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711.
712.
Yasushi Shigeri Shinya Ikeda Akikazu Yasuda Masanori Ando Hiroaki Sato Tomoya Kinumi 《Journal of mass spectrometry : JMS》2014,49(8):742-749
The reagents 19 hydrazide and 14 hydrazine were examined to function as reactive matrices for matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) to detect gaseous aldehydes. Among them, two hydrazide (2‐hydroxybenzohydrazide and 3‐hydroxy‐2‐naphthoic acid hydrazide) and two hydrazine reagents [2‐hydrazinoquinoline and 2,4‐dinitrophenylhydrazine (DNPH)] were found to react efficiently with carbonyl groups of gaseous aldehydes (formaldehyde, acetaldehyde and propionaldehyde); these are the main factors for sick building syndrome and operate as reactive matrices for MALDI‐MS. Results from accurate mass measurements by JMS‐S3000 Spiral‐TOF suggested that protonated ion peaks corresponding to [M + H]+ from the resulting derivatives were observed in all cases with the gaseous aldehydes in an incubation, time‐dependent manner. The two hydrazide and two hydrazine reagents all possessed absorbances at 337 nm (wavelength of MALDI nitrogen laser), with, significant electrical conductivity of the matrix crystal and functional groups, such as hydroxy group and amino group, being important for desorption/ionization efficiency in MALDI‐MS. To our knowledge, this is the first report that gaseous molecules could be derivatized and detected directly in a single step by MALDI‐MS using novel reactive matrices that were derivatizing agents with the ability to enhance desorption/ionization efficiency. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
713.
714.
Jun Lu 《Tetrahedron letters》2008,49(37):5389-5392
Chiral 2-azanorbornyl-3-methanol is used as an organocatalyst for the highly enantioselective direct vinylogous Michael addition reaction of vinyl malononitriles to α,β-unsaturated aldehydes. In many cases, the products can be obtained in almost optically pure form (>95% ee) after a single recrystallization. 相似文献
715.
A general method for the synthesis of β-(2-furyl)-α,β-unsaturated aldehydes is described using the Suzuki coupling reaction of furan-2-boronic acids and β-bromo-α,β-unsaturated aldehyde derivatives. 相似文献
716.
Density functional theory calculations were carried out to reveal the mechanistic details of aldehyde–alkyne reductive couplings with trialkylsilane/dialkylsilane. The reaction with trialkylsilane is found to proceed through oxidative cyclization, Si-H/Ni-O σ-bond metathesis, and C(sp2)-H reductive elimination, leading to silylated allylic alcohols. The steric hindrance between the n-pent group of alkyne and iPr group of the NHC ligand determines the regioselectivity. While for the reaction with dialkylsilane, the present calculations propose a new mechanism, which consists of oxidative cyclization, Si−H/Ni−O σ-bond metathesis, Ni−C/Si−H σ-bond metathesis, and dehydrogenation, resulting in oxasilacyclopentenes. The calculated energy profiles rationalize the experimentally observed chemodivergence. 相似文献
717.
718.
研究了不同脂肪族和芳香族醛与6-甲基-6-苯基-7-烯-1,5-辛二醇的烯丙基转移反应, 同时考察了溶剂对反应的影响. 结果发现, 在In(OTf)3催化下, 以甲苯为溶剂, 由脂肪族醛合成的直链高烯丙基醇较芳香族醛具有较高的产率和较好的选择性, 所得产物结构经1H NMR, 13C NMR, IR, HRMS表征. 相似文献
719.
A series of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes were prepared under solvent‐free conditions by Yb(OTf)3 catalyzed condensation reactions of β‐naphthol with various aldehydes. The process presented here is operationally simple, environmentally benign and has good to excellent yields. Furthermore, the catalyst can be recovered conveniently and reused efficiently. 相似文献
720.
通过吡咯和相应的醛合成了五个新型的以组氨酸修饰的卟啉类化合物.其反应条件得到优化,并通过紫外、质谱和核磁确证了产物的结构. 相似文献