二氧杂环丙烷参与的烯烃环氧化反应

酮是催化烯烃环氧化反应的一类重要催化剂, 酮与氧化剂KHSO₅ (Oxone)可原位产生二氧杂环丙烷中间体, 然后二氧杂环丙烷中间体将氧原子传递给烯烃使之成为环氧化物, 而自身又生成原来的酮. 酮的催化效能大小与酮产生二氧杂环丙烷的能力、二氧杂环丙烷将氧原子传给烯烃的能力以及反应条件下酮的稳定性有关. 本工作对各种脂肪酮、脂环酮、杂环酮对烯烃环氧化催化能力的大小及其影响因素进行了评述.     

Sulfinyl-Mediated Stereoselective Functionalization of Acyclic Conjugated Dienes

The chemo- and stereocontrolled functionalization of conjugated sulfinyl dienes in a cascade process that involves a conjugate addition, diastereoselective protonation and a [2,3]-sigmatropic rearrangement is reported. Enantioenriched 1,4-diol and 1,4-aminoalcohol derivatives are obtained in a very straightforward manner. Further functionalization of these structures, including highly stereoselective epoxidation, dihydroxylation and the stereodivergent synthesis of several polyols in a controlled fashion is described.     

Nickel-Catalyzed Allylmethylation of Alkynes with Allylic Alcohols and AlMe3: Facile Access to Skipped Dienes and Trienes

We present herein an unprecedented allylative dicarbofunctionalization of alkynes with allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD)₂, triphenylphosphine, and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all-carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes.     

The Stereoselective Epoxidation by a New Type of Soluble Polymer-Supported Catalysts

As the phase transfer catalyst (PTC) is one of most important catalysts in organic synthesis. Here, we represent initial results of a research program aimed at the rational design of a variety of new two centers, soluble polyethylene glycol (PEG) supported catalysts based on the cinchona alkaloid system and their application in asymmetric expoxidation process.Table 1 and Table 2 summarized the results of epoxidation of substituted chalcone As shown in Table 1 and Table 2, chalcone derivatives as reactive olefins afforded the corresponding epoxided with modest to good enantiomeric excesses. In contrast, a definite trend to higher ee value is displayed by solvent effect. It was found that enantioselectivity becomes higher with the polarity increases(Table 1, Table 2). Changing catalyst 1 to catalyst 2, ee value was increased (entry 6 in Table 1) as well. Compared with Me, NO2 groups, substitution on the aromatic ring of the enone carbonyl function by OMe group increased the enantioselectivity(entry 3 in Table 1 and entry 3' in Table 2).     

Mycobacterium E3休止细胞催化烯烃立体选择性环氧化

初步研究了ＭｙｃｏｂａｃｔｅｒｉｕｍＥ３的生长和产酶特性，利用ＭｙｃｏｂａｃｔｅｒｉｕｍＥ３休止细胞催化烷羟化和烯烃环氧化，研究结果表明，烷烃不能被羟化，烯烃环氧化具有底物选择性，对烯丙基型底物ＸＣＨ２ＣＨ＝ＣＨ２（Ｘ＝Ｈ，Ｃｌ，Ｂｒ，ＯＨ）取代基大小显著性环氧化活性，ＭｙｃｏｂａｃｔｅｒｉｕｍＥ３中烯烃单加氧酶和另一种结构未知的酶的存在导致烯烃环氧化过程中存在环氧化物的立体选择性形成和非立体选择     

Nickel‐Catalyzed Allylmethylation of Alkynes with Allylic Alcohols and AlMe3: Facile Access to Skipped Dienes and Trienes

We present herein an unprecedented allylative dicarbofunctionalization of alkynes with allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD)₂, triphenylphosphine, and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all‐carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes.     

Formal Synthesis of (+)-Altholactone by Stereoselective Epoxidation Using Magnesium Monoperoxyphthalate (MMPP)

( + ) Ａｌｔｈｏｌａｃｔｏｎｅ ,ａｍｅｍｂｅｒｏｆｎｅｗｔｙｐｅｏｆｃｙｔｏ ｔｏｘｉｃｎａｔｕｒａｌｓｔｙｒｙｌｌａｃｔｏｎｅ ,ｈａｓｂｅｅｎｋｎｏｗｎｔｏｐｏｓｓｅｓｓａｎｔｉｔｕｍｏｒａｃｔｉｖｉｔｙａｇａｉｎｓｔｍｕｒｉｎｅＰ338ｌｅｕｋｅｍｉａａｎｄｓｈｏｗｌｅｔｈａｌｉｔｙｔｏｂｒｉｎｅｓｈｒｉｍｐ .1Ｒｅｃｅｎｔｌｙ ,ａｒｅｐｏｒｔｏｎｉｔｓｓｔｒｕｃ ｔｕｒｅ ａｃｔｉｖｉｔｙｒｅｌａｔｉｏｎｓｈｉｐ2 ａｎｄｐａｐｅｒｓｏｎｔｈｅａｐｐｌｉｃａｔｉｏｎｏｆｎｅｗｓｙｎｔｈｅｔｉｃｍｅ…     

