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1.
Salicylaldehyde reacts with dimethyl acetylenedicarboxylate in benzene solution to give a mixture of dimethyl o-formylphenoxymaleate, dimethyl o-formylphenoxyfumarate, 2,3-dicarbomethoxychrom - 2 - en - 4 - ol, 2,3 - dicarbomethoxychrom - 3 - en - 2 - ol, dimethyl (2,3 - dicarbomethoxychrom - 2 - en - 4 - yl) - oxalacetate and dimethyl fumarate. 2,3 - Dicarbomethoxychrom - 3 - en - 2 - ol in this reaction is formed from 2,3 - dicarbomethoxychrom - 2 - en - 4 - ol through a benzopyrylium intermediate. The reaction of salicylaldehyde with excess of dimethyl acetylenedicarboxylate, however, gives a mixture of 2,3 - dicarbomethoxychrom - 3 - en - 2 - ol and dimethyl (2,3 - dicarbomethoxychrom - 3 - en) - 2 - oxyfumarate. 2,3 - Dicarbomethoxychrom - 3 - en - 2 - ol itself reacts further with dimethyl acetylenedicarboxylate to give 2,3,12 - tricarbomethoxychrom - 3,4 - eno[2,3 - b] pyrone. Similarly, the reaction of o-hydroxyacetophenone with dimethyl acetylendicarboxylate gives a mixture of dimethyl o-acetylphenoxymaleate, dimethyl o-acetylphenoxyfumarate, 2,3 - dicarbomethoxy - 4 - methylchrom - 2 - en - 4 - ol and 2,3 - dicarbomethoxy - 4 - methylchrom - 3 - en - 2 - ol. Both 2-hydroxychalcone and 2 - hydroxy - 4′ - methoxychalcone give mixtures of chalcone - 2 - oxymaleate and chalcone - 2 - oxyfumarate. The reaction of 2,2t?-dihydroxychalcone, however, gives 2′-hydroxyflavone, in addition to the expected maleate and fumarate. Similar reactions of 5 - chloro - 2,2′ - dihydroxychalcone and of 3,5 - dibromo - 2,2′ - dihydroxychalcone, on the other hand, give 2,3 - dicarbomethoxy - 4 - (o - hydroxyphenacyl) - 6 - chlorochrom - 2 - ene and 2,3 - dicarbomethoxy - 4 - (o - hydroxyphenacyl) 6,8 - dibromochrom - 2 - ene, respectively, together with the corresponding maleates and fumarates. 相似文献
2.
The pentasaccharide α - Tyv - (1→3) - β - d - Man - (1→4) - α - l - Rha - (1→3) - d - Gal - (4←1) -α - d - Glc 1, the repeating unit of the O-specific polysaccharide chain of the lipopolysaccharide from S. Strasbourg, was obtained by glycosylation of benzyl - 2,6 - di - O - benzyl - 4 - O - (2,3,4 - tri - O - benzyl - 6 - O - benzoyl - α - d - glucopyranosyl) - β - d - galactopyranoside with 1,2 - methylorthoacetyl - 3 - O - acetyl - 4- O - [3 - O - (2,4 - di - O - acetyl - 3, 6 - dideoxy,- α - d - arabino - hexopyranosyl) - 2,4,6 - tri - O - acetyl - β - d - mannopyranosyl] - β - l - rhamnopyranose 3 followed by removal of protecting groups. The structure of the synthetic pentasaccharide was proved by methylation analysis and 13C NMR. 相似文献
3.
Oxidation of 1 - phenylcarbamoylidazolidine - 2 - thione gives 2,3,5,6 - tetrahydro - 2 - phenylimidazo [1,2-d]- (1,2,4) - thiadiazole - 3 - one which undergoes addition reactions with heterocumulenes leading to various heteropentalenes. Oxidation of 1 - phenylthiocarbamoylimidazlidine- 2 - thione yields 1- (benzothiazol - 2- yl) - imidazolidine - 2 - thione, also obtained by acid catalysed decomposition of 3,4 - ethano - 2,3,4,5 - tetrahydro - 2, 5 - bisphenylimino - 1,6,6aSIV - trithia - 3,4 - diazapentalene. A similar acid catalysed decomposition to a benzothiazole occurs with 2,3,4,5 - tetrahydro - 1,6 - diphenyl - 3,4 - propano - 6aSIV - thia - 1,3,4,6 - tetraazapentalene -2, 5- dithione. 相似文献
4.
