Base catalyzed isomerization of epoxides. I. The isomerization of β-chloroepoxides

The base catalyzed isomerizations of epichlorohydrin, 1-chloro-2,3-epoxy-2-methylpropane, 1-chloro-2,3-epoxybutane, and 3-chloro-1,2-epoxybutane have been studied, using lithium ortho-phosphate as the basic catalyst. Chloroketones and dichloro-alcohols are the major products. This is the first example of a compound with an electron withdrawing group attached to the carbon atom adjacent to the oxirane ring which undergoes the α-elimination pathway. A bidirectional mechanism is proposed to explain the experimental results. The stereochemistry of the hydrochlorination of 1-chloro-2,3-epoxybutane and 3-chloro-1,2-epoxybutane has also been studied.     

Kinetics and mechanism of the N7-hydroxyalkylation of guanosine

The kinetics of the N₇-hydroxyalkylation of guanosine by the equally substituted epoxide, trans-2,3-epoxybutane, and the unequally substituted epoxides, 3-chloro-1,2-epoxypropane, and 1,2-epoxypropane in glacial acetic acid, have been measured by a spectrophotomeric method over the range 20-40°. Activation parameters have been determined. Comparative rates calculated from the ratios of second-order rate constants indicate that 1,2-epoxypropane reacts with guanosine about three times faster than does trans-2,3-epoxybutane and about two times faster than 3-chloro-1,2-epoxypropane. These results coupled with the results of a previous report on the structural analysis of the products from these reactions are consistent with a “push-pull” mechanism in which N₇ of guanosine reacts preferentially at the least substituted carbon of the epoxide with simultaneous transfer of a proton from acetic acid to the oxygen of the epoxide. The lower reactivities of trans-2,3-epoxybutane and 3-chloro-1,2-epoxypropane in comparison to that of 1,2-epoxypropane are discussed in terms of steric factors and electronic factors which determine the stability of the requisite transition state for a “push-pull” mechanism model.     

Ring-opening reaction of 1,2-expoxybutane with alcohols over H-zeolites in liquid phase

H-Z-Y5.6 (Y-type zeolite) shows the highest activity for the ring-opening reaction of 1,2-epoxybutane, and H-Z-HM15 (mordenite type of zeolite) shows the highest regioselectivity for the formation of 2-methoxybutanol by comparing the reaction rates. The regioselectivity obtained by the zeolite using various alcohols is higher or similar than that in acidic conditions using H₂SO₄ catalyst.     

Formation of gallaoxetanes: C-O activation of 1,2-epoxybutane by ground-state Ga atoms

(69/71)Ga atoms were reacted with 1,2-epoxybutane and its isotopomers, 1,2-epoxybutane-1,1-d(2) (CH(3)CH(2)CHOCD(2)) and 1,2-epoxybutane-2-d(1) (CH(3)CH(2)CDOCH(2)), under matrix-isolation conditions. The novel gallaoxetanes CH(3)CH(2)CHCH(2)GaO and CH(3)CH(2)CHCH(2)OGa, resulting from the insertion of the metal atom in the C(1)-O and C(2)-O bonds, respectively, of the 1,2-epoxybutane, were detected by EPR spectroscopy. The Ga and H hyperfine interaction (hfi) values of the gallaoxetanes, calculated using a DFT method, were used to help assign the EPR spectra. A third Ga-centered species, detected at 190 K, underwent spectral changes similar to those of the C(2)-O insertion product upon isotopic substitution of the 1,2-epoxybutane. Although the Ga hfi for this species was 36% smaller than that of the C(2)-O insertion product, the values for the H hfi were similar, suggesting that the carrier of the spectrum was the C(2)-O insertion product where Ga was perturbed by the matrix constraints. The alkyl radical CH(3)CH(2)(?CH)CH(2)OGa, resulting from ring-opening at the C(2)-O bond of 1,2-epoxybutane, was observed at temperatures below 150 K. This radical has been implicated in the formation of the C(2)-O insertion product. The unusually small value found for two of the β-hydrogens of the alkyl radical is discussed.     

Ionic and radical addition of chlorine,bromine and some halogen systems of butadiene monoxide (4)

Ionic reactions of bromine, chlorine, methyl hypochlorite or N-bromosuccinimide with butadiene monoxide ( 4 ) give only 1,2-addition products. The Markownikoff (1-halo-2-methoxy-3,4-epoxybutane) and anti-Markownikoff (2-halo-1-methoxy-3,4-epoxybutane) product ratios for ionic reaction of methyl hypochlorite and N-bromosuccinimide in methanol with 4 are similar to those obtained with 1-hexene. These data indicate that a rather symmetrical halonium ion is formed in the ionic halogenation of 4 . Free radical reaction of bromine, chlorine, or trichloramine to 4 does not give ring-opened products as one might expect for formation of an epoxy carbonyl intermediate. The mechanistic implications from these observations are discussed.     

