钐试剂在有机合成中应用的若干新进展

综述了本课题组最近几年关于钐试剂在有机合成中应用的研究进展. 主要包括以下几部分内容: (1) 二碘化钐促进的有机反应研究; (2) 金属钐直接应用于有机合成的研究; (3) 其它钐试剂 (三碘化钐, 烯丙基溴化钐) 促进的有机反应研究.     

Catalytic Cyclotrimerization of Arylnitriles Using the Novel Samarium(II) Complexes as Catalysts

ＩｎｔｒｏｄｕｃｔｉｏｎＴｒｉａｚｉｎｅｓａｒｅｕｓｅｆｕｌｐｒｅｃｕｒｓｏｒｓｏｆｍａｎｙｂｉｏｌｏｇｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｓ ,1 3 ａｎｄｓｅｖｅｒａｌｓ ｔｒｉａｚｉｎｅｓ4 ,5ａｒｅａｌｓｏｒｅｃｏｇｎｉｚｅｄｔｏｂｅｔｈｅｐｏｗｅｒｆｕｌｃｈｅｌａｔｉｎｇａｇｅｎｔｓ .Ｔｈｅｃｏｍ ｍｏｎｍｅｔｈｏｄｓｌｅａｄｉｎｇｔｏｓ ｔｒｉａｚｉｎｅｓｉｎｃｌｕｄｅｏｘｉｄａｔｉｏｎｏｆａｒｏｍａｔｉｃａｌｄｅｈｙｄｅｓａｎｄｃｙｃｌｏｔｒｉｍｅｒｉｚａｔｉｏｎｏｆｎｉｔｒｉｌｅｓ .…     

Samarium diiodide induced reductive cleavage of the Te–Si bond in phenyltellurotrimethylsilane: A novel method for the synthesis of alkylphenyl tellurides,telluroesters, and β‐phenyltelluro esters (nitriles)

Phentyltellurotrimethylsilane (1) was reduced by samarium diiodide in tetrahydrofuran (THF) to produce samarium phenyltellurolate. This new tellurolate anion reacted smoothly with alkyl and benzyl halides to give alkyl and benzyl‐phenyl tellurides in good yields under mild and neutral conditions. The samarium tellurolate also reacted with acyl halides or anhydrides to give telluroesters, and the 1,4‐addition of samarium tellurolate to α, β‐unsaturated esters (nitriles) gave β‐phenyltelluro esters (nitriles). © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 471–474, 1999     

Sm对MoO3-Bi2O3催化剂性能的影响

在MoO3-B i2O3催化剂中加入稀土氧化物Sm2O3,在固定床反应器中考查了Sm2O3添加量、反应温度、异丁烯浓度、原料气流量等对异丁烯转化为甲基丙烯醛反应的影响。实验表明,添加Sm2O3可明显提高异丁烯的转化率和甲基丙烯醛的选择性。用XRD技术研究了催化剂的组成,Mo-B i-O催化剂的成分主要是B i2O3和MoO3的混合物,添加Sm后出现了Sm2Mo3O12的衍射峰,且衍射峰的强度随着Sm添加量的增加而增强。     

Synthesis of nano-pore samarium (III)-imprinted polymer for preconcentrative separation of samarium ions from other lanthanide ions via solid phase extraction

A batch process was developed to separate samarium ions from some lanthanide ions by a novel solid phase which was prepared via the ion-imprinting technique. The samarium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of samarium ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Then, thermally copolymerization with styrene (functional monomer, STY) and divinylbenzene (cross-linking monomer, DVB) followed in the presence of 2-methoxy ethanol (porogen) and 2,2′-azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed by stirring the above particles with 50% (v/v) HCl to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the samarium ions. The unleached and leached IIP particles were characterized by X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Finally, preconcentration and selectivity studies for samarium and the other lanthanide ions were carried out. The preconcentration of the samarium (III) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the elution times, the eluent volume and the aqueous phase volume. These studies indicated that the samarium (III) amount as low as 1 μg, present in 200 mL, could be preconcentrated into 25 mL of 1.0 M HCl.     

Selective accumulation of light or heavy rare earth elements using gram-positive bacteria

The accumulation of samarium from a solution only containing samarium by Arthrobacter nicotianae was examined. The amount of accumulated samarium was strongly affected by the concentration of samarium and pH of the solution. The accumulation of samarium by the strain was very rapid and reached equilibrium within 3 h. The accumulation of samarium-europium or europium-gadolinium from the solution containing the two metals using various actinomycetes and gram-positive bacteria was also examined. Most of the tested strains could accumulate similar amounts of samarium and europium; however, most of the tested strains could accumulate a greater amount of europium than gadolinium. Especially, the amounts of accumulated europium using gram-positive bacteria were higher than those using actinomycetes. The selective accumulations of light or heavy rare earth elements (REEs) using A. nicotianae and Streptomyces albus were also examined. The amounts of accumulated samarium and europium were higher than those of the other light REEs using both microorganisms. S. albus can accumulate greater lutetium than other REEs from a solution containing yttrium and eight heavy REEs. On the other hand, A. nicotianae can accumulate higher amounts of terbium and ytterbium than that of the other heavy REEs from the same solution. A. nicotianae can also accumulated higher amounts of Sm than other REEs from a solution containing six light REEs.     

