中药青蒿萜类代谢物谱分析及青蒿素生物合成的研究

青蒿素是从中药青蒿，学名黄花蒿（Artemisia annua L.）植物地上部分分离出的抗疟疾有效单体，为一种倍半萜内酯类化合物，其生物合成途径属于植物类异戊二烯代谢途径。青蒿素生物合成途径及其调控机制仍不完全清楚，本论文采用GC-MS 和GC×GC-TOFMS 方法对青蒿萜类代谢物谱进行检测，用多维统计学方法对检测结果进行整理和比较分析，研究青蒿素生物合成及其与青蒿中其他萜类代谢的关系，取得了以下结果： 一、通过GC×GC-TOFMS 方法对青蒿挥发油成分进行分析，共鉴定出303 种组分。其中挥发油中相对百分含量大于1%的10 种组分中有9 种为萜类化合物，含量接近总挥发油的50%。在相对百分含量大于0.1%的49 种成分中，有30 种萜类化合物。有27 种相对百分含量大于0.1%的成分首次在青蒿挥发油中报道，其中包括10 种萜类化合物。 二、利用GC-MS 方法分析了青蒿001 和SP18 两个青蒿素高产株系不同生长时期萜类代谢物谱，结果表明：青蒿中萜类化合物在不同时期合成和积累是动态变化的，萜类化合物的种类和数量在营养生长期随生长时间的延长而提高，在营养生长后期和现蕾前期达到最高水平，进入生殖生长后随生长时间的延长而迅速降低。通过多维统计PLS-DA（Partial Leasted Square Discriminant Analysis） 分析，确定001 中有17 个化合物的含量在不同生长时期有明显变化，其中15 个为萜类化合物。SP18 中有18 个化合物的含量在不同生长时期有明显变化，其中16 个为萜类化合物。青蒿素，青蒿酸，二氢青蒿酸，青蒿素B 都是含量变化明显的标记物。其中青蒿酸和二氢青蒿酸含量在营养生长后期达到最高水平，进入生殖生长后迅速下降，而青蒿素和青蒿素B 在整个检测时期含量变化相对较小，在营养生长时期含量已经较高，在现蕾前期含量稍有上升，进入现蕾期后有所下降，本研究确定现蕾前期为代谢物谱分析最佳取样时期，并为药材采收提供指导。 三、不同基因型青蒿代谢物谱研究表明，青蒿素高产株系SP18 和001 代谢物表现出一定的差异，通过多维统计PLS-DA 分析，共找出了22 种在两种基因型中差异明显的化合物，其中包括倍半萜化合物12 种，单萜化合物3 种，三萜化合物4 种。SP18 特征化合物为樟脑和两个未鉴定倍半萜化合物，而001 特征化合物是龙脑和β-法呢烯。另外两种基因型中青蒿素及相关前体化合物的积累模式差异明显，SP18 中二氢青蒿酸和青蒿素含量高，而青蒿酸和青蒿素B 含量极低；001 中二氢青蒿酸和青蒿素含量相对SP18 要低，但青蒿素B 和青蒿酸含量比SP18 要高。该结果表明在青蒿素高产株系中，青蒿素含量与二氢青蒿酸的含量呈正相关，结合Brown 等的活体标记研究结果分析，从二氢青蒿酸到青蒿素的转化可能是青蒿素合成的限速步骤。 四、利用GC×GC-TOFMS 方法对转基因青蒿萜类代谢物谱进行了分析，共对200 个左右化合物峰进行PLS-DA 和OSC-PLS (Orthogonal Signal Correction–Partial leasted Square)多维统计分析，结果表明：青蒿萜类代谢物谱在外源基因转入后发生显著变化，与对照株系相比均呈现显著差异。其中过量表达Amorpha-4,11-diene 合酶基因（ads）株系中青蒿素及相关化合物变化最明显，而过量表达FPP 合酶基因（fps）株系中青蒿素及相关化合物变化相对较小，在受到调控而成为差异标记物的化合物中，70%是倍半萜类化合物。 五、考察了外源茉莉酸甲酯对青蒿素生物合成的影响，结果表明：300 μM 外源茉莉酸甲酯能提高青蒿素含量，在处理后第8 天青蒿素含量提高38%。青蒿萜类代谢物谱研究表明，茉莉酸甲酯不仅可以诱导青蒿中青蒿素的合成，还能诱导很多化合物，特别是倍半萜和三萜类的合成。OSC-PLS 分析结果找出了9 个处理后含量明显提高的标记物，其中6 个倍半萜化合物，3 个三萜化合物。标记物鲨烯含量提高了67%，另一个未鉴定出结构的倍半萜提高了60%，这些化合物可能与青蒿素有着类似的调控机制，而外源喷洒茉莉酸甲酯可以作为提高青蒿素产量的有效途径之一。

