ABSTRACT A novel nitrene transfer‐triggered oxa −Pictet−Spengler reaction has been developed for the efficient synthesis of amino‐functionalized dihydropyran scaffolds under rhodium catalysis. With Rh 2 (TPA) 4 as the optimal catalyst, the reaction exhibits broad substrate scope, delivering the corresponding products (20 examples) in good yields (32%–89%). Gram‐scale synthesis proceeds smoothly, and facile deprotection of the Ns group affords primary amines in good efficiency. Kinetic isotope effect studies (k H /k D = 2.2) reveal that C−H bond cleavage is involved in the rate‐determining step. This work provides a versatile strategy for accessing amino‐dihydropyran scaffolds, merging nitrene transfer with the oxa −Pictet−Spengler reaction for the first time.
Yang et al. (Sat,) studied this question.