1-卤代杂氮硅三环的合成

作者曾对具不同环骨架和不同R取代基的杂氮硅三环(silatrane,简称硅三环)进行过研究.其中硅与R间均为Si—C键.标题化合物中高电负性的卤素与硅直接成键,因而是一组考察硅三环各种性质的典型化合物.     

氮杂硅三环类化合物的质谱研究

本文对二十四个氮杂硅三环类化合物进行了质谱研究.测定了它们的低分辨质谱,收集了大部分化合物的高分辨质谱数据并进行了亚稳跃迁测定。结果表明,分子离子的稳定性、基峰的生成方式以及碎片离子的多少主要取决于取代基R的性质.分子的电子轰击质谱裂解存在三种基本方式:(1)断裂Si～R键,生成高度稳定的(M-R)~ 离子,碎片离子较少;(2)开环,失去碎片C_2H_3O;(3)开环,失去碎片CH_2O或CH_3O.用电荷自由基定域理论解释这类化合物的质谱裂解机理,并对影响分子离子稳定性的有关因素及影响基峰形成的原因进行了讨论.     

取代杂氮硅三环的核磁共振及分子动力学研究

对取代的杂氮硅三环类化合物(Silatrane)-(3R,4S)-1-氯甲基杂氮硅三环-4-羧酸(1)和(3R,4S)-1-氯甲基-3-甲基杂氮硅三环-4-羧酸(2)及它们相应的三乙基铵盐(3)和(4)的结构采用^1H,^1^3C,^2^9Si NMR进行研究, 其一维^1H NMR谱根据二维同核和异核相关谱进行了归属。从测得的偶合常数及化学位移分析, 得出羧基及其铵盐的取代造成相邻另外两环上的-CH2-CH2-O-链上二面角发生扭拐,成为拐折旁式构象。分子动力学方法的模拟计算证明了这种构象变化。另外根据溶液中^2^9Si及^1H的化学位移实验结果, 讨论了该类化合物环上取代对分子内配键(N-Si)的影响。     

杂氮硅三环类化合物的X-射线光电子能谱(XPS)和EHMO计算研究

本文用X-射线光电子能谱(XPS)研究了二十种硅上带有不同取代基(R)的杂氮硅三环类化合物,并对其中R为F,Cl,Br,I,CH_3,H,CH=CH_2,CH_2Cl,CHCl_2等九种该类化合物做了EHMO(广义Hückel分子轨道法)理论计算处理。从杂氮硅三环类化合物各组成元素的XPS谱,不但再次证明了这类化合物分子中N→Si配位键的存在,并得到不同取代基(R)对N→Si配位键强度的影响。EHMO计算求得的原子净电荷(Q)与不同取代基(R)所引起的N_(1s)和Si_(2p)结合能位移有线性关系。而计算的键序能很好地预言实验中取代基(R)的改变对N→Si配位键强度的影响。同时计算表明,在该类化合物中,其N→Si配位键的强度约为相应的Si—O共价键平均键强的一半。     

杂氮硅三环类化合物15N NMR研究

本文对杂氮硅三环类化合物作了15N核磁共振研究,并用CNDO/II方法对部分化合物进行了量子化学计算。导出了15N化学位移随硅上取代基R的Taft极性取代常数σ和氮原子净电荷密度线性变化的规律。从实验和理论两方面进一步证实了杂氮硅三环类化合物分子中存在着Si←N配位键。     

乙撑双(2,2,5,5-四甲基-1-氮-2,5-二硅环戊烷)的合成及结构

2,2,5,5-四甲基-1-氮2,5-二硅环戊烷及双-(二乙氨基二甲基硅基)乙烷分别与乙二胺进行胺解反应均生成标题化合物,结构单晶经X射线分析确证.晶体属正交晶系,空间群为Pcab,晶胞参数a=11.043(3),b=12.811(2),c=16.090(4)A;V=2276A[3];Z=4;D0=1.01g.cm[-3],μ=2.53cm[-1].结构分析表明,分子具有对称中心,环系中的五个原子处于近乎同一平面内,氮原子系平面构型,因而使氮原子的未公用电子对所占P轨道与相连硅的3d轨道之间的作用更为有利;环中的Si-N-Si键角为114.5度.较相应开链类似物[(CH3)3Si]2NH中的Si-N-Si键角(131.3度)显著为小,这可能就是乙二胺中氮上的四个氢在胺解条件下能同时被四个硅基取代的原因.     

