N-(2-氯乙基)-N'-2-(O~6-苄基-9-鸟嘌呤基)乙基-N-亚硝基脲的合成

以O~6-苄基鸟嘌呤为原料,经取代反应和盖布瑞尔反应制得N9-(2-胺基)乙基-O6-苄基鸟嘌呤(4);4与异氰酸酯经取代反应和经亚硝化反应合成了N-(2-氯乙基)-N'-2-(O6-苄基-9-鸟嘌呤基)乙基-N-亚硝基脲(6)。4和6为新化合物,其结构经UV-Vis,1H NMR,13C NMR,IR和HR-ESI-MS表征。     

2-碘腺苷合成新方法

报道了核苷药物中间体2-碘腺苷的合成新方法.以2-氨基-6-氯-2′,3′,5′-三-O-乙酰基嘌呤核苷为原料,以CH3CN为溶剂,I2为碘源,5%的Cu I为催化剂,合成了到2-碘-6-氯-2′,3′,5′-三-O-乙酰基嘌呤核苷,继而在饱和的NH3/CH3OH溶液中氨解,以两步和78.2%的总收率得到2-碘腺苷.反应规模可以扩大到公斤级,收率没有降低.中间体及产物的分离、纯化不需要柱层析.该方法高效、简便、易于操作,显示出很好的应用前景.     

N6-烷基-2-烷氧基腺苷化合物的合成及抗血小板凝集活性

以鸟瞟呤核苷(1)为原料,经羟基保护得到2’,3’,5’-三-O-乙酰基鸟嘌呤核苷(2),2与三氯氧磷反应得到2-氨基-6-氯-9-(2’,3’,5’-三-O-乙酰基-β-D-呋喃核糖)嘌呤(3),3经重氮化、水解和O-烷基化得到2-烷氧基-6-氯-9-(2’,3’,5’-三-O-乙酰基-β-D-呋喃核糖)嘌呤(4a～...     

利塞膦酸钠关键中间体3-乙酰基吡啶的合成

3-乙酰基吡啶是合成利塞膦酸钠的关键中间体.室温下,以3-乙炔基吡啶在CF_3SO_3H/CF_3CH_2OH(n(CF_3SO_3H)/n(CF_3CH_2OH)=20%)催化体系中顺利进行马氏水合反应,反应收率较高,环境友好,该方法同时具有原料易得、反应条件温和、操作简便、适合工业化生产等优点.     

ω-氯氟烷基醇,烯烃及环氧化物的合成

本文报道在引发剂存在下, ω-氯氟烷基碘与烯丙基化合物(CH~2=CH-CH~2X, X=OH,OAC) 及乙烯基化合物CH~2=CH-OAC 发生自由基加成反应, 生成相应的加成产物Cl(CF~2)~nCH~2CHICH~2OH (2a～d), Cl(CF~2)~nCH~2CHICH~2OAC (3a～d)和Cl(CF~2)~nCH~2CHIOAC (4a～d) , 产率较好.2a～d用LiAlH~4脱碘生成Cl(CF~2)~nCH~2CH~2CH~2OH(5a～d), 反应条件温和. 2a～d与KOH-CH~3OH反应， 主要得到醇Cl(CF~2)~nCH=CHCH~2OH (6a～c), 若2a～d与NaOH-水溶液反应则得到环氧丙烷化合物. 在少量HOAC存在下， 异丙醇溶剂中， 锌粉与2a～d和3a～d反应得到消除产物Cl(CF~2)~n-CH~2CH=CH~2 (8a～d) . 4a～d与锌反应，再经KOH-CH~3OH-H~2O水解得到Cl(CF~2)~n(CH~2)~2OH(10a～d).     

嘌呤N-6-吡啶盐中间体的形成及其在嘌呤核苷合成上的应用

本文报道以次黄苷为原料, 经酯化, 再在缩合剂4-氯苯磷酰二氯存在下与吡啶反应, 形成嘌呤N-6-吡啶盐中间体2, 该中间体2分别与碱性强弱不同的胺或氨及2moldm^-^3NaOH的醇溶液在室温反应, 可方便的合成6-NH2, 6-OCH3以及6-OCH2CH3-9-(β-D-呋喃核糖)嘌呤衍生物。并对以上产物形成的机制作了探讨。     

6-甲基-5-硝基-3-吡啶硼酸频哪酯合成工艺的改进

以2-氯-3-硝基-5-溴吡啶为起始原料,经取代反应、水解反应、Suzuki偶联反应得到6-甲基-5-硝基-3-吡啶硼酸频哪酯。反应总收率为51%,中间体及目标产物结构由IR和1H-NMR表征。     

