Schmidt Reaction of ω-Azido Valeryl Chlorides Followed by Intermolecular Trapping of the Rearrangement Ions: Synthesis of Assoanine and Related Pyrrolophenanthridine Alkaloids.

The Schmidt reaction of ω-azido valeryl chlorides in the presence of an additional nucleophile was explored. The arenes, alcohols, and amines were demonstrated as the intermolecular trapping reagents for isocyanate ion and N-acyliminium ion from the Schmidt rearrangement, affording the corresponding products with moderate to excellent yields. Two 2-oxoindoles from the reaction were successfully converted into four natural alkaloids, namely, assoanine, anhydrolycorine, oxoassoanine, and anhydrolycorinone.