Intramolecular C-H bond amination catalyzed by myoglobin reconstituted with iron porphycene
Yoshiyuki Kagawa, Koji Oohora, Takashi Hayashi
Abstract
C − H bond amination is an effective way to obtain nitrogen-containing products. In this work, we demonstrate that myoglobin reconstituted with iron porphycene (rMb(FePc)) catalyzes intramolecular C(sp3) − H bond amination of arylsulfonyl azides to yield corresponding sultam analogs. The total turnover number of rMb(FePc) is up to 5.7 × 104 for the C − H bond amination of 2,4,6-triisopropylbenzenesulfonyl azide. Moreover, rMb(FePc) exhibits higher selectivity for the desired CH bond amination than the competing azide reduction compared to native myoglobin. Kinetic studies reveal that the kcat value of rMb(FePc) is 4-fold higher than that of native myoglobin. Furthermore, H64A, H64V and H64I mutants of rMb(FePc) enhance the turnover number (TON) and enantioselectivity for the C − H bond amination of 2,4,6-triethylbenzenesulfonyl azide. The present findings indicate that iron porphycene is an attractive artificial cofactor for myoglobin toward the C − H bond amination reaction.