6-烷基鸟嘌呤与DNA碱基间氢键作用的理论研究

用密度泛函B3LYP方法在6-311＋G**基组水平上对鸟嘌呤及顺(cis-)、反式(anti-)-6-烷基鸟嘌呤(O⁶-AlkylG)与DNA碱基(胸腺嘧啶T、胞嘧啶C、腺嘌呤A、鸟嘌呤G)的氢键二聚体结构进行了优化. 在MP2/cc-pVXZ(X＝D,T)// B3LYP/6-311＋G**水平上, 采用完全基组外推方法校正了氢键二聚体的相互作用能, 并用完全均衡校正法(CP)校正了基组重叠误差(BSSE). 在B3LYP/6-311＋G**水平上计算了各氢键碱基对的全电子波函数, 并用分子中的原子理论(AIM)分析了碱基间的弱相互作用. 计算结果显示, 鸟嘌呤6-O烷基化改变了碱基间的氢键作用模式, 使碱基对发生了明显的螺旋桨式扭转和不同程度的位移, 碱基间的电子密度分布和氢键作用能明显减小. O⁶-AlkylG对DNA碱基间的氢键作用是去稳定化的, 去稳定化影响的顺序为GC＞GG＞GA≈GT. 计算结果与文献给出的实验结论基本一致.     

2-氨基-6-甲氧基-3-硝基吡啶的合成

以2-氯-5-硝基吡啶为原料,经甲氧基化反应得2-甲氧基-5-硝基吡啶(2),2再与液氨/高锰酸钾进行氨化反应制得2-氨基-6-甲氧基-3-硝基吡啶,总收率77%。     

一种有效制备2-氨基-3,5-二硝基-6-氯吡啶及其衍生物的方法

研究了2-氨基-3,5-二硝基-6-氯吡啶(4)及其衍生物的制备新方法.以廉价易得的2,6-二氯吡啶(1)为起始原料,通过硝化、氨化、硝化反应步骤得到中间体2-氨基-3,5-二硝基-6-氯吡啶(4),再与氨、叠氮化钠等亲核试剂反应分别得到2-氨基-3,5-二硝基吡啶-6-取代衍生物5~7.研究表明该方法具有原料便宜易得、后处理操作简单和产品纯度高等优点.     

Transient silylation of the guanosine O6 and amino groups facilitates N-acylation

[reaction: see text] The formation of a guanosine derivative silylated at both the O6 and amino groups was identified by (15)N NMR. This intermediate allows facile reaction with acetyl chloride or phenoxyacetyl chloride to give in high yield the corresponding N-protected guanosine derivatives, suitable for use in RNA synthesis. The acetyl and phenoxyacetyl amino protecting groups are, respectively, 4 and 230 times more labile than the isobutyryl group to methylamine/ethanol deprotection.     

6-bromopurine nucleosides as reagents for nucleoside analogue synthesis.

Surprisingly facile direct substitution reactions with acetyl-protected 6-bromopurine nucleosides are described. Included in the series of bromonucleosides studied is the guanosine derivative N(2)-2',3',5'-tetraacetyl-6-bromopurine ribonucleoside, the synthesis of which is reported here for the first time. Brominated nucleosides had not previously been considered optimal substrates for S(N)Ar reactions given the general reactivity trend for halogenated aromatic systems (i.e. F > Cl > Br > I). However, even weakly nucleophilic aromatic amines give high yields of the substitution products in polar solvents with these 6-bromopurine nucleosides. For primary aromatic amines, secondary aliphatic amines, and imidazole, reaction takes place only at C6, with no effect on the acetyl-protected ribose. In addition, we report the first synthesis of 3',5'-di-O-acetyl-6-bromopurine-2'-deoxyribonucleoside and its reaction with an arylamine in MeOH in the absence of added metal catalyst. Thus, C6-arylamine derivatives of both adenosine and 2'-deoxyadenosine can be prepared via simple S(N)Ar reactions with the corresponding 6-bromo precursor. We also describe high yielding and C6-selective substitution reactions with 6-bromonucleosides using alcohol and thiol nucleophiles in the presence of added base (DBU). Finally, C6-bromonucleosides are shown to be readily hydrogenated to give purine or 2-aminopurine products in good yield. This work increases the arsenal of reactions and strategies available for the synthesis of nucleoside analogues as potential biochemical tools or new therapeutics.     

G-quartet formation from an N2-modified guanosine derivative

[structure: see text] We report G-quartet formation from an N2-modified lipophilic guanosine nucleoside, N2-(4-n-butylphenyl)-2',3',5'-O-triacetylguanosine. We show that, in the presence of either K+ or Na+, this guanosine derivative self-assembles into a D4-symmetric octamer consisting of two stacking all-syn G-quartets in a tail-to-tail (or head-to-head) fashion and a central ion.     

