含酯基烯烃选择性硼氢化碘化反应：两种昆虫性信息素的合成

不饱和烃经硼氢化反应生成的硼烷在碱性及温和条件下与碘作用,可以获得产率较高的碘化物。然而,硼氢化碘化反应因需要强碱性条件而可能对许多对碱敏感基团产生不利影响,而且反应中需要过量硼烷。硼烷R_3B中一般只有1～2个R基可以利用,反应产率以烯烃计算只有50％～65％,我们进行含酯末端烯烃的硼氢化碘化时,发现在强碱性醇钠条件     

二烯烃的硼氢化反应

单烯烃与硼烷的硼氢化反应及相关反应 ,已经研究得很多 ,各教学参考书中均有讨论。然而二烯烃尤其是共轭二烯烃的硼氢化反应并不常见。在高等教育出版社出版的高等师范专科学校教材《有机化学》[1] 中有一道习题 :　　　　 ＣＨ212 (ＢＨ3 ) 2 　 ?　 Ｈ2 Ｏ2ＯＨ-　 ?这是一道关于共轭二烯烃与硼烷反应的题目。反应怎样进行 ?是发生 1 ,4 加成还是只与其中一个双键加成或者与两个双键同时加成 ?历届学生都对此感到困惑。笔者为此查阅了一些相关书籍和文献 ,对二烯烃硼氢化反应的机理、影响因素及规律进行了较详细的论述 ,并据此给出习题的…     

具有表面活性ATRP引发剂的合成及其在无皂乳液聚合中的应用

以2-溴异丁酰溴、1,2-乙二醇、1,6-己二醇、顺丁烯二酸酐为主要原料,通过三步反应合成了具有阴离子表面活性的原子转移自由基聚合(ATRP)引发剂——4-[2-(2-溴-2-甲基丙酰氧基)乙氧基]-4-氧代-2-磺酸基丁酸二钠(1a)和4-[6-(2-溴-2-甲基丙酰氧基)己氧基]-4-氧代-2-磺酸基丁酸二钠(1b),其结构经1HNMR,IR和元素分析表征。用1引发无皂乳液聚合,研究结果表明反应是活性自由基乳液聚合,所得乳液非常稳定。     

含官能团的取代烯烃的硼氢化反应——Ⅰ.巴豆醛的硼氢化反应

巴豆醛在过量乙硼氢的硼氢化反应中得到的主要产物是正丁醇。本文论证这一反应的历程,其中包括有“二硼酸”型的β-消除反应。还讨论有电负性元素取代的烯烃的硼氢化反应。巴豆醛在低温(-25°)硼氢化,可使这类消除反应大为减少,主要得到硼氢化的正常产物——丁二醇。     

具有阳离子表面活性ATRP引发剂的合成

以2-溴异丁酰溴、2-溴乙醇、6-氯-1-己醇及N,N-二甲基正十二烷基胺为主要原料,分别通过两步或三步反应合成了具有阳离子表面活性的原子转移自由基聚合(ATRP)引发剂——N-[2-(2-溴-2-甲基丙酰氧基)乙基]-N,N-二甲基正十二烷基溴化铵或N-[6-(2-溴-2-甲基丙酰氧基)己基]-N,N-二甲基正十二烷基碘化铵,其结构经1H NMR,13C NMR,IR和元素分析表征。     

4-二甲胺基吡啶-硼自由基促进的缺电子烯烃区域选择性硼氢化反应

含硼有机化合物在合成化学中具有重要的应用价值,硼氢化反应是构建有机硼化合物最常用的方法之一.利用4-二甲氨基吡啶硼自由基与缺电子烯烃的自由基硼氢化反应,高区域选择性地构建了α-硼取代产物.该反应条件温和,官能团容忍性好,底物范围广.多种α,β-不饱和酯、酰胺、羧酸、腈、三氟甲基化合物、砜以及磷酸酯均能顺利发生反应,得到...     