The mechanism of epoxide carbonylation by [Lewis Acid]+[Co(CO)4]- catalysts

A detailed mechanistic investigation of epoxide carbonylation by the catalyst [(salph)Al(THF)2]+ [Co(CO)4]- (1, salph = N,N'-o-phenylenebis(3,5-di-tert-butylsalicylideneimine), THF = tetrahydrofuran) is reported. When the carbonylation of 1,2-epoxybutane (EB) to beta-valerolactone is performed in 1,2-dimethoxyethane solution, the reaction rate is independent of the epoxide concentration and the carbon monoxide pressure but first order in 1. The rate of lactone formation varies considerably in different solvents and depends primarily on the coordinating ability of the solvent. In mixtures of THF and cis/trans-2,5-dimethyltetrahydrofuran, the reaction is first order in THF. From spectroscopic and kinetic data, the catalyst resting state was assigned to be the neutral (beta-aluminoxy)acylcobalt species (salph)AlOCH(Et)CH2COCo(CO)4 (3a), which was successfully trapped with isocyanates. As the formation of 3a from EB, CO, and 1 is rapid, lactone ring closing is rate-determining. The favorable impact of donating solvents was attributed to the necessity of stabilizing the aluminum cation formed upon generation of the lactone.     

Catalytic activity of salenCo(III)OAc complex in the reaction of addition of carboxylic acids to terminal epoxides

The catalytic activity and regioselectivity were studied of the salenCo(III)OAc complex in the reaction of addition of aliphatic carboxylic acids to a series of terminal epoxides (epichlorohydrin, 1,2-epoxybutane, propylene oxide, tert-butyl glycidyl ether and 2,3-epoxypropyl phenyl ether). The reduction in the activity in the order: acetic > acrylic > methacrylic acid was found. The regioselectivity of the addition was independent on carboxylic acid nature and depended on the nature of the epoxide. The best regioselectivity for the addition to epichlorohydrin was observed. The catalytic activity and regioselectivity of salenCo(III)OAc were compared with those for chromium(III) acetate catalyst.     

Reaction of Epoxides with (Alkylthio)methyl Chloride

The reaction of (methylthio)methylchloride with 1,2-epoxybutane and styrene oxide furnishes eleven and eight compounds, respectively. The probable mechanism of their formation and their mass spectral characterization are presented in this article.     

钛硅分子筛催化1-丁烯环氧化反应溶剂效应和酸碱效应研究

研究了用双氧水为氧化剂，钛硅分子筛TS-1催化1-丁烯环氧化反应的溶剂效应．研究发现，在质子性溶剂中1-丁烯环氧化反应活性高于非质子性溶剂，而以甲醇为溶剂H2O2转化率最高．分别利用碱性添加物稀氨水溶液和酸性添加物稀盐酸溶液调变反应介质的pH值，考察了介质的pH值对1-丁烯环氧化反应的影响，结果表明，随pH值提高，1，2-环氧丁烷(B0)的选择性略提高，但是过量稀氨水的加入会导致催化剂失活，双氧水的转化率及利用率明显下降．与钛硅分子筛催化丙烯环氧化相比，酸性添加物的加入对反应结果的影响不大，随反应介质的pH值降低1，2-环氧丁烷的选择性没有明显下降．     

Efficient preparation of 9-Z-11-methylretinal and 11-Z-11-methylretinal

[2-(β-Ionylidene)propyl]triphenylphosphonium bromide is reacted with 3-methyl-4-oxobut-2-enenitrile in refluxing 1,2-epoxybutane to give a mixture of 11-Z- and all-E-11-methylretinal via DIBAL-H reduction. In an analogous fashion, β-ionyl triphenylphosphonium bromide is reacted with 3,5-dimethyl-6-oxohexa-2,4-dienenitrile in 1,2-epoxybutane followed by subsequent DIBAL-H reduction to afford a mixture of new products consisting of 9-Z-11-methylretinal, its all-E isomer and 1-(2′,6′,6′-trimethylcyclohex-2′-en-1′-yl)-6-(buten-2″-al-3″-yl)-3,5-dimethylcyclohexa-1,3-diene. These molecules were obtained in pure form by HPLC.     

