octahydroindol-2-ones. A chiral induction of N-[2-(3,4-dimethoxy)phenylcyclohex-1-en-1-yl]-α-(methylthio)acetamide having an (R)-1-(1-naphthyl)ethyl group on the nitrogen atom led to the synthesis of (−)-mesembrane and (−)-trans-mesembrane.     

Infrared chemiluminescence in the reactions of 0.45 eV hydrogen atoms with Cl2, SCl2 and PCl3

Infrared chemiluminescence from HCl has been observed in “arrested relaxation” experiments to yield vibrational and rotational distributions from the reactions $\text{H}$+Cl₂, SCl₂ and PCl₃, where $\text{H}$ denotes hydrogen atoms with translational energy of 0.45 eV. The following relative populations were determined: N_v-1: N_v-2: N_v-3: N_v-4: N_v-5: N_v-6 = 0.89:1.00:0.84:0.47:0.26:0.11 for $\text{H}$+Cl₂: N_v-1: N_v-2: N_v-3: N_v-4: N_v-5: N_v-6 = 0.80:1.00:0.72:0.48:0.24:0.10 for $\text{H}$+SCl₂: N_v-1: N_v-2: N_v-3: N_v-4: N_v-5 = 0.79:1.00:0.88:0.36:0.14 for H+PCl₃. In all three reaction systems the chemiluminescence was attributed to the primary chlorine abstraction. Comparison with the results of the thermal processes (0.04 eV hydrogen atoms) led to the following conclusions: for H+Cl₂ the excess of translational energy is transformed into translational product energy and rotational energy of the molecule HCl; for H+SCl₂ the excess of translational energy is transformed mainly into translational energy of the products and perhaps internal energy of SCl; for H+PCl₃ the excess of translational energy allows the observation of the primary abstraction reaction, which could in earlier experiments at 300 K not be separated from secondary chemiluminescent processes. Bimodal rotational distributions were confirmed for several vibrational states of HCl formed in the systems $\text{H}$+Cl₂, and $\text{H}$+SCl₂. Bimodal rotational distributions were also detected in the chemiluminescent reaction H(0.04 eV)+CH₃SCl → HCl(v ? 5)+CH₃S.     

Photosynthesis-Inhibiting Activity of N-(Disubstituted-phenyl)-3-hydroxynaphthalene-2-carboxamides

A set of twenty-four 3-hydroxynaphthalene-2-carboxanilides, disubstituted on the anilide ring by combinations of methoxy/methyl/fluoro/chloro/bromo and ditrifluoromethyl groups at different positions, was prepared. The compounds were tested for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. N-(3,5-Difluorophenyl)-, N-(3,5-dimethylphenyl)-, N-(2,5-difluorophenyl)- and N-(2,5-dimethylphenyl)-3-hydroxynaphthalene-2-carboxamides showed the highest PET-inhibiting activity (IC₅₀ ~ 10 µM) within the series. These compounds were able to inhibit PET in photosystem II. It has been found that PET-inhibiting activity strongly depends on the position of the individual substituents on the anilide ring and on the lipophilicity of the compounds. The electron-withdrawing properties of the substituents contribute towards the PET activity of these compounds.     

Synthesis of 1H-pyrrolo[3,2-c]quinoline derivatives via palladium-catalyzed heteroannulation of 2-aryl-3-iodo-4-(phenylamino)quinolines and 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinolines

Palladium(0)/copper iodide catalyzed Sonogashira cross-coupling of 2-aryl-3-iodo-4-(phenylamino)quinolines with terminal alkynes afforded series of 1,2,4-trisubstituted 1H-pyrrolo[3,2-c]quinolines in a single-step operation. Conversely, the 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinoline derivatives were found to undergo PdCl₂(PPh₃)₂/CuI catalyzed intramolecular Heck reaction to yield the corresponding 1,3,4-trisubstituted 1H-pyrrolo[3,2-c]quinolines.     

Structure and properties of protonated N-alkyl-2-aza[3]ferrocenophanes

Protonation of N-alkyl-2-aza[3]ferrocenophanes by HCl and NH₄PF₆ affords hexafluorophosphate salts having a trialkylammonium group. Structures of the protonated and unprotonated N-(p-methylbezyl)-2-aza[3]ferrocenophanes were determined by X-ray crystallography. Variable temperature ¹³C{¹H} NMR spectra of the N-protonated N-hexyl-2-aza[3]ferrocenophane revealed inversion of the nitrogen of the 2-aza[3]ferrocenophane on the NMR time scale probably via partial deprotonation of the nitrogen atom. Cyclic voltammograms of the N-protonated compounds exhibited reversible redox peaks at higher potentials than those of the corresponding neutral ferrocenophanes.     

Stereoconvergent synthesis of N-Boc-(2R,3S)-3-hydroxy-2-phenylpiperidine

The stereoconvergent synthesis of N-Boc-(2R,3S)-3-hydroxy-2-phenylpiperidine from (R)-1-(2-((tert-butyldimethylsilyl)oxy)-1-phenylethyl)piperidin-2-one is described. The key steps involved are α-hydroxylation of quiral lactam with O₂, stereoconvergent reduction of (R)- or (S)-3-(benzyloxy)-piperidin-2-one with Red-Al® which afforded in both cases the trans-bicyclic oxazolidine in high stereoselectivity after chromatographic purification and a stereospecific Grignard addition to chiral bicyclic oxazolidine.     

