1575-48-0Relevant articles and documents
Gold-catalyzed cascade oxidative cyclization and arylation of allenoates
Zhang, Rui,Xu, Qin,Chen, Kai,Gu, Peng,Shi, Min
supporting information, p. 7366 - 7371 (2013/11/19)
An AuI/AuIII catalytic system was found to be effective for the cascade oxidative arylation and cyclization of allenoates with arylboronic acids to give the corresponding cyclic adducts in moderate yields. This reaction system constitutes a new method for the synthesis of β-aryl-γ-butenolides under mild conditions. Based on the previous mechanistic studies, a proposed AuI/AuIII redox catalytic cycle has been outlined. An AuI/AuIII catalytic system was found to be effective for the cascade oxidative arylation and cyclization of allenoates with various arylboronic acids to give the corresponding cyclic adducts in moderate yields. This reaction system enabled the synthesis β-aryl-γ-butenolides under mild conditions. Based on previous mechanistic studies, an AuI/AuIII redox catalytic cycle has been outlined. Copyright
Selective synthesis of unsymmetrical 3,4-disubstituted and 4-substituted 2(5H)-furanones
Rossi,Bellina,Raugei
, p. 1749 - 1752 (2007/10/03)
Easily available 3,4-dibromo-2(5H)-furanone undergoes regioselective palladium-catalyzed reaction with aryl(trialkyl)stannanes to give the corresponding 4-aryl-3-bromo-2(5H)-furanones in satisfactory yields. These monobromo derivatives have proven to be useful precursors to unsymmetrical 3,4-diaryl-2(5H)-furanones, 4-aryl-3-methyl-2(5H)-furanones and 4-aryl-2(5H)-furanones.
The reaction of α-diazo-β-hydroxy esters with boron trifluoride etherate: Generation and rearrangement of destabilized vinyl cations. A detailed experimental and theoretical study
Pellicciari, Roberto,Natalini, Benedetto,Sadeghpour, Bahman M.,Marinozzi, Maura,Snyder, James P.,Williamson, Bobby L.,Kuethe, Jeffrey T.,Padwa, Albert
, p. 1 - 12 (2007/10/03)
Cyclic ethyl 2-diazo-3-hydroxy carboxylates were prepared by treating ethyl diazoacetate with LDA followed by reaction with a series of cyclic ketones. Further treatment of these α-diazo-β-hydroxy esters with boron trifluoride etherate in various solvents affords an unusual array of products. Product types and ratios were found to be strongly dependent on ring size and the solvent used. The reaction proceeds by Lewis acid complexation of the alcohol functionality of the diazo hydroxy ester with BF3 etherate followed by neighboring-group participation of the diazo moiety to generate a cycloalkylidene diazonium salt. Loss of nitrogen produces a highly reactive, destabilized, linear vinyl cation. Ring expansion via a 1,2-methylene shift leads to the formation of a more stable, bent cycloalkenyl vinyl cation. A subsequent 1,2-methylene shift results in ring contraction ultimately leading to a stable allylic cation. This cation is either trapped by the solvent or else undergoes cyclization with the adjacent ester group to give a lactone. Computational studies at the 6-31G* level were performed to determine the geometry of the optimized vinyl cations. Relative energies suggest a moderate energy gain for isomerization of the initial vinyl cation V1 to the rearranged vinyl cation V2 followed by a large stabilization in energy for subsequent conversion to the allyl cation A1. Compared with isolated product distributions, the energy profiles suggest kinetically-controlled V1 → V2 → A1 migrations. Finally, the calculations suggest that in diethyl ether the carbocations may be coordinated to a molecule of solvent resulting in "protected" cationic intermediates with nonlinear geometries.
