Expanding
Nature’s catalytic repertoire to include reactions
important in synthetic chemistry opens new opportunities for biocatalysis.
An intramolecular C–H amination route to imidazolidin-4-ones
via α-functionalization of 2-aminoacetamides catalyzed by evolved
variants of cytochrome P450BM3 (CYP102A1) from Bacillus megaterium has been developed. Screening
of a library of ca. 100 variants based on four template mutants with
enhanced activity for the oxidation of unnatural substrates and preparative
scale reactions in vitro and in vivo show that the enzymes give up
to 98% isolated yield of cyclization products for diverse substrates.
2-Aminoacetamides with one- and two-ring cyclic amines bearing substituents
and aliphatic, alicyclic, and substituted aromatic amides are cyclized.
Regiodivergent C–H amination was achieved at benzylic and nonbenzylic
positions in a tetrahydroisoquinolinyl substrate by the use of different
mutants. This C–H amination reaction offers a scalable route
to imidazolidin-4-ones with varied functionalized substituents that
may have desirable biological activity.
Biocatalytic direct monohydroxylation of anilides has been achieved on preparative scale using mutant cytochrome P450 enzymes. Representative mono- and disubstituted N-trifluoromethanesulfonyl anilides are shown to be converted in most cases to the corresponding 4-hydroxy derivatives, with substituent hydroxylation also occurring in two cases. By mutation variation, it is possible to achieve selective hydroxylation of either ring- or side-chain sites.
Small molecules inducing protein degradation are important pharmacological tools to interrogate complex biology and are rapidly translating into clinical agents. However, to fully realise the potential of these molecules, selectivity remains a limiting challenge. Herein, we addressed the issue of selectivity in the design of CRL4CRBN recruiting PROteolysis TArgeting Chimeras (PROTACs). Thalidomide derivatives used to generate CRL4CRBN recruiting PROTACs have well described intrinsic monovalent degradation profiles by inducing the recruitment of neo‐substrates such as GSPT1, Ikaros and Aiolos. We leveraged structural insights from known CRL4CRBN neo‐substrates to attenuate and indeed remove this monovalent degradation function in well‐known CRL4CRBN molecular glues degraders, namely CC‐885 and Pomalidomide. We then applied these design principles on a previously published BRD9 PROTAC (dBRD9‐A) and generated an analogue with improved selectivity profile. Finally, we implemented a computational modelling pipeline to show that our degron blocking design does not impact PROTAC induced ternary complex formation. We believe that the tools and principles presented in this work will be valuable to support the development of targeted protein degradation.
Cyclic alkenylsiloxanes were synthesized by semihydrogenation of alkynylsilanes—a reaction previously plagued by poor stereoselectivity. The silanes, which can be synthesized on multigram scale, undergo Hiyama–Denmark coupling to give (Z)-alkenyl polyene motifs found in bioactive natural products. The ring size of the silane is crucial: five-membered cyclic siloxanes also couple under fluoride-free conditions, whilst their six-membered homologues do not, enabling orthogonality within this structural motif.
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