氟代糖的合成

本文综述了氟代糖合成的新进展及利用选择性氟化合成具有生物活性的物质。     

Synthesis of Methylene Tetrahydrofurane-Fused Carbohydrates

A reliable method is disclosed to introduce a fused methylene tetrahydrofuran ring into carbohydrates. The resulting bicyclic saccharides can be used as scaffolds in medicinal chemistry and drug design. In addition, the enol ether functionality serves as a handle that enables modification in biological systems via photoclick chemistry. The approach is based on the regioselective oxidation of the C-3 hydroxy group in gluco-configured pyranosides, followed by stereoselective indium-mediated allylation. The ring formation is induced by an iodocyclization reaction with a neighboring hydroxy group. Subsequent dehydrohalogenation affords the desired methylene-tetrahydrofuran-containing carbohydrates.     

Mechanochemical Synthesis of Fluorinated Imines

A number of imines, including 12 new compounds, previously not reported in the literature, derived from variously fluorinated benzaldehydes and different anilines or chiral benzylamines were synthesized by a solvent-free mechanochemical method, which was based on the manual grinding of equimolar amounts of the substrates at the room temperature. In a very short reaction time of only 15 min, the method produced the expected products with good-to-excellent yields. The yields were comparable or significantly higher than those reported in the literature for the imines synthesized by other methods. Importantly, the conditions used for the reactions with aniline derivatives also resulted in the high yields of imines obtained from chiral benzylamines, and can be extended to the synthesis with other similar amines. Structures of all imines were confirmed by NMR spectroscopy: ¹H, ¹³C and ¹⁹F. For four compounds, X-ray structures were also obtained. The synthetic approach presented in this paper contributes to the prevention of environmental pollution and can be easily extended for larger-scale syntheses. The mechanochemical solvent-free method provides a convenient strategy particularly useful for the preparation of fluorinated imines being versatile intermediates or starting material in the synthesis of drugs and other fine chemicals.     

Synthesis of N-Hetarylthiourea Derivatives of Carbohydrates

ABSTRACT

The syntheses of N-hetaryl (thiazole-2-yl, 2-thiazoline-2-yl, 4,4-diphenyloxazoline-2-yl, cis-3a,4,5,6,7,7a-hexahydrobenzoxazole-2-yl)-N′-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl) thioureas (1a-1d), N-hetaryl (2-thiazoline-2-yl, 4,4-diphenyloxazoline-2-yl)-N′-(2,3,4,6-tetra-O-benzoyl-β-D-galactopyranosyl) thioureas (2b, 2c) and 1,2,3,4,6-tetra-O-acetyl-2-deoxy-2-[3-(4′, 4′-diphenyl-2′-y1) thioureido]-β-D-glucopyranose (3c) are described. The structures and conformational properties of prepared compounds are based on analytical and spectroscopic (UV, IR, NMR and MS) data.     

Synthesis of Chiral Spiroacetals from Carbohydrates

Chiral spiroacetals of the 1,7-dioxaspiro[5.5]undecane, 1,6-dioxaspiro[4.5]decane, and 1,6-dioxaspiro[4.4]nonane types have been prepared from carbohydrates in pyranose or furanose forms. The spirocyclization reaction has been accomplished from a conveniently homologated carbohydrate by an intramolecular hydrogen abstraction reaction promoted by alkoxy radicals. Thus, 2,3,4,6-tetra-O-benzyl-1-deoxy-1-(3'-hydroxypropyl)-alpha-D-glucopyranose (2) was photolyzed with visible light in the presence of (diacetoxyiodo)benzene and iodine to give a mixture of (1R)-(3) and (1S)-2,3,4,6-tetra-O-benzyl-1-deoxy-D-glucopyranose-1-spiro-2'-tetrahydrofuran (4). The photolysis of methyl 6-deoxy-6-(2'-hydroxyethyl)-2,3,4-tri-O-methyl-alpha-D-glucopyranoside (8) gave the isomeric spiroacetals methyl (5S)- (9) and (5R)-6-deoxy-5,2'-epoxy-6-ethyl-2,3,4-tri-O-methyl-alpha-D-glucopyranoside (10) in which the spirocenter is now located at C-5. The spiroacetals of the [5.5]undecane series: methyl (5R)- (19) and (5S)-6-deoxy-5,3'-epoxy-2,3,4-tri-O-methyl-6-propyl-beta-D-glucopyranoside (20) have been prepared starting from methyl 6-deoxy-6-(3'-hydroxypropyl)-2,3,4-tri-O-methyl-beta-D-glucopyranoside (18). The reaction has also been applied to hexofuranoses and 1-deoxy-1-(3'-hydroxypropyl)-2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose (21) gave rise to (1S)- (22) and (1R)-1-deoxy-2,3:5,6-di-O-isopropylidene-D-mannofuranose-1-spiro-2'-tetrahydrofuran (23); and 1-deoxy-1-(4'-hydroxybutyl)-2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose (28) to (1R)- (30) and (1S)-1-deoxy-2,3:5,6-di-O-isopropylidene-D-mannofuranose-1-spiro-2'-tetrahydropyran (32). Both spiroacetal enantiomers are formally available from the same carbohydrate.     

