bronsted酸性离子液体催化合成阿司匹林

以邻苯二胺和环丙基甲酸为原料,以多聚磷酸(PPA)为催化剂,在微波辐射下合成了环丙基苯并咪唑,用碘甲烷季胺化得到未见文献报道的环丙基苯并咪唑盐,通过苯并咪唑盐与Grignard试剂加成后水解反应制备环丙基甲基酮。经元素分析和红外光谱、质谱、核磁共振测试技术表征确证了结构。环丙基甲基酮为无色液体,合成环丙基甲基酮方法的产率为67%,为环丙基甲基酮提供了一种未见文献报道的合成方法。     

Preparation of large ring acetylenic lactones by iodo lactonisation

Reaction of ω-ene-7-yne carboxylic acids with (biscollidine)iodine(I) hexafluorophosphate led to large ring acetylenic lactones. In the case of 5- or 6-yne carboxylic acids, iodo enol lactones were preferentially obtained.     

Manganese-Catalyzed Carbomagnesation of Alkynes

The development of manganese-catalyzed carbomagnesation of alkynes is reviewed. Manganese salts mediate the efficient addition of a variety of Grignard reagents to alkynes. Allyl, aryl, and alkyl Grignard reagents participate in these reactions. In many cases, a hetero atom such as oxygen or nitrogen in substrates facilitates the addition reaction. Stoichiometric carbometalation reactions with manganese ate complexes are also discussed, as is cyclization of 1,6-diynes and 1,6-enynes via carbometalation with triallylmanganate.     

A facile access to natural and unnatural dialkylsubstituted maleic anhydrides

A facile new route to the potential building blocks 2-bromomethyl-3-alkylmaleic anhydrides 15a/b for the synthesis of natural and unnatural dialkylsubstituted maleic anhydrides has been demonstrated, starting from dimethyl citraconate (9) via NBS-bromination, S_N2′ Grignard coupling reactions, hydrolysis, molecular bromine addition and dehydrative ring closure reactions pathway with 49-51% overall yield in 5-steps. Chemoselective allylic substitution of bromoatom in 15a/b with Grignard reagents has been described to obtain the unsymmetrical maleic anhydride 16 and symmetrically dialkylsubstituted maleic anhydrides 25a/b in 55% yield. The naturally occurring 2-carboxymethyl-3-hexylmaleic anhydride (1) has been synthesized from 16 via esterification, ozonolysis and an oxidation route. The synthesis of two naturally occurring 2-(β-carboxyethyl)-3-alkylmaleic anhydrides 2a/b have been completed via a chemoselective diethylmalonate coupling reaction followed by acid induced hydrolysis. In our hands the S_N2 or S_N2′ coupling of Grignard reagent with 21 to obtain 1 and Reformatsky reaction with 15a/b to obtain 2c/d met with failure.     

Syntheses of β－Hydroxy Ketones by Organosamarium

An organosamarium reagent was prepared via the reaction of a-bromoacetophenone with samarium. This organosamarium reagent reacted with aldehydes to give β-hydroxy ketones. A possible reaction process was suggested.     

p-(5-Fluor-2,4-dinitro-1-phenylazo)-N,N-dimethylanilin,ein neues Reagens zur flüssigchromatographischen Bestimmung von Phenolen

The synthesis ofp-(5-fluoro-2,4-dinitro-1-phenylazo)-N,N-dimethylaniline and its reactions with phenoles top-(2,4-dinitro-5-phenoxy-1-phenylazo)-N,N-dimethylanilines and the use of the resulting coloured products for the TLC determination of phenoles is described.

     

Experimental and semiemprical studies of chemical reactivity of dialkylcadmium reagents addition to α,β-enones

Experimental and semiempirical calculations were carried out to study the reactivity of dialkylcadmium reagents addition to α,β-enones. It was demonstrated that α,β-enone such as benzoquinone with low lying LUMO energy reacts via single electron transfer (SET) mechanism with the formation of the 1,2 or 1,4-type alkyl addition product depending on the reaction temperature and substrate structure. Site and chemoselectivity in unsymmetrical benzoquinone derivatives are determined by the stability of the cadmium coordinated semienone complex intermediates and the carbon spin densities of these reactive species respectively. On the other hand, by increasing the LUMO energy of α,β-enone system, the reaction mechanism changes from SET to polar addition affording the 1,4-type alkyl addition product. The establishment of a correlation scale between substrate LUMO energies and reaction mechanism presented in this article will be discussed.     

Cobalt- and rhodium-catalyzed cross-coupling reaction of allylic ethers and halides with organometallic reagents

Reactions of 2-alkenyl methyl ether with phenyl, trimethylsilylmethyl, and allyl Grignard reagents in the presence of cobalt(II) complexes are discussed. The success of the reactions heavily depends on the combination of the substrate, ligand, and Grignard reagent. In the reaction of cinnamyl methyl ether, the formation of the linear coupling products predominates over that of the relevant branched products. In the cobalt-catalyzed allylation of allylic ethers, addition of a diphosphine ligand can change the regioselectivity, mainly providing the corresponding branched products. Rhodium complexes catalyze the reactions of allylic ethers and halides with allylmagnesium chloride and allylzinc bromide, respectively, in which the branched coupling product is the major product.     

Selective adduct formation by furan chemical ionization reagent in gas chromatography ion trap mass spectrometry

The analytical potential of furan as a chemical ionization (CI) reagent was evaluated for selectivity with nine monosubstituted naphthalene compounds. The ion-molecule reactions of furan and tetrahydrofuran (THF) were compared with those of methane, methanol and acetonitrile (prominently producing [M + H](+) ion base peaks) with naphthalene compounds in chemical ionization mass spectrometry (CI-MS). Reactions with furan predominantly show M(+) and [M + 39](+) ions. Based on this phenomenon, investigations were carried out for some of the molecular factors such as proton affinity, substituent effects and the preferred site of [C(3)H(3)](+) ion attachment that influence reactivity in furan CI. High selectivity with different substituents is observed in the formation of [M + 39](+) adduct ion, suggesting its usefulness as selective ionization reagent liquid. The selectivity and sensitivity are illustrated in the analysis of mixture of amino acids. Furthermore, the structure determination and reaction mechanism study is characterized by collision-activated dissociation experiments in CI-MS/MS and CI-MS/MS/MS.     

N-烷基-N-酰基磺酰胺聚苯乙烯基微球作为固相酰化剂的研究

一种可循环使用的固相试剂：N-烷基-N-酰基磺酰胺聚苯乙烯基微球(5), 通过对聚苯乙烯磺酰氯微球树脂进行两步功能基化的修饰反应来制备. 制备过程如下：聚苯磺酰氯树脂(1)与伯胺(2)反应得到聚苯乙烯基N-烷基磺酰胺树脂(3), 树脂3用酰氯(4)或酸酐酰化得到N-烷基-N-酰基磺酰胺聚苯乙烯基树脂(5). 酰化的树脂5作为酰基转移试剂与亲核试剂胺反应得到二级酰胺. 根据5上取代基对酰胺生成的程度的影响结果表明, 烷基R¹和酰基(R²CO)对酰基转移反应活性的大小依次分别为：苯基＞苄基＞甲基＞正丁基＞＞H和对硝基苯甲酰基(苯甲酰基＞乙酰基. 胺的亲核能力对酰胺的收率也有一定的影响. N-苯基-N-苯甲酰基磺酰胺树脂重复使用3次没有发现活性降低.