Efficient chemoenzymatic synthesis of (2S,3R)-3-hydroxy-3-methylproline, a key fragment in polyoxypeptin A and FR225659

Abstract

We report an efficient synthesis of protected (2S,3R)-3-hydroxy-3-methylproline that proceeds in three steps with complete stereoselectivity. This route represents a significant improvement over previous approaches to this noncanonical amino acid. Key to this success is the development of a one-pot chemoenzymatic procedure for the preparation of (2S,3S)-3-methylproline from Lisoleucine. This work lays the foundation for future chemoenzymatic syntheses of polyoxypeptin A and FR225659.

Concise Chemoenzymatic Total Synthesis of GE81112 B1 and Simplified Analogs Enable Elucidation of Its Key Pharmaco-phores

“…Thus, our strategy not only constitutes a distinct departure from contemporary approaches to morphed peptide synthesis, but also provides a robust solution to some of the shortcomings encountered in previous synthetic studies on GE81112 A. 4 Similar to our previous work, 8,9,19 this report highlights the strategic benefits of using enzymatic C-H oxidation to streamline access to complex, bioactive natural products. Our efficient strategy to access GE81112 B1 also enabled the preparation of six analogs, which in turn allowed us to elucidate the key pharmacophores of GE81112 B1 and obtain the first SAR insights into its inhibitory activity.…”

“…GetF was recently used to hydroxylate 3-methylproline in the synthesis of 3-hydroxy-3-methylproline, although a large-scale reaction with L-Pip has not been reported. 8 GetF was initially found to suffer from poor soluble expression when expressed as N-His6-tagged protein, but co-expression of chaperones GroES/GroEL resulted in a dramatic improvement in soluble enzyme expression. 8,9 For large-scale reactions, L-Pip was combined with These conditions presumably proceed through the intermediacy of a silyl carbamate, which is hydrolyzed upon work-up.…”

“…8 GetF was initially found to suffer from poor soluble expression when expressed as N-His6-tagged protein, but co-expression of chaperones GroES/GroEL resulted in a dramatic improvement in soluble enzyme expression. 8,9 For large-scale reactions, L-Pip was combined with These conditions presumably proceed through the intermediacy of a silyl carbamate, which is hydrolyzed upon work-up. The resulting amine 7 was carried on crude to peptide coupling with 6, yielding 4…”

Nature’s Machinery, Repurposed: Expanding the Repertoire of Iron-Dependent Oxygenases

“…183,184 Likewise, native 2OG-dependent hydroxylases and halogenases have been utilized by the Renata Lab and others in the synthesis and tailoring of natural product compounds. [185][186][187][188][189][190][191][192][193][194][195] A few examples of the abiological transformations enabled by these platforms have already surfaced: the cyclopropyl core structures of the approved drugs levomilnacipran, ticagrelor, tranylcypromine, and tasimelteon, as well as a TRPV1 antagonist drug candidate, have been constructed with engineered P450s and globins. [196][197][198] Enzyme engineers ultimately aspire to see the products of their creativity and labor used directly in the manufacture of valuable compounds.…”

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

“…41 As an extension of this strategy, we also developed a chemoenzymatic approach to (2S,3R)-3-hydroxy-3-methylproline, a rare amino-acid motif found in two natural products: polyoxypeptin A and FR225659 (Scheme 1D). 42 Our approach commenced with iterative oxidation of L-Ile with UcsF, an isoleucine 5-hydroxylase from UCS-1025A biosynthesis, 43 to give the corresponding cyclic imine; this was followed by treatment in situ with NH 3 •BH 3 to afford the proline derivative 15. The final C3 hydroxylation was performed with GetF, a pipecolic acid hydroxylase from GE81112 biosynthesis that had previously been shown to exhibit promiscuous activity, 44 to complete the synthesis of the noncanonical amino acid target 16 after Boc protection for ease of isolation.…”