中药青蒿紫穗槐二烯合酶基因表达及调控的研究

青蒿素是从我国传统药用植物中药青蒿（Artemisia annua L.）中提取的新型抗疟特效药，其生物合成途径属于植物类异戊二烯代谢途径。目前，青蒿素生物合成的组织部位及其调控机制仍不完全清楚。紫穗槐二烯合酶（amorpha-4， 11-diene synthase, ADS）作为青蒿素生物合成分支途径的第一个关键酶，催化倍半萜化合物的通用前体法呢基焦磷酸环化，生成紫穗槐二烯。本论文通过对ADS 表达特性的分析，研究了青蒿素生物合成的组织特异性及其调控机制，主要研究结果如下： 一．紫穗槐二烯合酶基因启动子功能的研究 从青蒿高产株系001 中克隆得到了2850 bp 的ADS 启动子调控区。通过比较5’RACE 的测序结果与启动子序列，确定转录起始位点位于翻译起始位点上游44 bp，TATA 盒下游27 bp。该启动子序列包含的顺式作用元件有脱落酸应答元件(ABRE )、乙烯应答元件(ERE)、生长素应答元件(AUXRE）等植物激素反应元件，以及低温应答元件（LTRE）、高温应答元件（HSE）等与逆境有关的反应元件，还有与真菌诱导有关的W-box 元件等。将不同长度ADS 启动子与报告基因GUS 融合，构建了植物表达载体，通过农杆菌介导的方法获得稳定整合的转基因烟草。经过组织化学、GUS 荧光活性检测及RT-PCR 分析，发现该启动子的转录活性很低，无法通过GUS 染色进行观察。GUS 荧光活性检测及RT-PCR 结果表明，转录起始位点上游346 bp 是ADS 基础表达所必需的。高温、低温、干旱、水杨酸、茉莉酸甲酯等处理均能促进青蒿中ADS 的表达，而脱落酸和乙烯的作用效果较小，与启动子序列分析的结果并不完全一致。 二．紫穗槐二烯合酶基因表达特性的研究 以青蒿高产株系001 为材料，在基因和蛋白水平揭示了ADS 的表达特性。RT-PCR 和Western 分析结果表明，ADS 在幼叶和花蕾中大量表达，在老叶和完全开放的花中表达量很低，而在青蒿的根和茎中几乎检测不到ADS 的表达。石蜡切片和整体原位杂交的结果表明，ADS 在顶端分生组织、叶原基及分泌腺毛中表达，在非分泌的T 型腺毛中不表达。当叶片完全展开后，ADS 只在分泌腺毛中表达，而且随着叶片的生长和老化，ADS 的表达量逐渐减少。另一个非常有趣的发现是同一叶片上的分泌腺毛，有些有ADS 的表达，有些则没有。用强光、低温、高温和水杨酸等因素处理后，有ADS 表达的分泌腺毛的比例没有明显的变化。 三．外源水杨酸促进青蒿素的生物合成 研究了外源水杨酸对青蒿素生物合成的影响，结果表明：1 mM 水杨酸处理后，青蒿叶片中的游离态水杨酸含量快速增加，处理后4 h 达到 0.79 μg g-1 FW，是对照的3.5 倍。外源水杨酸能够抑制青蒿中过氧化氢酶活性，提高抗坏血酸过氧化物酶活性，并通过对抗氧化酶活性的抑制引起青蒿体内活性氧水平的迅速升高。在处理后4 h，青蒿中H2O2 和O2-的含量分别达到对照的2.1 倍和2.4 倍。青蒿素含量在水杨酸处理后的前8 h 缓慢升高，随后升高的速度增加。外源水杨酸处理后8 h 和96 h，青蒿素含量分别达到9.1 mg g-1DW 和13.9 mg g-1DW，比对照高21.7%和75.8%。处理后8 h，青蒿酸的含量没有明显变化，随后开始增加。处理后16 h，青蒿酸的含量达到3.6 mg g-1DW，比对照高90%， 随后继续升高，至96 h 达到4.98 mg g-1 DW，比对照高127%。二氢青蒿酸的含量在处理后的8 h 内有所下降，随后缓慢升高。处理后8 h，二氢青蒿酸的含量降低了23.3%，随后二氢青蒿酸的含量开始升高，在处理后96 h，达到7.4 mg g-1DW，比对照高72.1%。外源SA 处理提高了青蒿素及其前体的总含量，在处理后1、2、4 天分别比对照提高了1.3、1.5 和1.8 倍。Northern 结果表明，水杨酸强烈诱导了青蒿素生物合成基因HMGR、ADS 的表达，但是对FPS、CYP71AV1 的诱导作用较小。这些研究结果表明，外源水杨酸至少通过两条途径诱导青蒿素的生物合成：一是通过诱导活性氧的产生促进二氢青蒿酸向青蒿素的转化；二是上调部分青蒿素生物合成相关基因的表达。根据这一研究成果，在青蒿田间栽培中，可以在收获前通过喷施水杨酸来快速、有效和低成本地提高青蒿素产量。