4-二甲胺基吡啶-硼自由基促进的缺电子烯烃区域选择性硼氢化反应（英文）

含硼有机化合物在合成化学中具有重要的应用价值,硼氢化反应是构建有机硼化合物最常用的方法之一.利用4-二甲氨基吡啶硼自由基与缺电子烯烃的自由基硼氢化反应,高区域选择性地构建了α-硼取代产物.该反应条件温和,官能团容忍性好,底物范围广.多种α,β-不饱和酯、酰胺、羧酸、腈、三氟甲基化合物、砜以及磷酸酯均能顺利发生反应,得到的含硼产物可以进一步应用于后续碳-碳键的构建.     

炔烃与二氯硼烷-甲硫醚的硼氢化反应——偕-二硼和烯基硼化合物的合成和光谱特性

本文研究了在三氯化硼存在下,炔烃与二氯硼烷-甲硫醚(HCCl_2·SMe_2)的硼氢化反应。内炔烃和端炔烃与HBCl_2·SMe_2(摩尔比为1:2)在0℃反应,得到了高产率的双硼氢化产物——偕-双(二氯硼基)烷烃。在较低温度下,双硼氢化被显著地抑制。因此,在—20℃或—30℃下,内炔烃与HBCl_2·SMe_2(1.4:1)反应,定量地生成预期的烯基二氯硼烷。但在同样条件下,端炔烃既进行单硼氢化,也会经历硼氯化反应。当端炔烃在戊烷中与三氯化硼(1:1。1)反应时,高产率地得到硼氯化产物——2-氯-1-烯基二氯硼烷。各取代二氯硼烷易于醇解为相应的硼酸酯。所得化合物经IR,~1H,~(11)B,或~(13)C NMR表征。讨论了化合物的结构和它们的波谱特性之间的关系。基于化学位移,确证分子中的π-电子或孤对电子和硼原子的空ρ-轨道存在着明晰的(pp)π-相互作用。     

癸硼氢作为硼氢化试剂

本文指出癸硼氢可以作为一种新的硼氢化试剂;它与烯烃在四氢呋喃中反应,然后经碱性过氧化氢氧化水解,可获得正常的硼氢化产物.即自莰烯可获得内异莰醇和外异茨醛,自Δ~2-胆甾烯获得3α-,2α-和3β-胆甾醇的混合物,自Δ~5-胆甾烯获得6α-胆甾醇和6α-胆甾酮;癸硼氢也可将3-胆甾酮还原为3β和3α-胆甾醇的混合物.据反应进行情况以及产品的结构,证明癸硼氢的硼氢化反应亦是通过顺式加成的机制,并且从双键位阻较小的一面进行反应.在Δ~5-胆甾烯的硼氢化反应中,癸硼氢的反应性较乙硼氢差,空间效应可能是这种差别的原因之一.莰烯、Δ~2-胆甾烯及3-胆甾酮与癸硼氢的反应的分子比分别为2. 3至2. 5∶1;1. 5∶1和6至7∶1.     

环状和网络状有机硼化合物的研究 Ⅱ.1,2-氧硼杂戊环类化合物的合成与性质

2-烯丙氧基-1,2-氧硼杂戊环(1)的侧链有较大化学活性。(1)可与醇类酯交换制得2-烷氧基-1,2-氧硼杂戊环,如2-正戊氧基-、2-环己氧基-、2-环辛氧基、2-氨基乙氧基-1,2-氧硼杂戊环;与乙二醇反应可制得2,2′-次乙二氧基-双-(1,2-氧硼杂戊环)(6),同样,也可制得1,2-丙二醇和2,3-丁二醇衍生物(7)(8)。(1)与三丁基硼和三烯丙基硼热交换可制得2-正丁基-1,2-氧硼杂戊环和2-烯丙基-1,2-氧硼杂戊环(10)。(10)的侧链活性更大,易与醇、胺类反应制得相应衍生物,如2-正丁氧基-和2-烯丙胺基-1,2-氧硼杂戊环,反应机理可能是烯丙基型重排。(1)与氯化亚砜作用可制得2-氯-1,2-氧硼杂戊环(13),另外还有二个破环、氯转位的副产物,3-氯丙基硼酸二烯丙酯及酐。(6)、(7)、(8)的双环相互作用可能形成网络状结构以及(13)的X-衍射结晶结构正在深入研究中。通过1,2-氧硼杂戊环类侧链的交换反应,合成侧链上具有碳、氮、氧、氯的衍生物,不仅表明侧链的多变性,而且表明环本身有相对稳定性。     

