(1-Methoxyvinyl)boronic and (1-chlorovinyl)boronic esters

(s)-Pinanediol (1-methoxyvinyl)boronate ( 1 ) was prepared from (1-methoxyvinyl)-lithium and triisopropyl borate followed by (s)-pinanediol. Attempted reaction with (dichloromethyl)lithium failed, and reaction with butylmagnesium chloride followed by acetic acid yielded a mixture of diastereomers of (s)-pinanediol (1-methoxy-1-methyl-pentyl)boronate ( 2 ). (s)-Pinanediol (1-chlorovinyl)boronate ( 4 ) has been prepared by dehydrochlorination of (s)-pinanediol 1,1-dichloroethylboronate ( 3 ) with lithium chloride in dimethylformamide. Reaction of 4 with (dichloromethyl)lithium yielded (s)-pinanediol (1S)-(1,2-dichloroallyl)boronate ( 5 ) in 92% diastereomeric excess. Reaction of 5 with RMgX resulted in a 3 : 1 ratio of displacement of the 1-Cl from carbon by R to displacement of the entire 1,2-dichloroallyl group from boron by R. With lithium benzyl oxide, displacement of the 1-Cl from 5 failed entirely. Reaction of 4 with (dibromomethyl)lithium was inefficient and yielded a gross mixture of diastereomers.     

The 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) states of the SO(2) (+) ion studied using multiconfiguration second-order perturbation theory

The 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) electronic states of the SO(2) (+) ion have been studied using multiconfiguration second-order perturbation theory (CASPT2) and two contracted atomic natural orbital basis sets, S[6s4p3d1f]/O[5s3p2d1f] (ANO-L) and S[4s3p2d]/O[3s2p1d] (ANO-S), and the three states were considered to correspond to the observed X, B, and A states, respectively, in the previous experimental and theoretical studies. Based on the CASPT2/ANO-L adiabatic excitation energy calculations, the X, A, and B states of SO(2) (+) are assigned to 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2), respectively, and our assignments of the A and B states are contrary to the previous assignments (A to (2)A(2) and B to (2)B(2)). The CASPT2/ANO-L energetic calculations also indicate that the 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) states are, respectively, the ground, first excited, and second excited states at the ground-state (1 (2)A(1)) geometry of the ion and at the geometry of the ground-state SO(2) molecule. Based on the CASPT2/ANO-L results for the geometries, we realize that the experimental geometries (determined by assuming the bond lengths to be the same as the neutral ground state of SO(2)) were not accurate. The CASPT2/ANO-S calculations for the potential energy curves as functions of the OSO angle confirm that the 1 (2)B(2) and 1 (2)A(2) states are the results of the Renner-Teller effect in the degenerate (2)Pi(g) state at the linear geometry, and it is clearly shown that the 1 (2)B(2) curve, as the lower component of the Renner splitting, lies below the 1 (2)A(2) curve. The UB3LYP/cc-pVTZ adiabatic excitation energy calculations support the assignments (A to (2)B(2) and B to (2)A(2)) based on the CASPT2/ANO-L calculations.     

Fluorescence excitation spectra of the b (1)Pi(u), b(') (1)Sigma(u) (+), c(n) (1)Pi(u), and c(n) (') (1)Sigma(u) (+) states of N(2) in the 80-100 nm region

Fluorescence excitation spectra produced through photoexcitation of N(2) using synchrotron radiation in the spectral region between 80 and 100 nm have been studied. Two broadband detectors were employed to simultaneously monitor fluorescence in the 115-320 nm and 300-700 nm regions, respectively. The peaks in the vacuum ultraviolet fluorescence excitation spectra are found to correspond to excitation of absorption transitions from the ground electronic state to the b (1)Pi(u), b(') (1)Sigma(u) (+), c(n) (1)Pi(u) (with n=4-8), c(n) (') (1)Sigma(u) (+) (with n=5-9), and c(4) (')(v('))(1)Sigma(u) (+) (with v(')=0-8) states of N(2). The relative fluorescence production cross sections for the observed peaks are determined. No fluorescence has been produced through excitation of the most dominating absorption features of the b-X transition except for the (1,0), (5,0), (6,0), and (7,0) bands, in excellent agreement with recent lifetime measurements and theoretical calculations. Fluorescence peaks, which correlate with the long vibrational progressions of the c(4) (') (1)Sigma(u) (+) (with v(')=0-8) and the b(') (1)Sigma(u) (+) (with v(') up to 19), have been observed. The present results provide important information for further unraveling of complicated and intriguing interactions among the excited electronic states of N(2). Furthermore, solar photon excitation of N(2) leading to the production of c(4) (')(0) may provide useful data required for evaluating and analyzing dayglow models relevant to the interpretation of c(4) (')(0) in the atmospheres of Earth, Jupiter, Saturn, Titan, and Triton.     

