2287-45-8Relevant academic research and scientific papers
E2 TRANSITION STATE: ELIMINATION REACTIONS OF 2-(2,4-DINITROPHENYL)ETHYL HALIDES.
Gandler,Yokoyama
, p. 130 - 135 (1984)
The base-catalyzed elimination reactions of 2-(2,4-dinitrophenyl)ethyl halides in aqueous solution have been investigated. The relative rate constants for the hydroxide ion catalyzed reactions of the fluoride, chloride, bromide, and iodide are 1:2:9:14, r
Organocatalytic enantioselective direct additions of aldehydes to 4-vinylpyridines and electron-deficient vinylarenes and their synthetic applications
Wang, Sinan,Li, Xiangmin,Liu, Hongwei,Xu, Li,Zhuang, Jinchen,Li, Jian,Li, Hao,Wang, Wei
supporting information, p. 2303 - 2310 (2015/03/04)
We describe a synergistic catalysis strategy for the asymmetric direct addition of simple aldehydes to 4-vinylpyridines. By means of independent activation of weakly electrophilic 4-vinylpyridines by the Bronsted acid CF3SO3H (TfOH) and aldehydes by chiral diphenylprolinol tert-butyldimethylsilyl (TBDMS) ether-catalyzed formation of nucleophilic enamines in a cooperative manner, the previously unattainable highly enantioselective addition process has been realized for the first time. Notably, the power of the addition process is fueled by its high efficiency in the production of synthetically valued chiral pyridines. 1H NMR studies of the process suggested that the nucleophilic enamine formed in situ from the chiral amine catalyst and the aldehyde is directly added to the trimeric 4-vinylpyridinium-derived species as a highly active electrophile generated from the 4-vinylpyridine in the presence of TfOH. Moreover, inspired by the similar electronic natures of pyridine and nitrobenzene, we have achieved an unprecedented chiral diphenylprolinol TBDMS ether-promoted, highly enantioselective direct addition of aldehydes to 2-nitrostyrenes without the use of TfOH as a cocatalyst. In this approach, introducing a strong electron-withdrawing group such as NO2, CF3, SO2Me, etc. on the 2-nitrostyrene creates a highly electrophilic vinyl moiety, which enables the direct addition of the in situ-formed enamine derived from the chiral amine promoter and the aldehyde. This method significantly expands the scope of the enantioselective addition process. While the electron-withdrawing nitro group is essential for activation of the vinyl group, we have demonstrated that it can be readily transformed to diverse functionalities. Furthermore, as shown, a chiral pyridine adduct serves as a key building block in the synthesis of the potent fibrinogen receptor antagonist L-734,217.
A one-step, safe synthesis of 2,4-dinitrostyrene and related (Di)nitrodivinylbenzenes via Stille coupling
Eloy, Nathalie,Pasquinet, Eric,Grech, Eric,David-Quillot, Frank,Besnard, Olivier,Poullain, Didier
, p. 1805 - 1807 (2008/12/22)
A one-step synthesis of 2,4-dinitrostyrene is described. Based on a Stille coupling, the procedure is more amenable to scale-up than the existing methods that require longer reaction sequences and hazardous nitration processes. This easily polymerizable monomer was isolated using a continuous extraction method. The reaction was extended to the synthesis of two other related vinyl monomers including the previously unknown l,3-dinitro-4,6-divinylbenzene.
Synthesis of Coumarins by Nucleophilic Denitrocyclization Reaction
Oda, Noriichi,Yoshida, Yukio,Nagai, Shin-ichi,Ueda, Taisei,Sakakibara, Jinsaku
, p. 1796 - 1802 (2007/10/02)
2-propanedioic acids(2a-c) were denitrocyclized to coumarins (3a-c) by heating in quinoline in the presence of copper powder. 2-(4-Methoxiphenyl)-3-(2-nitrophenyl)-(Z)-2-propenoic acids (6a,b,d,e) were also similarly denitrocycli
Nucleotide. XIV. Substituierte β-Phenylaethyl-Gruppen. Neue Schutzgruppen fuer Oligonucleotid-Synthesen nach dem Phosphorsaeuretriester-Verfahren
Uhlmann, Eugen,Pfleiderer, Wolfgang
, p. 1688 - 1703 (2007/10/02)
Various o- and p-substituted β-phenylethanols (2-10) have been synthesized and investigated as blocking groups in the phosphotriester approach.A large number of 5'-O-tritylated thymidine-3'-phosphotriesters (13-36) with two different phosphate protecting groups have been prepared, characterized, and studied according to their chemical stability and usefullness for oligonucleotide syntheses.The combination of a 5'-O-monomethoxytrityl- and a 3'-(2,5-dichlorophenyl, p-nitrophenylethyl)-phosphate function as in 18 turned out to possess optimal properties as a monomeric nucleotide building block due to the fact that these blocking groups can be quantitatively and selectively be removed without harming each other by trifluoroacetic acid in chloroform to 41, by oximate to 42, and by DBU to 43.The base-catalyzed removal of the monosubstituted phenylethyl groups by DBU or DBN respectively as well as the disubstituted phenylethyl groups by triethylamine in aprotic solvents is a β-elimination process leading to phosphodiesters without attack on the P-center.
