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.     

An Efficient Synthesis of Stable Sulfur-Containing Phosphoranes Derived from 1-Methylimidazole-2-thiol

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of 1-methylimidazole-2-thiol. These sulfur-containing phosphoranes exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. Using dibenzoylacetylene as Michael acceptor, yields 2-[1-methyl-1 H -imidazole-2-yl)sulfanyl]-1,4-diphenyl-butane-1,4-dione.     

Stable 1,6-Diionic Phosphorus Betaines Derived from Electron-Deficient Acetylenic Compounds

The addition of triphenylphosphine to methyl propiolate, ethyl propiolate, or ethynyl methyl ketone in the presence of a strong NH-acid, such as 5-nitro-2,4-dihydro-3 H -1,2,4-triazol-3-one, leads to stable 1,6-diionic organophosphorus compounds in excellent yields.     

Synthesis of a Bicyclic Diamine Derived from Kemp's Acid

A bicyclic diamine with defined and stable conformation in solution was prepared from Kemp's triacid. The efficient four-step synthesis of the Boc-protected diamine requires only a single purification by column chromatography. X-ray analysis and NMR spectroscopy confirm the structure of the diamine in the solid state and in solution.     

A Simple Synthesis of Stable Phosphoranes Derived from Imidazole Derivatives

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of strong NH-acids, such as imidazole, 2-methylimidazole, 4-methylimidazole, 2-ethylimidazole, benzimidazole, and 5,6-dimethylbezimidazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

A Facile and Efficient Synthesis of Organocyclosiloxanes

A new facile preparative method for the synthesis of organocyclosiloxanes is reported. Ring closure of the dichlorosilanes with NaHCO 3 and pyridine gave mixture of organocyclosiloxanes with cyclotrisiloxane as a main product.     

A Simple Synthesis of Stable Heterocyclic Phosphorus Ylides Derived from NH-Acids

Crystalline phosphorus ylides are obtained in excellent yields from the addition reaction between triphenylphosphine, dimethyl acetylenedicarboxylate and strong NH-acids, such as 2-acetylpyrrole, indole, ethyl 3-indolylglyoxalate and N -benzyl-2-pyrrolylglyoxamate. Dynamic NMR effects are observed in the 1 H NMR spectra of stabilized ylides obtained from 2-acetylpyrrole and indole ( j G p = 67.1 and 68.8 kJmol m 1 respectively) and are attributed to restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

A Simple Synthesis of Stable Phosphoranes Derived from Imides or Acetanilide Derivatives

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and strong NH-acids, such as acetanilide, 4-methylacetanilide, 2-cyanoacetanilide, 4-bromoacetanilide, 4-methoxyacetanilide, succinimide, malimide, or phthalimide. These stabilized phosphoranes exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

Introduction of a Novel Reaction of Triacetylmethane: One-Pot Synthesis of Dialkyl-2-(3,1-hydroxyethylidene-2,4-pentanedione-3-yl)-3-(triphenylphosphoranylidene)-butanedioate

Protonation of reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylate by 3-(1-hydroxyethylidene)-2,4-pentanedione leads to vinyl phosphonium salts, which undergo Michael addition with the conjugate base of CH-acid to produce the title compounds in high yield.     

An Efficient Synthesis of Stable Phosphorus Ylides Derived from Hydantoin and 5,5-dialkylhydantoins

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as hydantoin and 5,5-dialkylhydantoins. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

Efficient,Simple Synthesis of Stable Phosphorus Ylides Derived from 4-Aryl Urazoles

Crystalline phosphorus ylides are obtained in nearly quantitative yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and 4-aryl urazoles.     

拓扑替康中三个有关物质的合成

采用易得的原料、简单的化学方法和方便的操作,设计了新的合成路线,制备了拓扑替康药物报批中的三种相关杂质。分别由拓扑替康盐酸盐(1)经游离、酯水解开环反应制备得到了拓扑替康羧酸钠盐(2),由拓扑替康(11)经正丙醇取代反应制备得到9-丙氧甲基-10-羟基喜树碱(4),以及由10-羟基喜树碱(5)经羟甲基化反应制备得到9-羟甲基-10-羟基喜树碱(3)。     

1,2,4-Triazoles,II Synthesis of 1,5-diphenyl-3-trifluoromethyl-1H-1,2,4-triazoles

Reaction of substituted phenylhydrazines1 a–f with methyl trifluoroacetimidate2 gives via the amidrazones3 after treatment with benzoyl chlorides4 the triazoles5 a–f which showed an anti-inflammatory effect.Presented at the 1st Belgian Organic Synthesis Symposium, Namur, 19–23 May, 1986.     