Trinorcucurbitane and cucurbitane triterpenoids from the roots of Momordica charantia

Five cucurbitacins, kuguacins A-E (1-5), together with three known analogues, 3 beta,7 beta,25-trihydroxycucurbita-5,(23E)-diene-19-al (6), 3 beta,25-dihydroxy-5 beta,19-epoxycucurbita-6,(23E)-diene (7), and momordicine I (8), were isolated from roots of

铬系催化剂聚合1,3-双烯烃的研究

铬系催化剂是合成1,2-聚丁二烯和3,4-聚异戊二烯的一种主要催化剂体系，1,2-聚丁二烯和3,4-聚异戊二烯是制造高性能轮胎的重要原料。本论文研究了以含氮化合物和含磷化合物为配体的铬催化剂合成1,2-聚丁二烯和3,4-聚异戊二烯的反应规律。 1. 以邻菲咯啉为配体的铬催化剂在己烷中50℃下可获得1,2-结构、顺-1,4-结构和反-1,4-结构单元含量分别约为50%、30%和20%，分子量呈双峰分布的聚丁二烯。改变聚合温度，可有效控制聚合物的1,2-结构含量和分子量及分布。催化剂通过预陈化方式，可有效抑制低聚物的生成。 2. 以亚磷酸二烷基酯为配体的铬催化剂是合成1,2-聚丁二烯的高效催化剂，所得聚合物具有高的1,2-结构含量（> 78%）。改变烷基铝和亚磷酸二烷基酯的结构，可以得到高熔点或低熔点间同1,2-聚丁二烯和无规1,2-聚丁二烯。催化剂以现配方式的活性最高。 3. 以磷酸三苯酯为配体的铬催化剂可获得间同1,2-聚丁二烯，而聚合物中含有低聚物。催化剂以现配方式的活性最高。聚合物的熔点，低聚物的含量与磷酸三苯酯的结构有一定的关系。 4. 以邻菲咯啉为配体的铬催化剂在50℃下聚合异戊二烯，具有高的催化活性，可获得3,4-结构含量约67%的高分子量无规3,4-聚异戊二烯。催化剂的组成对聚合物的微观结构无明显影响。改变聚合温度，可有效控制聚合物的3,4-结构含量和分子量及分布。

