55131-28-7Relevant 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.
Efficient Pd-Catalyzed Regio- and Stereoselective Carboxylation of Allylic Alcohols with Formic Acid
Fu, Ming-Chen,Shang, Rui,Cheng, Wan-Min,Fu, Yao
, p. 8818 - 8822 (2017/07/11)
Formic acid is efficiently used as a C1 source to directly carboxylate allylic alcohols in the presence of a low loading of palladium catalyst and acetic anhydride as additive to afford β,γ-unsaturated carboxylic acids with excellent chemo-, regio-, and stereoselectivity. The reaction proceeds through a carbonylation process with in situ-generated carbon monoxide under mild conditions, avoiding the use of high-pressure gaseous CO. A bisphosphine ligand with a large bite angle (4,5-bis{diphenylphosphino}-9,9-dimethylxanthene, Xantphos) was found to be uniquely effective for this transformation. The regio- and stereoconvergence of this reaction is ascribed to the thermodynamically favored isomerization of the allylic electrophile in the presence of the palladium catalyst.
A new synthesis of β,γ-alkenyl carboxylic acids from α,β-alkenyl carboxylic acid chlorides and α,β-alkenyl aldehydes with one-carbon elongation
Satoh, Tsuyoshi,Nakamura, Akira,Iriuchijima, Atsuko,Hayashi, Yasumasa,Kubota, Ko-Ichi
, p. 9689 - 9696 (2007/10/03)
Reaction of the lithium α-sulfinyl carbanion of chloromethyl phenyl sulfoxide with α,β-alkenyl carboxylic acid chlorides gave γ,δ-alkenyl α-chloro-β-keto sulfoxides in variable yields. The keto sulfoxides were also synthesized from α,β-alkenyl aldehydes in two steps in good overall yields: addition of the lithium α-sulfinyl carbanion of chloromethyl phenyl sulfoxide to α,β-alkenyl aldehydes followed by oxidation of the adducts with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or Dess-Martin periodinane. These products were treated in sequence with potassium hydride, tert-butyllithium, and 5% aqueous sodium hydroxide, in one flask to give β,γ-alkenyl carboxylic acids with one-carbon elongation in good yields. The procedure offers a new method for synthesizing β,γ-alkenyl carboxylic acids from α,β-alkenyl carboxylic acid chlorides and α,β-alkenyl aldehydes with one-carbon elongation.
Enecarboxylation with Diethyl Oxomalonate as an Enophilic Equivalent of Carbon Dioxide. A Synthesis of Allylcarboxylic Acids
Salomon, Mary F.,Pardo, Simon N.,Salomon, Robert G.
, p. 3797 - 3802 (2007/10/02)
Allylcarboxylic acids are prepared from alkenes by a two-stage process which is synthetically equivalent to an ene reaction of carbon dioxide: (1) ene reaction with diethyl oxomalonate to afford an α-hydroxylmalonic ester and (2) oxidative bisdecarboxylation of the derived α-hydroxymalonic acid.The oxidative bisdecarboxylation of α-hydroxymalonic acids can sometimes be achieved with sodium periodate.However, occasionally decarboxylation is only partial, leading to pyruvic rather than carboxylic acids.While the bisdecarboxylations with periodate have previously been "buffered with a little pyridine", the latter is now shown to inhibit the reaction.In fact the pyruvate:carboxylate ratio can be a sensitive function of the amount of pyridine present in the reaction mixture, and the oxidative decarboxylation can be controlled to yield almost exclusively carboxylic or pyruvic acid.An effective new reagent, ceric ammonium nitrate in aqueous acetonitrile, was discovered for oxidative bisdecarboxylation of α-hydroxymalonic acids.Fortunately this reagent provides good to excellent yields of allylcarboxylic acids in many cases for which sodium periodate proved unsatisfactory.