High resolution vacuum ultraviolet emission spectrum of D(2) from 78 to 103 nm: The D (1)Pi(u)-->X (1)Sigma(g) (+) and D(') (1)Pi(u) (-)-->X (1)Sigma(g) (+) band systems

The emission spectrum of the D(2) molecule has been studied at high resolution in the vacuum ultraviolet region 78.5-102.7 nm. A detailed analysis of the two D (1)Pi(u)-->X (1)Sigma(g) (+) and D(') (1)Pi(u) (-)-->X (1)Sigma(g) (+) electronic band systems is reported. New and improved values of the level energies of the two upper states have been derived with the help of the program IDEN [V. I. Azarov, Phys. Scr. 44, 528 (1991); 48, 656 (1993)], originally developed for atomic spectral analysis. A detailed comparison is made between the observed energy levels and solutions of coupled equations using the newest ab initio potentials by Wolniewicz and co-workers [J. Chem. Phys. 103, 1792 (1995); 99, 1851 (1993); J. Mol. Spectros. 212, 208 (2002); 220, 45 (2003)] taking into account the nonadiabatic coupling terms for the D (1)Pi(u) state with the lowest electronic states B (1)Sigma(u) (+), C (1)Pi(u), and B(') (1)Sigma(u) (+). A satisfactory agreement has been found for most of the level energies belonging to the D and D(') states. The remaining differences between observation and theory are probably due to nonadiabatic couplings with other higher electronic states which were neglected in the calculations.     

1-Borabenzonitrile (B-cyanoboratabenzene)

The reaction of 1-chloro-2-(trimethylsilyl)-1-boracyclohexa-2,5-diene with [(n)Bu(4)N]C≡N provides the 1-borabenzonitrile salt [(n)Bu(4)N][C(5)H(5)BC≡N] which in turn reacts with [Ru(4)(μ-Cl)(4)(η-C(5)Me(5))(4)] to afford the sandwich complex [Ru(η(6)-C(5)H(5)BC≡N)(η-C(5)Me(5))]. The bonding of 1-borabenzonitrile is discussed with recourse to crystallographic data for [(n)Bu(4)N][C(5)H(5)BC≡N] and [Ru(η(6)-C(5)H(5)BC≡N)(η-C(5)Me(5))].     

Synthesis of (pentacarbonyl)tungstate(−1) and (pentacarbonyl)molybdate(−1) dinucleotides

New methods for preparation of metallo dinucleotides with transition metals directly bonded to phosphorus are presented. (Pentacarbonyl)tungstate(−1) and (pentacarbonyl)molybdate(−1) dimers are prepared by the reaction of dinucleotide-H-phosphonate with M(CO)₅(THF) (M = W, Mo). These syntheses can be completed in solution or on solid-phase.     

Interaction between chicken protein tyrosine phosphatase 1 (CPTP1)-like rat protein phosphatase 1 (PTP1) and p60(v-src) in v-src-transformed Rat-1 fibroblasts

CPTP1 is a nontransmembrane chicken protein tyrosine phosphatase having 92% sequence homology to the corresponding 321 amino acids of human protein tyrosine phosphatase 1B (HPTP1B). Using anti-CPTP1 antibody, we identified CPTP1-like rat PTP1 of 51 kDa in Rat-1 and v-src-transformed Rat-1 fibroblasts. Here we show that CPTP1-like rat PTP1 binds to p60(v-src) in vivo and CPTP1 also can associate with p60(v-src) in cell lysate of v-src- transformed Rat-1 fibroblasts. Interaction between HPTP1B-type PTPs, CPTP1-like rat PTP1 and CPTP1, and p60(v-src) was reduced by vanadate treatment for 13 h due to down regulation of the protein level of p60(v-src) in vivo. Interestingly, CPTP1-like rat PTP1 was coimmunoprecipitated with a 70-kDa protein which has a possibility to be tyrosine- phosphorylated by p60(v-src) in v-src-transformed Rat-1 fibroblasts. These results suggest that HPTP1B-type PTPs may play an important role in p60(src) dependent signal pathway in eucaryotic cells.     

Sensitivity of (1)J[C(1)-H(1)] magnitudes to anomeric stereochemistry in 2,3-anhydro-O-furanosides.

