Combination of NH2OH·HCl and NaIO4: an effective reagent for molecular iodine-free regioselective 1,2-difunctionalization of olefins and easy access of terminal acetals
Regioselective transformation of alkynes into cyclic acetals and thioacetals with a gold(I) catalyst: comparison with Brønsted acid catalysts
作者:Laura L. Santos、Violeta R. Ruiz、Maria J. Sabater、Avelino Corma
DOI:10.1016/j.tet.2008.06.032
日期:2008.8
Au(I) catalyzes the transformation of alkynes into cyclic acetals and thioacetals at much higher rate than Brønsted 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
Synthesis of dioxolanes and oxazolidines by silica gel catalysis
作者:Taoufik Rohand、Jérôme Savary、István E. Markó
DOI:10.1007/s00706-018-2198-7
日期:2018.8
AbstractEthylene glycol condensed with carbonyl compounds in the presence of silicagel or alumina, without solvent and under pressure, affords 1,3-dioxolanes. 2-Amino-2-methylpropanol also condensed with carbonyl compounds in the presence of silicagel or an acid-activated clay, without solvent and under pressure, produces oxazolidines. To explain these results, we propose that the glycol and the
Treatment of terminal olefinsbearingelectron-withdrawing groups with (R,R)-pentane-2,4-diol (2) in the presence of PdCl2–CuCl–O2 in 1,2-dimethoxyethane gives cyclic acetals such as (3) and (12b)via attack at the terminal carbon atom; the corresponding acetals are similarly formed from propane-1,3-diol (5) and ethylene glycol (8).
Dialkylation of ethyleneketals by 1,8-bis(trimethylsilyl)-2,6-octadiene led to 1,3-divinyl-2-methyl-2-alkylcyclopentanes (mixture of isomers) in moderate yield.