Effects of Phosphorus Substituents on Reactions of α-Alkoxyphosphonium Salts with Nucleophiles

The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph₃P with Grignard reagents was observed to take place in the presence of O₂ to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments.     

Effects of Phosphorus Substituents on Reactions of α-Alkoxyphosphonium Salts with Nucleophiles

The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph(3) P with Grignard reagents was observed to take place in the presence of O(2) to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments.     

The First Hyperpolarizabilities of Merocarbocyanines

IntroductionPhotorefractive(PR)materialscanbeusedinvariousaPplications,suchasimageprocessing,highdensityopticaldatastorage,opticalinterconnects,andopticalphaseconjugations.However,mostofthereportedPRcomPositesaredopingsystems.ThephaseseparationofcomPonentshaslimitedtheirinvestigation.Toovercomethisdisadvantage,theuseofthemulti-propertieschromophoresmaybeoneoftheeffectiveapproaches.Merocyaninesarenotonlygoodphotoconductivedyes,butalsowidelyusedaschromophoresinnonlinearopticalLBfilmsduetothe…     

The Studies of Rhodium-catalyzed Ring Opening Reaction of N-Boc-azabenzonorbornadiene with Heteroatom Nucleophiles

Since M. Lautens first reported a rhodium-catalyzed asymmetric ring opening reaction of oxabicyclic alkenes to produce dihydronaphthalenol products in high yield and excellent enantioselectivity (ee>90%)1. This methodology also has been applied to the rin…     

Reactions of Dicarbonyl(η5-Cyclopentadienyl)Iron(II)-Complexes of Two Cyclic Enol Ethers with Selected Nucleophiles

Dicarbonyl(η⁵-cyclopentadienyl)iron(II)-complexes of 2,3-dihydrofuran and 3,4-dihydro-2H-pyran rapidly react with carbanionic nucleophiles. The adducts of certain nucleophiles, such as the anion of diethyl malonate, readily isomerise to ring opened products. Ligand exchange reactions and polymerisation compete with the nucleophilic addition reactions of neutral nucleophiles such as enol ethers and indole.     

The First Total Synthesis of 16-Hydroxygeranylgeraniol

Facile synthesis of 16-hydroxygeranylgeranio 1,a naturally occurring alicyclic diterpene,by alkylation reaction of allylic iodide 3 with phenyl sulfone 4,is described.     

The First Total Synthesis of Saurufuran B

First total synthesis of saurufuran B 1, a furanoditerpene, from （E, E）-farnesol 2 and citraconic anhydride 3 through thirteen steps is described. Our work involves two key steps： （1） High regioselective alkylation of 2-（tert-butyldimethylsiloxy）-4-methylfuran 6 with aUylic iodides 5 in the presence of silver wifluoroacetate and （2） Conversion of substituted 7-1actone 7 into furan derivative 8.     

The First Twenty Years of Chinese Journal of Chemistry

尊敬的读者、作者 :　　诞生在祖国改革开放初期的“ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＣｈｅｍｉｓｔｒｙ”(《中国化学》) ,在出版了 2 0 0 2年第 1 2期后 ,已经历经坎坷走过了二十个年头 .值此ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＣｈｅｍｉｓｔｒｙ创刊 2 0周年之际 ,ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＣｈｅｍｉｓｔｒｙ编辑部全体工作人员向多年来一直关心和支持ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＣｈｅｍｉｓｔｒｙ的广大科研工作者和读者表示衷心的感谢 ,向多年来始终关心支持ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＣｈｅｍｉｓｔｒｙ的老…     

First Example of Transition‐Metal‐Free Glaser‐Type Coupling Reaction

In the presence of potassium tert‐butoxide and in toluene, 1,1‐dibromo‐1‐alkenes smoothly generated the corresponding Glaser‐type coupling‐reaction products (1,3‐diynes) in moderate to good yields.     

The First Example of a Supramolecular Structure Containing [2-（1H-Pyrazol-3-yl）-pyridine] Complex and both α- and β-Octamolybdates

The title compound, [Ni（C8N3H7）3]4[Mo8O26]2·6H2O 1, has been synthesized from the reaction of 2-（1H-pyrazol-3-yl）-pyridine （L） with （NH4）2MoO4·2H2O and NiCl2·6H2O. Elemental analysis, IR, UV spectra and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure of the compound. Crystal data： C96H96Mo16N36Ni4O58, Mr = 4451.97, monoclinic system, space group P21/n, a = 20.846（5）, b = 14.825（5）, c = 23.122（5） A ,β= 91.594（5）°, V = 7143（3）A^3, Z = 2, F（000） = 4344, Dc = 2.070 g/cm^3,μ = 1.968 mm^-1, R = 0.0452 and wR = 0.1056 for 17102 independent reflections （Rint = 0.0442） and 11074 observed reflections （I 〉 2σ（I））. Structural analysis indicates that two kinds of octamolybdates （[α-Mo8026]^4- and [β-Mo8026]^4-） co-exist in the compound. This is the first example of a supramolecular structure containing L complex as well as both α- and β-octamolybdate clusters.     