The magnitude of the one-bond coupling constant between C(1) and H(1) in 2,3-anhydro-O-furanosides has been shown to be sensitive to the stereochemistry at the anomeric center. A panel of 24 compounds was studied and in cases where the anomeric hydrogen is trans to the epoxide moiety, (1)J[C(1)-H(1)] = 163-168 Hz; and when this hydrogen is cis to the oxirane ring, ((1)J[C(1)-H(1)] = 171-174 Hz. In contrast, for 2,3-anhydro-S-glycosides, the size of the (1)J[C(1)-H(1)] is not sensitive to C(1) stereochemistry. Computational studies on all four methyl 2,3-anhydro-O-furanosides (5-8) demonstrated that (1)J[C(1)-H(1)] was inversely proportional to the length of the C(1)-H(1) bond. A previously reported equation, which relates C(1)-H(1) bond distance and atomic charges to (1)J[C(1)-H(1)] magnitudes, could be used to accurately predict the J values in the alpha-lyxo (5) and beta-ribo (8) isomers. In contrast, with the beta-lyxo (6) and alpha-ribo isomers (7), this equation underestimated the size of these coupling constants by 10-20 Hz.     

13C-labeled platinum(IV)-carbohydrate complexes: structure determination based on (1)H-(1)H, (13)C-(1)H, and (13)C-(13)C spin-spin coupling constants

The reaction of D-mannose and D-allose with [PtMe(3)(Me(2)CO)(3)]BF(4) 1 in acetone affords complexes [PtMe(3)L]BF(4) 5 and 6 (5, L = alpha-D-mannofuranose; 6, L = beta-D-allofuranose). The coordination mode and conformation of the carbohydrate ligands in 5 and 6 in acetone-d(6) have been determined from an analysis of J(HH), J(CH), and J(CC) in complexes formed using site-specific (13)C-labeled D-mannose and D-allose. These coupling data are compared to those measured in (13)C-labeled complex [PtMe(3)L]BF(4) 2 (L = 1, 2-O-isopropylidene-alpha-D-glucofuranose) and 1, 2-O-isopropylidene-alpha-D-glucofuranose 3, whose solid-state structures are known, and in (13)C-labeled 1,2;5, 6-di-O-isopropylidene-alpha-D-glucofuranose 4. The preferred furanose ring conformations in 2 and 5 are very similar ((3)E/E(4) and E(4)/(o)E/E(1), respectively; eastern hemisphere of the pseudorotational itinerary), with platinum coordination involving O3, O5, and O6 of the saccharide. In contrast, the furanose ring of 6 prefers an (4)E/E(o)/(1)E geometry (western hemisphere of the pseudorotational itinerary) resulting from altered complexation involving O1, O5, and O6. Couplings within the exocyclic fragments of 2, 5, and 6 also support the existence of two different platinum coordination modes. In addition to establishing the structures and conformations of 2, 5, and 6 in solution, one-, two-, and three-bond J(CH) and J(CC) observed in these complexes provide new insights into the effect of structure and conformation on the magnitudes of these couplings in saccharides. Weak platinum(IV) complexation with the carbohydrate conformationally restricts the furanose and exocyclic fragment without introducing undesirable structural strain, thereby allowing more reliable correlations between structure and coupling magnitude.     

Low-temperature magnetic behavior of perovskite compounds PbFe(1/2)Ta(1/2)O3 and PbFe(1/2)Nb(1/2)O3

The isostructural perovskite compounds PbFe(1/2)Ta(1/2)O3 and PbFe(1/2)Nb(1/2)O3 have been known for long time, and they are part of the important class of materials called multiferroic, where ferroelasticity, ferroelectricity, and ferromagnetism coexist. In the literature regarding PbFe(1/2)Ta(1/2)O3 and PbFe(1/2)Nb(1/2)O3, an "anomaly" of their low-temperature magnetic behavior has not always been reported. Moreover, both the origin of this behavior, and the cause for which it was not always observed, were never completely explained. In this paper, the magnetic behavior of the two compounds at low temperature has been extensively studied and explained as the occurring of a spin-glasslike transition.     

DBU-promoted cyclization of ortho-(3-hydroxy-1-alkynyl)benzamide: synthesis of trans-3,4-dihydroisoquinolin-1(2H)-ones and (E)-4-(1-alkenyl)isoquinolin-1(2H)-ones

DBU-promoted cyclization of ortho-(3-hydroxy-1-alkynyl)benzamide is presented, providing an efficient method for the synthesis of trans-3,4-dihydroisoquinolin-1(2H)-ones and (E)-4-(1-alkenyl)isoquinolin-1(2H)-ones under mild conditions.     

