Intramolecular [4+2]-cycloaddition reactions of cyclic 2-thiomethyl-5-amidofurans
作者:John D Ginn、Stephen M Lynch、Albert Padwa
DOI:10.1016/s0040-4039(00)01455-6
日期:2000.12
possessing tethered π-bonds were prepared by a dimethyl(methyl-thio) sulfonium tetrafluoroborate (DMTSF) induced cyclization of various amido dithioacetals. Upon heating, these systems undergo an intramolecular4+2-cycloaddition reaction. The initially formed Diels–Alder cycloadduct further rearranges by ring opening of the oxygen bridge followed by a subsequent 1,2-thiomethyl shift.
Synthesis of Azapolycyclic Systems via the Intramolecular [4 + 2] Cycloaddition Chemistry of 2-(Alkylthio)-5-amidofurans
作者:Albert Padwa、John D. Ginn、Scott K. Bur、Cheryl K. Eidell、Stephen M. Lynch
DOI:10.1021/jo0111816
日期:2002.5.1
prepared via the reaction of dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) with beta-alkoxy-gamma-dithiane amides 13-16 and 27-32 in 40-70% yield. Thermolysis of these furans resulted in an intramolecular Diels-Alder reaction (IMDAF). With the exception of 45 and 46, the oxa-bridged cycloadducts could not be isolated but immediately underwent a 1,2-methylthio shift to form bicyclic lactams in 60-100%