Remote C–H Hydroxylation by an α-Ketoglutarate-Dependent Dioxygenase Enables Efficient Chemoenzymatic Synthesis of Manzacidin C and Proline Analogs

Abstract

Selective C-H functionalization at distal positions remains a highly challenging problem in organic synthesis. Though Nature has evolved a myriad of enzymes capable of such feat, their synthetic utility has largely been overlooked. Here, we functionally characterize an α-ketoglutarate-dependent dioxygenase (Fe/αKG) that selectively hydroxylates the δ position of various aliphatic amino acids. Kinetic analysis and substrate profiling of the enzyme show superior catalytic efficiency and substrate promiscuity relative to other Fe/αKGs that catalyze similar reactions. We demonstrate the practical utility of this transformation in the concise syntheses of a rare alkaloid, manzacidin C, and densely substituted amino acid derivatives with remarkable step efficiency. This work provides a blueprint for future applications of Fe/αKG hydroxylation in complex molecule synthesis and the development of powerful synthetic paradigms centered on enzymatic C-H functionalization logic.

Discovery and Biocatalytic Application of a PLP-Dependent Amino Acid γ-Substitution Enzyme that Catalyzes C-C Bond Formation

“…[4][5] 12 Table S2. 13 C spectrum data of citrinadin A (CDCl 3, 125 MHz)in comparison with published data. 4-5 13 Table S3.…”

Catalytic Aerobic Oxidation of C(sp3)−H Bonds

“…[148] Fort his reaction an a-ketoglutarate-dependent (aKG) dioxygenase was used in combination with ferrous salts and ascorbic acid. [148] Fort his reaction an a-ketoglutarate-dependent (aKG) dioxygenase was used in combination with ferrous salts and ascorbic acid.…”

Exploration of Iron- and α-Ketoglutarate-Dependent Dioxygenases as Practical Biocatalysts in Natural Product Synthesis

“…Initial experimentations with GriE revealed it to be a highly active enzyme capable of hydroxylating L-leucine with very high total turnover number, as judged by LC/MS. 36 Despite this promising start, several key issues still needed to be addressed, especially with regards to a standardized reaction procedure and product isolation and purification. Initially, three different reaction conditions were examined: reaction with purified GriE, reaction with whole-cell Escherichia coli expressing GriE, and reaction with lysates of E. coli cells expressing the enzyme.…”