Poly(alkylene oxide) ionomers. X. Copolymerization of methyl ω-epoxyalkanoates and characterization of the polymers

Selected methyl ω-epoxyalkanoates ranging from methyl 3,4-epoxybutanoate to methyl 7,8-epoxyoctanoate were copolymerized with a number of oxiranes and with oxetane. Tetrahydrofuran did not take part in the attempted methyl ω-epoxyalkanote–tetrahydrofuran copolymerization, but acted only as the solvent. The oxirane copolymers had polymer compositions similar to the comonomer feed ratio. Oxirane comonomers used were propylene oxide (1,2-epoxypropane), butylene oxide (1,2-epoxybutane), 1,2-epoxyhexane, epichlorohydrin, and phenylglycidyl ether. The initiator system used was triethylaluminum/water/acetylacetone (1.0/0.5/1.0) in about 5 mol %. In the copolymerizations using methyl 3,4-epoxybutanoate as a comonomer, only small yields of polymer (in the range of 1 to 2%) were realized, while for methyl 4,5-epoxypentanoate the yields were generally in the range of 20 to 60%. Methyl 7,8-epoxyoctanoate copolymerized readily and gave yields of copolymers of 50 to 90%.     

Synthesis and properties of poly(cis-1,4-dihydroxy-2,3-epoxybutane)

The cyclic acetone ketal of 1,4-dihydroxy-2,3-epoxybutane (DMTO) polymerizes with i-Bu₃Al-0.7 H₂O catalyst by a cationic mechanism at ?78°C to a moderate molecular weight (η_inh up to 0.7), atactic (based on ¹³C-NMR) polymer (PDMTO). At higher temperature and in bulk, up to 14% crosslinked polymer is obtained as a result of epoxide and ketal ring opening. Triethylaluminum is an effective catalyst at 0–50°C in bulk. Coordination catalysts were less effective but the results indicate that an effective one can be designed. PDMTO is readily hydrolyzed with aqueous HCl treatment to atactic, water-soluble poly(1,4-dihydroxy-2,3-epoxybutane) (PDHEB) with a T_g of 80°C. PDHEB is melt stable to 200°C and can be molded to give brittle, clear films that readily pick up 5–10% H₂O from the atmosphere to give properties like those of plasticized poly(vinyl chloride). PDHEB is degraded by electron beam radiation but can be crosslinked with glyoxal plus toluene sulfonic acid/The bis(trimethylsilyl) ether of cis-1,4-dihydroxy-2,3-epoxybutane was polymerized cationically with the i-Bu₃Al-0.7 H₂O catalyst at ?78°C to a fairly tactic, presumably racemic di-isotactic, amorphous polymer, with η_inh of 0.16. A mechanism is proposed for this stereoregular polymerization based on a complexation of the Si side group of the last chain unit with the propagating oxonium on.     

Formation of a THF adduct of the organometallic samarium oxide [(C5Me5) 2Sm]2(μ-O)

(C₅Me₅)₂Sm(THF)₂ reacts with 1,2-epoxybutane in toluene to form, in addition to the toluene soluble [(C₅ Me₅)₂Sm]₂(μ-O), 1, the hexane soluble [(C₅Me₅)₂Sm(THF)]₂(μ-O), 2. In hexane, 2 loses THF to form 1 as a precipitate, but 1 cannot be converted to 2 by addition of THF at room temperature. Compound 1 does convert to 2 in low yield in THF at reflux. The reaction of (C₅Me₅)₂SM(phthalan) with 1,2-epoxybutane generates 1 and a phthalan analog of 2, [(C₅Me₅)₂Sm(phthalan)]₂(μ,-O), 3. Compound 2 reacts with Me₃CCN to form [(C₅Me₅)₂Sm(NCCMe₃)]₂(μ-O), 4, by displacement of THF.     

Polymerization of propadiene. I. Comparison of catalytic systems in relation to polymer structure and polymerization by a new Ni-based catalyst

A literature survey is given of the methods of preparation of 1,2-and 1,2,2,1-polyallene. The spectroscopic data and other physico-chemical properties are compiled. Spectral analysis of the products in relation to the catalyst used leads to conclusions with regard to the effect of electron-donating and electron-withdrawing ligands to the transition metal of the catalyst on the ratio of 1,2 to 1,2,2,1-polyallene structural units in the polymer obtained. This hypothesis enabled us to prepare a structurally homogeneous 1,2 polyallene in almost quantitative yield. The catalyst was prepared by adding propadiene to a benzene solution of Ni(II) acetylacetonate followed by addition of triisobutylaluminum. This sequence of addition appeared to be the essential factor for obtaining an active catalyst. A kinetic scheme for the polymerization is put forward.     