The First Total Synthesis of 4,4′-Biisofraxidin

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　 4 ,4′ Ｂｉｉｓｏｆｒａｘｉｄｉｎ (1) ,ａｎｅｗｂｉｓｃｏｕｍａｒｉｎ ,1ｗａｓｉｓｏｌａｔｅｄｂｙＷａｎｃｈａｉＤｅ Ｅｋｎａｍｋｕｌａｎｄｈｉｓｃｏ ｗｏｒｋｅｒｓｆｒｏｍｔｈｅｒｏｏｔｃｕｌｔｕｒｅｓｏｆｉｍｐａｔｉｅｎｓｂａｌｓａｍｉｎａＬ . (Ｂａｌ ｓａｍｉｎａｃｅａｅ) ,ｗｈｉｃｈｈａｓｌｏｎｇｂｅｅｎｕｓｅｄｉｎＴｈａｉｌａｎｄａｓａｔｒａｄｉｔｉｏｎａｌｆｏｌｋｍｅｄｉｃｉｎｅ .ＴｈｅｌｅａｖｅｓｏｆＢａｌｓａｍｉｎａｃｅａｅａｒｅｕｓｕａｌｌｙｕｓｅｄｆ…     

The First Synthesis of α-Methylene Isophosphindoline Oxide

Abstract

Over the last decade the intramolecular palladium-catalyzed coupling of haloarenes and haloalkenes with alkenes has proven to be a particularly valuable route to a wide variety of the structurally demanding cyclic and polycyclic systems We wish now to demonstrate its successhl application to the synthesis of the first parent representative of the five-membered ring carbon-phosphorus heterocycles possessing exocyclic unsaturation, a class of compounds remaining to date practically unexplored The effected synthesis of the a-methylene isophosphindoline oxide I is delineated in the equation which reveals also the optimized catalytic system and the prerequisite reaction conditions Of those, the reaction temperature is the most crucial parameter as the desired product undergoes unexpectedly facile thermal cyclodimerization to the spiropolycyclic system 2 frequently even precluding the isolation of 1.     

The First Total Synthesis of Triprenylquinone and Hydroquinones

Marine natural products have received much attention for their attractive structural features and biological activities1. Since the isolation of the moritoside, about 10 related triprenylquinones and hydroquinones were isolated. Some of these natural products exhibit interesting biological effects including inhibit cell division of fertilized starfish eggs2 and anti-HIV3. Triprenylquinone and hydroquinones 1, 2 and 3 were recently isolated from endemic nudibranch Leminda millecra collected i…     

First Example of Intramolecular C-H Insertion Reaction in an Amino Acid Derived α-Diazoketone

Rh-Catalyzed intramolecular C-H insertion reaction of L-leucine derived α-diazoketone is described.     

Scope and Limitation for the Reaction of α,β-Unsaturated Carbonyl Compounds with Phosphorus Nucleophiles by Determination of the Half-Wave Potential

Abstract

During the formation of oxaphospholenes the phosphorus in the reagent gets oxidized and the double bond in the enones gets reduced.     

The Importance of Ligand-Induced Backdonation in the Stabilization of Square Planar d10 Nickel π-Complexes

The electronic nature of Ni π-complexes is underexplored even though these complexes have been widely postulated as intermediates in organometallic chemistry. Herein, the geometric and electronic structure of a series of nickel π-complexes, Ni(dtbpe)(X) (dtbpe=1,2-bis(di-tert-butyl)phosphinoethane; X=alkene or carbonyl containing π-ligands), is probed using a combination of ³¹P NMR, Ni K-edge XAS, Ni K_β XES, and DFT calculations. These complexes are best described as square planar d¹⁰ complexes with π-backbonding acting as the dominant contributor to M−L bonding to the π-ligand. The degree of backbonding correlates with ²J_PP from NMR and the energy of the Ni 1s→4p_z pre-edge in the Ni K-edge XAS data, and is determined by the energy of the π*_ip ligand acceptor orbital. Thus, unactivated olefinic ligands tend to be poor π-acids whereas ketones, aldehydes, and esters allow for greater backbonding. However, backbonding is still significant even in cases in which metal contributions are minor. In such cases, backbonding is dominated by charge donation from the diphosphine, which allows for strong backdonation, although the metal centre retains a formal d¹⁰ electronic configuration. This ligand-induced backbonding can be formally described as a 3-centre-4-electron (3c-4e) interaction, in which the nickel centre mediates charge transfer from the phosphine σ-donors to the π*_ip ligand acceptor orbital. The implications of this bonding motif are described with respect to both structure and reactivity.