Stereodynamics of N-isopropyl-N-methylpropargylamine. Dynamic NMR studies. Molecular mechanics calculations.

N-Isopropyl-N-methylpropargylamine (N-isopropyl-N-methyl-2-propyn-1-amine; IMPA) is chiral at the pyramidal nitrogen. Racemization occurs via an inversion-rotation process. Both 13C(1H) and 1H dynamic NMR (DNMR) spectra decoalesce in response to slowing inversion-rotation (delta G++ = 7.7 +/- 0.1 kcal/mol). While aspects of the DNMR spectra suggest the presence of minor conformations, the spectrum at 100 K shows a strong preference for one conformation. The NMR data suggest that the preferred conformation has both the isopropyl methine proton and the ethynyl group anti to the lone pair. Both isopropyl methyl groups are gauche to the lone pair. This conformational preference is in significant contrast to N-ethyl-N-methyl-2-aminopropane in which the population of that conformation having the ethyl methyl group and the isopropyl methine proton both anti to the lone pair is only 5% at 95 K. The NMR data, supported by molecular mechanics (MMX) calculations, suggest a special stabilization for the ethynyl group being oriented anti to the lone pair.     

On the Structures,Lifetimes, and Infrared Spectra of Alkylmercury Hydrides

A series of six small alkylmercury hydrides of the general formula RHgH with R=methyl, ethyl, n‐propyl, isopropyl, n‐butyl, and 3‐butenyl were obtained by reduction in vacuo of the corresponding mercury halide with tributyltin hydride in the presence of a radical inhibitor. These very reactive compounds, which have to be removed from the reaction mixture as they are formed, were characterized by ¹H NMR and ¹³C NMR spectroscopy. The IR spectra of n‐propyl‐, isopropyl‐, n‐butyl‐, and 3‐butenylmercury hydride were recorded for the first time. All compounds were then studied by density functional theory calculations on the basis of a recent theoretical assessment for alkylmercury compounds performed by our group. Comparison of the experimental and theoretical results allowed the assignment of the vibrational modes in an unambiguous way, in spite of the low intrinsic stability of some of the derivatives investigated. The experimental procedure implemented for registering the IR spectra of these unstable species in the gas phase allowed us to obtain reasonable estimates of their lifetimes.     

PHOSPHORUS-NITROGEN COMPOUNDS. PART 52.1 THE SYNTHESIS OF SOME 1,3,2-BENZODIAZAPHOSPHORINE 2-OXIDES AND 2-SULPHIDES

Abstract

The reactions of 4-methyl-2-[N-(p-toluidinyl)methyl]aniline with phosphorus oxychloride, thiophosphoryl chloride, and their derivatives yield 1,3,2-benzodiazaphosphorine 2-oxides and 2-sulphides. Their ¹H NMR and infrared spectra are discussed. Related 1,3,2-benzodiazophosphorine and 1,3,2-dibenzodiazaphosphocine 2-oxides and 2-sulphides are compared.     

Conformational analysis of N-isopropylbenzohydroxamic acids: crystal structure, DFT, and NMR studies

X-ray crystal structure determinations together with density functional theory (DFT) calculations in vacuo and NMR studies in solution have been carried out for 4-MeOC₆H₄CONPrⁱOH 2a and 3,5-(NO₂)₂C₆H₃CONPrⁱOH 2b. The results were compared with that for the respective N-methyl benzohydroxamic acids. For crystal structures as well as for DFT-optimized geometries of 2 (both isomers) in vacuo, the effect of substituents in aromatic ring manifested by changing of charges is inconspicuous. Studies of potential energy surfaces showed that libration barrier around ω ₁ = 0° is low enough to make electron conjugation feasible, and that for 2b rotation barrier around C(O)N bond is higher by 6 kcal/mol and additionally, that rotation around N–C bond is hindered. A careful analysis of low-temperature ¹H NMR spectra confirmed the greater stability of Z-2a, the greater rigidity of E-2b and the influence of solvent on both isomers population. Despite solvent-dependent conformational alteration, both 2a and 2b crystallize exclusively as E isomers from ethyl acetate solution. Correlations of absolute ¹H, ¹³C, and ¹⁵N shielding calculations with experimental data were also analyzed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Trans influences of Cl−, NCO− and NCS− donors on planar NiS2PN(CO), NiS2PN(CS), NiS2PCl and NiS2P2 chromophores: synthesis,NMR spectral and single crystal X-ray structural studies

