- Enzymatic C(sp3)-H amination: P450-catalyzed conversion of carbonazidates into oxazolidinones
-
Cytochrome P450 enzymes can effectively promote the activation and cyclization of carbonazidate substrates to yield oxazolidinones via an intramolecular nitrene C-H insertion reaction. Investigation of the substrate scope shows that while benzylic/allylic C-H bonds are most readily aminated by these biocatalysts, stronger, secondary C-H bonds are also accessible to functionalization. Leveraging this "non-native" reactivity and assisted by fingerprint-based predictions, improved active-site variants of the bacterial P450 CYP102A1 could be identified to mediate the aminofunctionalization of two terpene natural products with high regio- and stereoselectivity. Mechanistic studies and KIE experiments show that the C-H activation step in these reactions is rate-limiting and proceeds in a stepwise manner, namely, via hydrogen atom abstraction followed by radical recombination. This study expands the reactivity scope of P450-based catalysts in the context of nitrene transfer transformations and provides first-time insights into the mechanism of P450-catalyzed C-H amination reactions.
- Singh, Ritesh,Kolev, Joshua N.,Sutera, Philip A.,Fasan, Rudi
-
-
Read Online
- Versatile Cp*Co(III)(LX) Catalyst System for Selective Intramolecular C-H Amidation Reactions
-
Herein, we report the development of a tailored cobalt catalyst system of Cp*Co(III)(LX) toward intramolecular C-H nitrene insertion of azidoformates to afford cyclic carbamates. The cobalt complexes were easy to prepare and bench-stable, thus offering a convenient reaction protocol. The catalytic reactivity was significantly improved by the electronic tuning of the bidentate LX ligands, and the observed regioselectivity was rationalized by the conformational analysis and DFT calculations of the transition states. The superior performance of the newly developed cobalt catalyst system could be broadly applied to both C(sp2)-H and C(sp3)-H carbamation reactions under mild conditions.
- Chang, Sukbok,Jung, Hoimin,Kim, Dongwook,Lee, Jeonghyo,Lee, Jia,Park, Juhyeon
-
p. 12324 - 12332
(2020/08/06)
-
- C?H Amination via Nitrene Transfer Catalyzed by Mononuclear Non-Heme Iron-Dependent Enzymes
-
Expanding the reaction scope of natural metalloenzymes can provide new opportunities for biocatalysis. Mononuclear non-heme iron-dependent enzymes represent a large class of biological catalysts involved in the biosynthesis of natural products and catabolism of xenobiotics, among other processes. Here, we report that several members of this enzyme family, including Rieske dioxygenases as well as α-ketoglutarate-dependent dioxygenases and halogenases, are able to catalyze the intramolecular C?H amination of a sulfonyl azide substrate, thereby exhibiting a promiscuous nitrene transfer reactivity. One of these enzymes, naphthalene dioxygenase (NDO), was further engineered resulting in several active site variants that function as C?H aminases. Furthermore, this enzyme could be applied to execute this non-native transformation on a gram scale in a bioreactor, thus demonstrating its potential for synthetic applications. These studies highlight the functional versatility of non-heme iron-dependent enzymes and pave the way to their further investigation and development as promising biocatalysts for non-native metal-catalyzed transformations.
- Vila, Maria Agustina,Steck, Viktoria,Rodriguez Giordano, Sonia,Carrera, Ignacio,Fasan, Rudi
-
p. 1981 - 1987
(2020/04/17)
-
- Aminotellurinylation of Olefins and Its Utilization for Synthesis of 2-Oxazolidinones
-
Benzenetellurinyl acetate or trifluoroacetate in combination with ethyl carbamate effected regio- and stereoselective aminotellurinylation of olefins in the presence of boron trifluoride etherate in chloroform under reflux to give ethyl carbamates in high yields.Benzenetellurinyl trifluoromethanesulfonate similarly did it even at the lower temperature of refluxing dichloromethane without Lewis acid.This reaction was successfully extended to cyclofunctionalization of olefinic carbamates into nitrogen heterocycles.Furthermore, when the aminotellurinylation was carried out in refluxing 1,2-dichloroethane, 2-oxazolidinone was obtained in a high yield.A mechanism of addition followed by intramolecular substitution in proposed on the basis of the stereochemistry of 2-oxazolidinone derivatives.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
-
p. 4398 - 4404
(2007/10/02)
-
- Organotellurium-mediated Synthesis of Oxazolidin-2-ones from Alkenes
-
Phenyltellurinyl trifluoroacetate in combination with ethyl carbamate and boron trifluoride-diethyl ether reacted with alkenes in refluxed 1,2-dichloroethane, regio- and stereo-selectively giving oxazolidin-2-ones in high yields.
- Hu, Nan X.,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
-
p. 1447 - 1448
(2007/10/02)
-
- Cyclic Carbonylation of 3-Hydroxycarbohydroxamic Acids with 1,1'-Carbonyldiimidazole
-
The reaction of 3-hydroxycarbohydroxamic acids 3 with 1,1'-carbonyldiimidazole produces as a function of the substitution of 3 heterocycles of type 1, 4, and 5.In the presence of imidazole the 3-(2-hydroxyalkyl)-1,4,2-dioxazol-5-ones 1 undergo rearrangeme
- Geffken, Detlef
-
p. 219 - 225
(2007/10/02)
-