Ag(I)-Catalyzed rapid access to 2-amino-4-methylenethiazolines with potential applications in bioconjugation chemistry

Regioselective 5-exo-dig (halo)cyclization of N-propargyloxycarbonyl guanidine derivatives under mild conditions

A highly regioselective 5-exo-dig cyclization of aromatic N-propargyloxycarbonyl guanidines was developed via an Ag(I)-catalyzed intramolecular hydroamination reaction. This method features a fast reaction rate and mild reaction conditions. Furthermore, it was extended to access halogenated analogues via a one-pot Ag(I)-catalyzed bromocyclization reaction or an I2-mediated iodocyclization reaction with high E/Z selectivity.

Regioselective Access to 2-Iminoimidazolidines via AgF-Mediated Cascade Reactions

A convergent access to substituted 2-iminoimidazolidines from aromatic amines and N-propargyl S-methylthiourea is developed via Ag(I)-mediated cascade guanylation-cyclization reactions. This method features high regioselectivity, excellent efficiency, and mild reaction conditions. Subsequent deprotection of the Boc (tert-butyloxycarbonyl) group under acidic conditions provides expedient access to aryl 2-aminoimidazole derivatives in a convenient manner.