Thermolyses of 3-alkyl-4-phenyl-2-oxetanones and related compounds
作者:Toshiro Imai、Shinya Nishida
DOI:10.1021/jo01300a017
日期:1980.6
Cinchona Alkaloid-Lewis Acid Catalyst Systems for Enantioselective Ketene−Aldehyde Cycloadditions
作者:Cheng Zhu、Xiaoqiang Shen、Scott G. Nelson
DOI:10.1021/ja0492900
日期:2004.5.1
Asymmetric cinchona alkaloid-catalyzed acid chloride-aldehyde cyclocondensation (AAC) reactions afford enantioenriched 4-substituted and 3,4-disubstituted beta-lactones with near perfect absolute and relative stereocontrol. These reactions are characterized by the operational simplicity derived from using commercially available or easily obtained (one-step) reaction catalysts and in situ ketene generation from acid chlorides. The range of aldehyde substrates that serve as effective AAC substrates include sterically hindered aldehydes such as cyclohexanecarboxaldehyde and pivaldehyde.
The azido acid approach to β-peptides: parallel synthesis of a tri-β-peptide library by fluorous tagging
作者:Xiao Wang、Scott G. Nelson、Dennis P. Curran
DOI:10.1016/j.tet.2007.03.034
日期:2007.7
A small tri-beta-peptide library was prepared starting from three enantio- and diastereopure azido acids. Fluorous tagging followed by two cycles of azide reduction, fluorous solid phase extraction (f-SPE), peptide coupling with the original azido acids, and f-SPE provided 27 protected azido peptides. Reduction and HPLC purification provided 25 of the 27 targeted tri-beta-peptides in acceptable yields and excellent purities. (c) 2007 Elsevier Ltd. All rights reserved.
Catalytic Asymmetric Acyl Halide−Aldehyde Cyclocondensation Reactions of Substituted Ketenes
作者:Scott G. Nelson、Cheng Zhu、Xiaoqiang Shen
DOI:10.1021/ja0391208
日期:2004.1.1
Catalyticasymmetricacylhalide-aldehydecyclocondensation (AAC) reactions of alkyl-substituted ketenes with structurally diverse aldehydes provide cis-disubstituted beta-lactones with high enantioselectivity. The AAC reactions utilize a novel Al(III)-triamine catalyst in which the metal's dynamic coordination geometry leads to a highly selective catalyst complex. These AAC reactions represent a functional