Chemoselective, Enzymatic C-H Bond Amination Catalyzed by a Cytochrome P450 Containing an Ir(Me)-PIX Cofactor
Chemoselective, Enzymatic C-H Bond Amination Catalyzed by a Cytochrome P450 Containing an Ir(Me)-PIX Cofactor
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DOI：
10.1021/jacs.6b11410
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发表时间：
2017-02-08
影响因子：
15
通讯作者：
Hartwig, John F.
中科院分区：
文献类型：
--
作者：
Dydio, Pawel;Key, Hanna M.;Hartwig, John F.
细胞色素P450酶已被设计用于催化非生物C-H键胺化反应，但这些反应的产率受到C-H键胺化的低化学选择性的限制，而不是竞争性地将叠氮化物底物还原为磺胺。在这里，我们报道了来自嗜热生物的p450，含有铱卟啉辅助因子（Ir(Me)-PIX）代替血红素，催化了磺酰叠氮化物的分子内C-H键胺化反应。与含铁卟啉的酶相比，这些反应发生时，亚硝基单位插入C-H键的化学选择性比叠氮化物还原为磺胺的化学选择性更高，底物范围更广。C-H胺化产物收率高达98%，产量约为300吨。在一种情况下，对映体过量达到95:5 er，反应可以在不同的位点选择性下发生。在所有情况下，C-H键胺化的化学选择性都大于20:1。通过评估细胞裂解物中含有Ir(Me)-PIX的CYP119突变体，而不是纯化酶，可以快速鉴定出具有这些特性的Ir(Me)-PIX CYP119突变体。这项研究为发现合适的酶来催化具有挑战性的C-H胺化反应奠定了基础。
Cytochrome P450 enzymes have been engineered to catalyze abiological C-H bond amination reactions, but the yields of these reactions have been limited by low chemoselectivity for the amination of C-H bonds over competing reduction of the azide substrate to a sulfonamide. Here we report that P450s derived from a thermophilic organism and containing an iridium porphyrin cofactor (Ir(Me)-PIX) in place of the heme catalyze enantioselective intramolecular C-H bond amination reactions of sulfonyl azides. These reactions occur with chemoselectivity for insertion of the nitrene units into C-H bonds over reduction of the azides to the sulfonamides that is higher and with substrate scope that is broader than those of enzymes containing iron porphyrins. The products from C-H amination are formed in up to 98% yield and similar to 300 TON. In one case, the enantiomeric excess reaches 95:5 er, and the reactions can occur with divergent site selectivity. The chemoselectivity for C-H bond amination is greater than 20:1 in all cases. Variants of the Ir(Me)-PIX CYP119 displaying these properties were identified rapidly by evaluating CYP119 mutants containing Ir(Me)-PIX in cell lysates, rather than as purified enzymes. This study sets the stage to discover suitable enzymes to catalyze challenging C-H amination reactions.