First Stereoselective Inverse Demand [4 + 2] Cycloaddition Reactions of Novel Chiral Allenamides with Heterodienes. Preparation of Highly Functionalized 2-Arylpyranyl Heterocycles
摘要:
The first stereoselective inverse demand [4 + 2] cycloaddition reactions of chiral allenamides with heterodienes are described here. These reactions lead to stereoselective synthesis of highly functionalized pyranyl heterocycles. A mechanistic model is also proposed here based on the stereochemical assignment and comparisons of stereoselectivities obtained from various chiral allenamides.
Syntheses and Reactions of Optically Active α-Aminoallenylstannanes
作者:Peter B. D. Ranslow、Louis S. Hegedus、Cristobal de los Rios
DOI:10.1021/jo0302861
日期:2004.1.1
Lithiation/stannylation of opticallyactive N-propargyloxazolidinones produced opticallyactive α-oxazolidinonylallenylstannanes. Reaction of these with aldehydes in the presence of BF3·OEt2 produced β-hydroxypropargylamines with high syn diastereoselectivity and ee. These were converted to γ-hydroxy-β-amino acids by oxidative cleavage of the alkyne.