Sulfone reagents in organic synthesis. 8. Cyclobutadiene intermediates in cycloaddition reactions of 1-alkynyl sulfones with 1-alkynylamines
摘要:
The initially formed product from ynamines, such as diethyl(1-propynl)amine, and 1-alkynyl sulfones is in fact the corresponding cyclobutadiene and not the 2-sulfinyl-4-aminofuran proposed by Himbert. The formation of the cyclobutadiene ring has been established by MS, IR, and H-1 NMR data, as well as by chemical trapping experiments.
Sulfone reagents in organic synthesis. Part 4. [2 + 2]-Cycloadditions of ynamines with .alpha.,.beta.-unsaturated sulfones: approach to versatile four-membered carbocyclic intermediates