Organoboranes for synthesis. 9. Rapid reaction of organoboranes with iodine under the influence of base. a convenient procedure for the conversion of alkenes into iodides via hydroboration

The reaction of organoborane with iodine is strongly accelerated by sodium hydroxide. Organoboranes derived from terminal alkenes react with the utilization of approximately two of the three alkyl groups attached to boron, providing a maximum of 67% yield of alkyl iodide. Thus, hydroboration-iodination of 1-decene gives a 60% yield ofn-decyl iodide. Secondary alkyl groups, derived from internal alkenes, react more sluggishly and only one of the three alkyl groups attached to boron is converted to the iodide. Thus, the procedure applied to 2-butene provides a 30% yield of 2-butyl iodide. The use of disiamylboranebis-(3-methyl-2-butylborane, Sia₂BH) as hydroborating agent increases the yield of iodides from terminal alkenes since the primary alkyl groups react in preference to the secondary siamyl groups. Consequently, hydroboration of 1-decene with Sia₂BH, followed by iodination gives a 95% yield ofn-decyl iodide. The use of methanolic sodium methoxide in place of sodium hydroxide provides alkyl iodides in considerably higher yields. The combination of hydroboration with iodination in the presence of a base provides a convenient method for theanti-Markovnikov hydroiodination of alkenes. The base-induced iodination of organoboranes proceeds with the inversion of configuration at the reaction center, as shown by the formation ofendo-2iodonorbomane from tri-exo-norbomylborane.     

由有机硼烷立体选择合成(Z)、(E)链烯-1-醇乙酸酯类昆虫性信息素

等摩尔的甲硼烷甲硫醚(H₃B·SMe₂)与四溴化碳在60℃下反应20h,定量得到一溴硼烷甲硫醚。从链端烯烃、一卤硼烷甲硫醚和2-[7-辛炔-1-氧基]四氢吡喃及其8-溴代衍生物出发,经硼氢化反应和Zweifel的顺-,反-烯烃合成法,立体选择地合成了鳞翅目昆虫性信息素:(Z)-7-十四烯-1-醇乙酸酯9a、(Z)-7-十六烯-1-醇乙酸酯9b、(E)-7-十四烯-1-醇乙酸酯12及其相应的醇13。产物经GC分析和MS、¹H及¹³C NMR数据证实了它们的纯度和几何构型。     

In quest of factors that control the enantioselective catalytic Markovnikov hydroboration/oxidation of vinylarenes

This study attempts to rationalise the unpredictable performance of transition metal catalysed asymmetric hydroboration of vinylarenes on varying the precursor of the catalyst from cationic to neutral species, [M(cod)(L-L)]BF4, [M(mu-Cl)(cod)]2/(L-L), the metal (M=Rh and Ir), and the hydroborating reagent (catecholborane, pinacolborane). The approaches are based on the agreement between experimental data provided by (R)-Binap and (R)-Quinap modified catalytic systems and computational data evidenced by DFT calculations and QM/MM strategies. Unprecedentedly high enantiomeric excesses in the hydroboration/oxidation of vinylarenes with both electron-withdrawing substituents ((R)-(+)-1-p-F-phenylethanol, ee up to 92 %) and electron-releasing substituents ((R)-(+)-1-p-MeO-phenylethanol, ee up to 98 %), can be attributed to a rhodium halide key intermediate.     