Joanna Szpunar-obiska Claudia Witte Ryszard obinski Freddy C. Adams 《Fresenius' Journal of Analytical Chemistry》1995,351(4-5):351-377
A comprehensive review of the state-of-the-art of the separation of various organically-bound metals and metalloids for speciation analysis is presented. Recent developments in chromatographic (gas, liquid and supercritical fluid), electrophoretic (free-flow and gel) and fractionation techniques are discussed, followed by a survey of pertinent applications to speciation analysis for organometals and metalloids. The required sample characteristics for a given separation technique are specified and appropriate derivatization procedures are characterized. Methods applicable to the speciation of organic species of a particular element in various matrices are critically evaluated.List of abbreviations APS
ammonium pentanesulfonate
- CCC
counter current chromatography
- CZE
capillary zone electrophoresis
- DBT
dibutyltin
- DCyT
dicyclohexyltin
- DDTC
diethyldithicarbamate
- DEAE
diethylaminoethyl gel (anion exchanger)
- DEL
diethyllead
- DET
diethyltin
- DMA
dimethylarsinic acid
- DMGe
dimethylgermanium
- DMHg
dimethylmercury
- DML
dimethyllead
- DMSb
dimethylstibinic acid
- DMT
dimethyltin
- DPhT
diphenyltin
- DPrT
dipropyltin
- EDTA
ethylenediaminetetraacetate
- FFF
field flow fractionation
- GC
gas chromatography
- HEPES
4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid
- HPLC
high performance liquid chromatography
- ICP
inductively coupled plasma
- IEC
ion exchange chromatography
- IIC
ion interaction chromatography
- LC
liquid chromatography
- MBT
monobutyltin
- MCyT
monocyclohexyltin
- MEA
monoethylarsinic acid
- MEHg
monoethylmercury
- MEL
monoethyllead
- MET
monoethyltin
- MIP
microwave induced plasma
- MMA
monomethylarsonic acid
- MMGe
monomethylgermanium
- MMHg
monomethylmercury
- MML
monomethyllead
- MMSb
monomethylstibonic acid
- MMT
monomethyltin
- MPhHg
monophenylmercury
- MPhT
monophenyltin
- MPrT
monopropyltin
- MS
mass spectrometry
- NAA
neutron activation analysis
- NaBS
sodium 1-butanesulfonate
- NaDS
sodium dodecylsulfonate
- NaPS
sodium pentanesulfonate
- PAGE
polyacrylamide gel electrophoresis
- PAR
4-(2-pyridylazo)resorcinol
- PIXE
proton induced X-ray emission
- QF
quartz furnace
- RPC
reversed phase partition chromatography
- SDS
sodium dodecyl sulfate
- SEC
size exclusion chromatography
- SFC
supercritical fluid chromatography
- TBAP
tetrabutylammonium phosphate
- TAL
tetraalkyllead
- TBT
tributyltin
- TCyT
tricyclohexyltin
- TeEL
tetraethyllead
- TEL
triethyllead
- TeML
tetramethyllead
- TET
triethyltin
- TGME
thioglycolic methyl ester
- THF
tetrahydrofuran
- TMA
trimethylarsinic acid
- TMAH
tetramethylammonium hydroxide
- TMGe
trimethylgermanium
- TML
trimethyllead
- TMT
trimethyltin
- TPhT
triphenyltin
- TPrT
tripropyltin
- Tris
tris(hydroxymethyl)aminomethane 相似文献
5.