铁系催化剂聚合1，3-双烯烃的研究

1，2-聚丁二烯和3，4-聚异戊二烯是制造高性能轮胎的原料。本论文研究了以含磷化合物为第三组份的铁催化剂合成1，2-聚丁二烯和3，4-聚异戊二烯的反应规律：1．以二乙基亚磷酸酷为第三组份的铁催化剂可在己烷中，较高温度（50℃）下聚合1，3-丁二烯。通过控制催化剂组份的配比，可制备间同和无规1，2-聚丁二烯。所得间同1，2-聚丁二烯的1，2-结构含量为91％，间规度为90％；所得无规1，2-聚丁二烯的硫化胶具有优异的抗干、湿滑性能。2．以三苯基磷酸酷为第三组份的铁催化剂是合成高间同1，2一聚丁二烯的高效催化剂。所得聚合物具有高的1，2-结构含量（ca.95％），高的间规度（ca.95％）。聚合物的微观结构与催化剂组成等反应因素无关。3．以二烷基亚磷酸醋为第三组份的铁催化剂可在己烷中，较高温度（50℃）下聚合异戊二烯。二烷基亚磷酸醋中烷基影响聚合活性的顺序为乙基一甲基＞正丁基＞异辛基。所得聚异戊二烯的3，4（含1，2）结构含量保持在60％左右，不受反应条件的影响。4．改性甲基铝氧烷（MMAO）活化的铁催化剂聚合异戊二烯，在相当低的MMAO用量下（Al／Fe=20，摩尔比）即有高的催化活性。溶剂影响聚合活性的顺序为甲苯＞环己烷＞己烷＞二氯甲烷。所得聚异戊二烯的3，4（含1，2）结构含量稳定在60％。

禄春安息香种子和攀援孔药花全草的化学成分研究

本文对禄春安息香（Styrax macranthus）种子和攀援孔药花（Porandra scandens）全草的化学成分进行了研究，共获得30个化合物，其中2个为新化合物。 从禄春安息香种子95%乙醇提取物中分离并鉴定了12个化合物，其中2个新化合物鉴定为3-[7-methoxy-2-(3,4-methylenedioxy phenyl) benzofuran-5-yl] propyl 3-[7-methoxy-2-(3,4-methylenedioxyphenyl)benzofuran-5-yl] propanoate (1) 和去甲氧基-egonol-龙胆双糖甙 (2)；已知化合物分别为2-(3,4-二氧亚甲基苯基)-5-甲酰基-7-甲氧基-苯并呋喃 (3)、egonol (4)、去甲氧基-egonol (5)、去甲基-egonol (6)、egonol-葡萄糖甙 (7)、egonol-龙胆双糖甙 (8)、egonol-龙胆三糖甙 (9)、豆甾醇 (10)、二十四烷酸 1-甘油酯 (11) 和胡萝卜甙 (12)。生物活性测试发现，化合物2具有促进雌激素E2合成的作用。 从攀援孔药花全草95%乙醇提取物中分离并鉴定了19个化合物：(2S,3S,4R)-2-[(2R)-2-羟基-二十一烷酰基氨基]-二十一烷-1,3,4-三醇 (13)、(2S,3S,4R)–2–二十四烷酰基氨基-十八烷-1,3,4-三醇 (14)、胡萝卜甙 (12)、β-谷甾醇 (15)、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇 (16)、6β-羟基-豆甾-4-烯-3-酮 (17)、十六烷酸 1-甘油酯 (18)、桦木酸 (19)、大黄素 (20)、二十二烷酸 1-甘油酯 (21)、对羟基苯甲醛 (22)、十七烷酸 1-甘油酯 (23)、金色酰胺醇乙酸酯(24)、十九烷酸 1-甘油酯 (25)、棕榈酸 (26)、(E)-p-香豆酸 (27)、(22E,24S)-24-麦角甾醇-7,22-二烯-3β,5α,6β-三醇 (28)、2-去氧-β-蜕皮激素 (29)和auranamide (30)。 综述了近十年来发现的2－芳基苯并呋喃类新木脂素的结构特征、来源、生物活性和化学全合成。 Phytochemical investigation on the seeds of Styrax macranthus and the whole plants of Porandra scandens led to the isolation of thirty compounds, two of which were new ones. Two new 2-aryl benzofuran derivatives, 3-[7-methoxy-2-(3,4-methylenedioxy phenyl) benzofuran-5-yl]propyl 3-[7-methoxy-2-(3,4-methylenedioxyphenyl)benzo furan-5-yl]propanoate (1) and demethoxy egonol gentiobioside (2), were isolated from the 95% aqueous ethanolic extract of the seeds of Styrax macranthus, together with 7-methoxy-2-(3,4-methylenedioxyphenyl) benzofuran-5-carbaldehyde (3), egonol (4), demethoxy egonol (5), demethyl egonol (6), egonol glucoside (7), egonol gentiobioside (8), egonol gentiotrioside (9), stigmasterol (10), 2,3-dihydroxypropyl tetracosoate (11), and daucosterol (12). In vitro test, compound 2 promote the synthesis of estrogen E2. Nineteen compounds were isolated from the 95% aqueous ethanolic extract of the whole plant of Porandra scandens for the first time. Their structures were identified as (2S,3S,4R)-2-[(2R)-2-hydroxy-heneicosanoylamino]-1,3,4- heneicosanetriol (13), (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (14), daucosterol (15), β-sitosterol (12), (20S,22E,24R)-5α,8α-epidioxy-ergosta-6,22-diene- 3β-ol (16), 6β-hydroxylstigmast-4-en-3-one (17), 1-glycerol-1-hexadecoate (18), betulinic acid (19), emodin (20), 1-glycerol-1-docosoate (21), p-hydroxybenzaldehyde (22), 1-glycerol-1-heptadecoate (23), aurantiamide acetate (24), 1-glycerol-1- nonadecoate (25), palmatic acid (26), (E)-p-coumaric acid (27), (22E,24S)- 24-metbylcbolesta-7,22-diene-3β,5α,6β-triol (28), 2-deoxycrustecdysone (29), and auranamide (30). The characteristic, natural resource, bioactivity, and the total synthesis of 2-aryl benzofurans were reviewed.

