Stereoselective Synthesis of 1,5-Diionic Organophosphorus Compounds

The reactive 1:1 intermediate produced in the reaction between triphenylphosphine and alkyl propiolates or ethynyl phenyl ketone was trapped by isopropylidene Meldrum's acid (5-isopropylidene-2,2-dimethyl-1,3-dioxane-4,6-dione) to produce alkyl 3-(isopropylidenemalonate-5-yl-5-ylid)-3-methyl-2-triphenylphosphoniomethylidene-butanoates or 3-(isopropylidenemalonate-5-yl-5-ylid)-3-methyl-2-triphenylphosphoniomethylidene-butanone in 75-86% yield. These 1,5-diionic phosphorus betaines exist as (Z) geometrical isomer in CDCl 3 solution.     

Determination of betaines in vegetable oils by capillary electrophoresis tandem mass spectrometry--application to the detection of olive oil adulteration with seed oils

A CE–tandem mass spectrometry (MS²) methodology enabling the simultaneous determination of betaines (glycine betaine, trigonelline, proline betaine and total content of carnitines) in vegetable oils was developed. Betaines were derivatized with butanol previous to their baseline separation in 10 min using a 0.1 M formic acid buffer at pH 2.0. Ion trap conditions were optimized in order to maximize the selectivity and sensitivity. Analytical characteristics of the proposed method were established by evaluating its selectivity, linearity, precision (RSDs ranged from 4.8 to 10.7% for corrected peak areas) and accuracy by means of recovery studies (from 80 to 99%) and LODs and LOQs at 0.1 ppb level. The method was applied for the determination of the selected betaines in seed oils and extra virgin olive oils. MS² experiments provided the fingerprint fragmentation for the betaines identified in vegetable oils. In extra virgin olive oils, carnitines were not detected, making it possible to propose them as a feasible novel marker for the detection of adulterations of olive oils. Application of the developed method for the analysis of different mixtures of extra virgin olive oil with seed oil (between 2 and 10%) enabled the detection and quantitation of the total content of carnitines. The results obtained show the high potential of the developed method for the authentication and quality control of olive oils.     

Triphenylphosphonioacetylide: A Species Isoelectronic with Isocyanides

Stabilized only by triphenylphosphane , the title compound 1 was synthesized and investigated theoretically (the HOMO of 1 is depicted on the right). Both calculations and experimental NMR spectra show that no Lewis structure can describe the geometry and charge distribution accurately. Compound 1 undergoes an equivalent of the Passerini reaction. Ph₃P⁺−C≡C⁻: 1     

Der Einfluß von Phosphoryl‐Substituenten auf die Eigenschaften P‐substituierter 2‐Methylimidazolium‐Ionen und 2‐Methylenimidazoline [1]

The Influence of Phosphoryl Substituents on the Properties of P‐Substituted 2‐Methylimidazolium Ions and 2‐Methyleneimidazolines [1] The imidazolines ImCHP(E)Ph₂ [ 6 , E = S ( a ), Se ( b )] are obtained from ImCHPPh₂ ( 4 ) and sulfur or selenium. HBF₄ reaction yields the corresponding imidazolium salts [ImCH₂P(E)Ph₂][BF₄] [ 5 , E = S ( a ), Se ( b )]. 1, 3, 4, 5‐Tetramethyl‐2‐methylenimidazoline ( 1 , ImCH₂) reacts with Ph₂P(O)Cl to give the corresponding phosphane salt [ImCH₂P(O)Ph₂]Cl ( 7 ) from which the vinyl compound ImCHP(O)Ph₂ ( 8 ) is formed through deprotonation. 8 reacts with excess HBF₄ to give the phosphine oxide BF₃ adduct [ImCH₂P(O)Ph₂ · BF₃][BF₄] ( 9 ). The crystal structures of 5a , 5b , 6b , 7 · CH₂Cl₂ and 9 · H₂O as well as preliminary data of 8 are reported and discussed on comparison with the phosphanes [ImCH₂PPh₂][BF₄] ( 3b ) and ImCHPPh₂ ( 4 ). From structural data, π‐electron delocalisation is concluded for 6b and 8 .     