Efficient Protocol for Stereoselective Epoxidation of Cinnamic Esters Using TsNBr2

An efficient method has been developed for the synthesis of epoxide from cinnamic esters without any catalyst. The reaction was performed in CH₃CN–water (4:1) using N,N-dibromo-p-toluenesulfonamide (TsNBr₂) in alkaline conditions. This procedure can be utilized for stereoselective synthesis of epoxides from cinnamic esters in excellent yield in a shorter reaction time with exclusive formation of the trans-isomer. The method was further extended successfully for styrenes.     

Diels-Alder Reactions of 5,8-Ethano-5,8-dihydro-1,4-naphthoquinone with Cyclic Dienes

Diels-Alder cycloadditions of 1,3-cyclohexadiene and cyclopentadiene to π -facially dissymmetric 5,8-ethano-5,8-dihydro-1,4-naphtboquinone (1) were examined. The stereochemical outcome of the reactions, determined by a combination of chemical and spectral methods, indicates that addition of cyclic dienes to 1 occurs preferentially at the face syn to the etheno-bridge of 1. Cycloadducts 7a/7b and 8a/8b obtained from Diels-Alder reactions of 1 with cyclopentadiene and 1,3-cyclohexadiene undergo [2+2]-photocyclization to give caged compounds 9a/9b and 10a/10b , respectively. Stereoselective reduction of the enedione double bond in 7a/7b and 8a/8b with aqueous TiCl₃ in acetone affords cis-bis-bicyclic ring-fused 1,4-cyclo-hexadiones 11a/11b , and 12a/12b , respectively.     

Cyclic and Acyclic N═N Bonds in Reactions with Some Alkenes and Dienes

The kinetics of the Diels–Alder (DA) reactions of 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione 1 , trans‐diethyl azodicarboxylate 2 , and tetracyanoethene 3 with 1,3‐cyclohexadiene 4 , cycloheptatriene 5 , 1,3‐cycloheptadiene 6 , cyclooctatetraene 7 , and 1,3‐cyclooctadiene 8 in a range of temperatures and pressures has been studied. Values of the enthalpy, entropy, and volume of activation, as well as the enthalpy and volume of reaction have been obtained. Observed reaction rates of 5+1 and 7+1 have been compared with the known rate of norcaradiene 17 formation in the equilibrium , and that of bicyclo[4,2,0]‐octa‐2,4,7‐triene 20 in the equilibrium . The kinetic data show that the rate of formation of 17 from 5 is much greater than the loss rate of dienophile 1 in reaction of 5+1 . In contrast, the formation rate of tautomer 20 is less than the loss rate of dienophile 1 in reaction of 7+1 . This reflects that the consecutive reaction of 5 → 17 (+ 1 ) → 15 is possible whereas the consecutive reaction of 7 → 20 (+ 1 ) → 22 does not occur as the only way.     

Applications of Allylsamarium Bromide as a Grignard Reagent and a Single‐Electron Transfer Reagent in the One‐Pot Synthesis of Dienes and Trienes

The utility of allylsamarium bromide, both as a nucleophilic reagent and a single‐electron transfer (SET) reagent in the reaction of α‐halo, γ‐halo‐α,β‐unsaturated ketones and esters with allylsamarium bromide is reported for the first time in this paper. From a synthetic point of view, a general, efficient and experimentally simple one‐pot method for the preparation of 1,4‐dienes and trienes is developed. A possible mechanism of the transformation is proposed.     

Stereoselective synthesis and Diels-Alder reactions of bis-Ether 1,3 Dienes. A further test for cooperativity during cycloaddition reactions.

A stereoselective synthesis of dienes $\text{1a}$ and $\text{1b}$, using butadiene-iron tricarbonyl complexes, is described. Higher diastereoselectivity is observed during Diels-Alder reaction of $\text{1a}$ as compared with $\text{1c}$, affording good evidence for cooperativity in these cycloadditions.     

过氧化酮(Dioxiranes)的研究和应用新进展

介绍了近十年过氧化酮的研究及应用情况, 并对其机理研究进行了跟踪.