α-Styrylarsines

The compounds (1) formed by the addition of arsenic trichloride to phenylacetylenes contain several reactive sites and hence are useful synthetic intermediates. We have prepared these compounds in high yield by this route and have examined certain of their properties. The vinylic chlorine, generally stable to reduction, may be quantitatively and readily reduced using a lithium aluminium hydride-lithium hydride mixture. The chlorine atoms attached to arsenic are extremely reactive and readily hydrolysed and hence precautions must be taken to exclude atmospheric moisture from the reaction system. The chlorine atoms will also react on treatment with a Grignard reagent to give the diphenylstyrylarsine (2)     

Ionic liquid-promoted Wagner-Meerwein rearrangement of 16α,17α-epoxyandrostanes and 16α,17α-epoxyestranes

Ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim](+)[PF(6)](-)) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim](+)[BF(4)](-)) were found to promote an unusual Wagner-Meerwein rearrangement of steroidal 16α,17α-epoxides leading to unnatural 13-epi-18-nor-16-one derivatives as the main products. These compounds were isolated in good to excellent yields. 16α-Hydroxy-Δ(13)-18-norsteroids, the results of the usual rearrangement, were obtained as minor components of the reaction mixtures. The ionic liquid [bmim](+)[PF(6)](-) was shown to induce C-ring aromatization of 16α,17α-epoxyestranes due to the formation of HF, the hydrolysis product of [PF(6)](-). Increasing amounts of HF and [PO(2)F(2)](-) were detected by (19)F and (31)P NMR when the ionic liquid was reused. The structures of the steroidal products, 16-oxo-18-nor-13α-steroid derivatives, 16α-hydroxy-Δ(13)-18-norsteroids, and C-aromatic compounds were determined by two-dimensional NMR techniques and high-resolution mass spectrometry (HRMS). The ionic liquids were recirculated efficiently.     

α,α-Difluoro-α-phenylsulfanyl-α-trimethylsilylmethane as a difluoromethyl building block: A general strategy to α,α-difluoromethyl aryl ketones

The synthetic utility of α,α-difluoro-α-phenylsulfanyl-α-trimethylsilylmethane (PhSCF₂SiMe₃; 1) as a difluoromethyl building block providing a general strategy to α,α-difluoromethyl aryl ketones was demonstrated. Oxidation, by using m-chloroperoxybenzoic acid, of the readily available 1-aryl-2,2-difluoro-2-phenylsulfanyl-1-trimethylsiloxyethanes obtained from fluoride-catalyzed nucleophilic addition of PhSCF₂SiMe₃ with aromatic aldehydes followed by flash vacuum pyrolytic elimination provided α,α-difluoromethyl aryl ketones in moderate overall yields.     

Überα,α'-Dichlordimethyläther

Ohne ZusammenfassungMit 1 Abbildung.     

α-Hydroxy- and (α-acyloxyimino)benzylphosphonates

N-Hydroxyfluorobenzimidoylphosphonates and their O-acyl derivatives are synthesized. Reaction of phosphorylated oximes with sulfinyl chloride proceeds with rearrangement and leads to synthetically prospective N-sulfonylimidoylphosphonates. By the method of ¹⁹F NMR are revealed values of σ-constants of N-hydroxy- and N-acyloxy substituted imidoylphosphonate groups.     

Methyl 2,6-Dideoxy-4-α-Methyl-α-D-Arabino-Hexopyranoside

Abstract

Synthesis of methyl 2,6-dideoxy-4-O-methyl-α-D-arabino-hexopyranoside (2) has been accomplished starting from readily available methyl 2-deoxy-α-D-arabino-hexopyranoside (3). The derived 4,6-dimesylate derivative 7 was simultaneously deoxygenated and hydrolysed at C-6 and C-4 with lithium aiuminatm hydride in refluxing tetrahydrofuran. subsequent methyíaíion and debenzy[icaron]ation of 8 gave the title product.     