1-杂环芳酰氧基-2,8,9-三氧杂-5-氮杂-1-硅杂三环[3.3.3.0~(1,5)]十一碳烷的研究

本文合成了六个1-杂环芳酰氧基杂氮硅三环和三个1-杂环芳酰氧甲基杂氮硅三环,这些化合物均未见文献报道。通过1~H NMR、IR 和 X 射线衍射的方法,确证上述化台物为五配位结构,分子内的 N→Si 配键强度较大。这是一类低毒或中毒化合物。     

杂氮硅三环侧链上基团转换反应的研究

2,8,9-三氧杂-5-氮杂-1-硅双环[3,3,3]十一碳烷(简称杂氮硅三环)是一类具有五配位键的有机硅化合物。有关它的合成方法和其物理化学性质,文献中已报道甚多。但有关硅三环上与硅侧链相连接的有机基团的转换反应或其它反应研究的还很不够。我们认为进行这方面工作是很有意义的,因为一般硅三环都是从相应的三烷氧基硅烷与三乙醇胺反应制得。如果能从一种硅三环开始进行基团转換来得到一系列其它基团的硅三环,这就为这一类化合物的合成提供新路线。与此同时,还可研究硅三环在各种合成条件     

大二环型侧向穴醚的合成

本文报道一个大二环型侧向穴醚的合成方法借2,6-二(溴甲基)吡啶与β-(N-对甲苯磺酰基)丙氨酸酯缩合,产物经水解成酸后转换为酰氯(8),8借高度稀释法与1,7-二氮杂-4,10-二硫杂环十二烷(5)缩合成环,然后还原羰基.脱对甲苯磺酰基后得大二环型侧向穴醚1,5,13,17,28-五氮杂-20,25-二硫杂-三环[15,5,5,1~(7,11)]-廿八-7,9,11(28)三烯(2).     

具有生物活性的有机硅化合物的研究VII.1-芳酰氧基-2,8,9-三氧杂-5-氮杂-1-硅杂三环[3,3,3,0[1.5]]十一碳烷的研究

用新的方法合成了九个1-芳酰氧基2,8,9-三氧杂-5-氮杂-1-硅杂三环[3.3.3.0[1,5]]十一碳烷(简称 1-芳酰氧基杂氮硅三环)。本方法具有产率高,后处理简便等优点。X-射线晶格衍射确定了该类化合物分子内N→Si键键长较短,说明配键强度较大。报道该类化合物的IR, 1H NMR及MS,并讨论了质谱断裂机理。     

含杂环卡宾碳的铁羰基簇合物的结构化学研究Ⅱ．—Fe_3(CO)_8[:CNHC(S)C(CH_3)_2NH]的合成和晶体结构

Ｆｅ３（ＣＯ）＿（１２）和取代２，４＿二硫代乙内酰脲反应，得到新的取代物Ｆｅ３（ＣＯ）＿８－［：ＣＮＨＣ（Ｓ）Ｃ（ＣＨ＿３）＿２ＮＨ］（μ＿３－Ｓ）＿２，并进行了ＩＲ、１￣ＨＮＭＲ、ＭＳ表征，测定了它的分子和晶体结构，讨论了杂环卡宾碎片：ＣＮＨＣ（Ｓ）Ｃ（ＣＨ＿３）＿２ＮＨ的取代位置，它是通过卡宾碳原子与Ｆｅ配位。     

Polymers containing formamidine groups. VI. Structural influences on the formation of cyclic trimers

