L-乙酰半胱氨酸对映体的手性荧光衍生化高效液相色谱法分析

以R-(-)/S-(+)-4-N,N-二甲基磺酰胺-7-(3-异氰酸吡咯烷)-2,1,3-苯并氧杂咪唑[R-(-)/S-DBD-PyNCS]为荧光手性衍生化试剂,用反相高效液相色谱法(RP/HPLC)对乙酰半胱氨酸(NAC)对映体进行分析。在含有1%吡啶溶液中,50℃下衍生化反应60 min,生成具有荧光特性的NAC非对映体衍生物,其结构用质谱(MS)表征。该衍生物在流动相为25 mmol/L磷酸钾缓冲溶液(pH5.9)-甲醇(体积比50∶28),流速1 mL/min时,在ODS HYPERSIL C18(200 mm×4.6 mm,5μm)色谱柱上进行分离,并在荧光检测器(λex=450nm,λem=550 nm)上检测。L-NAC在0.4~40 mg/L范围内与峰面积呈良好线性关系,回归方程为Y=2.716×104X+2.959×106,r=0.999 8,检出限(S/N=3)为0.4 ng。该方法可用于乙酰半胱氨酸制剂含量的测定。     

柱前手性荧光衍生反相高效液相色谱法分离甲状腺素对映体

以R(-)-4-N,N-二甲基磺酰胺-7-(3-异氰酸吡咯烷)-2,1,3-苯并氧杂咪唑（R(-)-DBD-PyNCS）为手性荧光衍生化试剂,成功地拆分了甲状腺素对映体D,L-四碘甲状腺原氨酸（T4）和L-三碘甲状腺原氨酸(T3)。在反应温度为40 ℃、反应时间为20 min时,R(-)-DBD-PyNCS在碱性介质中可与甲状腺素对映体生成稳定的非对映体衍生物。该衍生物在以乙腈-水-醋酸(体积比为60∶40∶1)为流动相,流速为1.0 mL/min,色谱柱为Intersil-ODS-3 C18柱(150 mm×4.6 mm,5 μm)的色谱条件下得到了充分的分离。采用荧光检测器在激发波长460 nm、发射波长550 nm下检测。D,L-T4和L-T3分别在0.016～0.30 μg/μL和0.0067～0.22 μg/μL范围内,峰面积与浓度呈良好的线性关系(r＞0.999)。D,L-T4和L-T3的最低检出限分别为0.02 μg/mL和0.85 μg/mL(S/N=3)。在D-T4、L-T4、L-T3质量浓度分别为0.10 μg/μL下测得峰面积的相对标准偏差分别为3.40%,1.63%,3.30%(n=7)。该方法成功地应用于甲状腺片中T4和T3的含量测定。     

手性荧光衍生化反相高效液相法分离肾上腺素对映体

 以R (- ) /S (+) 4 (N ,N dimethylaminosulfonyl) 7 (3 iso thiocyanatopyrrolidino) 2 ,1,3 benzoxadiazole(DBD PyNCS)为手性荧光衍生化试剂 ,用反相高效液相法 (RP HPLC)对 DL 肾上腺素对映体进行分离。衍生化反应是在含有 7%吡啶的溶剂中 ,6 5℃温度条件下反应 35min ,生成具有荧光特性的肾上腺素非对映体衍生物(λex=4 6 0nm ,λem=5 5 0nm)。生成的非对映体衍生物在流动相为乙腈 水 (体积比为 2 8∶72 ) ,流速为 1 0mL/min时 ,在DiamonsilTMC18柱 (15 0mm× 4 6mmi d ,5 μm)上分离度可达 2 6。     

荧光探针5-羰基咪唑苯并吖啶酮的合成及其LC-APCI-MS法测定胺

在不加任何催化剂条件下, 2-(12-苯并吖啶酮)-乙酸(BAAA)与N,N′-羰基双咪唑(CDI)缩合生成新型荧光探针5-羰基咪唑苯并吖啶酮(IEBA). IEBA在DMF溶剂中与胺类化合物形成的酰胺类衍生物不仅可发出强烈的荧光, 还具有较高的质谱离子化能力. 该衍生物在乙腈和甲醇-水溶液中的百分离子化δ值分别在0~57.32% 和0~62.14%范围内. 最大激发和发射波长λex/λem=272 nm/505 nm. 12种胺类衍生物的荧光检出限范围为0.15~0.50 ng/mL, 在线APCI-MS检出限范围为1.43~8.51 ng/mL.     

