1,3-Dipolar cycloadditions of fluorinated nitrones with thioketones
摘要:
Fluorinated nitrones derived from fluoral and difluoroacetaldehyde react with thioketones via [3 + 2] cycloaddition yielding 1,4,2-oxathiazolidines in a regioselective manner. Unexpectedly, cycloaliphatic thioketones react faster than aromatic thioketones. Due to the presence of a fluorinated alkyl group, the cycloadducts display a remarkable stability and do not decompose at room temperature in the crystalline form nor in solution. (C) 2014 Elsevier B.V. All rights reserved.
Fluorinated nitrones derived from fluoral and difluoroacetaldehyde react with thioketones via [3 + 2] cycloaddition yielding 1,4,2-oxathiazolidines in a regioselective manner. Unexpectedly, cycloaliphatic thioketones react faster than aromatic thioketones. Due to the presence of a fluorinated alkyl group, the cycloadducts display a remarkable stability and do not decompose at room temperature in the crystalline form nor in solution. (C) 2014 Elsevier B.V. All rights reserved.
First application of fluorinated nitrones for the synthesis of fluoroalkylated β-lactams via the Kinugasa reaction
作者:Marcin K. Kowalski、Grzegorz Mlostoń、Emilia Obijalska、Anthony Linden、Heinz Heimgartner
DOI:10.1016/j.tet.2016.06.073
日期:2016.9
The regioselective reactions of fluorinated nitrones with selected terminal alkynes (Kinugasareaction) was studied in the presence of Cu(I) iodide and TEA as a base. After chromatographic purification the desired β-lactams were obtained in high yields (up to 93%) and high diastereoselectivities (up to 9:1). The reactions performed in the presence of chiral, enantiomerically pure ligands led to enantiomerically