在DMF溶剂中,不外加催化剂使邻取代芳香醛(1)与5,5-二甲基-1,3-环己三酮(2)发生缩合和加成反应生成3,3,6,6-四甲基-4a-羟基-9-芳基-1,8二氧化-2,3,4,4a,5,6,7,8,9a-十氢化-1H氧杂蒽(3a~3d)。在同样条件下,邻羟基芳香醛与5,5-二甲基-1,3-环己三酮则发生缩合,加成和脱水反应生成3,3-二甲基-9-(5,5-二甲基-3-羟基-2-环己烯-1-酮-2-基)-1-氧代-2,3,4,9-四氢化-1 氧杂蒽(4a~4b)。用单晶X-射线分析法确定了产物3a和4a的晶体结构。 相似文献
6.
The possible occurrence of the ionic Cope rearrangement, and other non-concerted mechanisms is discussed. The synthesis of 2 - (1 - ethyl - 1 - propenyl) -2- (3 - p - methoxyphenylallyl)malononitrile (1b) and its clean thermal 1,3 rearrangement to (1 - ethyl - 5 - p - methoxyphenyl - 2 - methyl - 4 - pentenylidene)malononitrile (4) are reported. This result contrasts with the rearrangement of 2 - (1,1 - dideuterioallyl) - 2 -(1 - ethyl - 1 - propenyl)malononitrile (1c) which isomerizes cleanly in a 3,3 rearrangement. Rearrangement of 2 - (1 - cyclohexenyl) - 2 - (3 - p - methoxyphenylallyl)malononitrile (11), however, leads sluggishly to [2 - (p - methoxy - α - vinylbenzyl)cyclohexylidene]malononitrile (19) (3,3 shift) and rearrangement of 2 - (1 - isopropyl - 2 - methyl - 1 - propenyl) - 2 -(3 - p - methoxyphenylallyl)malononitrile (12) leads, also slowly, to (1 - isopropyl - 5-p- methoxyphenyl - 2,2 - dimethyl - 4 - pentenylidene)malononitrile (14) (1,3 shift). Rearrangement of 1b in the presence of sodium borohydride allows interception of the proposed ionic intermediates and isolation of 2 - (1 - ethylpropylidene)malononitrile (5) and anethole (21c). Ion trapping experiments also gave positive results in the 3,3 rearrangement of 11. These results are discussed in terms of the ionic Cope rearrangement. 相似文献
7.
相转移催化法合成1-O-酰基-四-O-乙酰基-β-D-吡喃己糖 总被引:10,自引:0,他引:10
以氯化三乙基苄基铵作为相转移催化剂, 用2, 3, 4, 6-四-O-乙酰基-β-D-溴代吡喃葡萄糖和2, 3, 4, 6-四-O-乙酰基-β-D-溴代吡喃半乳糖与羧酸反应, 合成了相应的1-O-酰基-2, 3, 4, 6-四-O-乙酰基-β-D-吡喃葡萄糖和半乳糖。通过解析这些化合物的^1H NMR和红外光谱, 确证其糖甙键构型为β。该相转移催化法具有反应条件温和, 后处理简单和立体选择性强等优点。 相似文献
8.
9.
By synthesis and 13C-NMR spectroscopic investigations of rhamnocitrin-, rhamnazin- and rhamnetin - 3 - O - [O - α - l - rhamnopyranosyl - (1 → 4) - O - α - l - rhamnopyranosyl - (1 → 6)] β - d - galactopyranosides and of rhamnocitrin - 3 - O - [O - α - l - rhamnopyranosyl - (1 → 3) - O - α - l - rhamnopyranosyl - (1 → 6)] - β - d - galactopyranoside (rhamnocitrin - 3 - O - β - rhamnisoide) it was proved that all naturally occurring flavonoltriosides, so far isolated from different Rhamnus species, contain the sugar-moiety rhamninose. Thus it was shown that catharticin (rhamnocitrin - 3 - O - β - rhamninoside) is identical with alaternin and xanthorhamnin A (rhamnetin - 3 - O - β - rhamninoside) with xanthorhamnin B, whereas xanthorhamnin C is rhamnazin - 3- O - β - rhamninoside. From Rhamnus saxatilis JACQ., ssp. saxat. a new flavonol - acetyl - trioside was isolated and the structure by MS and 13C-NMR spectroscopic means elucidated to be the rhamnetin - 3 - O - [O - α - l - rhamnopyranosyl - (1 → 3) - O - (4 - O - acetyl - ) - α - l - rhamnopyranosyl - (1 → 6)] - β - d - galactopyranoside. 相似文献
10.
