- Experimental and Theoretical Study of the Effectiveness and Stability of Gold(I) Catalysts Used in the Synthesis of Cyclic Acetals
-
Different [AuL]+ fragments (L = tertiary phosphines, ylides, or NHC carbene) have been tested under mild conditions as suitable catalysts for the transformation of terminal or internal alkynes into the corresponding cyclic acetals upon reaction
- Cordón, Jesús,López-De-Luzuriaga, José M.,Monge, Miguel
-
p. 732 - 740
(2016/06/01)
-
- Regioselective transformation of alkynes into cyclic acetals and thioacetals with a gold(I) catalyst: comparison with Br?nsted acid catalysts
-
Au(I) catalyzes the transformation of alkynes into cyclic acetals and thioacetals at much higher rate than Br?nsted acids. The reaction appears to be general for a range of alkynes and diols or dithiols, which are efficiently transformed with high selectivities. One of the salient features of this reaction process is the high reactivity of the enol ether or enol thioether intermediates, which undergo a rapid isomerization reaction to afford the cyclic acetals or thioacetals, so that isolation or subsequent activation processes are not required. This type of reactions allows us to synthesize a series of fragrances.
- Santos, Laura L.,Ruiz, Violeta R.,Sabater, Maria J.,Corma, Avelino
-
p. 7902 - 7909
(2008/12/21)
-
- Radicals through Photoinduced Electron Transfer. Addition to Olefin and Addition to Olefin-Aromatic Substitution Reactions
-
The radical cations of 2,2-dialkyl- and 2-alkyl-2-aryl-1,3-dioxolanes, when generated in solution by photoinduced electron transfer to 1,2,4,5-benzenetetracarbonitrile (TCB), fragment to yield alkyl radicals.These are trapped by electron-withdrawing substituted alkenes (acrylonitrile, methyl acrylate, methyl vinyl ketone, as well as dimethyl maleate and fumarate).The radicals thus formed are either reduced by the TCB radical anion or add to it.In the first process (observed only with the diesters) the end result is reductive alkylation of the olefin, while the latter process results in an addition to the olefin-aromatic substitution reaction.The selectivity of the process is explained on the basis of steric hindrance, since the radicals react when still in the cage with the aromatic radical anion.
- Mella, Mariella,Fagnoni, Maurizio,Albini, Angelo
-
p. 5614 - 5622
(2007/10/02)
-