α-烷基-α-氨基酸的合成

本文研究了八种酮在相转移催化剂存在下与氯仿和氨水的作用。一步得到α-烷基-α-氨基酸和它们的酰胺。用脂肪族甲基酮和环戊酮作原料时,仅得到α-烷基-α-氨基酸一种产物。     

Aryl-NNO-azoxy-α-nitroalkanes

Two methods of synthesis of aryl-NNO-azoxy--nitroalkanes bearing either one or two reactive hydrogen atoms to the azoxy and nitro groups are described. These methods involve protection of the latter by easily removable groupings, those used being acetoxy-methyl and acetal fragments. The regiochemical nature of the diazene oxide groupings in aryl-NNO-azoxy--nitroalkanes obtained by oxidation of the appropriate diazenes has been established by heteronuclear NMR and x-ray structural examination. Some of the chemical properties of these diazene oxides have been examined.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2400–2412, October, 1992.     

Ab Initio Study of Prednisolone, 6α-Fluoroprednisolone, 9α-Fluoroprednisolone,and 6α,9α-Difluoroprednisolone

A theoretical study of prednisolone, 6-fluoroprednisolone, 9-fluoroprednisolone, and 6,9-difluoroprednisolone has been performed at the ab initio HF/6-31G, MP2/6-31G, and B3LYP/6-31G levels. Structural information and the electronic features of prednisolone and its derivatives and the synergistic effect of 6,9-difluoroprednisolone was examined. Contrary to the AM1 and MNDO results, we found 9-fluoroprednisolone is more stable than the 6-fluoroprednisolone. The increased corticosteroid activity of the 6,9-difluoroprednisolone is most likely due to electronic effects, mainly related to the receptor binding.     

α-Heterosubstituted Phosphites

Available hemiacetals and hemithioacetals of -halo--oxoaldehydes were reacted with phosphorochloridites in the presence of organic bases to obtain previously unknown -heterosubstituted phosphites. It is found that the phosphites, depending on the nature of the carbonyl fragment and the heteroatom, enter intramolecular Perkow reaction or decompose to give unsaturated thioethers and chlorophosphate.     

α-酮酸、α-酮酸酯及α-酮酰胺的合成进展

详细综述了双羰化反应和格氏试剂、草酸二乙酯一步法制备不同结构的α－酮酸、α－酮酸酯及α－酮酰胺的研究进展,参考文献23篇。     

一锅煮法合成α,α—双酰基和α—酰基—α—烷氧羰基烯酮环氧硫缩酮

a-氧代烯酮二硫代缩酮是一类具有多个反应中心的合成中间体．近年来，有关其合成、结构及其在有机合成中的应用的研究已有报道．经由a，a－H基烯酮二甲硫代缩酮及活性类似的该类化合物1和胺、醇胺等的取代反应可方便地制得N，N-、N，S-和N，O-缩酮类化合物[4]．虽经许多努力，但试图用1和醇钠反应制取O，S-缩酮的工作一直未获成功［5］．Junjappa[5]用酮和黄酸酯经两步反应实现了a-氧代烯酮O，S-缩酮的合成，我们[6]和李正名等[4]则用巯基乙醇和1的反应合成了这类化合物．上述合成方法若以带活泼亚甲基的化合物为起始物，则为两步反应…     

α,α‘—联吡啶光度法测定微量钌

研究了钌与α，α‘－联吡啶配位反应。在ｐＨ４．６的ＨＡｃ－ＮａＡｃ缓冲溶液和ＮＨ２ＯＨ．ＨＣ存在下，在沸水浴中加热近５ｍｉｎ，钌与α，α’－联吡啶反应形成了１：３配合物，在４５６ｎｍ表观摩尔吸光系数为１．１×１０＾４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１。钌的比尔定律范围０－７０μｇ／２５ｍＬ，方法已被用于氯碱厂阳极泥中钌含量的测定。     