Planar [Ni(bedtc)(PPh₃)Cl] (1), [Ni(bedtc)(PPh₃)(NCO)] (2), [Ni(bedtc)(PPh₃)(NCS)] (3), [Ni(bedtc)(PPh₃)(CN)] (4) and [Ni(bedtc)(dppe)]ClO₄ (5) (where bedtc = N-benzyl-N-(2-hydroxyethyl)dithiocarbamate anion, PPh₃ = triphenylphosphine and dppe = 1,2-bis((diphenylphosphino)ethane)) were prepared from [Ni(bedtc)₂]. Complexes 1–5 were characterized by elemental analysis, electronic, IR and NMR (¹H, ¹³C, and ³¹P) spectra. Electronic spectra of the complexes show bands corresponding to dz ² → dxy/dx ² ? y ² transitions. The complexes were diamagnetic. IR and ¹³C NMR studies indicate the mesomeric flow of π-electron density from the dithiocarbamate towards the nickel. In ¹H NMR, α-CH₂–and β-CH₂–protons of–CH₂–CH₂–OH were equally deshielded. The deshielding for the coordinated phosphorus signals in ³¹P NMR spectra for all the cases compared with the free phosphine clearly manifests the drift of electron density from the phosphorus toward the metal on complexation. Single crystal X-ray structures of 1–3 indicate that nickel is in a planar environment with short >S₂C–N bond distances. In 2, a rare mode of coordination between nickel and cyanate (NCO^?) through the nitrogen is observed. Significant asymmetry in Ni–S bond distances were observed for 1–3 clearly supporting the trans influences of Cl^?, NCO^? and NCS^?, respectively, over PPh₃.     

1-(2,6-二氯-4-三氟甲基苯基)-3-氰基-5-氨基吡唑及其酰胺、二酰亚胺的合成及晶体结构

2,6-二氯-4-三氟甲基苯胺经重氮化后与2,3-二氰基丙酸酯反应合成了1-(2,6-二氯-4-三氟甲基苯基)-3-氰基-5-氨基吡唑(1), 1与乙酸酐、顺丁烯二酸酐、苯甲酰氯反应得到1的乙酰胺2a、顺丁烯酰亚胺2b和苯甲酰胺2c. 通过元素分析、红外光谱、核磁共振氢谱、核磁共振碳谱、质谱等手段对其结构进行了表征. 用X射线单晶衍射测定了化合物2a, 2b和2c的晶体结构. 2a属于单斜晶系, C2/c空间群, 晶胞参数a＝1.88282(6) nm, b＝0.86541(3) nm, c＝1.90766(6) nm, β＝95.5830(10)°, V＝3.09362 nm³, Z＝8, R＝0.064, wR＝0.170. 2b属于单斜晶系, P2₁/n空间群, 晶胞参数 a＝1.28261(10) nm, b＝0.89942(7) nm, c＝1.46896(12) nm, β＝104.217(1)°, V＝1.6427(2) nm³, Z＝4, R＝0.055, wR＝0.165. 2c属于三斜晶系, P-1空间群, 晶胞参数a＝0.84613(11) nm, b＝0.98923(13) nm, c＝1.14305(15) nm, β＝96.002(2)°, V＝0.9326 nm³, Z＝2, R＝0.0684, wR＝0.1795.     