钮子瓜和袋花忍冬的化学成分研究

钮子瓜（Zehneria maysorensis Arn.）是一种常用的中草药，其性味苦、凉，主要功效为清热利湿、散风止痛，主治膀胱炎、头痛。体外活性筛选实验表明，袋花忍冬（Lonicera saccata Rehd.）95%乙醇提取物的乙酸乙酯部分对血管紧张素转化酶显示较强的抑制活性。为明确钮子瓜的药用物质基础和袋花忍冬中具有ACE抑制活性的成分，首次对两个植物的成分进行了研究。 1. 从钮子瓜95%乙醇提取物中主要通过色谱方法首次分离了14个化合物，通过波谱方法鉴定为(2S,3S,4R,10E)-2-[(2R)-2-羟基二十四烷酰基氨基]-10-十八烷-1,3,4-三醇（1）、(2S,3S,4R)-2-二十四烷酰基氨基-十八烷-1,3,4-三醇 （2）、胡萝卜苷（3）、swertish （4）、苯甲酸（5）、水杨酸（6）、loliolide （7）、胸腺嘧啶（8）、尿嘧啶（9）、(23Z)-9,19-环阿尔廷-23-烯-3β,25-二醇（10）、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇（11）、十六烷酸 1-甘油酯（12）、大豆脑苷Ⅰ（13）和(22E,24S)-24-甲基-5α-胆甾-7,22-二烯-3β,5α,6β-三醇（14）。其中化合物4为一黄酮碳苷，具有旋转异构现象，有止痛作用；化合物6具有抗炎、镇痛、减热的活性，它们可能是钮子瓜药用物质基础的一部分。 2. 从袋花忍冬95%乙醇提取物中首次分离并鉴定了16个已知化合物：胡萝卜苷（3）、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇（11）、十六烷酸 1-甘油酯（12）、E-p-coumaryl behenate (15)、谷甾醇（16）、2,6-dihydroxyhumula-3(12), 7(13),9(E)-triene (17)、环阿尔廷-25-烯-3β,24ξ-二醇 (18)、二十四烷酸 (19)、2,4-二羟基-3,6-二甲基苯甲酸甲酯 (20)、乌苏酸 (21)、柚皮素 (22)、木犀草素 (23)、柏双黄酮（24）咖啡酸 (25)、洋芹素（26）和木犀草素-7-O-β-D-葡萄糖苷 (27)。其中木犀草素（23）和咖啡酸（25）含量较高，它们为抑制ACE活性的成分。 3．综述了黄酮碳苷的旋转异构现象。 Zehneria maysorensis is a folk medicine for the treatment of cystitis and headache. The ethyl acetate soluble fraction of the 95% ethanol extract of Lonicera saccata showed obvious ACE inhibitory activity in vitro. To reveal their active constitutents, they were subjected to chemically study. From the 95% ethanol extract of the whole plants of Zehneria maysroensis fourteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were characterized to be (2S,3S,4R,10E)-2-[(2R)-2-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (1), (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (2), daucosterol (3), swertish (4), benzoic acid (5), salicylic acid (6), loliolide (7), thymine (8), uracil (9), (23Z)-9,19-cycloart-23-ene-3β,25-diol (10), (20S,22E,24R)-5α,8α-epidioxy-ergosta- 6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), soya-cerebroside (13) and (22E,24S)-24-methyl-5α-cholesta-7,22-diene-3β,5α,6β-triol (14). Compound 4, a C-glycosylflavone, showed a very interesting rotational isomerism. Compounds 4 and 6 may be the active constituents of Zehneria maysorensis considering their sedative and anti-inflammation activity, respectively. From the whole plants of Lonicera saccata, sixteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were identified to be daucosterol (3), (20S,22E,24R)-5α,8α-epidioxy- ergosta-6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), E-p-coumaryl behenate (15), β-sitosterol (16), 2,6-dihydroxyhumula-3(12),7(13),9(E)-triene (17), cycloart-25-ene-3β,24ξ-diol (18), tetracosanoic acid (19), methyl 2,4-dihydroxy- 3,6-dimethylbenzoate (20), ursolic acid (21), naringenin (22), luteolin (23), cupressuflavone (24), caffeic acid (25), apigenin (26) and luteolin-7-O-β-D- glucopyranoside (27). Luteolin (23) and caffeic acid (25) were the ACE inhibitory active constituents. Rotational isomerism for C-glycosylflavonoid was reviewed.

