71785-82-5Relevant academic research and scientific papers
Formation of quaternary stereogenic centers by copper-catalyzed asymmetric conjugate addition reactions of alkenylaluminums to trisubstituted enones
Mueller, Daniel,Alexakis, Alexandre
supporting information, p. 15226 - 15239 (2013/11/06)
Alkenylaluminums undergo asymmetric copper-catalyzed conjugate addition (ACA) to β-substituted enones allowing the formation of stereogenic all-carbon quaternary centers. Phosphinamine-copper complexes proved to be particularly active and selective compared with phosphoramidite ligands. After extensive optimization, high enantioselectivities (up to 96 % ee) were obtained for the addition of alkenylalanes to β-substituted enones. Two strategies for the generation of the requisite alkenylaluminums were explored allowing for the introduction of aryl- and alkyl-substituted alkenyl nucleophiles. Moreover, alkyl-substituted phosphinamine (SimplePhos) ligands were identified for the first time as highly efficient ligands for the Cu-catalyzed ACA. Chiral synthesis made easy: The copper-catalyzed conjugate addition of alkenylaluminum reagents to 3-substituted cyclic enones allows for the formation of all-carbon chiral quaternary centers (see scheme; CuTC=copper(I) thiophene-2-carboxylate). Chiral phosphinamine (SimplePhos) ligands were found to be highly efficient for this transformation.
SYNTHETIC STUDIES ON TAXANE DITERPENES X-RAY STRUCTURE OF A KEY INTERMEDIATE
Andriamialisoa, R. Z.,Fetizon, M.,Hanna, I.
, p. 4285 - 4296 (2007/10/02)
Michael condensation of the dienone (3) with the vinyllactone (19) leads to the compound (20).Attempts to construct the B ring of the taxane skeleton by direct cyclization of (20) are reported.The stereochemistry of (20) is established by X-ray structure
