126580-12-9Relevant academic research and scientific papers
Intramolecular Cyclization of Vinyldiazoacetates as a Versatile Route to Substituted Pyrazoles
Drikermann, Denis,G?rls, Helmar,Kerndl, Valerie,Vilotijevic, Ivan
supporting information, p. 1158 - 1162 (2020/07/20)
Vinyldiazo compounds undergo a thermal electrocyclization to form pyrazoles in yields of up to 95percent. The reactions are operationally simple, use readily available starting materials, require no intervention of a catalyst, and enable the synthesis of mono-, di- A nd tri-substituted pyrazoles. With the ability to produce highly substituted pyrazoles and the flexibility in installing various types of substituents, this method constitutes a new entry to this valuable heterocyclic scaffold and may be of interest to all branches of the chemical industry.
Palladium-Catalyzed C-H Functionalization of Acyldiazomethane and Tandem Cross-Coupling Reactions
Ye, Fei,Qu, Shuanglin,Zhou, Lei,Peng, Cheng,Wang, Chengpeng,Cheng, Jiajia,Hossain, Mohammad Lokman,Liu, Yizhou,Zhang, Yan,Wang, Zhi-Xiang,Wang, Jianbo
supporting information, p. 4435 - 4444 (2015/04/14)
Palladium-catalyzed C-H functionalization of acyldiazomethanes with aryl iodides has been developed. This reaction is featured by the retention of the diazo functionality in the transformation, thus constituting a novel method for the introduction of diazo functionality to organic molecules. Consistent with the experimental results, the density functional theory (DFT) calculation indicates that the formation of Pd-carbene species in the catalytic cycle through dinitrogen extrusion from the palladium ethyl diazoacetate (Pd-EDA) complex is less favorable. The reaction instead proceeds through Ag2CO3 assisted deprotonation and subsequently reductive elimination to afford the products with diazo functionality remained. This C-H functionalization transformation can be further combined with the recently evolved palladium-catalyzed cross-coupling reaction of diazo compounds with aryl iodides to develop a tandem coupling process for the synthesis of α,α-diaryl esters. DFT calculation supports the involvement of Pd-carbene as reactive intermediate in the catalytic cycle, which goes through facile carbene migratory insertion with a low energy barrier (3.8 kcal/mol). (Chemical Equation Presented).
Synthesis of pyridines by carbenoid-mediated ring opening of 2H-azirines
Loy, Nicole S. Y.,Singh, Alok,Xu, Xianxiu,Park, Cheol-Min
supporting information, p. 2212 - 2216 (2013/04/10)
Roaming the range: The title reaction tolerates a wide range of substituents on the resulting pyridine ring using mild reaction conditions (see scheme; esp=α,α,α′,α′-tetramethyl-1,3- benzenedipropionic acid). The formation of the key intermediate is catal
A Stereospecific Access to Allylic Systems Using Rhodium(II)-Vinyl Carbenoid Insertion into Si-H, O-H, and N-H Bonds
Bulugahapitiya, Priyadarshanie,Landais, Yannick,Parra-Rapado, Liliana,Planchenault, Denis,Weber, Valery
, p. 1630 - 1641 (2007/10/03)
Rhodium-catalyzed decomposition of α-vinyldiazoesters in the presence of silanes, alcohols, ethers, amines, and thiols have been shown to produce the corresponding α-silyl, α-hydroxy, α-alkoxy, α-amino, and α-thioalkoxy esters in generally good yield with a complete retention of the stereochemistry of the double bond of the diazo precursor. An extension of the process in homochiral series has also been devised using either a chiral auxiliary attached to the ester function or achiral α-vinyldiazoesters and Doyle's chiral catalyst Rh2(MEPY)4. In the former approach, pantolactone as chiral auxiliary gave diastereoselectivities of up to 70%, while the second approach produced the desired allylsilane with ee as high as 72%. On the other hand, Rh2(MEPY)4-catalyzed insertion into the O-H bond of water led to poor or no enantioselectivity in good agreement with recent literature reports.
Rhodium(II)-vinylcarbenoid insertion into the Si - H bond. A new stereospecific synthesis of allylsilanes
Landais, Yannick,Planchenault, Denis,Weber, Valery
, p. 9549 - 9552 (2007/10/02)
Rh2(OAc)4 catalysed decomposition of vinyldiazocarbonyl compounds in the presence of organosilanes led stereospecifically to the corresponding allylsilanes in good yields. An asymmetric approach has also been considered as well as the extension of the methodology to the synthesis of other allylic systems.
Reaction of Carbonyl Compounds with Ethyl Lithiodiazoacetate. Studies Dealing with the Rhodium(II)-Catalyzed Behavior of the Resulting Adducts
Padwa, Albert,Kulkarni, Yashwant S.,Zhang, Zhijia
, p. 4144 - 4153 (2007/10/02)
The carbenoid intermediate derived by treating ethyl 2-diazo-4-phthalimidobutyrate with rhodium(II) octanoate undergoes transannular cyclization onto the adjacent imido carbonyl group.The resulting cyclic carbonyl ylide diploe was trapped with several dipolarophiles.In an attempt to prepare related substrates for cyclization studies, the reaction of ethyl lithiodiazoacetate with various aldehydes and ketones was studied.Treatment of the α-diazo-β-hydroxy ester derived from acetone or cyclopentanone with rhodium(II) octanoate gave rise to a β-keto ester.The exclusive phenyl shift encountered with acetophenone is in keeping with migration to an electron-deficient center.The reaction works well with acrolein, leading to high yields of 3-oxo-4-pentenoate.The 1,2-hydrogen shift pathway was found to proceed much faster than intramolecular cyclopropanation.Dehydration of the α-diazo-β-hydroxy esters generates vinyl diazo esters, which readily cyclize to 1H-pyrazoles on thermolysis.