The effect of acidity on olefin aromatization over potassium modified ZSM-5 catalysts

The transformation of olefin to aromatics over ZSM-5 catalysts with different K-loadings has been investigated both in a continuous flow fixed-bed reactor and in a pulse microreactor. Investigation of variation of olefin aromatization activity with K-loadings shows that strong acid sites are indispensable for the converting of olefin to aromatics. As intermediates of olefin aromatization process, butadiene and cyclopentene not only show much higher aromatization activity than mono-olefins, but also can be transformed into aromatics over relatively weak acid sites of K/ZSM-5. A proposal is put forward, stating that among all the steps experienced in olefins aromatization, the formation of diene or cycloolfin from mono-olefins through hydrogen transfer is the key step and can be catalyzed by strong acid sites.

Thermoplastic Elastomers Based on Compatibilized Poly(butylene terephthalate) Blends: Effect of Functional Groups and Dynamic Curing

Two sets of graft copolymers were prepared by grafting glycidyl methacrylate (GMA) or ally] (3-isocyanate-4-tolyl) carbamate (TAI) onto ethylene/propylene/diene terpolymer (EPDM) in an internal mixer. These graft copolymers were used as the compatibilizer to prepare the thermoplastic elastomers (TPEs) containing 50 wt%, of poly(butylene terephthalate), PBT, 30 wt% of compatibilizer, and 20 wt% of nitrile-butadiene rubber, NBR. The indirect, two-step mixer process was chosen for dynamic curing.

Highly 3,4-selective living polymerization of isoprene with rare earth metal fluorenyl N-heterocyclic carbene precursors

Fluorenyl modified N-heterocyclic carbene ligated rare earth metal bis(alkyl) complexes, (Flu-NHC)Ln(CH2SiMe3)2 (Flu-NHC = (C13H8CH2CH2(NCHCCHN)C6H2Me3-2,4,6); Ln = Sc (1a); Ln = Y (1b); Ln = Ho (1c); Ln = Lit (1d)), were synthesized and fully characterized by NMR and X-ray diffraction analyses. Complexes Ib-d with the activation of (AlBu3)-Bu-i and [Ph3C][B(C6F5)4] exhibited high activity, medium syndio-but remarkably high 3,4-regio-selectivity, and the unprecedented livingness for the polymerization of isoprene. Such distinguished catalytic performances could be maintained under various monomer-to-initiator ratios (500-5000) and broad polymerization temperatures (25-80 degrees C).

New rare earth metal bis(alkyl)s bearing an iminophosphonamido ligand. Synthesis and catalysis toward highly 3,4-selective polymerization of isoprene

Newrareearth metal bis(alkyl) complexes [(NPNPh)Ln(CH2SiMe3)(2)(THF) (NPNPh:N(Ph)PPh2=NC6H2Me3-2,4,6; Ln = Sc (3a), Ln = Y (3b), Ln = Lu (3c)) and [(NPNPy)Sc(CH2SiMe3)(2)(THF)1 (NPNPY = N(Py)PPh2=NC6H2Me3-2,4,6) (3d)) have been prepared via protonolysis reaction between rare earth metal tris(alkyl)s and the corresponding iminophosphonamines. Complexes 3a-d are analogous monomers of THF solvate. Each metal ion coordinates to a eta(2)-chelated NPN ligand and two cis-located alkyl groups, adopting tetrahedron geometry.