Spectrophotometric determination of samarium(III) with chrome azurol S in the presence of cetylpyridinium chloride

A sensitive, simple method for the determination of trace amounts of samarium by spectrophotometry is described based on the formation of the samarium-chrome azurol S (CAS) complex in micellar medium. The molar absorptivities of the complexes at pH 7.5 at 505 nm were 3.6x10(4) and 1.4x10(5) l mol(-1) cm(-1) for water media and cetylpyridinium chloride (CPC), respectively. Beer's law is obeyed from 0.05-2 mg l(-1) of samarium at 505 nm as Sm-CAS-CPC complex. Optimal conditions such as reagent amounts, and pH for the samarium determination were reported. The effects of foreign ions were also investigated. The proposed method was successfully applied to the determination of samarium contents in synthetic samples.     

Synthesis of (E)-α,β-unsaturated ketones with total or high diastereoselectivity by using samarium diiodide or triiodide

(E)-α,β-Unsaturated ketones are obtained by reaction of α-chloro-β-hydroxy ketones with samarium diiodide or with samarium triiodide with total or high diastereoselectivity and in good yield.     

二碘化钐促进的 β-碲代酯(腈)的合成

本文报道在室温, 中性介质中研究二碘化钐在合成中的应用. 在二碘化钐作用下,二碲醚发生Te-Te键还原断裂, 生成碲负离子物种, 后者再与α,β-不饱和酯(腈)发生Michael加成, 得到β-碲代酯(腈), 产率较高.     

二碘化钐在脱氧、还原和碳-碳键形成反应中的应用

本文研究了二碘化钐对一些有机化合物的脱氧反应, 以及它在醇存在下对α-卤代酮、偶氮苯和苯醌的还原反应。首次报道了在二碘化钐作用下α-卤代酮与醛之间的碳-碳键形成瓜在, 高产率地制备了各种α,β-不饱和酮; 同时提出了涉及由α-卤代酮同时与Sm(II)和Sm(III)/I^-物种作用形成烯醇钐盐中间体的可能机理。     

A mechanistic study of the samarium(II)-mediated reduction of aryl nitro compounds to the corresponding crylamines. The crystal structures of [Sm[N(SiMe(3))(2)](2)(thf)](2)(mu(2)-O) and [(Me(3)Si)(2)N](2)Sm(thf)(mu-PhNNPh)Sm[N(SiMe(3))(2)](2)

Treatment of nitrobenzene and other various nitroarenes with 6 equiv of samarium(II) under strictly anhydrous conditions allows for the isolation of aniline or the corresponding arylamine. Reducing the number of samarium(II) equivalents allows for the isolation of intermediate species, e.g., azoarenes or hydrazines. Use of Sm[N(SiMe(3))(2)](2), in place of the typically used SmI(2), has allowed for the detailed examination of the aqueous and nonaqueous species formed in this reduction and has been instrumental in delineation of the stepwise reaction mechanism. This is the first time that the reaction intermediates of an organic reaction mediated by samarium(II) have been isolated and analyzed by (1)H NMR and X-ray crystallography.     

Reductive Cleavage of Te-Te Bond in Ditellurides by Sm / ZrCl4 System : a Novel Method for the Synthesis of β-Telluroesters (and Nitriles)

Diaryl ditellurides were conveniently reduced by a system consisting of samarium and zirconium tetrachloride in tetrahydrofuran to produce samarium aryltellurolates. This new tellurolate anion species reacted smoothly with α, β-unsaturated esters (and nitriles) to give β-telluroesters (and nitriles) in good yields.     

Comparison of Stereoselectivity of Intramolecular Cyclization of Aldehydes Tethered with Conjugated Esters Induced by O-Stannyl and O-Samarium Ketyls to Form the Tetrahydrofuran Ring Systems

Several (E)- and (Z)-ω-formyl-5-oxa-2-substituted-α,β-unsaturated esters ( 6Za-6Zc; 6Ea-6Ec; 6Eb′-6Ec′; 6Zb′-6Zc′ ) were prepared in high yields. They were subjected to cyclization of their intramolecular ketyl radicals induced by either samarium(II) iodide or tributyltin hydride. These two reagents gave distinct stereoselectivities. More bicylic lactone than monocyclic hydroxy-ester was formed when tributyltin hydride was used, but the opposite stereoselectivity was obtained when samarium(II) iodide was used. The effect of double-bond configuration, heteroatom and substituent on stereoselectivity is described.     