2-(对羟基苯氧基)乙基取代的Cyclen的合成和结构研究

在酸性条件下(pH＝2～3), 1,4,7,10-四氮杂环十二烷(Cyclen)和氯甲酸苄酯反应, 得到高选择性1,7-二保护Cyclen衍生物1,7-二(苄氧基羰基)-1,4,7,10-四氮杂环十二烷(4), 然后在二异丙基乙胺作用下和化合物1-苄氧基-4-(2-溴乙氧基)苯(2)一锅法有效合成了中间体1,7-二(2-对苄氧基苯氧基)乙基-4,10-二(苄氧基羰基)-1,4,7,10-四氮杂环十二烷(5)和4-(2-对苄氧基苯氧基)乙基-1,7-二(苄氧基羰基)-1,4,7,10-四氮杂环十二烷(6), 在乙醇溶液中经Pd/C催化氢解得到两种新型的用取代苯酚基修饰的Cyclen衍生物1,7-二(2-对羟基苯氧基)乙基-1,4,7,10-四氮杂环十二烷(7)和1-(2-对羟基苯氧基)乙基-1,4,7,10-四氮杂环十二烷(8), 其结构经¹H NMR, IR和MS确证. 用单晶X射线衍射法测定了化合物7的晶体结构, 晶体属单斜晶系, C2/c空间群, 晶胞参数a＝2.4145(6) nm, b＝1.6012(4) nm, c＝1.6632(4) nm, α＝γ＝90°, β＝120.360(3)°, V＝5.5486(6) nm³, Z＝8, D_c＝1.146 g/cm³, F(000)＝2056, μ＝0.082 mm^－1, R＝0.0853, wR＝0.2331 [I＞2σ(I)].     

Meso- und Rac-Decaisopropylstannocen: Stereoisomerie bedingt durch parallele Anordnung zweier Pentaisopropylcyclopentadienyl-Liganden in Schaufelrad-Konformation

Meso- and Rac-Decaisopropylstannocene: Stereoisomerism Caused by Parallel Arrangement of Two Pentaisopropylcyclopentadienyl Ligands in Paddlewheel Conformation Decaisopropylstannocene 1 is the first Decaisopropylmetallocene, where X-ray diffraction data could be successfully refined and the third example of a group 14 Metallocene with a symmetric sandwich structure. Due to the directionality of the isopropyl substituents 1 occurs as a mixture of diastereomers in the crystalline state as well as in solution. The stereoisomers exhibit the expected signals in solution (¹H and ¹³C NMR) and in the crystal (CPMAS ¹¹⁹Sn NMR).     

13C n.m.r. spectra of rotameric dimethyl 1-isopropyldibenzo[b,e]bicyclo[2.2.2]octatriene-7,8-dicarboxylate: Non-equivalency of carbons along the rotational axis

¹³C n.m.r. spectra of dimethyl 1-isopropyldibenzo[b,e]bicyclo[2.2.2]octatriene-7,8-dicarboxylate disclose the existence of both dl and meso isomers, whereas ¹H n.m.r. spectra were interpreted by the sole existence of the former. Characteristic chemical shifts for the rotamers were found, among others, for carbons along the rotational axis. The non-equivalence is most probably attributed to the difference in geometry about the carbons in question. An unusual fact was also that the more compressed methyl carbon of the isopropyl group gives a signal at higher field.     

Aldisin及其衍生物的合成和α-葡萄糖苷酶抑制活性研究

以三氯氧磷为环化试剂, 回流状态下, N-(2-吡咯甲酰基)-β-丙氨酸经分子内酰化环化反应, 合成了吡咯[2,3-c]氮杂二酮稠环化合物Aldisin及其衍生物1-Methylaldisin和3-Bromoaldisin, 通过¹H NMR, ¹³C NMR, IR, FABMS和元素分析对其结构进行了表征. 以X射线衍射法研究了3-Methylaldisin的晶体结构. 测定了三个化合物对α-葡萄糖苷酶的抑制作用.     