几个新型含氟化合物的合成

以3-硝基-4-氯三氟甲苯(1)为起始原料, 合成了新型含氟杂环化合物8和3个含氟中间体4, 5, 6. 通过IR, NMR, MS和元素分析对它们的结构进行了表征. 探讨了反应条件对产物结构的影响, 提出了化合物4可能的形成机理.     

Synthesis of New Fluorinated Podophyllotoxin Derivatives

Five fluorinated podophyUotoxin derivatives were synthesized using dimethylamino-sulfurtrifluoride (DAST).     

氟代有机硅化合物的合成新方法

本工作利用CuCl/HOC₂H₄NH₂催化剂,将1,2-二溴四氟乙烷与烯基有机硅化合物进行加威反应,制备了一系列新的含氟有机硅化合物,并进行了分析鉴定。对影响反应的诸因素做了初步探讨。     

Synthesis of Highly Functionalized Fluorinated Porphyrins

Highly functionalized fluorinated porphyrins were synthesized by a convergent strategy. Nucleophilic substitution using fluorinated branched unit and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin afforded highly functionalized fluorinated porphyrin 8 containing 24 fluorinated chains in the peripheral region.     

含氟聚合物的合成进展

含氟聚合物由于其优异的化学和物理性能以及广泛的应用前景而受到关注。根据聚合反应单体结构不同,可以通过不同方法合成各种结构的含氟聚合物。这些聚合方法主要是可控／“活性”聚合,例如：原子转移自由基聚合（ATRP）、原子转移自由基一乙烯基自缩合聚合（ATR—SCVP）、可逆加成一断裂链转移聚合（RAFT）、氮氧稳定自由基聚合...     

Fluorinated aminooxazolines. Synthesis and properties

4-Amino-2,2,5,5-tetrakis(trifluoromethyl)-3-oxazoline ( 3a ) was prepared from the reaction of sodium cyanide with hexafluoroacetone and hexafluoroacetone imine, and from the reaction of hexafluoroacetone cyanohydrin with the imine. Several other oxazolines were also prepared by related reactions of other fluoroketones and imines. The proton nmr spectrum of an ¹⁵N-labeled sample of 3a shows that it exists in solution primarily as the amino tautomer and not as the imino tautomer 3b . Comparison of 3a with the closely related, pharmacologically active 4-amino-2,2,5,5-tetrakis(trifluoromethyl)-3-imidazoline ( 2 ) has shown large differences in ΔH of complex formation and reactivity with electrophilic reagents.     

Synthesis and Rearrangement Reactions of C-Alkylidene Carbohydrates

Direct: olefinations on one hand in comparison to eliminations of aldols cf various uloses on the other each proved to be specific as to the sice of unsaturation in the branched-chain products, found to be interconvertible with one exception under a variety of conditions. Although shown to be generally equivalent to its Witcig-counterpart:, the Peterson reagent employed is liable to cause eliminations in the initial olefin. One of the branched-chain products appears to be of unusual molecular rigidity as evidenced by a large 5J coupling.     

Fluorinated fullerenes: Synthesis and characterization

The existence of the fully fluorinated fullerene, C₆₀F₆₀, is still subject to controversy. Mass spectrometric evidence shows that it exists, albeit in trace amounts five orders of magnitude in concentration below the most abundant C₆₀F_40-42. Generally, mixtures of C₆₀F_n are obtained where n ranges from 30 to 52, depending on fluorinating conditions. The species with n = 36 is particularly stable. Attempts to increase n by use of the strongly fluorinating halogen fluorides, ClF₃ or BrF₅, have led to products C₆₀F_XX_yO_z (X = Br or Cl), where the origin of the oxygen is probably hydrolysis during analysis. Fluorinated C₆₀ crystallizes as a mixture of hexagonal close packed (40%) and face-centered cubic (60%) phases. X-ray analysis yields an average C-F bond length of 1.49A. Fluorination of C₇₀ leads to mixtures with maximum average stoichiometries of C₇₀F₅₂.     

含氟聚氨酯的研究进展

综述了溶剂性、水性含氟聚氨酯的合成及研究，并进行了讨论。     

可溶性含氟聚酰亚胺三元共聚物的合成

通过两步法实现了1,4双-(1,4二-氨基)苯氧基苯(TPEQ),4,4二-氨基二苯醚(ODA)和4,4′-六氟亚异丙基-邻苯二甲酸酐(6FDA)的三元共聚,所得共聚物(PAA)经高温法或化学法脱水环化得对应的可溶性含氟聚酰亚胺(PI)。通过粘度,DSC,TG和1H NMR等分析数据比较了其综合性能。对PI的研究结果表明,化学法的粘度一般高于高温法,所有的PI均具有良好的溶解性和耐热性;不仅溶于DMF,还能很好的溶于CHC l3和THF,有效地改善了其加工性能;Tg>227℃,热损失5%的温度多在488℃以上,m.p.>550℃。其中PI3具有最好的综合性能,粘度1.065 dL.g-1,Tg 241.7℃,热损失5%的温度488℃,m.p.557.9℃,拉伸强度108.81MPa。     

A Modified Synthesis of Fluorinated 1,3-Diketones

The reinvestigation of acylation reactions of fluorinated aryl methylketones with ethyl esters at 0°C afforded fluorinated 1, 3-diketones in excellent yields.     

氟改性聚氨酯乳液的合成及其表面性能

氟改性聚氨酯乳液的合成及其表面性能;氟改性;聚氨酯乳液;表面性能