Practical Enantioselective Synthesis of β-Lactones Catalyzed by Aluminum Bissulfonamide Complexes
作者:Thomas Kull、René Peters
DOI:10.1002/adsc.200700084
日期:2007.7.2
practical aluminum-bissulfonamide complex catalyzed enantioselective formation of β-lactones by [2+2] cycloaddition of ketene (generated in situ from acetyl bromide by dehydrobromination) with various α-unbranched and -branched aliphatic aldehydes is presented. The methodology offers the advantage of operational simplicity not only as the ligand synthesis requires just a single sulfonylation step from commercially
A catalytic enantioselective reaction using a C2-symmetric disulfonamide as a chiral ligand: Alkylation of aldehydes catalyzed by disulfonamide-Ti(O-i-Pr)4-Dialkyl zinc system
Reversal of enantioselectivity on protonation of enol(ate)s derived from 2-methyl-1-tetralone using C2-symmetric sulfonamides
作者:Ewan Boyd、Gregory S. Coumbarides、Jason Eames、Alastair Hay、Ray V.H. Jones、Rachel A. Stenson、Michael J. Suggate
DOI:10.1016/j.tetlet.2004.10.087
日期:2004.12
The synthesis of enantiomerically enriched (R)-2-methyl-1-tetralone 1 (64% e.e.) was achieved through protonation of its lithium enolate 3 using a C-2-symmetrical bis-sulfonamide 5d as an internal proton source. Access to the complementary (S)-enantiomer 1 (45% e.e.) can be achieved using an external quench strategy involving acetic acid as the external proton source. (C) 2004 Elsevier Ltd. All rights reserved.