A new reagent for the synthesis of [26]hexaphyrin: N-sulfonyl aldimine

The selective synthesis of [26]hexaphyrin(1.1.1.1.1.1) has been achieved by the reaction of meso-substituted tripyrrane and N-sulfonyl aldimine. The protocol is simple and requires only a catalytic amount of copper(II) triflate under mild reaction conditions.     

镍催化α,β-不饱和醛的选择性α,β-双芳基化反应

三组分双官能化反应是一种高效、简便构建C―C键、C―X键的方式. 双键广泛存在于众多有机化合物中, 对双键的双官能化反应研究有巨大的应用潜力. 本工作以Ni(COD)₂为催化剂, 以芳基溴化镁、芳基溴化物为芳基化试剂, 实现了3-芳基-2-丙烯醛亚胺中碳碳双键的双芳基化反应. 该反应建立了一个新的镍催化α,β-不饱和醛的α,β-双芳基化方法, 可以高度区域选择性地向底物分子中引入两个不同取代的芳环, 得到多种2,3,3-三芳基丙醛骨架的产物. 利用这一反应作为核心步骤实现了天然产物Quebecol的简便合成. 机理研究表明, 该反应可能经历了亲核加成、金属交换、还原消除的历程.     

Chiral trans-carboxylic trifluoromethyl 2-imidazolines by a Ag2O-catalyzed Mannich-type reaction

Trifluoromethyl aldimines derived from α-amino esters have proven to be very good starting materials to obtain the title compounds. A Ag₂O-catalyzed Mannich-type/cyclization cascade reaction starting from suitable α-isocyano acetates leads to enantiopure valuable trans-carboxylic trifluoromethyl substituted 2-imidazolines by a highly stereoselective addition without the need to add organocatalysts.     

含有三苯胺环类席夫碱的合成

以4,4’-二甲酰基三苯胺为原料,通过Wittig和胺醛缩合反应合成了两个含有三苯胺环席夫碱类化合物——4-(对甲基苯乙烯基)-4’-亚(α-萘胺)甲基三苯胺和4-(对甲基苯乙烯基)-4’-亚(2-氨基芴)甲基三苯胺,其结构经1H NMR,13CNMR和IR确证。     

Tridentate anilido‐aldimine magnesium and zinc complexes as efficient catalysts for ring‐opening polymerization of ε‐caprolactone and L‐lactide

A novel tridentate anilido‐aldimine ligand, [o‐C₆H₄(NHAr)? HC?NCH₂CH₂NMe₂] (Ar = 2,6‐ⁱPr₂C₆H₃, L ‐H, 1 ), has been prepared by the condensation of N, N‐dimethylethylenediamine with one molar equivalent of 2‐fluoro‐benzaldehyde in hexane, followed by the addition of the lithium salt of diisopropylaniline in THF. Magnesium (Mg) and zinc (Zn) complexes supported by the tridentate anilido‐aldimine ligand have been synthesized and structurally characterized. Reaction of L ‐H ( 1 ) with an equivalent amount of MgⁿBu₂ or ZnEt₂ produces the monomeric complex [ L MgⁿBu] ( 2 ) or [ L ZnEt] ( 3 ), respectively. Experimental results show that complexes 2 and 3 are efficient catalysts for ring‐opening polymerization of ε‐caprolactone (CL) and L ‐lactide (LA) in the presence of benzyl alcohol and catalyze the polymerization of ε‐CL and L ‐LA in a controlled fashion yielding polymers with a narrow polydispersity index. In both polymerizations, the activity of Mg complex 2 is higher than that of Zn complex 3 , which is probably due to the higher Lewis acidity and better oxophilic nature of Mg²⁺ metal. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4927–4936, 2009     

Chemoselective Synthesis of β‐Amino Ester or β‐Lactam via Sonochemical Reformatsky Reaction

A series of β‐amino esters were synthesized by the reaction of N‐tosyl aldimine or N‐hydroxy aldimine with bromoacetate by sonochemical Reformatsky reaction. The β‐N‐hydroxyamino ester was obtained and the formed sensitive hydroxylamino functionality was resistant under the reaction condition. The β‐lactam also was synthesized by the reaction of N‐p‐methoxy aldimine as reacting substrate under this sonochemical Reformatsky reaction condition.     

Green,Catalyst-Free Protocol for the Efficient Synthesis of N-Sulfonyl Aldimines and Ketimines in Ionic Liquid [Bmim]Br

Sulfonamides are efficiently condensed with aldehydes as well as ketones in the absence of catalyst in 1-butyl-3-methylimidazolium bromide ([bmim]Br) under microwave irradiation to afford N-sulfonyl aldimines and ketimines in good to excellent yields in short reaction times.     

Synthesis of 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl

Condensation of -(hydroxylamino)-2-methylpropanal with acetone and ammonia afforded 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl, the first member of a series of stable nitroxyl radicals which are derivatives of 3-imidazoline. It was shown that 2,2,5,5-tetramethyl-2, 5-dihydropyrazine-1,4-dioxide can reversibly add two molecules of water or ammonia to the nitrone groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 931–933, May, 1993.     

3,3-二取代3-吲哚-3'-基氧化吲哚的立体选择性合成

以10 mol%(R,R)-环己二胺衍生的手性双功能硫脲叔胺(4b)为催化剂,3'-吲哚-3-氧化吲哚与α-氨基砜为原料,经3'-吲哚-3-氧化吲哚与原位生成的N-Boc芳香醛亚胺的不对称Mannich反应,合成了20个3,3-二取代3-吲哚-3'-基氧化吲哚类化合物(3a~3t),分离收率54%~98%,dr值90∶10~99∶1,其结构经~1H NMR,~(13)C NMR和HR-MS(ESI-TOF)表征。     

Imine Reduction with Me2S-BH3

Although there exists a variety of different catalysts for hydroboration of organic substrates such as aldehydes, ketones, imines, nitriles etc., recent evidence suggests that tetra-coordinate borohydride species, formed by activation, redistribution, or decomposition of boron reagents, are the true hydride donors. We then proposed that Me₂S-BH₃ could also act as a hydride donor for the reduction of various imines, as similar compounds have been observed to reduce carbonyl substrates. This boron reagent was shown to be an effective and chemoselective hydroboration reagent for a wide variety of imines.