Break the template boundary: Test of different protein scaffolds by genetic code expansion resulted in NADPH-dependent secondary amine catalysis

Here, incorporation of secondary amine by genetic code expansion was used to expand the potential protein templates for artificial enzyme design. Pyrrolysine analogue containing a D-proline could be stably incorporated into proteins, including the multidrug-binding LmrR and nucleotide-binding dihydrofolate reductase (DHFR). Both modified scaffolds were catalytically active, mediating transfer hydrogenation with a relaxed substrate scope. The protein templates played a distinctive role in that, while the LmrR variants were confined to the biomimetic BNAH as the hydride source, the optimal DHFR variant favorably used the pro-R hydride from NADPH for reactions. Due to the cofactor compatibility, the DHFR secondary amine catalysis could also be coupled to an enzymatic recycling scheme. This work has illustrated the unique advantages of using proteins as hosts, and thus the presented concept is expected to find uses in enabling tailored secondary amine catalysis.

Photoredox Mediated Asymmetric Cross-Dehydrogenative Coupling of Enones and Tertiary Amines by Chiral Primary Amine Catalysis

We report herein a catalytic asymmetric dehydrogenative cross-coupling reaction between enones and tertiary amines enabled by synergistic photoredox and chiral primary amine catalysis. The reaction was proposed to proceed via the interception of iminium ion intermediate, in situ generated from photoredox oxidation, by dienamine at α-position, following by isomerization, leading to aza-Morita-Baylis-Hillman-type products with good diastereo- and enantio- selectivity.

Synergistic photoredox and tertiary amine catalysis: Generation of allylic sulfones from Morita-Baylis-Hillman acetates and sulfur dioxide

The first example for the synthesis of allylic sulfones through synergistic photoredox and tertiary amine catalysis, starting from MBH acetates, DABCO·(SO2)2 and 4-substituted Hantzsch esters or potassium alkyltrifluoroborates via a...

Decarboxylative Propargylation/Hydroamination/Aromatization Enabled by Copper/ Amine Cooperative Catalysis: Construction of Cyclopenta[b]indole Derivatives

An efficient decarboxylative cycloaddition of 2,3-dioxopyrrolidines and ethynyl benzoxazinanones has been established by cooperative copper/amine catalysis. A copper– allenylidene complex and enolate intermediate, each catalytically generated from distinct substrates, underwent a cascade propargylation/hydroamination/aromatization process to construct a big library of cyclopenta[b]indole derivatives with good to excellent yields and excellent diastereoselectivity.