18521-02-3Relevant academic research and scientific papers
Evidence against Reversible Wittig Reaction of a Stabilized Ylide: High (E)-Olefin Selectivity under Kinetic Control
Vedejs, E.,Fleck, T.,Hara, S.
, p. 4637 - 4639 (1987)
The betaine 10, generated by deprotonation from deuterium-labeled 8-d, decomposes stereospecifically to the (Z)-alkene.The corresponding Wittig reaction of ylide 4 with cyclohexanecarboxaldehyde, which gives a 95:5 (E)-/(Z)-alkene ratio, therefore occurs under kinetic control, without equilibration or Wittig reversal.
Bu 4 N + -Controlled Addition and Olefination with Ethyl 2-(Trimethylsilyl)acetate via Silicon Activation
Das, Manas,Manvar, Atul,Fox, Ian,Roberts, Dilwyn J.,O'Shea, Donal F.
supporting information, p. 2401 - 2406 (2017/09/30)
Catalytic Bu 4 NOAc as silicon activator of ethyl 2-(trimethylsilyl)acetate, in THF, was utilized for the synthesis of β-hydroxy esters, whereas employing catalytic Bu 4 NOTMS gave α,β-unsaturated esters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated β-hydroxy esters with subsequent elimination to form the α,β-unsaturated ester has been demonstrated. The key to selective product formation lies in use of the weaker acetate activator which suppresses subsequent elimination whereas stronger TMSO - activator (and base) facilitates both addition and elimination steps. The use of tetrabutyl ammonium salts for both acetate and trimethylsilyloxide activators provide enhanced silicon activation when compared to their inorganic cation counterparts.
Highly syn-selective elimination of peterson anti-adducts to give Z-α,β-unsaturated esters
Murai, Yutaka,Nakagawa, Akira,Kojima, Satoshi
supporting information, p. 228 - 231 (2017/02/10)
Peterson adducts have been known to stereospecifically give syn-elimination products upon treatment with base except when the product olefin is in conjugation with an electron-withdrawing group. The missing piece has been put in place by using a catalytic amount of DBU, by which syn-elimination could be effected to provide the thermally less stable Z-olefin from the anti-adduct with high selectivity.
A graphene/hemin hybrid material as an efficient green catalyst for stereoselective olefination of aldehydes
Joshi, Chetan,Kumar, Pawan,Behera, Babita,Barras, Alexandre,Szunerits, Sabine,Boukherroub, Rabah,Jain, Suman L.
, p. 100011 - 100017 (2015/12/04)
A hemin/graphene composite, prepared by mixing an aqueous solution of graphene oxide (GO) with hemin and sonicating the suspension for 5 h at room temperature, was investigated for olefination of aldehydes using ethyl diazoacetate in the presence of triphenylphosphine. Efficient olefination of aromatic aldehydes with high (E)-selectivity was obtained, revealing that rGO/hemin is a promising heterogeneous catalyst for the olefination reaction. The as-synthesized catalyst could easily be recovered from the reaction mixture and was subsequently used for several runs without any significantly loss in activity and selectivity.
Stereoselective synthesis of either (E)- or (Z)-silyl enol ether from the same acyclic α,β-unsaturated ketone using cationic rhodium complex-catalyzed 1,4-hydrosilylation
Onodera, Gen,Hachisuka, Ryosuke,Noguchi, Tomomi,Miura, Hiroki,Hashimoto, Toru,Takeuchi, Ryo
supporting information, p. 310 - 313 (2014/01/06)
The stereoselective synthesis of either (E)- or (Z)-silyl enol ether from the same acyclic α,β-unsaturated ketone is reported. Highly (Z)-selective conditions were the use of [Rh(cod)2]BF 4/DPPE at room temperature with no solvent, whereas (E)-selective conditions were the use of [Rh(cod)2]BF4/P(1-Nap) 3 (1-Nap = 1-naphthyl) under refluxing dichloromethane.
Update: An efficient synthesis of poly(ethylene glycol)-supported iron(II) porphyrin using a click reaction and its application for the catalytic olefination of aldehydes
Chinnusamy, Tamilselvi,Rodionov, Valentin,Kuehn, Fritz E.,Reiser, Oliver
supporting information; experimental part, p. 1827 - 1831 (2012/08/08)
The facile synthesis of polyethylene glycol (PEG)-immobilized iron(II) porphyrin using a copper-catalyzed azide-alkyne [3+2] cycloaddition "click" reaction is reported. The prepared complex 5 (PEG-C 51H39FeN7O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG-supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss. Copyright
Key structural features of cis-cinnamic acid as an allelochemical
Abe, Masato,Nishikawa, Keisuke,Okuda, Katsuhiro,Shindo, Mitsuru,Fukuda, Hiroshi,Nakanishi, Kazunari,Tazawa, Yuta,Taniguchi, Tomoya,Park, So-Young,Hiradate, Syuntaro,Fujii, Yoshiharu
, p. 56 - 67,12 (2012/12/12)
1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated.
A protocol for accessing the β-azidation of α,β-unsaturated carboxylic acids
Angelini, Tommaso,Bonollo, Simona,Lanari, Daniela,Pizzo, Ferdinando,Vaccaro, Luigi
supporting information, p. 4610 - 4613 (2012/10/30)
This contribution reports the preparation and use of a new immobilized catalyst, PS-DABCOF (9), which has been specifically designed to access for the first time the efficient β-azidation of α,β-unsaturated carboxylic acids.
New polymer-supported phosphonate reagents for the synthesis of Z-α,β-unsaturated esters
Ando, Kaori,Suzuki, Yusaku
scheme or table, p. 2323 - 2325 (2010/06/13)
New polymer-supported phosphonate reagents have been prepared and evaluated for the synthesis of Z-α,β-unsaturated esters. High Z-selectivity was obtained using the reagent having two o-t-BuC6H4 groups.
P[N(i-Bu)CH2CH2]3N: Nonionic Lewis base for promoting the room-temperature synthesis of α,β-unsaturated esters, fluorides, ketones, and nitriles using Wadsworth - Emmons phosphonates
Chintareddy, Venkat Reddy,Ellern, Arkady,Verkade, John G.
supporting information; experimental part, p. 7166 - 7174 (2010/12/25)
The bicyclic triaminophosphine P(RNCH2CH2) 3N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of α,β-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and 1d led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.
