1206552-30-8Relevant academic research and scientific papers
Access to indoles via Diels-Alder reactions of 5-methylthio-2-vinylpyrroles with maleimides
Noland, Wayland E.,Lanzatella, Nicholas P.,Dickson, Rozalin R.,Messner, Mary E.,Nguyen, Huy H.
, p. 795 - 808 (2013/08/23)
Diels-Alder reactions of 5-methylthio-2-vinyl-1H-pyrroles with maleimides followed by isomerization gave tetrahydroindoles in moderate to good yield. Aromatization using activated MnO2 in refluxing toluene gave the corresponding 2-methylthioindoles in good yields, and demethylthioation using Raney nickel gave the 2-H indoles in excellent yields. The protection of the adducts produced aromatization in improved yield, demonstrating the effectiveness of the methylthio group as a protecting group for pyrroles; however, 5-methylthio-2-vinylpyrrole was shown to perform with slightly less efficiency than 2-vinylpyrrole in Diels-Alder reactions, indicating the protective group was more deactivating than desired. This route toward indoles offers high convergency and conveniently available starting materials that are easily purified. Bis-methylthioated vinylpyrroles were shown to have potential as highly activated Diels-Alder dienes.
Access to indoles via Diels-Alder reactions of 2-vinylpyrroles with maleimides
Noland, Wayland E.,Lanzatella, Nicholas P.,Venkatraman, Lakshmanan,Anderson, Nicholas F.,Gullickson, Glen C.
experimental part, p. 1154 - 1176 (2010/03/04)
(Chemical Equation Presented) Variously substituted 2-vinylpyrroles underwent an endo-addition [4+2] cycloaddition reaction with maleimides followed by a spontaneous highly diastereoselective (93-98% de) isomerization to give tetrahydroindoles in moderate to excellent yield. Treatment with activated MnO2 in refluxing toluene provided the corresponding indoles in moderate to good yield. This highly convergent methodology for formation of indoles is versatile and the starting materials are conveniently prepared.