报道了采用溴氧化3-异丙烯基(艹卓)酚酮和3-肉桂酰基(艹卓)酚酮合成杂环并(艹卓)酮化合物的新方法。3-异丙烯基(艹卓)酚酮5位偶联产物1a~1f和3-肉桂酰基(艹卓)酚酮5位偶联产物3a~3d分别在吡啶介质中与过量溴作用生成5-取代苯偶氮基-7-溴-3-甲基-8-氢环庚并呋喃-8-酮2a~2f和6-取代苯偶氮基-2-苯基-8-溴-4,9-二氢环庚并吡喃-4,9-二酮4a~4d。 相似文献
11.
用分子动力学模拟退火找出苯并氮杂冠醚(C~1~8H~2~3O~7N)的最低能量构型后,用半经验量子化学方法AM1分别优化出了该苯并氮杂冠醚的顺、反式构型,对反式进行了前沿轨道、电荷密度计算,并作了振动分析。优化计算苯并氮杂冠醚反式构型的化合物结构数据与X射线晶体测定结果一致。对其振动分析,指认了化合物不同种类键的振动红外特征吸收峰。结构分析表明这种苯并氮杂冠醚的反式结构呈马蹄铁型,分子内有较大空腔,能够嵌入稀土金属阳离子,有较好的配位性。 相似文献
12.
The incorporation of the “base-bearing amino acids”, DL - β - (uracil - 1 - yl)alanine 1 (Uala), DL - β - (thymin - 1 - yl)alanine 2 (Tala), DL - β - (cytosin - 1 - yl)alanine 3 (Cala) and DL - β - (adenin - 9 - yl 4 (Aala) into peptides has been studied. The carboxyl group of each of these compounds was protected by the formation of the ethyl ester. The t - butoxycarbonyl (t-BOC) group was suitable for the protection of the α-amino group of 1 but not that of 2, 3 and 4 because of the formation of ring substituted compounds. Peptides containing the amino acids 1–4 and L-serine were synthesised, however, by the mixed anhydride method; uracil, thymine and adenine residues needed no protection, neither did the cytosine residue provided that it was not present in the intermediate which was treated with ethyl chloroformate to produce the mixed anhydride. In this case reaction with the cytosine residue occurred. By these procedures, four protected dipeptides, namely α - N - t - BOC - L - seryl derivatives of 1–4 and three protected tetrapeptides, namely α - N - t - BOC - L - seryl - DL - β - (thymin - 1 - yl)alanyl - L - ethyl ester (t - BOC - Ser - Tala - Ser - Tala - OEt), t - BOC - Ser - Aala - Ser - Aala - OEt and t - BOC - Ser - Uala - Ser - Uala - OEt were obtained. For the protection of the α-amino group of 2 or 3 the formyl group was found to be satisfactory. 相似文献
13.
The different steps leading to oligosaccharide synthesis on polymeric support have been studied in the case of a functionalized ”popcorn” polystyrene: anchoring of the first glucidic group, unblocking of a selectively protected hydroxyl group, glycosylation and cleavage of the glucide support bond. The first glucidic unit is attached by a benzoic ester bond cleaved by methanolysis (Zemplén's method); β-benzoylpropionic ester was used as temporary protecting group. The synthesis of benzyl - 2 - acetamido - 4,6 - di - O - acetyl - 3 - O - (2 - acetamido - 3,4,6 - tri - O - acetyl - 2 - deoxy - β - D - glucopyranosyl) - 2 - deoxy - α - D - glucopyranoside is described as an example. 相似文献
14.