Ring opening of 2-(cyanomethyl)aziridines by acid chlorides: synthesis of novel 4-amino-2-butenenitrile derivatives through intermediate aziridinium salts

1-Arylmethyl-2-(cyanomethyl)aziridines were transformed into novel N-arylmethyl-N-(2-chloro-3-cyanopropyl)amides as the major reaction products upon treatment with acid chlorides in CH₂Cl₂ through the ring opening of intermediate aziridinium salts. Subsequently, N-arylmethyl-N-(2-chloro-3-cyanopropyl)amides were converted into stable N-arylmethyl-N-(3-cyano-2-propenyl)amides for the first time by means of a dehydrochlorination mediated by Et₃N in CH₂Cl₂.     

Synthesis of chiral β-3-amino-2-hydroxyalkanoates and 3-alkyl-3-hydroxy-β-lactams by double asymmetric induction

Reactions of chiral (2S)-enolates of dioxolan-4-ones, derived from lactic, mandelic, and phenyllactic acids, with aliphatic (S_S)- and (S_R)-tert-butylsulfinyl aldimines afforded conformationally restrained C2-disubstituted N,O-orthogonally protected 3-amino-2-hydroxyalkanoates in the form of N-sulfinyl protected 1′-aminodioxolan-4-ones. The product distribution showed that there is significant kinetic selectivity, due to the presence of ‘matched’ and ‘mismatched’ components, between the (S)- or (R)-tert-butylsulfinyl aldimines and the (2S)-enolates of the 1,3-dioxolan-4-ones. Selective methoxide-induced removal of the acetal group of the N-sulfinyl-1′-aminodioxolanones yielded the corresponding N-sulfinyl protected methyl alkanoates. In addition, the selective acid-induced removal of the sulfinyl group of the N-sulfinyl-1′-aminodioxolanones provided the corresponding N-unprotected 1′-aminodioxolanones, whose base-induced cyclization afforded the corresponding β-lactams.     

Preparation and properties of dinitrogen trimethylphosphine complexes of molybdenum and tungsten—II: Synthesis and crystal structures of [MCl(N2)(PMe3)4] (M = Mo,W) and trans-[MoCl2(PMe3)4]

Sodium amalgam reduction of the complexes [MCl₃(PMe₃)₃] (M = Mo, W) in tetrahydrofuran, under dinitrogen, yields dark red-brown suspensions from which red-orange crystals of composition trans-[MCl(N₂)· (PMe₃)₄] can be collected. Spectroscopic and chemical evidence indicate the compounds are best formulated as mixtures of trans-[M(N₂)₂(PMe₃)₄] and trans-[MCl₂(PMe₃)₄] species, but attempts to isolate the pure bis(dinitro derivatives have proved unsuccessful. Single crystals of analytical composition [MCl(N₂)(PMe₃)₄] have been studied by X-ray crystallography, and the structure of trans-[MoCl₂(PMe₃)₄] has been determined for comparison. trans-[MCl(N₂)(PMe₃)₄] (M = Mo, W) and trans-[MoCl₂(PMe₃)₄] are all isostructural, crystallizing in the tetragonal space group I$\text{4}$2 trans-[MoCl(N₂)(PMe₃)₄] has a = 9.597(5), b = 12.294(6) Å, D_c = 1.36g cm^?3 Z = 2 and was refined to a final R value of 0.021 based on 319 independent observed reflections. The tungsten analogue has a = 9.573(4), b = 12.278(5) Å, D_c = 1.63g cm^?3 for Z = 2 and was refined to R = 0.19 with 322 independent observed reflections. trans-[MoCl₂(PMe₃)₄] has cell parameters a = 9.675(5), b = 12.311(6) Å D_c = 1.36 g cm^?3 for Z = 2 and was refined to R = 0.043 with 316 independent observed reflections. In each case the metal atom resides on a crystallographic $\text{4}$2m position. For trans-[MoCl(N₂)(PMe₃)₄] (M = Mo, W) the chlorine and dinitrogen ligands are disordered. M-N distances of 2.08(1) ? (M = Mo) and 2.04(2) ? (M = W) and M-Cl bond lengths of 2.415(8) Å (M = Mo) and 2.46(1) Å (M = W) are observed. In trans-[MoCl₂(PMe₃)₄], where there is no disorder, the Mo-Cl distance is 2.420(6) Å.     

Arylation of adamantanamines: VI. Palladium-catalyzed arylation of amines and diamines of the adamantane series with 3-bromopyridine

Palladium-catalyzed amination of 3-bromopyridine with amines of the adamantane series in the presence of Pd(dba)₂/L [L = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl or 2-dimethylamino-2′-dicyclohexylphosphinobiphenyl] gave the desired N-(pyridin-3-yl)-substituted amines in 74–97% yields. Diamines of the adamantane series reacted with 2 equiv of 3-bromopyridine in a complicated fashion to produce mono- and triaryl-substituted derivatives as by-products, while the yields of N,N′-diarylation products were 18–56%.     

Reactions of 1,1,1-trihalo-3-nitrobut-2-enes with enamines derived from cycloalkanones. Rearrangement of trifluoromethylated 1,2-oxazine N-oxide into 1-pyrroline N-oxides and stereochemistry of the products

1,2-Oxazine N-oxides derived from (E)-1,1,1-trifluoro-3-nitrobut-2-ene and cyclohexanone enamines underwent spontaneous rearrangement with ring contraction to give 1-pyrroline N-oxides. Reactions of (E)-1,1,1-trifluoro(trichloro)-3-nitrobut-2-enes with N-cyclopent-enylmorpholine resulted in a series of novel CX₃-containing nitroalkyl enamines and g-nitro ketones; the stereochemistry of the synthesized compounds were studied by NMR spectroscopy and X-ray diffraction.