Two Titanium-Catalyzed Reaction Sequences for Syntheses of Pyrroles from (E/Z)-Chloroenynes or α-Haloalkynols
摘要:
Titanium-catalyzed intermolecular hydroaminations of (E/Z)-chloroenynes enabled an efficient pyrrole synthesis, which set the stage for the development of a user-friendly one-pot reaction for the regioselective preparation of fully substituted pyrroles from easily accessible alpha-haloalkynols.
A new metal-free synthesis of pyrrole from allyl ketone and amine has been established. The reaction proceeds via an thiolative activation of the C–C double bond with dimethyl(methylthio)sulfonium trifluoromethanesulfonate, followed by a nucleophilic ring-opening addition of primary amine to the generated episulfonium intermediate, and then an internal condensation and aromatization. This mild procedure