以肌苷为原料的2,6-二氯嘌呤核苷的合成

以廉价的肌苷为原料,经过糖基的乙酰化和嘌呤碱基6位羰基的氯代,得到2',3',5'-三-O-乙酰基-6-氯嘌呤核苷,然后以二氯甲烷为溶剂,在三氟乙酸酐和四丁基硝酸铵的作用下,在嘌呤2位引入硝基。最后在HCl/Et OH溶液中,完成脱除乙酰基和硝基氯代两步反应,得到2,6-二氯嘌呤核苷,纯度98%(HPLC),总收率63%。考察了硝基来源、氯原子来源和反应规模对收率的影响,且反应规模扩大到200 g规模时,收率无明显下降。     

2',3'-双脱氧尿苷合成的新方法

通过用乙酸酐保护2',3'-O-甲氧甲叉尿苷分子上的羟基得到2,2'-脱水-1-(3',5'-双-O-乙酰基-β-D-阿拉呋喃糖基)尿嘧啶,接着以它为关键中间体与乙酰溴作用得到溴代核苷衍生物,在经过脱溴、脱酰氧基成烯,催化氢化还原,碱性条件下醇解得到2',3'-双脱氧尿苷。     

9-β-D-阿拉伯呋喃糖-2-氟腺嘌呤的合成改进

2,6-二氨基嘌呤经酰化后再与2,3,5-三-O-苄基-D-阿拉伯呋喃糖基氯化物反应得2,6-二乙酰氨基-9(2,3,5三-O-苄基-β-D-阿拉伯呋喃糖基)嘌呤,该产物脱去氨基上的保护基后在氟硼酸四氢呋喃中经重氮化氟化得9(2,3,5三-O-苄基-β-阿拉伯呋喃糖基)2氟腺嘌呤,最后在三氯化硼作用下脱去苄基得9-β-D-阿拉伯呋喃糖2氟腺嘌呤。反应总收率为30.0%。     

氮苷1-(2'''',3'''',4'''',6''''-O-四乙酰基-β-D-吡喃葡萄糖基)-咪唑的制备

以D-葡萄糖(Ⅰ)、醋酸酐为原料,在无水吡啶中制得中间体1,2,3,4,6-O-五乙酰基-D-葡萄糖(Ⅱ),收率为87.5%.在HBr/CH3COOH条件下对Ⅱ异头碳上的乙酰基进行溴代,制得1-溴-2,3,4,6-O-四乙酰基-D-葡萄糖(Ⅲ),不经分离,在相转移催化剂TEBA催化下,Ⅲ直接与2,4-二硝基苯酚反应得到酚苷1-O-(2',4'-二硝基苯)-2,3,4,6-O-四乙酰基-β-D-葡萄糖苷(Ⅳ),最后Ⅳ与1-三甲基硅基-咪唑在无水四氯化锡的催化下,室温反应52 h制得氮苷1-(2',3',4',6'-O-四乙酰基-β-D-吡喃葡萄糖基)-咪唑(Ⅴ),此步反应收率为90%.     

5'-脱氧-5-氟-N-[(戊氧基)羰基]胞苷-2',3'-二乙酸酯的合成改进

5'-脱氧-5-氟-N-[(戊氧基)羰基]胞苷-2',3'-二乙酸酯是合成卡培他滨的关键中间体,它是由1,2,3-三-O-乙酰基-5-脱氧-D-核糖与用三甲基硅烷保护的5-氟胞嘧啶进行缩合反应得中间体5-脱氧-2,3-二-D-乙酰基-5-氟胞苷,再与氯甲酸正戊酯进行酰胺化制得。总收率约70%。     

2-氯-4-硝基苯基-β-D-吡喃岩藻糖苷的合成

2-氯-4-硝基苯基糖苷是一类重要的糖基酶底物试剂,在相关酶抑制剂制备、酶生物活性研究中有着广泛的应用.以D-半乳糖为原料,通过4步反应得到中间体D-岩藻糖;再经乙酰化制备1,2,3,4-三-O-乙酰基-α,β-D-吡喃岩藻糖,溴代反应获得1-溴-2,3,4-三-O-乙酰基-α-D-吡喃岩藻糖,通过溴代糖与2-氯4-硝基苯酚偶联,立体选择性获得2-氯-4-硝基苯-2,3,4-三-O-乙酰基-β-D-吡喃岩藻糖基糖苷,最后脱除乙酰基保护得标题化合物.该化合物可以作为一种新型的β-D-岩藻糖苷酶底物试剂,用于酶活性测试,其合成方法未见文献报道.     

