The Research Of Rhodium-catalyzed Cycloaddition And Rearrange-ment Reaction Of1-sulfonyl-1,2,3-triazoles

Metal-stabilized carbenes derived from diazo compounds have become broadlyuseful reactive intermediates for organic synthesis. In recent years,N-sulfonyl-1,2,3-triazoles as precursors for the formation of metal-bound iminocarbene intermediates has been concerned by many of chemists, becausecarben-carbon and imino-nitrogen-atoms can be attacked by nucleophile andelectrophile respectively. Hence, these intermediates undergo a variety ofsynthetically useful transformations, such as transannulation reactions to generate newheterocycles, cyclopropanation and subsequent ring expansions, ylide formation withsubsequent rearrangements, C–H functionalization and so on. This paper mainlyfocuses on the cycloaddition reactions and cycloaddition/rearrangement reactions of1-sulfonyl-1,2,3-triazoles.(1) Synthesis of3-Pyrrolin-2-ones by Rhodium-Catalyzed Transannulation of1-Sulfonyl-1,2,3-triazole with Ketene Silyl Acetal. Under a nitrogen atmosphere, theuse of1mol%of Rh2(OAc)4,1-sulfonyl-1,2,3-triazole and1.8equivalents of ketenesilyl acetal in1,2-DCE at80℃gave the best result. Most1-Sulfonyl-1,2,3-triazoleand ketene silyl acetal we investigated reacted smoothly to afford3-pyrrolin-2-onescompounds in moderate to high yield. The CH3O-, Br-, F-, CF3-, CH3COO-group aretolerated in the reaction. In addition, we have investigated the mechanism of thereaction, NMR studies showed that two mechanisms to rationalize the formation ofB-9is plausible: intramolecular nucleophilic attack of the electrophilicmetallocarbene center or cyclopropanation.(2) Synthesis of N-Acylamidines via Rhodium-Catalyzed Reaction of Nitrosob-enzene Derivatives with1-Sulfonyl-1,2,3-triazoles. Under the best reaction condition,when1-sulfonyl-1,2,3-triazole and nitrosobenzene derivatives were treated with2 mol%of Rh2(oct)4in refluxing1,2-DCE, N-acylamidines compounds could beobtained in moderate to high yield. Most1-sulfonyl-1,2,3-triazole and nitrosoben-zene derivatives we investigated reacted smoothly to afford the correspondingN-acylamidines compounds and the CH3O-, Br-, Cl-, F-, CF3-, CH3COO-group werewell tolerated in the reaction.