碘催化亚胺与二氢呋喃反应合成四氢喹啉衍生物

碘催化N-苯基苄基亚胺与二氢呋喃反应合成了四氢喹啉衍生物,其结构经~1H NMR,~(13)C NMR和HR-MS表征.     

新型有机硒化合物的合成及其离子识别研究

设计合成了四个含有氢蒽基团的新型有机硒化合物1,8-二-(2-苄硒基)丙氧基-9,10-二氢蒽(L_1)、1,8-氧双(亚乙硒基丙氧基)-9,10-二氢蒽(L_2)、1,8-二-(2-苄硒基)乙氧基-9,10-二氢蒽(L_3)、1,8-氧双(亚乙硒基亚乙氧基)-9,10-二氢蒽(L_4),利用~1H NMR、~(13)C NMR对化合物进行了结构表征,采用荧光光谱法测定了主体对客体阳离子的识别性能。研究结果发现只有化合物L_1对Ag~+具有选择识别能力,且对Ag~+表现出"off-on"开关性能。化合物L_2与Ag~+和K~+络合后荧光略有增强。     

四氢硫芴和六氢硫芴的合成

以2-溴环己酮及苯硫酚为原料,经Tilak反应,然后环化合成了四氢硫芴(1);在三氟乙酸与锌粉存在下1于室温加氢制得六氢硫芴,其结构经1H NMR和GC-MS确证.     

去氢枞醇杂环类化合物的合成及细胞毒性研究

以去氢枞酸(1)为原料,经氢化铝锂还原得到去氢枞醇(2),2与氯乙酰氯在氮气保护和DMAP催化条件下反应合成中间产物去氢枞醇氯乙酸酯(3),3与杂环化合物经亲核取代反应合成了12个新型去氢枞醇杂环类化合物(4a ～41).利用IR、1H NMR、13C NMR和HR-MS等对目标化合物的结构进行表征,采用MTT法测试目...     

新型4-芳基-5,6,7,8-四氢喹唑啉-2-胺类化合物的合成及其生物活性研究

以α-蒎烯为原料,经加成-氧化后与多种芳香醛缩合制得中间体4-芳亚甲基异松蒎酮3a~3h,3a~3h与盐酸胍在叔丁醇钾催化作用下合成8种新型4-芳取代-5,6,7,8,-四氢喹唑啉-2-胺类化合物4a~4h.其结构经IR,1H NMR,13C NMR,GC-MS和元素分析表征.初步探讨了所合成化合物对人乳腺癌细胞MCF-7和人肺癌细胞A549的体外生物活性,结果显示部分化合物具有很好的抗肿瘤活性.     

1-甲基-5,6,7,8-四氢异喹啉酮-4-甲胺的合成研究

以环己酮为起始原料,经缩合、酰化及酸性水解反应制得2 乙酰基环己酮（1）;在三乙烯二胺催化下,1与氰基乙酰胺环化得四氢异喹啉酮（2）和四氢喹啉酮（3）混合物,在乙醇中回流并趁热过滤进行分离纯化得2和3; 2经催化加氢反应合成1-甲基-5,6,7,8-四氢异喹啉酮-4-甲胺,3步总收率39.8%,其结构经¹H NMR、¹³C NMR、 ¹H-¹⁵N HMBC和MS确证。     

四氢喹啉-4-醇类衍生物的合成

以1,2,3,4-四氢喹啉为初始原料,经N-酰基保护、氧化、脱保护、还原等反应合成了一系列1,2,3,4-四氢喹啉-4-醇类的衍生物,总产率17%~41%,其结构经1H NMR和13C NMR确证。     

新型Venetoclax四氢吡喃衍生物的合成

以1-Boc-3-氮杂环丁酮和甲基三苯基溴化磷为起始原料，经Wittig反应、加成环化、脱卤、羰基还原、成醚、哌嗪取代、苯甲酸甲酯衍生物取代、水解、磺胺缩合、脱Boc和四氢吡喃取代反应，合成了一个新型的含四元螺环胺四氢吡喃结构的磺胺类Venetoclax衍生物，总产率22%，其结构经¹H NMR和HR-MS(ESI)表征。     

四氢咪唑并[2',1':2,3]噻吩并[5,4-c]哌啶衍生物的合成及抗肿瘤活性

以4-哌啶酮为原料,经过胺基保护、缩合、环合、脱保护等步骤,设计合成了一系列新型的5,6,7,8-四氢咪唑并[2',1':2-3]噻吩并[5,4-c]哌啶类化合物。通过核磁共振波谱仪(~1H NMR、~(13)C NMR)、质谱(MS)和元素分析确证了其结构。对其体外活性研究发现,该类化合物对乳腺癌细胞MCF-7具有一定的抑制活性,其中化合物5a的抑制活性最为显著,半数抑制浓度(IC_(50))值达到了8.6μmol/L。为此类化合物的抗肿瘤活性研究提供了参考。     