The reaction of different metasubstituted aromatic diamines with triethylorthoformate (TEOF) was investigated. Whereas the conversion of 1,3‐phenylenediamine 1a resulted in an oligomeric polyformamidine, the formation of cyclic trimers was observed when nitrogen‐containing aromatic diamines such as 2,6‐diaminopyridine 1b , 2,4‐diaminopyrimidine 1c , and 2,4‐diamino‐6‐methyl‐1,3,5‐triazine 1d were used. The extent of cyclization depended on the number of nitrogen atoms in the aromatic ring and could be attributed to energetically favored conformations of the chain segments. In the case of 1b , cyclization was quantitative. The results were supported by a conformational analysis concerning the rotational barriers of the aromatic rings in the respective dimers. The reaction products were characterized by means of NMR and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric investigations. In the reaction product of 1d , strong hydrogen‐bonded associates between the oligomers and the monomer were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1280–1287, 2001     

亚硫酸四氟乙二醇酯的环断裂反应

含有亚硫酸四氟乙二醇酯(1)的四氟乙烷磺内酯(2)与H(CF_2)_4CH_2OH和三乙胺反应可获得草酸酯(CO_2CH_2CF_2CF_2—CF_2CF_2H)_2(3)。化合物(3)生成的机理解释为由于1的破环,生成了SOF_2和(COF)_2,后者进一步与H(CF_2)_4CH_2OH反应生成3。 3与二乙胺反应生成Et_2NCOCO_2CH_2(CF_2)_4H(4)。3和4皆为新化合物。     

Formal homo-Nazarov and other cyclization reactions of activated cyclopropanes

The Nazarov cyclization of divinyl ketones gives access to cyclopentenones. Replacing one of the vinyl groups by a cyclopropane leads to a formal homo‐Nazarov process for the synthesis of cyclohexenones. In contrast to the Nazarov reaction, the cyclization of vinyl‐cyclopropyl ketones is a stepwise process, often requiring harsh conditions. Herein, we describe two different approaches for further polarization of the three‐membered ring of vinyl‐cyclopropyl ketones to allow the formal homo‐Nazarov reaction under mild catalytic conditions. In the first approach, the introduction of an ester group α to the carbonyl on the cyclopropane gave a more than tenfold increase in reaction rate, allowing us to extend the scope of the reaction to non‐electron‐rich aryl donor substituents in the β position to the carbonyl on the cyclopropane. In this case, a proof of principle for asymmetric induction could be achieved using chiral Lewis acid catalysts. In the second approach, heteroatoms, especially nitrogen, were introduced β to the carbonyl on the cyclopropane. In this case, the reaction was especially successful when the vinyl group was replaced by an indole heterocycle. With a free indole, the formal homo‐Nazarov cyclization on the C3 position of indole was observed using a copper catalyst. In contrast, a new cyclization reaction on the N1 position was observed with Brønsted acid catalysts. Both reactions were applied to the synthesis of natural alkaloids. Preliminary investigations on the rationalization of the observed regioselectivity are also reported.     

5,15-二(对-取代苯基)八烷基卟啉及其金属配合物的合成

本文报道了五种5,15-二(对-取代苯基)-2,8,12,18-四乙基-3,7,13,17-四甲基卟啉(Ⅱa—Ⅱe)和五种5,15-二(对-取代苯基)-2,3,7,8,12,13,17,18-八甲基卟啉(Ⅰa—Ⅰe)以及它们的铜、铁、镍金属配合物的合成。这些化合物的结构均经元素分析、UV、~1HNMR和MS鉴定。芳环上不同取代基对卟啉成环反应有一定影响,拉电子基团有利于反应。其顺序如下:NO_2>H>CH_3>OCH_3>N(CH_3)_2。     

Mechanistic study on the regioselectivity of Co-catalyzed hydroacylation of 1,3-dienes