以肌苷为原料合成水粉蕈素

肌苷通过乙酰化和氯代反应得到了2′,3′,5′-三-O-乙酰基-6-氯嘌呤核苷(Ⅳ);接着,化合物Ⅳ与三苯基膦反应,得到了2′,3′,5′-三-O-乙酰基-6-三苯基膦嘌呤核苷(Ⅴ);最后,中间体Ⅴ在碳酸钾作用下断裂C—P键,同时脱掉乙酰基,以4步反应得到产物水粉蕈素,其总分离收率为62％.考察了C—P键的生成和断裂对...     

9-(2-羟基乙基)-6-氨基-2-烷硫基嘌呤衍生物的合成

以2-氨基-6-氯嘌呤为原料,与2-溴乙基乙酸酯反应得到9-乙酰氧基乙基-2-氨基-6-氯嘌呤(Ⅰ),收率65.6%;Ⅰ经重氮-烷硫化得到9-乙酰氧基乙基-2-烷硫基-6-氯嘌呤(Ⅱ),收率58.3%~72.1%;Ⅱ与叠氮化钠反应得到9-乙酰氧基乙基-2-烷硫基-6-叠氮嘌呤(Ⅲ),收率86.4%~92.0%。经核磁检测Ⅲ在溶液中存在叠氮结构(A)和四氮唑结构(T)的互变异构现象,CDCl3中叠氮结构比例在61.5%~67.2%。采用PPh3-HCl-DMSO为反应体系,"一锅法"将叠氮基还原为氨基同时将酯基彻底水解,高收率(~90%)得到9-(2-羟基乙基)-6-氨基-2-烷硫基嘌呤衍生物(Ⅳ)。这些化合物的结构经IR、1HNMR、13CNMR及HRMS得到确证。     

2-氨基-6-烷氧基嘌呤的合成

2-氨基-6-烷氧基嘌呤是重要的核苷类药物的中间体。以鸟嘌呤为原料,通过酰化制得N2.9-二乙酰鸟嘌呤(Ⅰ),收率95.8%。氯化水解得到2-氨基-6-氯嘌呤(Ⅱ),收率75.8%。通过2-氨基-6-氯嘌呤(Ⅱ)与醇钠反应得到2-氨基-6-甲氧基嘌呤(Ⅲa),收率96.5%;2-氨基-6-乙氧基嘌呤(Ⅲb),收率79.6%;2-氨基-6-异丙氧基嘌呤(Ⅲc),收率73.2%;2-氨基-6-三氟乙氧基嘌呤(Ⅲd),收率49.8%。用元素分析,核磁共振,质谱,红外光谱对所得产品进行了分析,证明所得产品为目标产品。重点研究了2-氨基-6-三氟乙氧基嘌呤(Ⅲd)的合成,其合成的最佳工艺条件为:n(Ⅱ)∶n(NaOCH2CF3)=1∶5,用二甲亚砜(DMSO)作为反应溶剂,其用量为m(DMSO)∶m(Ⅱ)=13∶1,用碘化亚铜(CuI)为催化剂,其用量为n(CuI)∶n(Ⅱ)=2∶1,反应温度为160℃。     

龙眼核中的神经酰胺和脑苷脂的分离和鉴定

研究龙眼(Dimocarpus longan Lour.)果核的化学成分,采用硅胶柱色谱对龙眼果核石油醚提取物和体积分数95%乙醇提取物进行分离,并利用理化性质和光谱数据鉴定化合物的结构。从龙眼果核的提取物中分离得到一组混合神经酰胺(化合物1、2)和一组混合脑苷脂(化合物3～6),结构鉴定为Rel-(3S,4S,5S)-3-[(2'R)-2'-羟基二十二酰胺]-4-羟基-5-[(4″Z)-十四烷-4″-烯]-2,3,4,5-四氢呋喃(1)、Rel-(3S,4S,5S)-3-[(2'R)-2'-羟基二十四酰胺]-4-羟基-5-[(4″Z)-十四烷-4″-烯]-2,3,4,5-四氢呋喃(2)、1-O-(β-D-吡喃葡萄糖基)-(2S,3S,4R,8E)-2-(2'-羟基二十四酰胺)-8-十八烯-1,3,4-三醇(3)、1-O-(β-D-吡喃葡萄糖基)-(2S,3S,4R,8Z)-2-(2'-羟基二十四酰胺)-8-十八烯-1,3,4-三醇(4)、1-O-(β-D-吡喃葡萄糖基)-(2S,3S,4R,8E)-2-(2'-羟基二十二酰胺)-8-十八烯-1,3,4-三醇(5)、1-O-(β-D-吡喃葡萄糖基)-(2S,3S,4R,8Z)-2-(2'-羟基二十二酰胺)-8-十八烯-1,3,4-三醇(6)。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。