Chemistry of sulfonyl isocyanates and sulfonyl isothiocyanates. XII. Cyclizations with epoxides

4-Toluenesulfonyl isothiocyanate reacted with 1,2-epoxy-3-phenoxypropane and 2,3-epoxypropyl 4-methoxyphenyl ether to give, respectively, 3-(4-toluenesulfonyl)-5-phenoxymethylene-2-oxazolidmethione ( I ) and 3-(4-toluenesulfonyl)-5-(4-methoxyphenoxymethylene)-2-oxazolidinethione ( II ) in high yields. The sulfonyl isothiocyanate reacted further with styrene oxide to give a mixture of oxazolidinethiones from which a solid III was isolated. The structure of III is either the 4- or 5-phenyl derivative of 3-(4-toluenesulfonyl)-2-oxazolidinethione. Reactions of the isothiocyanate with 3-chloro-1,2-epoxypropane and 1,2-epoxybutane afforded, respectively, 3-(4-toluenesulfonyl)-5-chloromethyl-2-oxazolidinethione ( IV ) and 3-(4-toluenesulfonyl)-4-ethyl-2-oxazolidinethione ( V ). Evidence for structures was by pmr, ir, and elemental analyses.     

First total synthesis of the E type I phytoprostanes

The first total synthesis of two E type I phytoprostanes from furan, azelaic acid monomethyl ester and rac-1,2-epoxybutane is described. The key features of our synthetic strategy encompass an enzymatic kinetic resolution of a hydroxycyclopentenone, a Co-salen hydrolytic kinetic resolution of a terminal epoxide and a tandem conjugate addition/diastereoselective protonation sequence to construct the protected phytoprostanes. Mild cleavage of the silyl protective groups followed by enzymatic ester hydrolysis afforded the free E-type phytoprostanes.     

Tetrafluoroboric acid — A new catalyst for the synthesis of 1,3-dioxolanes. Preparation of hydroxyacetone

It is established that tetrafluoroboric acid (HBF₄) is an effective catalyst for halogen substitution reactions of oxiranes (epichlorohydrin and 1-bromo-3-methyl-2,3-epoxybutane) with aldehydes and ketones, forming 1,3-dioxolanes in high yields.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 33–36, January, 1991.     

Characterization of oxygenated derivatives of isoprene related to 2-methyltetrols in Amazonian aerosols using trimethylsilylation and gas chromatography/ion trap mass spectrometry

In the present study, we have tentatively identified the structures of three oxygenated derivatives of isoprene in Amazonian rain forest aerosols as the C(5) alkene triols, 2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene. The formation of these oxygenated derivatives of isoprene can be explained by acid-catalyzed ring opening of epoxydiol derivatives of isoprene, namely, 1,2-epoxy-2-methyl-3,4-dihydroxybutane and 1,2-dihydroxy-2-methyl-3,4-epoxybutane. The structural proposals of the C(5) alkene triols were based on chemical derivatization reactions and detailed interpretation of electron and chemical ionization mass spectral data, including data obtained from first-order mass spectra, deuterium labeling of the trimethylsilyl methyl groups, and MS(2) ion trap experiments. The characterization of 2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene in forest aerosols is important from an atmospheric chemistry viewpoint in that these compounds hint at the formation of intermediate isomeric epoxydiol derivatives of isoprene and as such provide mechanistic insights into the formation of the previously reported 2-methyltetrols through photooxidation of isoprene.     

手性磷酰胺类配体不对称催化串联反应合成手性3-取代苯酞化合物

以反式-1,2-二苯基乙二胺为原料合成了一系列磷酰胺类配体, 考察了该类配体在催化1,2-加成/内酯化串联反应合成手性3-取代苯酞化合物过程中的催化活性. 在最优条件下, 即在配体7d摩尔分数为20%时, 可以获得高达90%的收率及大于80% e.e.值的3-取代苯酞化合物; 该配体合成简单, 虽然作为催化剂使用量较大但较易回收再利用. 对反应机理进行了推测, 认为反应过程中形成的环状过渡态有助于提高反应的对映选择性.     

离子液体接枝的有机介孔催化剂的制备及催化碳酸丙烯酯水解反应

以甲基咪唑和3-氯-1丙醇为原料合成离子液体（1-羟丙基-3-甲基咪唑四氟硼酸盐,NpmimBF4）,并将其接枝固载到有机介孔材料（FDU-15）上,合成制备了有机介孔催化剂（NpmimBF4- FDU）。采用热重、Ｘ射线衍射、红外光谱及透射电子显微镜等技术手段对催化剂结构进行了表征,并考察了催化剂在碳酸丙烯酯（PC）水解反应中的催化性能,结果表明,该催化体系在常压下能有效催化碳酸丙烯酯水解生成1,2-丙二醇。在催化剂的质量分数为4%、温度80 ℃、反应时间2 h的条件下,1,2-丙二醇的产率大于99%。经简单分离后催化剂可重复使用5次,但活性变化较大。同时对催化碳酸丙烯酯水解生成1,2-丙二醇（PG）的反应机理进行了初步探讨。