Density functional theory(DFT) method was used to explore the origin of the regioselectivity of Cocatalyzed hydroacylation of 1,3-dienes.The reaction of 2-methyl-1,3-butadiene and benzaldehyde with1,3-bis(diphenylphosphino)propane ligand was chosen as the model reaction.The energies of the intermediates and transition states in the stages of oxidative cyclization,β-H elimination and C-H reductive elimination were investigated.Computational results show that β-H elimination is the ratedetermining step for the whole catalytic cycle.C1-Selective oxidative cyclization is favored over C4-selective oxidative cyclization.Besides.C4-selective oxidative cyclization is kinetically disfavored than all the steps in C1-hydroacylation mechanisms,consistent with the experimentally obtained C1-selective hydroacylation products.Analyzing the reason for such observation,we suggest that both electronic and steric effects contribute to the C1-selectivity.On the electronic aspect,C1 is more electron rich than C4 due to the methyl group on C2,which makes the electrophilic attack of aldehyde carbon on C1 more favorable.On the steric aspect,the methyl group locates farther from the ligands in the transition state of C1-selective oxidative cyclization than in that of C4-selective oxidative cyclization.     

CH4-CO2两步反应直接合成含氧有机物的研究——添加氢的影响

 以热力学分析和动力学分析为基础，设计了几种实现CH4－CO2低温转化直接合成含氧有机物的混氢进料方式，通过实验对这些进料方式进行了初步探讨，并考察了甲烷活化及二氧化碳反应过程中混氢比例的影响．结果表明，与CH4／CO2进料方式相比，几种混氢进料方式都能提高乙酸收率，但需要很好地控制二氧化碳加氢反应．在甲烷活化过程中混氢，13．8％的氢气比例对甲烷的转化最有利，乙酸收率可达最高；在二氧化碳反应过程中混氢，混氢比例为50％时乙酸收率最高．催化剂的催化特性与其反应前后表面特征的变化相吻合．     

Formation and characterization of 1-substituted 1,2-dithiolanyl radicals by laser flash photolysis

Photolyses of 1-alkylthio-3-propanethiols, 1,3-propanedtthiol and 1-phenylthio-3-propanethiol in acetonitrtle, 2-propanol or aqueous mixtures of these solvents lead to five membered cyclic sulfuranyl radicals of the type \(\left[ {R - \overline {S - S - CH_2 - CH_2 - C} H_2 } \right]\) which exhibit characteristic uv/vis absorption spectra. These 1-substituted 1,2-dithiolanyl radicals are formed by intramolecular cyclization of the primarily formed thiyl radicals generaeed by S-H- bond cleavage in the excited starting material. The wavelength of the absorption maximum observed for these transients depends on the natuee of the substituntt R on the sulfur atom (R=H, alkyl, aryl).     

合成1,3,2-氧氮磷杂萘衍生物的新方法

通过一个尚未见文献报道的新型环化反应，合成了四个新型1,3,2-氧氮磷杂萘类化合物，并提出了该反应的机理。     

Lipase-catalyzed domino kinetic resolution/intramolecular Diels-Alder reaction: one-pot synthesis of optically active 7-oxabicyclo[2.2.1]heptenes from furfuryl alcohols and beta-substituted acrylic acids

The first lipase-catalyzed domino reaction is described in which the acyl moiety formed during the enzymatic kinetic resolution of furfuryl alcohols (+/-)-3 with a 1-ethoxyvinyl ester 2 was utilized as a part of the constituent structure for the subsequent Diels-Alder reaction. The preparation of ester 2 from carboxylic acid 1 and the subsequent domino reaction were carried out in a one-pot reaction. Therefore, this procedure provides a convenient preparation of the optically active 7-oxabicyclo[2.2.1]heptene derivatives 5, which has five chiral, non-racemic carbon centers, from achiral 1 and racemic 3. The overall efficiency of this process was dependent on the substituent at the C-3 position of 3, and the use of the 3-methylfurfuryl derivatives, (+/-)-3 b and (+/-)-3 f, exclusively produced diastereoselectivity with excellent enantioselectivity to give (2R)-syn-5 (91->/=99 % ee) and (S)-3 (96->/=99 % ee). Similar procedures starting from the 3-bromofurfuryl alcohols (+/-)-3 h-j provided the cycloadducts (2R)-syn-5 j-q (93->/=99 % ee), in which the bromo group was utilized for the installation of bulky substituents to the 7-oxabicycloheptene core.