Inner-valence photoionization of O((1)D): experimental evidence for the 2s(2)2p(4)((1)D)-->2s(1)2p(5)((1)P) transition

Photoionization and autoionization of electronically excited atomic oxygen O((1)D) are investigated in the energy range between 12 and 26 eV using tunable laser-produced plasma radiation in combination with time-of-flight mass spectrometry. A broad, asymmetric, and intense feature is observed that is peaking at 20.53+/-0.05 eV. It is assigned to the 2s(2)2p(4)((1)D)-->2s(1)2p(5)((1)P) transition, which subsequently autoionizes by a Coster-Kronig transition, as predicted by the previous theoretical work [K. L. Bell et al., J. Phys. B 22, 3197 (1989)]. Specifically, the energy of the unperturbed transition occurs at 20.35+/-0.07 eV. Its shape is described by a Fano profile revealing a q parameter of 4.25+/-0.8 and a width of gamma=2.2+/-0.15 eV. Absolute photoionization cross section sigma is derived, yielding sigma=22.5+/-2.3 Mb at the maximum of the resonance. In addition, weak contributions to the O((1)D) yield from dissociative ionization originating from molecular singlet oxygen [O(2)((1)Delta(g))] are identified as well. Possible applications of the 2s(2)2p(4)((1)D)-->2s(1)2p(5)((1)P) transition as a state-selective and sensitive probe of excited oxygen in combination with photoionization mass spectrometry are briefly discussed.     

The photodissociation reaction dynamics of CF(3)I at 304 nm ((3)Q(0+), (1)Q(1)<--(3)Q(0+), and (3)Q(1))

The photodissociation of CF(3)I at 304 nm has been studied using long time-delayed core-sampling photofragment translational spectroscopy. Due to its capability of detecting the kinetic energy distribution of iodine fragments with high resolution, it is able to directly assign the vibrational state distribution of CF(3) fragments. The vibrational state distributions of CF(3) fragments in the I(*)((2)P(12)) channel, i.e., (3)Q(0+) state, have a propensity of the nu(2) (') umbrella mode with a maximum distribution at the vibrational ground state. For the I((2)P(32)) channel, i.e., (1)Q(1)<--(3)Q(0+), the excitation of the nu(2) (') umbrella mode accounts for the majority of the vibrational excitation of the CF(3) fragments. The 1 nu(1) (') (symmetric CF stretch) +nnu(2) (') combination modes, which are associated with the major progression of the nu(2) (') umbrella mode, are observed for the photodissociation of CF(3)I at the I channel, i.e., (3)Q(1) state. The bond dissociation energy of the CI bond of CF(3)I is determined to be D(0)(CF(3)-I)相似文献   

含1,2-双(3,5-二氧哌嗪-1)乙烷和(±)-1,2-双(3,5-二氧哌嗪-1)丙烷低聚物的合成

<正> 将低分子药物或有药理活性的基团,通过高分子化,所得的高分子药物,具有较高的为细胞吞噬或胞饮等活性,并期望它们在体内崩解缓释,与相应的低分子药物相比,可以发挥长效、低毒的优点。 1,2双-(3,5-二氧哌嗪-1)乙烷和(±)1,2双(3,5-二氧哌嗪-1)丙烷,是临床使用     

1-(1-Adamantyl)diaziridine

The reaction of 1-aminoadamantane with CH₂O and H₂NOSO₃H in the presence of K₂CO₃ under phase-transfer conditions leads to hitherto unknown 1-(1-adamantyl)diaziridine and (1-adamantyl)aminoacetonitrile, characterized by spectral data. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 861–862, April, 1997.     

Crystallographic characterization of three cathinone hydrochlorides new on the NPS market: 1-(4-methylphenyl)-2-(pyrrolidin-1-yl)hexan-1-one (4-MPHP), 4-methyl-1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PiHP) and 2-(methylamino)-1-(4-methylphenyl)pentan-1-one (4-MPD)

Cathinones belong to a group of compounds of great interest in the new psychoactive substances (NPS) market. Constant changes to the chemical structure made by the producers of these compounds require a quick reaction from analytical laboratories in ascertaining their characteristics. In this article, three cathinone derivatives were characterized by X-ray crystallography. The investigated compounds were confirmed as: 1-[1-(4-methylphenyl)-1-oxohexan-2-yl]pyrrolidin-1-ium chloride ( 1 , C₁₇H₂₆NO⁺·Cl^?, the hydrochloride of 4-MPHP), 1-(4-methyl-1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride ( 2 ; C₁₆H₂₄NO⁺·Cl^?, the hydrochloride of α-PiHP) and methyl[1-(4-methylphenyl)-1-oxopentan-2-yl]azanium chloride ( 3 ; C₁₃H₂₀NO⁺·Cl^?, the hydrochloride of 4-MPD). All the salts crystallize in a monoclinic space group: 1 and 2 in P2₁/c, and 3 in P2₁/n. To the best of our knowledge, this study provides the first detailed and comprehensive crystallographic data on salts 1 – 3 .     

