Cu(II)-Promoted Methanolysis of N,N‑Bis(2-picolyl)carbamates: Rate-Limiting Metal Ion Delivery of Coordinated Alcoholate Nucleophile Followed by Fast Partitioning of a Tetrahedral Intermediate

Five O-aryl/alkyl N,N-bis(2-picolyl)carbamates were prepared with the O-aryl/alkyl portions being p-nitrophenoxy, m-nitrophenoxy, trifluoroethoxy, methoxy, and isopropoxy (4a,b,c,d,e, respectively) and the kinetics and reaction products of their methanolysis reactions in the presence of Cu(O3SCF3)2 determined. The catalyzed reactions have maximal rates for each substrate at a 1:1 ratio of [4]:[Cu2+] at s spH 7.9, where the active forms are Cu(II):4:(−OCH3). The reactions are fast, that for the complex of 4a having a t 1/2 of 30 s. The products of the reaction with 4a and 4b arise exclusively from C–OAr cleavage: those with 4d and 4e arise exclusively from C–N cleavage. With 4c, products from both C–O and C–N cleavage are observed in a 2.17:1 ratio. The common mechanism involves rate-limiting delivery of a Cu(II)-coordinated methoxide to the CO unit to form a tetrahedral intermediate followed by fast partitioning to products by two pathways with relative barriers dependent on the s spK a HOAr/HOR. The data allow one to predict an effective s spK a of ∼15.6 for the s spK a NH of Cu(II):bis(2-picolyl)amine.