叔胺催化的Sulfa-Michael-Aldol串联反应合成羟基取代的四氢噻吩类化合物

探究了叔胺1,4-二氮杂二环[2.2.2]辛烷(DABCO)催化的2,5-二羟基-1,4-二噻烷和羟基取代查尔酮的sulfa-Michael-aldol串联环化反应。考察了催化剂对反应收率的影响，以最高79%的收率合成了15个多取代的四氢噻吩化合物。 其代表产物的结构经X-ray单晶衍射实验确证，化合物结构经¹H NMR, ¹³C NMR, IR和HR-MS(ESI)表征。      

Glycosyl sulfonium ions as storable intermediates for glycosylations

Glycosyl sulfonium ions, which serve as persistent glycosyl cation equivalents, were prepared by the addition of diorganosulfides to an electrochemically generated glycosyl triflate. Low-temperature and variable-temperature NMR studies were performed to reveal the structure, stability, and reactivity of glycosyl sulfonium ions. The glycosyl sulfonium ions could be used as storable intermediates for reactions with various glycosyl acceptors including thioglycosides to give the corresponding disaccharides.     

Tris(trimethylsilyl)sulfonium and methylbis(trimethylsilyl)sulfonium ions: preparation, NMR spectroscopy, and theoretical studies(1)

Tris(trimethylsilyl)sulfonium 1 and methylbis(trimethylsilyl)sulfonium 2 ions were prepared as long-lived species by reacting trimethylsilane and trityl tetrakis(pentafluorophenyl)borate (Ph(3)C(+) TPFPB) in the presence of precursor sulfides and characterized by (1)H, (13)C, and (29)Si NMR spectroscopy at -78 degrees C. Attempted preparation of dimethyl(trimethylsilyl)sulfonium ion under similar conditions failed as a result of the formation of the more stabilized trimethylsulfonium ion. Structures, and (13)C and (29)Si NMR chemical shifts were calculated by density functional theory (DFT)/IGLO methods. The calculated results agree well with the experimental data.     

Studies directed toward the stereochemical structure determination of the naturally occurring glucosidase inhibitor, kotalanol: synthesis and inhibitory activities against human maltase glucoamylase of seven-carbon, chain-extended homologues of salacinol

The synthesis of new seven-carbon, chain-extended sulfonium salts of 1,4-anhydro-4-thio- d-arabinitol, analogues of the naturally occurring glycosidase inhibitor salacinol, are described. These compounds were designed on the basis of the structure activity data of chain-extended analogues of salacinol, with the intention of determining the hitherto unknown stereochemical structure of kotalanol, the naturally occurring seven-carbon chain-extended analogue of salacinol. The target zwitterionic compounds were synthesized by means of nucleophilic attack of the PMB-protected 1,4-anhydro-4-thio- d-arabinitols at the least hindered carbon atom of two 1,3-cyclic sulfates differing in stereochemistry at only one stereogenic center. The desired cyclic sulfates were synthesized starting from d-glucose via Wittig olefination and Sharpless asymmetric dihydroxylation. Deprotection of the coupled products by using a two-step sequence afforded two sulfonium sulfates. Optical rotation data for one of our compounds indicated a correspondence with that reported for kotalanol. However, comparison of (1)H and (13)C NMR spectral data of the synthetic compounds with those of kotalanol indicated discrepancies. The collective data from this and published work were used to propose a tentative structure for the naturally occurring compound, kotalanol. Comparison of physical data of previously synthesized analogues with those for the recently isolated six-carbon chain analogue, ponkoranol or reticulanol, also led to elucidation of this structure. Interestingly, both our compounds inhibited recombinant human maltase glucoamylase (MGA), as expected from our previous structure activity studies of lower homologues, with K i values of 0.13 +/- 0.02 and 0.10 +/- 0.02 microM.     

Quantification of the Electrophilicities of Diazoalkanes: Kinetics and Mechanism of Azo Couplings with Enamines and Sulfonium Ylides

Kinetics and mechanism of the reactions of methyl diazoacetate, dimethyl diazomalonate, 4-nitrophenyldiazomethane, and diphenyldiazomethane with sulfonium ylides and enamines were investigated by UV-Vis and NMR spectroscopy. Ordinary alkenes undergo 1,3-dipolar cycloadditions with these diazo compounds. In contrast, sulfonium ylides and enamines attack at the terminal nitrogen of the diazo alkanes to give zwitterions, which undergo various subsequent reactions. As only one new bond is formed in the rate-determining step of these reactions, the correlation lg k₂(20 °C)=s_N(N+E) could be used to determine the one-bond electrophilicities E of the diazo compounds from the measured second-order rate constants and the known reactivity indices N and s_N of the sulfonium ylides and enamines. The resulting electrophilicity parameters (−21<E<−18), which are 11–14 orders of magnitude smaller than that of the benzenediazonium ion, are used to define the scope of one-bond nucleophiles which may react with these diazoalkanes.     

