Synthesis of 2,3-Dihydropyrroles by Rhodium(II)-Catalyzed Transannulation of N -Sulfonyl-1,2,3-triazoles: Diversity Generation by One-Pot Methodologies

A versatile one-pot strategy for the generation of compounds of synthetic interest has been presented, promoting the development of practical processes. First, the transannulation of N-sulfonyltriazoles through alkenes and rhodium catalysis was described, giving 2,3-dihydropyrroles in 13-76% yield. As contributions of the strategy, the evaluation of alkenes with different properties, and the use of only drops of solvent (0.40 M) was highlighted. In addition, we described a methodology for the modulation of the N-sulfonyltriazoles, to obtain selectively cyclopropyl tosylimines or 2,3-dihydropyrroles. For the latter products, neat conditions were also included. Finally, the potential of the methodology was demonstrated by the synthesis of six structurally different analogues starting from the same substrates and late-stage transformation of bioactive molecules. These compounds were generated in 38-63% yield, after two or more conversion steps carried out in the same reaction vessel.