نتایج جستجو برای: nucleophilic displacement

تعداد نتایج: 59517  

2011
Mari Fe Flores Pilar Garcia Narciso M. Garrido Francisca Sanz David Diez

The title compound C(7)H(11)NO(3) was prepared by intra-molecular nucleophilic displacement of 2,3-O-iso-propyl-idene-d-erythronolactol. There are two mol-ecules in the asymmetric unit, which are related by a pseudo-inversion centre. The crystal structure determination confirms unequivocally the configuration of the chiral centres as 3S,4R. In the crystal structure, inter-molecular C-H⋯O inter-...

2015
Mohammad Abbasi Reza Khalifeh

An efficient and odourless procedure for a one-pot synthesis of thioesters by the reaction of benzoic anhydrides, thiourea and various organic halides (primary, allylic, and benzylic) or structurally diverse, electron-deficient alkenes (ketones, esters, and nitriles) in the presence of Et3N has been developed. In this method, thiobenzoic acids were in situ generated from the reaction of thioure...

Journal: :International journal of radiation applications and instrumentation. Part A, Applied radiation and isotopes 1990
D M Jewett S A Toorongian M A Bachelor M R Kilbourn

[18F]Fluoride for nucleophilic radiofluorination was recovered from target water by trapping on a fibrous anion exchange resin in the hydroxide form and subsequent displacement into wet methanolic K2CO3. Extraction into methanol facilitated rapid evaporation and resolubilization of the [18F]fluoride as an ion pair. The resin was first dried in situ and rehydrated with [18O]H2O to avoid isotopic...

Journal: :The Journal of organic chemistry 2002
Stanislaw F Wnuk Saiful M Chowdhury Pedro I Garcia Morris J Robins

Thermolysis of a 2'-[(16)O]-O-benzoyl-[(17)O]-5'-O-(tert-butyldimethylsilyl)-O(2),3'-cyclouridine derivative gave the more stable 3'-[(17)O]-O-benzoyl-[(16)O]- 5'-O-(tert-butyldimethylsilyl)-O(2),2'-cyclouridine isomer, which was converted into 3'-[(17)O]-2'-azido-2'-deoxyuridine by deprotection and nucleophilic ring opening at C2' with lithium azide. The 5'-diphosphate was prepared by nucleoph...

2013
Kezhi Jiang Hu Zhang Jianmei Wang Fei Li Mingrong Qian

The gas-phase fragmentation pathways of deprotonated diacylhydrazine derivatives (R1(C = O)-N(t-Bu)NH(C = O)R2, Compounds 1-6) were investigated by the combination of electrospray ionization tandem mass spectrometry (ESI-MS/MS) and theoretical calculations. Upon collisional activation, the deprotonated molecular ions [M - H](-) dissociate in two reaction channels, both of which involve intramol...

Journal: :Tetrahedron Letters 2022

The carbon–fluorine (C–F) bond is one of the strongest bonds in organic chemistry and generally inert toward nucleophilic substitution reactions. To overcome relative inertness C–F bond, this work focused on ability simple lithium salts (Lewis acid) to activate alkyl fluorides base) leading F/I exchange high yields selectivity for displacement fluoride versus chloride bromide. fluorine iodine w...

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