Complexes of Macroheterocyclic Compounds Derived from Substituted 1,2,4-Triazoles with Tetravalent Metals

Symmetrical marcoheterocyclic compounds derived from substituted 1,2,4-triazoles were reacted with tin(IV) and titanium(IV) chlorides to prepare the corresponding metal complexes. Macroheterocyclic compounds insoluble in organic solvents give mixtures of products on complex formation.     

Silver-Enabled Cycloaddition of Bicyclobutanes with Isocyanides for the Synthesis of Polysubstituted 3-Azabicyclo[3.1.1]heptanes

Synthesis of bicyclic scaffolds has emerged as an important research topic in modern drug development because they can serve as saturated bioisosters to enhance the physicochemical properties and metabolic profiles of drug candidates. Here we report a remarkably simple silver-enabled strategy to access polysubstituted 3-azabicyclo[3.1.1]heptanes in a single operation from readily accessible bicyclobutanes (BCBs) and isocyanides. The process is proposed to involve a formal (3+3)/(3+2)/retro-(3+2) cycloaddition sequence. This novel protocol allows for rapid generation of molecular complexity from simple starting materials, and the products can be easily derivatized, further enriching the BCB cycloaddition chemistry and the growing set of valuable sp³-rich bicyclic building blocks.     

A Simple Synthesis of Stable Phosphorus Ylides Derived from 2-Benzoxazolinone and 2-Mercaptobenzoxazole

The reaction of triphenylphosphine with dialkyl acetylenedicarboxylates in the presence of a strong SH-acid or NH-acid, such as 2-mercaptobenzoxazole and 2-benzoxazolinone, has been studied. In some cases, stable phosphorus ylides are obtained in excellent yields. The ylide moiety of these compounds is strongly conjugated with the adjacent carbonyl group, and the rotation about the partial double bond in (E) and (Z) geometrical isomers is slow on the NMR time scale at an ambient temperature. Thus, these exist as a mixture of geometrical isomers.     

赖氨酸衍生氮杂大环化合物的固相合成

基于固相载体的假稀释效应, 设计并合成了由赖氨酸为前体结构衍生的氮杂大环化合物8, 9, 10, 12及13. 合成中的关键构件是在固相树脂上肽链的N端键合的二个相邻的赖氨酸残基, 并以溴乙酸为桥连组份, 先后经酰化及亲核取代(S_N2)反应完成三氮杂十六元环骨架的构建. 5种粗产物的总收率在68.9%～86.1%之间, 并全部经氨基酸组成分析及ESI-MS分析表征.     

Synthesis and Reactivity of Bicyclic Phosphoric (and Thiophosphoric) Amides

This work summarizes studies on the preparation, structure, and reactivity of a new heterocyclic system containing phosphorus and nitrogen: 2,8-disubstituted-2,5,8-triaza-1 u 5 -phosphabicyclo[3.3.0]octane 1-oxide (and 1-sulfide).     

3'-氟-2'-O,3'-C-乙烯基键联并环尿苷的合成与表征

设计合成了氟化并环核苷衍生物3'-氟-2'-O,3'-C-乙烯基键联的并环尿苷(1), 并通过¹H NMR, ¹³C NMR和HRMS分析表征了其结构. 同时, 对具有乙炔基及氟原子取代的重要中间体7的结构进行了分析确证, 并提出其可能的形成机理.     

Vinylphosphonium Salt Mediated One-Pot Stereoselective Synthesis of Dialkyl 3,3-Diacetyl-3 a -hydroxy-8-oxo-2,3,3 a ,8-tetrahydrocyclopenta-[ a ]indene-1,2-dicarboxylates

Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine (or tributylphosphine) and dialkyl acetylenedicarboxylates by acetylacetone leads to sterically congested phosphorus ylides, which undergo an intermolecular Wittig reaction with ninhydrin and concomitant annulation in CH 2 Cl 2 at room temperature to produce dialkyl 3,3-diacetyl-3 a -hydroxy-8-oxo-2,3,3 a ,8-tetrahydrocyclopenta[ a ]indene-1,2-dicarboxylates in fairly high yields.