Reactions of Cyanothioacetamide: Synthesis of Several New Thioxohydro-pyridine-3-carbonitrile and Thieno[2,3-b]pyridine Derivatives

Cyanothioacetamide (f 1) reacted with α,β -unsaturated carbonyl compounds 2a–d to afford thioxohydropyridine-3-carbonitriles 5a–d, which were used as the starting materials for the preparation of several thienopyridines via their reactions with active halogen-containing compounds, e.g., 2-bromo-1-phenylethanone (7a), 2-bromo-1-p-tolyl-ethanone (7b), chloroacetone (10a), α -chloroacetylacetone (10b), and chloroacetic acid ethyl ester (13). The structure of the newly synthesized heterocyclic compounds were established based on the data of elemental analyses, IR, ¹ H NMR, and mass spectra.     

The synthesis of novel 4-(3,4-dimethoxyphenyl)chromenone-crown ethers and their cation binding,as determined using fluorescence spectra

o-Dihydroxy-4-(3,4-dimethoxyphenyl)-chromenones (coumarins; 3a,b) were synthesised from 1,2,3-trihydroxy- or 1,2,4-triacetoxybenzenes through a reaction with ethyl 3-(3,4-dimethoxyphenyl)-3-oxopropanoate in H₂SO₄ or CF₃COOH. The chromenone-crown ethers (4a–f) were prepared from the cyclic condensation of o-dihydroxy-4-(3,4-dimethoxyphenyl)chromenones (3a,b) with poly(ethylene glycol) ditosylates, in the presence of CH₃CN/alkali carbonates. The chromatographically purified original chromenone-crown ethers were identified by ¹H NMR, ¹³C NMR, MALDI-TOF mass spectrometry and elemental analysis. The 1:1 binding constants of Li⁺, Na⁺ and K⁺ with the chromenone-crown ethers were estimated in acetonitrile using fluorescence emission spectroscopy. The complexing-enhanced fluorescence spectra and complexing-enhanced quenching fluorescence spectra, along with the cationic recognition rules of the crown ethers allowed the ion binding powers to be determined.     

Anisochrony of isopropyl methyl groups in 1-isopropyl-substituted tetralins and indans

1-Isopropyl-5-methylindan, 1-isopropyl-7-methylindan and 1-isopropyl-1,2,3,4-tetrahydronaphthalene show a large anisochrony (magnctic non-equivalence) of the isopropyl methyl signals at room temperature in their ¹H NMR spectra. A decrease in magnitude of this anisochrony is observed, in each case, in the temperature range 30-150 °C. However, for 1-isopropyl-8-methyltetralin, the magnitude of the non-equivalence of the isopropyl methyl signals is unexpectedly small. These latter signals converge at 85 °C and then diverge in the opposite direction over the range 85-150 °C. This alteration in anisochrony with temperature change for all cases is observed as a continuous downfield migration of one signal which, in turn, results from variations in conformation populations.     

Synthesis and Characterization of Alkyl and Aryl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amines: X‐Ray Structures of Ethyl and Cyclohexyl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amine

Abstract

We have synthesized and characterized a series of alkyl and aryl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amines through a high‐yield, three‐step procedure starting from 4‐methylquinolin‐2‐ol. Nitration using concentrated nitric/sulfuric acids, followed by chlorination in phosphorus oxychloride, yielded 2‐chloro‐4‐methyl‐6‐nitro‐quinoline. All of the intermediates and aminated products have been characterized by multinuclear (¹H and ¹³C) NMR spectroscopy, elemental analysis, and, in the case of the two title compounds (ethyl and cyclohexyl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amine), a single crystal X‐ray structure was obtained to verify the nature of the new materials.     

α-氨基膦酸酯衍生物的合成及其表征

合成了一系列N端含有均三唑并噻二唑的α-氨基膦酸酯衍生物, 其结构经过红外、核磁共振氢谱、磷谱、质谱和高分辨质谱等确证.     

