N-苄氧羰基-L-丙氨酸合成研究

以L-丙氨酸和N-(苄羰氧基)丁二酰胺为起始原料合成了N-苄氧羰基-L-丙氨酸,采用正交实验等方法考察了缚酸剂种类、L-丙氨酸、碳酸氢钠和N-(苄羰氧基)丁二酰胺的物质的量比、有机溶剂、反应时间、反应温度及二氧六环与水的体积比对收率的影响。采用红外、核磁共振、元素分析对产品结构进行表征确认。结果表明,反应最佳工艺为:n(碳酸氢钠)∶n(N-(苄羰氧基)丁二酰胺)∶n(L-丙氨酸)=2∶1.2∶1,二氧六环与水的体积比为1.5∶1,25℃,反应3h,收率达到97.7%。     

盐酸咪达普利的合成

N-苄氧羰基-L-天冬酰胺经环化、酯化、甲基化,脱苄氧羰基得到关键中间体(4S)-1-甲基-2-氧代咪唑啉-4-羧酸叔丁酯.再与由N-[ (S) -1-乙氧羰基-3-苯丙基]-L-丙氨酸进行酰化反应,利用氯化氢脱去叔丁基,得到咪达普利盐酸盐,总收率约为26％(以N-苄氧羰基-L-天冬酰胺计).     

N-苄氧羰基氨基酸的合成

以甘氨酸和氯甲酸苄酯为原料,合成N-苄氧羰基甘氨酸,通过正交实验考察工艺条件对反应的影响。结果表明,最佳工艺条件为:底物摩尔比n(甘氨酸)∶n(氯甲酸苄酯)=1∶1,反应时间2 h,反应温度20℃,反应液pH值为9,收率90.2%。此法反应条件温和,操作简单,收率良好。     

N-苄氧羰基-L-丝氨酸苄酯的合成

以苄氧羰基氯、L-丝氨酸为原料,合成了N-苄氧羰基-L-丝氨酸。通过正交实验考察了反应温度、pH、原料的摩尔比、相转移催化剂对N-苄氧羰基-L-丝氨酸收率的影响。优化反应条件后N-苄氧羰基-L-丝氨酸收率为93.2%。N-苄氧羰基-L-丝氨酸和苄溴反应生成了目标产物-N-苄氧羰基-L-丝氨酸苄酯,重点探讨了酯化过程中缚酸剂、原料的投料顺序及产品后处理对目标产物收率的影响。选择具有催化作用的三乙胺为缚酸剂,用质量分数10%的亚硫酸氢钠对产品进行后处理使N-苄氧羰基-L-丝氨酸苄酯的色谱纯度达98.5%。通过红外、核磁、熔点、旋光度等对目标产品进行了结构表征,用高效液相色谱对产品的纯度进行了测定。     

6,11-二氢二苯骈[b,e]氧杂-11-酮-2-乙酸的合成

采用对羟基苯乙酸(Ⅱ)和苯酞为原料,在甲醇钠的催化下,以n(Ⅱ)∶n(苯酞)∶n(甲醇钠)=1.0∶1.1∶2.2,于130℃反应7h制备4-(2-羧基苄氧基)苯乙酸(Ⅲ)。Ⅲ与乙酰氯经氯化、环合得6,11-二氢二苯骈[b,e]氧杂-11-酮-2-乙酸(Ⅰ),该步优化的反应条件为:n(Ⅲ)∶n(乙酰氯)=1∶1.25,反应温度为100℃,反应时间为6h。以Ⅱ计,总收率达48.16%,Ⅰ的结构经IR、1H NMR和MS确证。     

(Z或E)-4-氯-2-对硝基苄氧羰基甲氧亚胺-3-氧代丁酸的合成研究

以2-对硝基苄氧羰基甲氧亚胺基-3-氧代丁酸、磺酰氯为起始原料,在一定条件下经过反应、处理,得到(顺式或反式)即(Z或E)-4-氯-2-对硝基苄氧羰基甲氧亚胺-3-氧代丁酸。通过红外、核磁共振对其结构进行了表征。较佳工艺条件:原料摩尔比n(2-对硝基苄氧羰基甲氧亚胺基-3-氧代丁酸)∶n(磺酰氯)=1∶1.4,在50~55℃反应5~6 h,反应完调节体系pH值为6.5±0.1,顺式、反式异构体产品分离效果达到99%以上,收率分别是24%和48%,纯度均为98%。     

1-苯基吲哚的合成

以二苯胺和乙二酰氯为起始原料经偶联、酰化、还原反应得到1-苯基吲哚,并探索了其影响因素。结果表明合成中间体N,N-二苯基-2-氯-2-氧代乙酰胺的较佳条件为：n(二苯胺)：n(乙二酰氯)=1∶3,反应温度20～25 ℃,反应2.5 h,收率98.02%,HPLC纯度97.68%;产品1-苯基靛红的较优合成工艺条件为： n(N,N-二苯 基-2-氯-2-氧代乙酰胺) ：n(无水AlCl3)=1∶3,反应温度10 ℃,反应时间2 h,收率86.76%,HPLC纯度98.45%;目标产物1-苯基吲哚的最佳工艺条件为：n(1-苯基靛红)：n(硼氢化钠)=1∶3,n(1-苯基靛红)：n(氯化锌)=1∶0.05,反应温度110 ℃,反应时间12 h,收率72.41%,HPLC纯度98.14%。产品及中间体结构经1H NMR、MS和显微熔点仪分析表征确认。     

N-苄氧羰基-L-缬氨酸的合成

以氯甲酸苄酯和L-缬氨酸为原料,在NaOH的溶液中进行反应,以较高收率合成了N-苄氧羰基-L-缬氨酸。考察了反应物的配比、反应温度、重结晶方式对收率影响。得到最佳的反应条件为:反应温度为20℃、反应物L-缬氨酸:氯甲酸苄酯为1∶1.2(摩尔比),重结晶时先用乙醚与甲苯体积比为1∶1混合溶剂溶解粗品,然后滴加石油醚析出晶体,产品收率较高达95%,纯度为99%。     

N-苄氧羰基-L-丝氨酸苄酯的合成研究与改进

摘要：以苄氧羰基氯、L -丝氨酸为原料,合成了N -苄氧羰基-L-丝氨酸。通过正交实验考察了反应温度、pH、原料的摩尔比、相转移催化剂对N -苄氧羰基-L-丝氨酸收率的影响。优化反应条件后N-苄氧羰基-L-丝氨酸收率为93.2%。N -苄氧羰基-L-丝氨酸和苄溴反应生成了目标产物-N-苄氧羰基-L-丝氨酸苄酯,重点探讨了酯化过程中缚酸剂、原料的投料顺序及产品后处理对目标产物得率的影响。选择具有催化作用的三乙胺为缚酸剂,用10%的亚硫酸氢钠对产品进行后处理使得N-苄氧羰基-L-丝氨酸苄酯的纯度达98.5%。通过红外、核磁、熔点、旋光度等对目标产品进行了结构表征, 用高效液相色谱对产品的纯度进行了测定。     

苄氧羰基-L-丙氨酸制备工艺研究

用L-丙氨酸(L-A la)和苄氧羰基氯(Z-C l)为主要原料制备苄氧羰基-L-丙氨酸,研究了原料的量比、pH值、反应温度、反应时间对收率的影响,并用红外、高效液相色谱、薄层色谱等进行产品结构表征和纯度分析。结果表明,当Z-C l∶L-A la=1.3∶1(摩尔比),pH值为12~13,反应温度为10~20℃,反应8 h,所得产品纯度大于98.5%,产率大于97%。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.