Indole anion cycloadditions with methyl coumalate

Abstract

DedicationWe honor Professor Gordon Gribble on his distinguished career in organic chemistry. His legacy of versatile synthetic methodology and total synthesis will continue to be valued by both academic and industrial researchersReceived 01-02-2018 Accepted 01-27-2018 Published on line 02-27-2018 AbstractThe reaction of the anion of indoles with methyl coumalate followed by selective opening of the lactone led to the preparation of tricyclic intermediates for indole alkaloid synthesis.

Inverse‐Electron‐Demand Diels–Alder Reactions of 2‐Pyrones: Bridged Lactones and Beyond

“…[21] Recently,K raus andc o-worker found that indolemagnesium iodides, generated in situ from nonprotectedi ndoles 72 with methylmagnesium iodide, reacted with methyl coumalate 12 a to access dihydrocarbazoles 73 in an inverse-electron-demand fashion (Scheme 17). [22] When 3-alkylindoles 72 b and 72 c were used as dienophiles, bridged lactones 74 could be isolated and characterized, but both of them underwent retro-DA reactions at room temperaturet og ive the starting materials. Under further treatmentw ith trifluoromethanesulfonic acid, bridged lac-tones 74 were convertedi nto dihydrocarbazoles 73 through lactone-opening reactions.…”