Novel Copolymers of Vinyl Acetate and Alkyl Ring‐Substituted 2‐Phenyl‐1,1‐dicyanoethylenes

Electrophilic trisubstituted ethylene monomers, alkyl ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC₆H₄CH?C(CN)₂ (where R is 2‐methyl, 3‐methyl,4‐methyl, 4‐ethyl, 4‐isopropyl, 4‐butyl, and 4‐t‐butyl), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C‐NMR, GPC, DSC, and TGA. High T_g of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–700°C range.     

1,3-双[3-芳基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑-6-基]丙烷类化合物的合成

戊二酸(1)与3-芳基-4-氨基-5-巯基-1,2,4-三唑(2a～2o)在相转移催化剂四丁基碘化铵和POCl₃作用下, 高收率合成了一系列新的1,2-双[3-芳基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑-6-基]丙烷(3a～3o). 其结构经IR, ¹H NMR, MS和元素分析确证.     

Solution and X-Ray Crystal Structures of the Di- and Tetra-allyl Ether of tert- utylcalix[4]arene

The di- and tetra-allyl ethers of tert-butylcalix[4]arene 1 and 2 have been prepared by alkylation of tert-butylcalix[4]arene with allyl bromide and K₂CO₃ using different reaction times. Solution ¹H NMR measurement of the di-allyl ether 1 and X-ray crystal structures of the complexes of 1 with chloroform (1a) or methanol (1b) indicate the cone conformation of 1 in which intramolecular hydrogen bonding can be maximized. The crystalline state conformers 1a and 1b are distorted in different grades depending on the solvent. While methanol is incorporated in the macrocycle, chloroform molecules do not occupy the cage. The solution ¹H NMR spectra of tetra-allyl ether 2 show the co-existence of the cone and partial cone conformation. The partial cone conformer of 2 was investigated by X-ray crystallography. In this compound hydrogen bonding is not existent. The conformer distribution is likely affected by steric and template effects.     

Chemical shift non-equivalence of the isopropyl methyl groups of two 10-isopropoxyergoline-8β-methanol derivatives

The chemical shift non-equivalence values (about 1 ppm) of the isopropyl methyl groups in the ¹H and ¹³C NMR spectra of the compounds having structure 1 is interpreted as due to the existence of a highly preferred conformation.     

1-(2,6-二氯-4-三氟甲基苯基)-3-氰基-5-氨基吡唑及其磺酰胺的合成及晶体结构

2,6-二氯-4-三氟甲基苯胺经重氮化后与2,3-二氰基丙酸酯反应合成了1-(2,6-二氯-4-三氟甲基苯基)-3-氰基-5-氨基吡唑(1), 1与苯磺酰氯、对甲基苯磺酰氯、甲基磺酰氯反应, 得到1的苯磺酰胺2a、对甲基苯磺酰胺2b和双甲基磺酰胺2c. 通过元素分析、红外光谱、核磁共振氢谱、核磁共振碳谱、质谱等手段对其结构进行了表征. 用X射线单晶衍射测定了化合物1, 2a和2c的晶体结构. 1属于正交斜方晶系, Pbca空间群, 晶胞参数 a＝1.61739(7) nm, b＝1.62480(7) nm, c＝3.10857(13) nm, ＝＝＝90, V＝8.1691 nm³, Z＝24, R＝0.1089, wR＝0.2545. 2a属于单斜晶系, C2/c空间群, 晶胞参数 a＝3.35144(18) nm, b＝0.97948(5) nm, c＝2.44717(12) nm, β＝102.460(1), V＝7.8440(7) nm³, Z＝8, R＝0.1831, wR＝0.2600. 2c属于三斜晶系, P-1空间群, 晶胞参数 a＝0.84681(7) nm, b＝0.89652(83) nm, c＝1.43497(12) nm, α＝75.198(2), β＝87.918(1), γ＝65.395(1), V＝0.9546 nm³, Z＝2, R＝0.049, wR＝0.135.