共生真菌巴西类壳小圆孢中环二肽类代谢产物研究

利用正相和反相柱色谱,Sephadex LH-20凝胶柱色谱及反相HPLC等方法从昆虫共生真菌Paraconiothyrium brasiliense的发酵产物中分离得到9个环二肽类化合物,经NMR,MS及理化性质等方法,结构确定为环(L-亮氨酸-L-酪氨酸)(1),环(L-色氨酸-L-脯氨酸)(2),环(L-脯氨酸-L-苯丙氨酸)(3),环(L-脯氨酸-L-酪氨酸)(4),环(L-脯氨酸-L-亮氨酸)(5),环(L-亮氨酸-反式-4-羟基-L-脯氨酸)(6),环(L-异亮氨酸-L-脯氨酸)(7),环(L-缬氨酸-L-脯氨酸)(8),环(L-亮氨酸-L-异亮氨酸)(9)。所有化合物均为首次从该属菌种中分离得到。     

(S)-2-烷基-四氢吡咯[1,2-e]咪唑-1,3-二酮的合成

从L-脯氨酸出发,经三步简单反应制得一种咪唑烷酮衍生物(S)-2-烷基-四氢吡咯[1,2-e]咪唑-1,3-二酮,并通过1 H NMR、13 C NMR、MS等方法对中间产物和目标产物的结构进行了表征,通过X-射线单晶衍射分析确定了(S)-2-环己基-四氢吡咯[1,2-e]咪唑-1,3-二酮的晶体结构.     

Empetrifranzinans A和Empetrifranzinans C的全合成及其抗肿瘤活性

以间苯三酚为起始原料,L-脯氨酸为催化剂,经由两步反应首次合成了Empetrifranzinans A(1a,总收率60%)和Empetrifranzinans C(总收率55%),其结构经1H NMR,13C NMR和HR-MS确证。初步药理筛选实验结果表明,1a对人结肠癌、肝癌、胃癌、肺腺癌、卵巢癌细胞表现出了较强的细胞毒作用,其IC50分别为<0.1,1.31,4.90,8.98和3.65μmol·L-1。     

L-脯氨酸催化的硝基烷烃与醛的缩合反应

研究了氨基酸催化的硝基烷烃与醛的缩合反应。以L-脯氨酸(5%~20%)为催化剂,高产率(77%~95%)地合成了一系列硝基烯烃类化合物,其结构经1H NMR,IR和MS表征。     

环(L-色-L-脯)衍生物的合成及其抑菌活性研究

以L-色氨酸甲酯盐酸盐、芳香醛和N-Fmoc-L-脯氨酸为原料,经过Pictet-Spengler反应、Schotten-Baumann反应、NBS开环反应、碱催化增环反应,得到4个环(L-色-L-脯)的衍生物,其结构均经过熔点测定、NMR、元素分析表征。在抑菌活性测试中发现,该类化合物对细菌有较好的抑制活性。     

壳聚糖负载L-脯氨酸对水中不对称Aldol反应的催化性能

以壳聚糖为载体制备了负载型L-脯氨酸不对称催化剂;将合成产物用于催化丙酮与取代苯甲醛在水中的直接不对称Aldol反应,考察了其催化性能.结果表明,与在有机溶剂中的L-脯氨酸催化剂相比,在水相中的壳聚糖负载L-脯氨酸催化剂表现出更好的催化活性;就间硝基苯甲醛与丙酮在水中的不对称Aldol反应而言,壳聚糖负载L-脯氨酸催化下的产率和ee值分别达95%和48%.此外,壳聚糖负载L-脯氨酸催化剂在水中具有很好的重复使用性能,重复使用10次后相应的产率和ee值分别为88%和68%.     

N-烷氧基苯丙-脯环二肽的一种新合成法

环二肽如L-组-L-脯环二肽、L-脯-L-羟脯环二肽等广泛存在于自然界,同时发现这些环肽显示出不同的生理活性.自然界存在的环肽中,常常包含一些非核糖体氨基酸,而这些结构往往是产生活性的重要结构单元.本研究应用脯氨酸为主要原料,在与α-烷氧亚氨苯丙酰氯反应生成N-α-烷氧亚氨苯丙酰脯氨酸后,再用氯化亚砜处理,得到对应的酰氯,E-构型肟N作为亲核试剂进攻酰氯环合得到N-烷氧基的盐,随后重排得到N-烷氧环二肽.其结构均通过IR,1H NMR,13C NMR,1H-1HNMR,MS和元素分析予以确认.研究发现,环化用有机碱如三乙胺催化时,所得环肽常常是消旋体,在没有碱存在时,得到的环肽具有旋光性.可能的原因是,前者是按烯酮机理环合的,后者是按加成-消去机理环合的.     

类产碱假单胞菌XW-40发酵-生物转化级联产生D-脯氨酸

建立了一个新颖的用于产生D-脯氨酸的发酵-生物转化过程.发酵过程中,以DL-脯氨酸为发酵前体,类产碱假单胞菌XW-40利用L-对映体诱导产生脯氨酸脱氢酶,D-对映体完全保留.在最优条件下,发酵阶段产生6 g/L D-脯氨酸.生物转化过程中,细胞不经分离,发酵液直接作为反应介质.采用分批补料策略实现DL-脯氨酸中L-对映体的转化.DL-脯氨酸单批补料浓度为10 g/L,补料次数达到5批.通过发酵和生物转化的级联,累积的D-脯氨酸浓度达到31 g/L,ee99%.推测了生物转化过程中D-脯氨酸产生的反应机理.     

助剂对L-脯氨酸催化直接不对称Aldol反应的影响

在L-脯氨酸催化的芳香醛与丙酮直接不对称aldol反应体系中添加二醇或二酚类助剂可有效提高反应活性.助剂的使用降低了该反应体系中L-脯氨酸的用量.特别是以邻苯二酚为助剂时,最佳反应条件下,仅用5mol％L-脯氨酸与1mol％助剂催化2-硝基苯甲醛与丙酮直接不对称aldol反应,aldol产物产率高达90％,对映选择性为...     

5-位苯基取代脯氨酸的不对称合成

以焦谷氨酸为原料,通过两种路线,分别合成了5-位反式苯基取代脯氨酸和5-位顺式苯基取代脯氨酸,总收率分别为43.9%和51.0%。其结构经1H NMR,13C NMR和MS表征。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。