Sulfonium‐Based Homolytic Substitution Observed for the Radical SAM Enzyme HemN

Sulfur‐based homolytic substitution (S_H reaction) plays an important role in synthetic chemistry, yet whether such a reaction could occur on the positively charged sulfonium compounds remains unknown. In the study of the anaerobic coproporphyrinogen III oxidase HemN, a radical S‐adenosyl‐l ‐methionine (SAM) enzyme involved in heme biosynthesis, we observed the production of di‐(5′‐deoxyadenosyl)methylsulfonium, which supports a deoxyadenosyl (dAdo) radical‐mediated S_H reaction on the sulfonium center of SAM. The sulfonium‐based S_H reactions were then investigated in detail by density functional theory calculations and model reactions, which showed that this type of reactions is thermodynamically favorable and kinetically competent. These findings represent the first report of sulfonium‐based S_H reactions, which could be useful in synthetic chemistry. Our study also demonstrates the remarkable catalytic promiscuity of the radical SAM superfamily enzymes.     

聚[2-甲氧基-5-(4-溴-丁氧基)对苯乙炔]新型前聚物的合成及表征]

采用不同方法由三锍盐合成新型的聚电解质前聚物及可溶于有机溶剂的侧链溴代聚对苯乙炔前聚物,发现侧链烷氧取代基上的锍盐并不参与聚合,所得前聚物加热后都可转化为聚对苯乙炔.光物理初步研究表明,溴代侧链聚对苯乙炔与C₆₀掺杂后具有良好的光电特性.以IR、UV-Vis、¹H NMR、DSC对单体及前聚物进行了表征.     

环三聚磷腈多齿配体的合成及DNA的切割活性

为了得到具有核酸切割功能的人工核酸酶, 设计合成了5种环三聚磷腈多齿配体, 并初步检测了其对DNA的切割活性. 目标化合物的结构由IR, 1H NMR, 31P NMR, 13C NMR和ESI-MS确认. 在生理条件下对pUC19 DNA切割活性的初步实验结果表明, 在化合物5a～5e的Cu(Ⅱ)配合物存在下, 保温24 h后, pUC19 DNA由Form Ⅰ断裂为Form Ⅱ, 即合成目标化合物有明显的DNA切割活性. 同时, 考察了配合物5b+Cu在不同时间下对DNA的切割活性的影响.     

β-(Trifluoromethyl)vinyl sulfonium salts: preparation and reactions with active methylene and methenyl compounds

Two trifluoromethyl-substituted building blocks β-(trifluoromethyl)vinyl sulfonium salts 1 and 2 were developed. Reactions of β-(trifluoromethyl)vinyl sulfonium salt 1 with active methylene compounds containing electron-withdrawing groups using DBU as the base in DMSO occurred to give trifluoromethyl-substituted cyclopropane derivatives 7 as the major products. In contrast, reactions of β-(trifluoromethyl)vinyl sulfonium salt 2 with active methylene compounds occurred with the migration of one of the electron-withdrawing groups to give the products 8 as the major products when NaH was used as the base in DMSO. Moreover, when NaH was used as base in THF/CH(2)Cl(2) at -78 °C, reaction of β-(trifluoromethyl)vinyl sulfonium salt 1 gave trifluoromethyl-substituted 2,3-dihydrofuran derivatives 9 as the major products. A working mechanism was proposed to explain the different behaviors of the β-(trifluoromethyl)vinyl sulfonium salts 1 or 2 with active methylene compounds under these different conditions.     

Selection of a high-energy bioactive conformation of a sulfonium-ion glycosidase inhibitor by the enzyme glucoamylase G2

Transferred nuclear Overhauser effect and rotating-frame Overhauser enhancement NMR spectroscopies are used to probe the conformation of a bicyclic sulfonium ion, which is an analogue of the naturally occurring glycosidase inhibitor castanospermine, bound to the enzyme glucoamylase G2. Enzyme inhibition assays indicate that the bicyclic sulfonium ion is a slightly better inhibitor (K(i) = 1.32 mM) of glucoamylase G2 than the naturally occurring sulfonium-ion glycosidase inhibitor, salacinol, with a K(i) value of 1.7 mM. The NMR results are interpreted in terms of the selection by the enzyme of a high-energy conformation of the ligand that is already represented in the ensemble of free-ligand conformations.     

Stereoselective glycosylations of 2-azido-2-deoxy-glucosides using intermediate sulfonium ions

TMSOTf-promoted glycosylations of 2-azido-2-deoxy-glucosyl trichloroacetimidates provide excellent alpha-anomeric selectivities when performed at a relatively high reaction temperature in the presence of PhSEt or thiophene. NMR and computation studies have shown that these glycosylations proceed through an equatorial anomeric sulfonium ion, which upon displacement by a sugar alcohol provides an axial glycoside. Computational studies have indicated that steric factors determine the selective formation of the beta-anomeric sulfonium ion.