1,5-Hydride-Shift-Triggered Cyclization for the Synthesis of Unsymmetric Julolidines

Abstract

Directly accessible 8-substituted tetrahydroquinolines undergo 1,5-hydride shift-triggered cyclization to provide hardly accessible julolidine derivatives in 20-98% yield under scandium (III) triflate catalysis. The scope of the reaction, several follow-up transformations and a remarkable side-process discovered during the conditions optimization are highlighted.

C(sp3)–H cyclizations of 2-(2-vinyl)phenoxy-tert-anilines

“…19 Moreover, the synthetic utility of the reaction and its signicant potential was recently demonstrated also by the preparation of unsymmetric julolidines from 8-vinyl-tetrahydroquinolines via [1,5]-H transfer/cyclization. 20 The tricyclic julolidine is a privileged scaffold in the design of uorescent probes, photoswitches or photolabile protecting groups, [21][22][23][24] therefore these elds could also benet from straightforward synthetic approaches towards julolidine building blocks. Recently, Lewis-and Bronsted-acid catalysed variants of the cyclization were developed, [25][26][27] allowing milder reaction conditions (of note, the rst variants used typically higher temperatures).…”