Samarium diiodide induced ketyl-(het)arene cyclisations towards novel N-heterocycles

In this tutorial review we discuss recent advances in the field of ketyl-(het)arene cyclisations promoted by samarium diiodide and related processes. Couplings of samarium ketyls with carbon-carbon multiple bonds are perhaps the most useful reactions to create carbocycles and heterocycles of various ring sizes. They have also successfully been exploited for the synthesis of biologically active compounds or natural products. In this article we intend to summarise our diversity orientated approaches towards nitrogen heterocycles and emphasize other approaches with SmI(2) as well as electrochemical cyclisation methods providing similar N-heterocycles. We also briefly discuss our recently published formal total synthesis of strychnine employing a new samarium diiodide induced cascade reaction as key step. All these examples demonstrate the high synthetic potential of samarium ketyl-(het)arene cyclisations for the preparation of various types of important heterocyclic compounds.     

Living polymerization of ethylphenylketene by samarium enolate

The living polymerization of ethylphenylketene (EPK) by a samarium enolate is described. Poly(EPK) with controlled molecular weight and low polydispersity was obtained in a quantitative yield by the polymerization with the samarium enolate and polar additives. A wide variety of polar additives including amides and ureas were shown to facilitate the formation of well‐defined poly(EPK).     

Third Order Derivative Molecular Absorption Spectrophotometry Determination of Traces of Samarium With Methyl Thymol Blue - CTAB or CPB

Abstract

A sensitive and selective method is described for the determination of traces of samarium by third order derivative molecular absorption spectrophotometry (TDMAS). The method is based on the formation of a stable, blue coloured water soluble ternary complex (Metal-Chromogenic reagent-surfactant) which is formed when cetyl trimethyl ammonium bromide or cetyl pyridinium bromide is added to binary samarium-methyl thymol blue system. The influence of various instrumental parameters and reaction conditions for maximum colour development is investigated. The ternary complex detection limit is 7.5 μg of samarium present in 25 ml of final solution. Linear calibration graphs are obtained for 0–30 μg of samarium. The relative standard deviation of the procedure was calculated to be 1.6%. Gd, Tb, Dy, Ho, Tm and Lu do not interfere in TDMAS determination of samarium. Methods are described for masking other interfering analytes.     

钐试剂在有机合成中的应用

钐试剂在有机合成中的应用是近年来有机合成方法学研究中的热点之一。综述了十余年来本课题组在钐试剂应用于有机合成方面所开展的有关工作：(1)二碘化钐作为偶联剂和还原剂在有机合成中的应用;(2)金属钐直接应用于有机合成;(3)三碘化钐作为路易斯酸应用于有机合成;(4)有机钐试剂在有机合成中的应用。     

Thermal-Decomposition Chemistry of Modified Lead-Titanate Aquo-Diol Gels Used for the Preparation of Thin Films

Lead-titanate gels and thin films modified with calcium, lanthanum or samarium have been prepared by chemical solution deposition (CSD) methods. Lead acetate, titanium di-isopropoxide bis-acetylacetonate and 1,3-propanediol were used for the synthesis of Pb-Ti-sols. Calcium, lanthanum or samarium were added to these sols as acetates or nitrates dissolved in water. The solutions were dried to obtain the gels or spin-coated onto platinised silicon substrates to obtain the films. Thermal decomposition of the gels was followed by means of simultaneous thermogravimetric and differential-thermal analysis (TGA/DTA) coupled with evolved gas analysis (EGA). Infrared (IR) analysis of the gels helped to identify the compounds formed during the thermal decomposition. Crystal structure and microstructure of the films were observed by grazing incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM). These analyses indicated that the structure and microstructure of the modified-lead-titanate thin films are related to the thermal decompositions of the corresponding gels. It was inferred from these studies that the decomposition sequence is linked to the type of modifier, Ca, La or Sm, and to the precursor salt (acetate or nitrate) used for the incorporation of the modifier into the Pb-Ti-sol.     

Temperature-controlled selective reduction of arenesulfonyl chlorides promoted by samarium metal in DMF

Promoted by samarium in DMF, arenesulfonyl chlorides can be selectively reduced to diaryldisulfones, diarylthiosulfonates and diaryldisulfides in good to excellent yields by reaction temperature control without the need to pretreat or activate the metallic samarium.     

A new strategy for the synthesis of α,β-diaroylpropionates promoted by samarium metal in DMF

When promoted by samarium in DMF, aroyl chlorides react readily with acrylates to afford α,β-diaroylpropionates in good to excellent yields without pretreating or activating the metallic samarium.