15.
16.
合成了两个新的有机晶体:反式-4-[4'-(N-羟乙基-N-甲基胺基)苯乙烯基]-N-甲基吡啶对甲苯磺酸盐trans-4-[4'-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridiniumtoluene-p-sulfonate(简称HMASPS)和反式-4-[4'-(N-羟乙基-N-乙基胺基)苯乙烯基]-N-甲基吡啶对甲苯磺酸盐trans-4-[4'-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridiniumtoluene-p-sulfonate(简称HEASPS)。用X射线衍射方法对这两个单晶进行了结构测定。测试了它们频率上转换荧光及激光性质。在1064nm的ps脉冲激光的激发下,HMASPS和HEASPS在溶液中均发出~625nm的上转荧光和激光,并且有可观的激光效率。 相似文献
17.
Three synthetic routes to derivatives of 3,6 - diamino - 2,3,4,6 - tetradeoxy - DL - threo - hexopyranose were investigated. Addition of sodium azide in acetic acid to 6 - phthalimido - 5,6 - dihydro - 2 - pyrone gave 4-azido compound (7) of the erythro configuration. From methyl 2,4 - dideoxy - β -dl- erythro - hexopyranoside threo 4 - phthalimido - 6 - phthalimidomethyl - tetrahydro - 2 - pyrone (17) was obtained in three steps in low overall yield. Addition of sodium azide in acetic acid to butyl 6 - oxo - 2 - hydroxy - hex - 4 - enoate followed by methylation, amonolysis of the ester group, and reduction gave methyl 3,6 - diacetamido - 2,3,4,6 - tetradeoxy - α - DL - threo - hexopyranoside (26). 相似文献
18.
以3-芳基-5-巯基-1,2,4-三唑为原料合成了20个3-芳基-1,2,4-三唑-5-巯基乙酸乙酯(2a~e)、3-芳基-1,2,4-三唑-5-巯基乙酸(3a~e)、3-芳基-5,6-二氢噻唑并[2,3-c]均三唑(5a~e)和3-芳基-6,7-二氢均三唑并[3,4-b][1,3]噻嗪(6a~e)。研究了3a~e在微波辐射下的环化反应,合成了5个3-芳基-5-氧代-6H-噻唑[2,3-c]均三唑(4a~e)。产物经元素分析、红外、核磁共振以及质谱方法确定了结构。初步研究了代表化合物的生物活性。 相似文献
19.
1-甲基-2-苯基吲哚(1)在甲醇中的琥红(RB)敏化单重态氧反应生成1-甲基-2-甲基氧-2-苯基-1, 2-二氢-3H-吲哚-3-酮(4)和1-甲基-2-羟基-2-苯基-1, 2-二氢-3H-吲哚-3-酮(6), 后者在强碱性介质下发生苯乙醇酸型重排生成1-甲基-3-羟基-3-苯基氧化吲哚(14)。研究了6的溶剂分解反应以及外加碱对光氧化反应的影响。探讨了光氧化产物的形成途径。结果表明: 4系两性离子中间体2的溶剂捕获、脱水产物, 而6则系二氧杂环丁烷中间体7的裂解、抽氢产物。 相似文献
20.
本文研究了十七种2-芳基吲哚(1a-1q)在甲醇-乙酸介质中的亚甲基蓝(MB)敏化光氧化反应, 发现有十五种吲哚(1a-1o)以85%-95%的产率给出2,2'-二芳基-[2,3'-联-1H-吲哚]-3(2H)-酮(2a-2o), 而2-(4-硝基苯基]吲哚(1p)和2-联苯基吲哚(1q)则分别生成2-甲氧基-2-(4-硝基苯基)-1,2-二氢-3H-吲哚-3-酮(7p)和2-联苯基-4H-3,1-苯并恶嗪-4-酮(11q), 其中7p在分离过程中失去甲醇分子给出2-(4-硝基苯基)-3H-吲哚-3-酮(10p)。 相似文献