(2S)-(+)-2-溴-1-(6'-甲氧基-2'-萘基)丙-1-酮的不对称合成

以(2R,3R)-酒石酸二甲酯为手性辅助剂,6-甲氧基-2-丙酰基萘经缩酮化、溴化铜不对称溴化、水解等反应合成了(2S)-2-溴-1-(6'-甲氧基-2'-萘基)丙-1-酮。总收率94%。     

3, 6-二取代-均三唑并[3, 4-b]-1, 3, 4-噻二唑的合成

研究了2-苯基-1, 2, 3-三唑-4-羧酸(1)与3-烷基/芳基-4-氨基-5-巯基-1, 2, 4-三唑(2a～o)在POCl~3催化下, 脱水缩合得到15个新的3-烷基/芳基-6-(2'-苯基-1', 2', 3'-三唑-4'-基)均三唑并[3,4-b]-1, 3, 4-噻二唑类化合物(3a～o)。     

Nucleic acid related compounds. 118. Nonaqueous diazotization of aminopurine derivatives. Convenient access to 6-halo- and 2,6-dihalopurine nucleosides and 2'-deoxynucleosides with acyl or silyl halides

Treatment of 9-(2,3,5-tri-O-acetyl-beta-d-ribofuranosyl)-2-amino-6-chloropurine (1) with TMS-Cl and benzyltriethylammonium nitrite (BTEA-NO2) in dichloromethane gave the crystalline 2,6-dichloropurine nucleoside 2, and acetyl chloride/BTEA-NO2 was equally effective ( approximately 85%, without chromatography). TMS-Br/tert-butyl nitrite/dibromomethane gave crystalline 2-bromo-6-chloro analogue 3 (85%). (Chloro or bromo)-dediazoniation of 3',5'-di-O-acetyl-2'-deoxyadenosine (4) gave the 6-[chloro (5, 63%) or bromo (6, 80%)]purine deoxynucleosides, and 2',3',5'-tri-O-acetyladenosine (8) was converted into the 6-chloropurine nucleoside 9 (71%).     

Structural analogues of the bimetallic reaction center in acetyl CoA synthase: a Ni--Ni model with bound CO

Models for the active site of the acetyl CoA synthase (ACS) were synthesized by attachment of Cu+ and Ni(0) to nickel diaminodithiolate (S2N2) and diamidodithiolate (S2N2') complexes. The Ni-Ni species form stable CO adducts, i.e., [{(CO)2Ni}{NiS2N2'}]2-, whereas the Cu-NiS2N2 and Cu-NiS2N2' models do not. These results provide supporting evidence for a biological role for reduced nickel in ACS.     

5-(2’-羧乙基)-6-烷基-3,4-二氢吡喃酮的合成

吡喃酮是许多天然产物的结构单元,我们曾由4-异丁酰基庚二酸在过量醋酸酐及乙酰氯存在下回流得到7-氧代-8,8-二甲基-△~9-六氢香豆素.本文由二氰乙基-β-二酮进行酮解水解反应得到4-酰基庚二酸1_(a-c)。 在过量醋酸酐、乙酰氯存在下由1_a、1_c为底物进行反应没有得到双环的香豆素衍生物.其产物和单纯以乙酐为缩合剂时的产物2_a、2_c相同,产率分别为68％、63％。2_c可在硫酸铁催化     

Self-assembly of N2-modified guanosine derivatives: formation of discrete G-octamers

In the presence of Na(+) ions, two N(2)-modified guanosine derivatives, N(2)-(4-n-butylphenyl)-2',3',5'-O-triacetylguanosine (G1) and N(2)-(4-pyrenylphenyl)-2',3',5'-O-triacetylguanosine (G2), are found to self-associate into discrete octamers that contain two G-quartets and a central ion. In each octamer, all eight guanosine molecules are in a syn conformation and the two G-quartets are stacked in a tail-to-tail fashion. On the basis of NMR spectroscopic evidence, we hypothesize that the pi-pi-stacking interaction between the N(2)-side arms (phenyl in G1 and pyrenyl in G2) can considerably stabilize the octamer structure. For G1, we have used NMR spectroscopic saturation-transfer experiments to monitor the kinetic ligand exchange process between monomers and octamers in CD(3)CN. The results show that the activation energy (E(a)) of the ligand exchange process is 31 +/-5 kJ mol(-1). An Eyring analysis of the saturation transfer data yields the enthalpy and entropy of activation for the transition state: DeltaH(not =)=29 +/-5 kJ mol(-1) and DeltaS(not =)=-151 +/-10 J mol(-1) K(-1). These results are consistent with an associative mechanism for ligand exchange.     

新型P,N配体及基1,4-共轭加成反应

以2-萘酚为起始原料,经过氧化偶联,消旋体的拆分得到手性骨架2-氨基-2'-羟基-1,1'-联萘(NOBIN),并以S-NOBIN为原料,经过六步反应合成了两个新型配体S-(+)-2-(2-吡啶酰胺基)-2'-二苯基膦基-1,1'-联萘(1a)和S-(+)-2-(6-甲基-2-吡啶酰胺基)-2'-二苯基膦基-1,1'-联萘(1b)。并进行了铜配合物催化的二乙基锌对2-环己烯酮的1,4-共轭加成反应的研究。反应产物3-乙基环己酮(13)的e.e.值高达92%。