Facile syntheses of 1-deoxynojirimycin (DNJ) and 1-deoxymannojirimycin (DMJ)

1-Deoxynojirimycin (DNJ) and 1-deoxymannojirimycin (DMJ) were synthesized through a concise and practicable pathway. A strategy of using carbohydrate derivatives bearing two leaving groups in the preparation of azasugars by di-N-alkylation of amines was developed. The strategy involved the selective partial protection of dibromo alditols.     

Order parameters based on (13)C(1)H, (13)C(1)H(2) and (13)C(1)H(3) heteronuclear dipolar powder patterns: a comparison of MAS-based solid-state NMR sequences

Order parameters describing conformational exchange processes on the nanosecond to microsecond timescale can be obtained from powder patterns in solid-state NMR (SSNMR) experiments. Extensions of these experiments to magic-angle spinning (MAS) based high-resolution experiments have been demonstrated, which show a great promise for site-specific probes of biopolymers. In this study, we present a detailed comparison of two pulse sequences, transverse Manfield-Rhim-Elleman-Vaughn (T-MREV) and Lee-Goldburg cross-polarization (LGCP), using experimental and simulation tools to explore their utility in the study of order parameters. We discuss systematic errors due to passively coupled (13)C or (1)H nuclei, as well as due to B(1) inhomogeneity. Both pulse sequences can provide quantitative measurements of the order parameter, but the LGCP experiment is capable of greater accuracy provided that the B(1) field is highly homogeneous. The T-MREV experiment is far better compensated for B(1) inhomogeneity, and it also performs better in situations with limited signal.     

Steroid derivatives of purine-6(1H)-thione (1a-c)

The products obtained as a result of the alkylation of purine-6(1H)-thione, and 6-alkylthiopurines with steroidal-21-(p-bromobenzenesullonates) (H) and 3-methoxy-16α-bromoestra-1,3,5 (10)-tricne-17-one (IV) is reported. The ratio of 9-alkylated to 7-alkylated purine in the alkylation of 6-methylthiopurine (VI) is presented. The use of the S-diphenylmethylprotecling group in the syntheses of sensitive 9-steroidal-9H-purine-6(1H)-thiones is discussed.     

A crossed molecular beam study on the formation of hexenediynyl radicals (H(2)CCCCCCH; C(6)H(3) (X(2)A')) via reactions of tricarbon molecules, C(3)(X(1)Sigma(g)(+)), with allene (H(2)CCCH(2); X(1)A(1)) and methylacetylene (CH(3)CCH; X(1)A(1))

Crossed molecular beams experiments have been utilized to investigate the reaction dynamics between two closed shell species, i.e. the reactions of tricarbon molecules, C(3)(X(1)Sigma(g)(+)), with allene (H(2)CCCH(2); X(1)A(1)), and with methylacetylene (CH(3)CCH; X(1)A(1)). Our investigations indicated that both these reactions featured characteristic threshold energies of 40-50 kJ mol(-1). The reaction dynamics are indirect and suggested the reactions proceeded via an initial addition of the tricarbon molecule to the unsaturated hydrocarbon molecules forming initially cyclic reaction intermediates of the generic formula C(6)H(4). The cyclic intermediates isomerize to yield eventually the acyclic isomers CH(3)CCCCCH (methylacetylene reaction) and H(2)CCCCCCH(2) (allene reaction). Both structures decompose via atomic hydrogen elimination to form the 1-hexene-3,4-diynyl-2 radical (C(6)H(3); H(2)CCCCCCH). Future flame studies utilizing the Advanced Light Source should therefore investigate the existence of 1-hexene-3,4-diynyl-2 radicals in high temperature methylacetylene and allene flames. Since the corresponding C(3)H(3), C(4)H(3), and C(5)H(3) radicals have been identified via their ionization potentials in combustion flames, the existence of the C(6)H(3) isomer 1-hexene-3,4-diynyl-2 can be predicted as well.