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.     

A facile stereoselective synthesis of (E)-1,2-disubstituted vinylstannanes via hydromagnesiation of alkylarylacetylenes

Hydromagnesiation of alkylarylacetylenes 1 in diethyl ether gave (E)-α-arylvinyl Grignard reagents 2, which reacted with trialkylstannyl chlorides 3 in diethyl ether to afford stereoselectively (E)-1,2-disubstituted vinylstannanes 4 in high yields.     

水溶性高负责担载二茂铁希夫碱与DNA的作用

利用荧光探针技术和凝胶电泳等分析方法，对水溶性高分子聚丙烯酸-N-乙烯 基吡咯烷酮和聚甲基丙烯酸-N-乙烯基吡咯烷酮担载的二茂铁希夫碱与DNA的作用进 行了初步研究。实验结果表明：所合成的高分子二茂铁希夫碱在同DNA作用时存在 有静电作用和嵌入模式，由于水性基团的引入和高分子链的协同效应，促进了配合 物同DNA的这种作用．     

用反相离子对色谱分离和检测水溶性维生素——十二烷基磺酸钠作离子对试剂

本文使用十二烷基磺酸钠(SDS)作离子对试剂,研究了用反相离子对色谱法对混合水溶性维生素的检测和分离,确定了最佳实验条件,包括SDS浓度,pH值,甲醇与水的配比,三乙胺浓度及柱温等。用本方法对九种混合水溶性维生素〔B_1,B_2,B_5(烟酰胺和烟酸),B_6(吡哆醛和吡哆醇),B_(11),B_(12)和C〕的标样和西瓜汁的分离表明,在所选定的实验条件下,可于10min内一次分离。     

A Facile Preparation of Tebbe Reagent and its Subsequent Reactions

A facile preparation of Tebbe reagent (1) by reacting AlMe₃ solution with Cp₁TiCl₂ is reported. After complete removal of solvent and excess of AlMe₃, the crude Tebbe reagent could be used without purification to react with ketones in a Wittig-type manner.     

新显色剂2—（4—安替比林偶氮）—4，5—二羧甲氧基苯甲酸与铋显色反应的研

光度分析法测定铋的显色剂较多，￣［１～４］但灵敏度不甚高。作者合成一尚未见报道的试剂，２—（４—安替比林偶氮）—４，５一二羧甲氧基苯甲酸（ＡＡＤＣＢ），能与Ｂｉ￣（３＋）发生高灵敏的显色反应（ε＝２０．８ｘ１０￣４Ｌ／ｍｏｌ．ｃｍ），且表现出较好选择性。     

Ab initio study of reactions of 1‐halogen‐3‐methoxy‐1‐propynes with Grignard reagent

The structures of coordination complexes of methylmagnesium chloride with 1‐halogen‐3‐methoxy‐1‐propynes have been studied by means of ab initio methods (RHF/3‐21G*, RHF/6‐31G* and RHF/6‐31G**), taking into account the electron correlation by Møller‐Plesset perturbation theory (MP2). Two pathways of the nucleophilic halogen substitution reaction between the reagents have been considered. The calculations predict the addition–elimination mechanism as advantageous for the reaction. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Synthesis and applications of 3,4-dihydroxy-2,5-bis-(2′-(4′-substituted-oxazolinyl)) furan

Three 3,4-dihydroxy-2,5-bis-(2′-(4′-substituted-oxazolinyl)) furans were synthesized at 90%–94% yields from reaction of 3,4-dihydroxyfuran-2,5-dicar-boxylic acid or its dimethyl ester with chiral β-amino alcohol via a one-step process. Their chemical structures were determined by ¹H NMR, IR, MS, and elemental analysis. With these chiral bisoxazoline ligands, the asymmetric reductive reaction of β-acetonaphthalene with KBH₄ or NaBH₄ was preliminarily studied. The enantiomeric excess of the reduction product was up to 83.2% with cyclohexane as the solvent, the molar ratio of ligand: reductive agent: β-acetonaphthalene is 0.04:1.6:1, and 72-hours reaction time at 0°C. Furancontaining bisoxazoline with 4-benzyl on oxazoline rings exhibited higher enatioselectivity than congeneric bisoxazolines with 4-ethyl on oxazoline rings. __________ Translated from Chinese Journal of Applied Chemistry, 2005, 22(12) (in Chinese)     

新荧光试剂5-(4′-氯-2′-羧基苯基偶氮)-4-氧代-2-硫代四氢噻唑的合成及分析应用研究

本文报道了新荧光试剂5-(4’-氯-2’-羧基苯基偶氮)-4-氧代-2-硫代四氢噻唑(CC-POST)的合成及其荧光分析应用。确证了其结构。在pH=5.0～5.4时。它与铜(Ⅱ)形成荧光螯合物。λ_(ex)/λ_(em)=310mn/408nm,检测限为0.5ng/g。用此法测定了茶叶中的痕量铜,结果满意。