荧光试剂柱前衍生高效液相色谱-荧光检测生物检材中的氟乙酸钠

建立了以4-溴甲基-7-甲氧基香豆素(BrMMC)为柱前荧光衍生试剂,反相高效液相色谱荧光检测(HPLC-FLD)生物检材中氟乙酸钠的分析方法。采用Hewlett Packard RP-18色谱柱,以甲醇-水(60/40,V/V)为流动相,流速1.0 mL/min,柱温26℃,荧光检测:eλx=319 nm,eλm=390 nm,进样量2μL。结果表明:该法在氟乙酸钠含量为0.1~20μg/mL范围内与其峰面积呈良好的线性关系,线性相关系数为0.9996,检出限(S/N=3)为5×10-10mol/mL,相对标准偏差(RSD)小于4%。本法用于中毒死亡者的血液样品及其它检材的测定,效果良好。     

高效液相色谱-荧光分析法同时测定人体尿液中黄蝶呤与异黄蝶呤

建立了高效液相色谱-荧光法同时测定癌症病人尿液中黄蝶呤及异黄蝶呤的新方法。选择荧光检测波长λex=345nm,λem=420nm。以磷酸盐缓冲溶液(pH=7.5)-甲醇(体积比为98∶2)为流动相,流速1.0mL/min,黄蝶呤与异黄蝶呤含量分别在0.0013～0.945μg/mL及0.00017～0.118μg/mL范围内与色谱峰面积呈良好的线性关系,线性相关系数分别为0.9999和0.9996,检出限分别为0.5ng/mL和0.05ng/mL,加标平均回收率在86.2%～107.5%之间。方法应用于癌症病人尿样分析,取得了较好的结果。     

非衍生毛细管气相色谱法直接测定紫苏子油中的α-亚麻酸

建立了非衍生毛细管气相色谱法直接测定紫苏子油中α-亚麻酸的方法。紫苏子油样品经0.5 mol/L的KOH-CH3OH溶液60℃皂化20 min6、mol/L的HCl酸化后用无水乙醚萃取,氮气流吹干乙醚后用甲醇定容,然后直接进行气相色谱分析。结果表明,在0.991~89.1 ng的范围内,峰面积A与α-亚麻酸的质量m成线性关系,线性方程为:A=11253m 72.98,相关系数为0.9996(n=7)。同一对照品溶液连续进样7次时,峰面积的相对标准偏差为0.76%。以S/N=3计算,方法的检出限为0.54 ng。被分析的紫苏子油中α-亚麻酸的质量分数为10.7%(RSD=1.24%,n=5),平均回收率为99.1%(RSD=3.7%,n=5)。     

超高效液相色谱法同时测定布洛芬注射液中布洛芬和精氨酸的含量

建立了一种同时测定布洛芬注射液中布洛芬和精氨酸含量的超高效液相色谱方法。精氨酸与衍生化试剂2,4-二硝基氟苯(DNFB)反应后,与布洛芬同时在超高效液相色谱-二极管阵列检测器(UPLC-PDA)上检测。采用BEH C18色谱柱(50 mm×2.1 mm, 1.7 μm),以乙腈-0.05 mol/L磷酸二氢钾缓冲液(pH 2.5)为流动相进行梯度洗脱,流速为0.4 mL/min,柱温为30 ℃,检测波长分别为357 nm(精氨酸衍生物)和220 nm(布洛芬)。结果表明,布洛芬与精氨酸分别在2.0～100.5 mg/L和1.7～84.5 mg/L范围内呈良好的线性关系,相关系数(r)均为0.9997;平均回收率分别为99.8%和99.6%,相对标准偏差(RSDs)分别为0.37%和0.25%;定量限(信噪比（S/N）=10)分别为0.1 ng和0.2 ng;检出限(S/N=3)分别为0.03 ng和0.05 ng。本方法快速、准确,重复性好,可较全面地评价布洛芬注射液的质量。     

高效液相色谱-荧光法同时测定人体尿液中的酪氨酸和色氨酸

建立了高效液相色谱-荧光检测法同时测定人体尿液中的酪氨酸(Tyr)和色氨酸(Typ)。采用Diamonsil C18柱(250×4.6mm,5μm),以水-乙腈(80∶20,V/V)为流动相,流速1.0mL/min,荧光检测波长为λex=260nm、λ_(em)=340nm。Tyr和Typ的含量分别在0.10~6.0μg/mL及0.050~6.0μg/mL范围内与色谱峰面积呈良好的线性关系(r=0.9993),检测限分别为0.05μg/mL和0.02μg/mL。在三个添加水平的回收中,两种氨基酸的平均回收率在86.3%~122.3%之间,相对标准偏差(RSD)小于8.51%。将所建立的方法应用于健康人、普通病人和癌症患者晨尿检测,结果发现:癌症患者尿样中色氨酸的水平与健康人和普通病人相比偏低。     

过氧化氢柱前荧光衍生化液相色谱法测定麻痹性贝毒的研究

液相色谱-荧光检测法(LC-FLD)测定贝类样品中石房蛤毒素(STX)和decarbamoylsaxitoxin(dcSTX)。样品经30 mmol/L HAc超声提取,C18固相萃取柱净化,2%碱性H2O2荧光衍生,C18色谱柱(4.6 mm×250 mm,5μm)分离,以乙腈-0.1 mol/L甲酸铵溶液(5∶95,V/V)作流动相,流速1.0 mL/m in。结果表明,STX和dcSTX衍生物在7m in内获得完全分离。在空白样品中添加标准品使浓度0.01~2.0μg/g,得到峰面积与浓度呈良好线性,线性相关系数>0.998。添加浓度在0.1、0.8和1.6μg/g的回收率为87%~97%(n=8);相对标准偏差为8%~13%。方法检出限(S/N=3)分别为STX 1.0 ng/g和dcSTX 0.3 ng/g。另外,采用四极杆-飞行时间质谱(Q-TOF-MS)对STX和dcSTX衍生物进行了结构解析。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.