An in-depth look at the effect of Lewis acid catalysts on Diels–Alder cycloadditions in ionic liquids
作者:Guadalupe Silvero、María José Arévalo、José Luis Bravo、Martín Ávalos、José Luis Jiménez、Ignacio López
DOI:10.1016/j.tet.2005.05.064
日期:2005.7
The present work explores in detail the Diels–Alderreaction between cyclopentadiene and a series of dienophiles, performed in an innovative medium such as an ionicliquid. The potential activation of differentLewisacid catalysts and their load effect when used in combination with this solvent have been explored, in order to settle the improvement on rates and selectivities.
Efficient monoacetal formation, unprecedented β-cleavage in caged cyclobutyl ketones and dual epimerization of 1,4-diones in the photochemistry of hexacyclo[10.2.1.0<sup>2,11</sup>.0<sup>4,9</sup>.0<sup>4,14</sup>.0<sup>9,13</sup>]pentadeca-5,7-diene-3,10-dione and related systems in alcoholic solvents
作者:Bipin Pandey、Umesh R. Zope、Nagaraj R. Ayyangar
DOI:10.1039/c39900000107
日期:——
Irradiation of the title compound and related caged cyclobutyl diones in alcoholic solvents at 300 nm furnishes good yields of monoacetals and leads to products arising from β-cleavage and dual epimerization.
A pharmaceutically important natural product, β-lapachone, was efficiently synthesized in four steps in 70 % overall yield starting from commercially available 1,4-naphthoquinone. The key step of the synthesis was the direct conversion of 2-prenyl-1,4-naphthoquinone into β-lapachone through an advantageous cyclization/hydration/oxidation cascade process.