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991.
WANG Yan-xia YE Song 《高等学校化学研究》2006,22(4):520-523
IntroductionPhotochemical reactions, which involve a three-membered ring, have been of great interest to experi-mental photochemists[1—10]. A main reason for thisphenomenon is that the cyclopropane ring exhibits somereaction characteristics of double bon… 相似文献
992.
Published data on methods for the synthesis of indole derivatives (isogramines) containing a dimethylamino group at positions 1, 2 and also at various positions of the benzene ring in the indole bicycle and their chemical properties are reviewed.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–504, April, 2005. 相似文献
993.
On the basis of the common feature among the electron transfer process and the ion hydration process as well as the relevant experimental kinetic data of electron transfer reaction,a new accurate hydration potential function scheme for the determination of electron transfer coupling matrix element is presented.The coupling matrix element between two hydrated ions of the reacting system in solution is calculated.The results and the applicability of this scheme are discussed. 相似文献
994.
Polymerase chain reaction (PCR) is an important diagnostic tool for the amplification of DNA. The PCR process can be treated as a problem in biochemical engineering. This study focuses on the development of a mathematical model of the polymerase chain reaction. The PCR process consists of three steps: denaturation of target DNA, annealing of sequence-specific oligonucleotide primers and the enzyme-catalyzed elongation of the annealed complex (primer:DNA:polymerase). The denaturation step separates the double strands of DNA; this model assumes denaturation is complete. The annealing step describes the formation of a primer-fragment complex followed by the attachment of the polymerase to form a ternary complex. This step is complicated by competitive annealing between primers and incomplete fragments including primer-primer reactions. The elongation step is modeled by a stochastic method. Species that compete during the elongation step are deoxynucleotide triphosphates dCTP, dATP, dTTP, dGTP, dUTP, and pyrophosphate. Thermal deamination of dCTP to form dUTP is included in the model. The probability for a species to arrive at the active site is based on its molar fraction. The number of random insertion events depends on the average processing speed of the polymerase and the elongation time of the simulation. The numerical stochastic experiment is repeated a sufficient number of times to construct a probability density distribution (PDF). The moment of the PDF and the annealing step products provide the product distribution at the end of the elongation step. The overall yield is compared to six experimental values of the yield. In all cases the comparisons are very good. 相似文献
995.
Synthesis of methylenedioxy-bearing 1-aryl-3-carboxylisoquinolines using a modified Ritter reaction procedure 总被引:1,自引:0,他引:1
This paper describes original approaches aimed at the preparation of electron-rich 1-aryl-3-carboxylisoquinolines. Our first attempt led to an efficient preparation of 1-hydroxyisoquinoline-3-carboxylic acid methyl ester starting from bromophthalide via a rearrangement of 2-acetylamino-2-(3-oxo-1,3-dihydroisobenzofuran-1-yl)-malonic acid dimethyl ester. However, as its eventual application to the synthesis of methylenedioxy-bearing substrates seemed rather long, a second approach involving an extension of the Ritter reaction to safrole was devised. We thus report that, under proper experimental settings, the use of 54% tetrafluoroboric acid in ether enables a Ritter reaction between safrole and 3,4,5-trimethoxybenzonitrile yielding 17% of 7-methyl-5-(3,4,5-trimethoxyphenyl)-7,8-dihydro-[1,3]dioxolo[4,5-g]isoquinoline. This acidic reagent avoids the extensive decomposition seen when using the classical Ritter reaction conditions (i.e.: concentrated sulfuric acid). Further chemical transformations of this methyl-bearing dihydroisoquinoline led to the methylenedioxy-bearing 1-aryl-3-carboxylisoquinoline. These derivatives are related to the peripheral benzodiazepine receptor ligand PK 11195 as well as falcipain-2 inhibitors and other potential antitumor agents. 相似文献
996.
Systematic studies were performed on SnCl2-mediated carbonyl allylation reaction between aldehydes and allyl halides in fully aqueous media. Totally three valuable reaction systems were discovered, which were SnCl2/CuCl2, SnCl2/TiCl3, and SnCl2/PdCl2. They all provided good to excellent yields in the allylation of aliphatic and aromatic aldehydes under very mild and convenient conditions. SnCl2, by itself, was also found to be effective for the allylation reaction when allyl bromide was employed. However, the SnCl2-only reaction could only tolerate very small amount of water as the solvent. The SnCl2/CuCl2, SnCl2/TiCl3, and SnCl2/PdCl2-mediated reactions exhibited good regioselectivity favoring the γ-adduct when cinnamyl halides were employed as the allylation reagent. The same reactions with cinnamyl halides also showed good diastereoselectivity favoring the anti-product. Mechanistic studies using proton NMR techniques suggested that the additive (i.e., CuCl2, TiCl3, PdCl2) could accelerate the formation of allyltin intermediate, but this step was shown not to be the most important for the allylation. Thus we proposed that the Lewis acid catalysis effect exerted by the additive was the main reason for the observed reactivity enhancement. 相似文献
997.
Marta Catellani Sara Deledda Françoise Hénin Jacques Muzart 《Journal of organometallic chemistry》2003,687(2):473-482
A novel reaction sequence leading to the synthesis of substituted biphenyls containing a carbonyl group in an aliphatic chain has been achieved in one-pot reaction starting from iodoarenes and allylic alcohols under the catalytic action of palladium and norbornene. The latter is temporarily incorporated into a palladacycle, which directs the reaction towards the selective formation of an arylaryl bond. Norbornene spontaneously deinserts to allow the biphenylylpalladium bond thus formed to react in its turn with the allylic alcohol. 相似文献
998.
通过三碘化锑和三碘化铋与硫脲间的室温固固反应合成了三碘化锑、三碘化铋的硫脲配合物 ,其组成为 :M[CS( NH2 ) 2 ]3 I3 ( M=Sb,Bi)。两种配合物的晶体结构均属于单斜晶系 ,锑配合物 Sb[CS( NH2 ) 2 ]3 I3 的晶胞参数为 :a=1 .4 772 nm,b=1 .6 5 82 nm,c=2 .0 6 74 nm,β=90 .81°,铋配合物 Bi[CS( NH2 ) 2 ]3 I3 的晶胞参数为 :a=1 .4 0 1 0 nm,b=2 .0 1 6 8nm,c=2 .0 397nm,β=90 .84°。远红外光谱表明硫脲中的 N原子而非硫原子参与了配位 相似文献
999.
Takaya Hisano 《Tetrahedron letters》2005,46(37):6293-6295
Highly regioselective transformation of acyclic α,α′-alkenediols and their corresponding diacetates to monoacetates using lipase was accomplished. The acetylation of the α,α′-alkenediol regioselectively gave (E)-monoacetate, whereas the (Z)-monoacetate were obtained by hydrolysis of the α,α′-diacetate. 相似文献
1000.