9-Borabicyclo[3.3.2]decanes and the asymmetric hydroboration of 1,1-disubstituted alkenes

The syntheses of the optically pure asymmetric hydroborating agents 1 (a, R = Ph; b, R = TMS) in both enantiomeric forms are reported. These reagents are effective for the hydroboration of cis-, trans- and trisubstituted alkenes. More significantly, they exhibit unprecedented levels of selectivity in the asymmetric hydroboration of 1,1-disubstituted alkenes (28-92% ee), a previously unanswered challenge in the nearly 50 year history of this reagent-controlled process. For example, the hydroboration of alpha-methylstyrene with 1a produces the corresponding alcohol 6f in 78% ee (cf., Ipc2BH, 5% ee). Suzuki coupling of the intermediate adducts 5 produces the nonracemic products 7 very effectively (50-84%) without loss of optical purity.     

New insights on the asymmetric hydroboration of perfluoroalkenes

Enantioselective access to Markovnikov regioisomeric perfluoroalcohols is achieved in the presence of chiral cationic rhodium complexes and specific hydroborating reagents.     

Synthesis and extension/contraction motion of spiroborate-based double-stranded helicates consisting of substituted oligophenol strands

A new class of ortho- and meta-substituted tetraphenols at the terminal phenyl residues with a biphenylene unit in the middle were synthesized and the effect of the substitution position on the spiroborate-based double-stranded helicate formation with sodium borohydride was investigated. The ortho-substitution considerably hampered the spiroborate formation between the terminal biphenol units and the boron atoms, whereas the meta-substituted oligomers formed a double-stranded helicate bridged by spiroborate groups accommodating a sodium cation in the center, which displayed an extension and contraction motion triggered by the removal and addition of sodium ions in solution.     

MNDO Analysis of Regio- and Stereoselectivity in Hydroboration

The origin of regioselectivity in hydroboration of olefins has been analyzed by MNDO methodology. With a standard transition structure derived from full MNDO optimizations, a linear correlation between calculated and experimental regioselectivities has been found. A similar approach applied to asymmetric inductions of hydroboration with chiral hydroborating agents lead also to an acceptable linear correlation between calculated and experimental results. The MNDO method has been used for a search of alternative hydroborating agents.     

Molten salts bearing anion receptor

A series of organoboron molten salts prepared by hydroboration of allyl imidazolium type molten salts with various hydroborating reagents such as monobromoborane dimethyl sulfide complex, 9-borabicyclo[3.3.1]nonane (9-BBN) and mesitylborane, and subsequent anion exchange reaction exhibited selective cation transporting property with ionic conductivity of 7.79 x 10(-5) - 6.25 x 10(-6) S cm(-1) at 323 K.     

Synthesis and Characterization of Bis(azido)bis(2‐chloropyridine)palladium(II), Bis(azido)bis(3‐chloropyridine)palladium(II), Bis(azido)bis(quinoline)palladium(II), and the Crystal Structure of Bis(azido)bis(quinoline)palladium(II)

Three new monomeric complexes of palladium(II) azide with 2‐chloropyridine ( 1 ), 3‐chloropyridine ( 2 ), and quinoline ( 3 ), have been synthesized by reaction of palladium nitrate and the respective Lewis‐base with sodium azide in a water/acetone mixture. All three compounds were characterized by IR, Raman, and multinuclear NMR spectroscopy. The composition of the complexes were confirmed by elemental analysis. The spectroscopic investigations confirm terminal azide ligands in trans position. Complex 3 was also characterized by crystallographic methods. Each palladium atom of 3 is surrounded in a distorted square planar fashion by 4 nitrogen atoms. The terminal azide ligands are in trans position.     

The direct production of monoisopinocampheylborane by the redistribution of diisopinocampheylborane with borane

Two simple and direct methods are outlined for the production of monoisopinocampheylphenylborane, a valuable chiral hydroborating agent.