Syndiotactically enriched 1,2-selective polymerization of 1,3-butadiene initiated by iron catalysts based on a new class of donors

A series of phosphoryl (P=O) contained compounds: triethylphosphate (a), diethyl phenyl phosphate (b), ethyldiphenylphosphate (c) triarylphosphates (d and h-m), triphenylphosphine oxide (e), phenyl diphenylphosphinate (f) and diphenyl phenylphosphonate (g) have been prepared. Iron catalysts, which are generated in situ by mixing the compounds with Fe(2-EHA)(3) and (AlBu3)-Bu-i in hexane, are tested for butadiene polymerization at 50 degrees C. Phosphates donated catalysts have been, unprecedently, found to conduct extremely high syndiotactically (pentad, rrrr=46.1-94.5%) enriched 1,2-selective (1,2-structure content=56.2-94.3%) polymerization of butadiene.

Metal dependent control of cis-/trans-1,4 regioselectivity in 1,3-butadiene polymerization catalyzed by transition metal complexes supported by 2,6-bis[1-(iminophenyl)ethyl]pyridine

Fe(III), Cr(III), Fe(II), Co(II) and Ni(II) chloride complexes supported by 2,6-bis[1-(iminophenyl)ethyl]pyridine have been synthesized and characterized along with single crystal X-ray diffraction. These complexes, in combination with MAO, have been examined in butadiene polymerization. The catalytic activity and regioselectivity are strongly controlled by metal center and cocatalyst (MAO/Co ratio dependent in the case of Co(II) complex). The activity decreases in the order of Fe(III) > Co(II) > Cr(III) approximate to Ni (II) complexes, in consistent with the space around the metal center. Polybutadiene with different microstructure content, from high trans-1,4 units (88-95% for iron(III) and Cr(III)), medium trans-1,4 and cis-1,4 units (55% and 35%, respectively, for iron(II)) to high cis-1,4 units 79% for Co(II) and 97% for Ni(II) call be easily achieved by varying of the metal center.

Highly 3,4-Selective Polymerization of Isoprene with NPN Ligand Stabilized Rare-Earth Metal Bis(alkyl)s. Structures and Performances

Deprotonation of (ArNHPPh2NAr2)-N-1 (H[NPN](n), n = 1 - 10) by Ln(CH2SiMe3)(3)(THF)(2) (Ln = Lu, Y, Sc, Er) generated a series of rare-earth metal bis(alkyl) complexes [NPN](n)Ln(CH2SiMe3)(2)(THF)(2) (1-10), which under activation with [Ph3C][B(C6F5)(4)] and AliBu(3) were tested for isoprene polymerization. The correlation between catalytic performances and molecular structures of the complexes has been investigated. Complexes 1-5 and 8, where Ar-1 is nonsubstituted or ortho-alkyl-substituted phenyl, adopt trigonal-bipyramidal geometry. The Ar-1 and Ar-2 rings are perpendicular in 1-4 and 8 but parallel in 5. When Ar-1 is pyridyl, the resultant lutetium and yttrium complexes 9a and 9b adopt tetragonal geometry with the ligand coordinating to the metal ions in a N,N,N-tridentate mode, whereas in the scandium analogue 9c, the ligand coordinates to the Sc3+ ion in a N,N-bidentate mode. These structural characteristics endow the complexes with versatile catalytic performances, With increase of the steric bulkiness of the ortho-substituents Ar-1 and Ar-2, the 3,4-selectivity increased stepwise from 81.6% for lutetium complex 1 to 96.8% for lutetium complex 6 and to 97.8% for lutetium complex 7a. However, further increase of the steric bulk of the ligand led to a slight drop of 3,4-selectivity for the attached complex 5 (95.1%).

[4+2] Annulation - Convenient Synthesis of Substituted Dihydropyranones in Aqueous Media

A facile and convenient synthesis of dihydropyranones has been developed by a formal [4+2] annulation of readily available alpha-acetyl ketene S,S-acetals with various aldehydes, involving a tandem aldol reaction and conjugate addition-elimination reaction, in the presence of NaOH in water.