催化光度法测定痕量α，α′－联吡啶

基于α，α′－联吡啶对Ｈ＿２Ｏ＿２氧化靛红的褪色反应的催化作用，本文建立了测定α，α′－联吡啶的新催化光度法，灵敏度为２．２５×１０￣（－９）ｍｏｌ·Ｌ￣（－１），测定范围为０～４×１０￣（－８）ｍｏｌ／２５ｍＬ。     

Aryl-ONN-azoxy-α,α-dinitroalkanes and some of their derivatives

Previously unknownN-dinitroalkyl-NNO-azoxybenzenes have been prepared (by nitration ofN-(-hydroximino) alkyl-NNO-azoxybenzenes) and transformed to some derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1972–1975, November, 1994     

Conformation of α,α,α′-Trisubstituted Cyclododecanone

Ten α,α,α′-trisubstituted cyclododecanones were synthesized and characterized by elemental analyses, infrared, 1^H NMR and 13^C NMR spectra, and X-ray diffraction. NMR data could not give conformational information clearly, but some of their ring skeleton conformations of cyclododecanone moiety were showed to remain the unchanged [3333]-2-one conformation with little distortion, while the others were changed to the [3324]-2-one conformation in their crystal structures. These are consistent with the results of molecular mechanics calculation with Sybyl 6.9 software and Tripos force field, and semi-empirical quantum calculation with AM 1 method in Gaussian 98 software. Two geminal substituting groups are located at α-corner carbon atom, and the third group is at α-side-exo carbon atom in both conformations. Both [3333]-2-one and [3324]-2-one conformations are present in a dynamic equilibrium in the solution, but only one preferred conformation exists in the crystal solid.     

抗meso-四(α,α,α,α-O-苯乙酰苯)卟啉抗体的酶学性质研究

利用小分子ｍｅｓｏ－四(α,α,α,α－Ｏ－苯乙酰苯)卟啉作为全抗原免疫小鼠,通过细胞融合等技术制备了单克隆抗体(ＭｃＡｂ)１Ｆ２,利用高效液相色谱(ＨＰＬＣ)、基质辅助激光解吸飞行时间质谱(ＭＡＬＤＩ/ＴＯＦＭＳ)证明纯化得到的单抗是很纯的．ＭｃＡｂ１Ｆ２的保留时间是２．６３ ｍｉｎ,亚型为ＩｇＧ２ａ,相对分子量为１５６ ６７８．８．ＭｃＡｂ １Ｆ２－卟啉复合物形成时,卟啉Ｓｏｒｅｔ带最大吸收峰从４０８ｎｍ红移到４１６ｎｍ,并有增色效应,说明ＭｃＡｂ１Ｆ２－卟啉是刚性且紧密结合．抗体酶稳定性很高,但比活力只有４．６８７ ５ Ｕ/ｍｇ,为天然酶ＨＲＰ的１．８９９%．抗体酶的Ｋｍ＝２０．２９ ｍｍｏｌ/Ｌ,ｋｃａｔ＝３９６．８２ ｍｉｎ－１,ｋｃａｔ/Ｋｍ＝１．９５５ ７×１０４Ｌ·ｍｏｌ－１·ｍｉｎ－１．     

催化光度法测定痕量α,α‘—联吡啶

基于α，α＇－联吡啶对Ｈ２Ｏ２氧化靛红的褪色反应的催化作用，本建立了测定α，α＇－联吡啶的新催化光度法，灵敏度为２．２５×１０＾－９ｍｏｌ．Ｌ＾－１，测定范围为０～４×１０＾－８ｍｏｌ／２５ｍＬ。     

α,α′-联吡啶光度法测定微量钌

研究了钌与α,α′－联吡啶配位反应。在ｐＨ４．６的ＨＡｃ－ＮａＡｃ缓冲溶液和ＮＨ２ＯＨ·ＨＣｌ存在下,在沸水浴中加热近５ｍｉｎ,钌与α,α′－联吡啶反应形成了１∶３配合物,在４５７ｎｍ表观摩尔吸光系数为１．１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１。钌的比尔定律范围０～７０μｇ／２５ｍＬ,方法已被用于氯碱厂阳极泥中钌含量的测定。