A New Method for the Preparation of 2-Thio Substituted Furans by Methylsulfanylation of γ-Dithiane Carbonyl Compounds
作者:Albert Padwa、Cheryl K. Eidell、John D. Ginn、Michael S. McClure
DOI:10.1021/jo010986a
日期:2002.3.1
a thionium ion from a gamma-dithianyl substituted carbonylcompound followed by cyclization of this reactive intermediate onto the tethered carbonyl group. Two methods for thionium ion generation were explored. One of these involved an acid-catalyzed reaction of beta-ketenedithioacetals, prepared from the condensation of 2,2-bis(methylsulfanyl)acetaldehyde with a variety of ketones. Cyclization followed
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%
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.
Studies on the Synthesis of (±)-Stenine: A Combined Intramolecular [4 + 2]-Cycloaddition/Rearrangement Cascade
作者:Albert Padwa、John D. Ginn
DOI:10.1021/jo050515e
日期:2005.6.1
prepared via the reaction of dimethyl(methylthio)sulfonium tetrafluoroborate (DMSTF) with β-alkoxy-γ-dithiane lactams. Thermolysis of these furans resulted in an intramolecularDiels−Alderreaction (IMDAF). The resulting oxa-bridge cycloadducts underwent a subsequent 1,2-methylthio shift to form tricyclic lactams in high yield. Furan 9, annealed to an azepine ring, underwent the IMDAF reaction at or below