盐处理下植物组织中甜菜碱和脯氨酸的HPLC-ESI-MS分析

通过高效液相色谱—电喷雾质谱(HPLC—ESI—MS)联用技术,优化了pH、流速、温度、鞘气和辅气等相关影响因素,建立了一个有选择性的、高灵敏度的分析方法,鉴定盐处理下植物组织提取物中的甜菜碱和脯氨酸,一次性快速地分析了甘氨酸甜菜碱、β—丙氨酸甜菜碱、葫芦巴碱、脯氨酸甜菜碱、4—羟脯氨酸甜菜碱和脯氨酸等6种化合物。其标准曲线(50～1000ng／mL)呈直线,线性相关系数大于0.999;相对标准偏差(RSD)为0．5％～15％,回收率在94．0％～97．0％之间。运用这一方法已经分析了大麦、小麦、大豆、甜菜和碱蓬等植物组织中的甜菜碱和脯氨酸,获得了较理想的实验数据,为揭示甜菜碱和脯氨酸与植物的耐盐性生理机制、耐盐品种的鉴定和选育提供了依据。     

Synthesis of novel 5-substituted isophthalates from vinamidinium salts

Novel 5-substituted isophthalates were synthesized from the reaction of 2-substituted 1,3-bis(dimethylamino)-trimethinium salts with 1,3-bis(alkoxycarbonyl)acetone derivatives in the presence of sodium methoxide in ethanol at reflux.     

Synthetic Applications of Heteroaromatic Betaines with Six-Membered Rings

The cycloadditions of 3-hydroxy-1-methylpyridinium betaines with electron-deficient olefins have been extended to a variety of 1-substituents in place of methyl. Application of resonance theory and later of quantum chemical methods led to rationalization of preceding results and prediction of new reactions. Thermal additions of 2π- and 6π-electron addends at the 2,6-positions and of 4π-electron addends at the 2,4-positions are described. The cycloadducts are highly interesting potential synthetic building blocks.     

Synthese und Deprotonierung eines Phosphinomethylimidazoliumsalzes. Zur Delokalisierung der π‐Elektronen in Aminovinylphosphanen [1]

Tetrafluorobo‐Synthesis and Deprotonation of a Phosphinomethylimidazolium Salt. On the π‐Electron Delocalization im Aminovinyl Phosphanes [1] The ylidic olefin 1, 3, 4, 5‐tetramethyl‐2‐methyleneimidazoline ( 1 , Im=CH₂) reacts with chlorodiphenylphosphane to give the phosphane salt [(Im‐CH₂)PPh₂]Cl ( 6 ) from which the vinylphosphane Im=CHPPh₂ ( 8 ) is obtained by deprotonation. 8 reacts with HBF₄ etherate to give the tetrafluoroborate salt [(Im‐CH₂)‐PPh₂] BF₄ ( 7 ). The crystal structures of 7 and 8 are determined and discussed. In 8 , π‐electron delocalisation is indicated both by structural data and temperature dependent n.m.r. spectroscopy     

Synthesis of Ammonium‐ and 4‐Dimethylaminopyridinium Amidofluorophosphates and Crystal Structure of [DMAPH][PO2F(NH2)]

NH₄[PO₂F(NH₂)] has been prepared by the reaction of a betaine py·PO₂F with excess ammonia in acetonitrile solution, while the ammonolysis of DMAP·PO₂F with a stoichiometric amount of NH₃ yields [DMAPH][PO₂F(NH₂)]. The crystal structure of the latter was determined by single‐crystal X‐ray diffraction, which revealed that the anions [PO₂F(NH₂)]^— are linked to infinite chains by double N—H···O bridges. Additional strong N—H···O bridging bonds connect each anion with its [DMAPH]⁺ counterion. The formation of a new betaine NH₃·PO₂F in the solution of py·PO₂F in liquid ammonia was proved by ³¹P NMR spectroscopy and by identification of its hydrolysis products.