Does the wittig-still rearrangement proceed via a metal free carbanion?
作者:Birgit Kruse、Reinhard Brückner
DOI:10.1016/s0040-4039(00)97638-x
日期:1990.1
The steric course of [2,3] rearrangements of allyloxy methanides is almost not affected by the counterion (M = Li, Na, K, Rb, Cs) as demonstrated by the nearly metal independent E,Z and anti,syn selectivities of rearrangements 4 → 6 and 7 → 8, respectively.
A new thiourea catalyst is reported for the enantioselective cationic polycyclization of hydroxylactams. Both the yield and enantioselectivity of this transformation were found to vary strongly with the identity of a single aromatic residue on a common catalyst framework, with more expansive and polarizable arenes proving optimal. Evidence is presented for a mechanism in which stabilizing cation-Pi interactions are a principal determinant of enantioselectivity.
Stereoselective Cyclization Cascade of Dihydroquinoxalinones by Visible-Light Photocatalysis: Access to the Polycyclic Quinoxalin-2(1<i>H</i>)-ones
作者:Raviramanujayya Tammisetti、Bor-Cherng Hong、Su-Ying Chien、Gene-Hsiang Lee