Superoxide mediated isomerization of 4-aryl-but-1-ynes to 1-aryl-1,3-butadienes
摘要:
A new role of superoxide ion in the isomerization of homobenzylic acetylenes leading to 1-aryl-1,3-butadienes is reported. The unconventional reagent 1(02 is found to be superior in performing this kind of isomerization over other the commonly used bases. For substrates containing arene moiety and triple bond connected through more than two methylene groups, and for propargylcyclohexanol the reagent selectively effected migration of the triple bond. Reactivity of 1(02 towards the substrates having disubstitution at benzylic position varied depending on the nature of the substitution, alkyl-substitution lead to isomerization to give mixture of allene (an intermediate in the isomerization of acetylene to 1,3-butadiene) and triple bond migration product; whereas phenyl-substituted compound gave 1,3-diene. The utility of the methodology was demonstrated through a Diels-Alder reaction of one of the dienes obtained by the isomerization with suitable dienophiles. (C) 2015 Elsevier Ltd. All rights reserved.
Aqueous Wittig reactions of semi-stabilized ylides. A straightforward synthesis of 1,3-dienes and 1,3,5-trienes
作者:James McNulty、Priyabrata Das
DOI:10.1016/j.tetlet.2009.07.133
日期:2009.10
A direct synthesis of 1,3-dienes and 1,3,5-trienes from the reaction of semi-stabilized ylides and a range of saturated and unsaturated aldehydes is reported in water as solvent, employing sodium hydroxide as base. The water-soluble phosphine oxide side product is removed simply by aqueous partitioning of the organic products.
Axially Chiral Triazoloisoquinolin-3-ylidene Ligands in Gold(I)-Catalyzed Asymmetric Intermolecular (4 + 2) Cycloadditions of Allenamides and Dienes
作者:Javier Francos、Francisca Grande-Carmona、Hélio Faustino、Javier Iglesias-Sigüenza、Elena Díez、Isaac Alonso、Rosario Fernández、José M. Lassaletta、Fernando López、José L. Mascareñas
DOI:10.1021/ja3065446
日期:2012.9.5
The first highly enantioselective intermolecular (4 + 2) cycloaddition between allenes and dienes is reported. The reaction provides good yields of optically active cyclohexenes featuring diverse substitution patterns and up to three stereocenters. Key to the success of the process is the use of newly designed axially chiral N-heterocyclic carbene-gold catalysts.
A practical copper-catalyzedhighlyregioselective 1,2-hydrocarboxylation of terminal 1,3-diene with carbon dioxide has been developed. Under mild reactionconditions, this chemistry afforded 2-benzyl-β,γ-unsaturated acid derivatives as products, which are a kind of important unit for bio-active molecules and versatile precursors for organic synthesis, with good functional group tolerance. The key
TBAI-Catalyzed Regioselective Hydroxyperoxidation of 1-Aryl/Alkyl-1,3-dienes
作者:Atul Kumar、Gulenur N. Khatun、Rodney A. Fernandes
DOI:10.1021/acs.orglett.3c01393
日期:2023.6.16
approach for regioselective synthesis of 4-aryl/alkyl-1-peroxy-but-3-en-2-ols from 1-substituted-1,3-butadienes using hydroperoxides and catalyzed by TBAI has been developed. This method can be executed in a simple operation with no dry conditions required and having tolerance to a wide range of substrates to access corresponding hydroxyperoxidates in good yields. Thus, an excellent regioselective orthogonal