- Acceptor-Controlled Transfer Dehydration of Amides to Nitriles
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Palladium-catalyzed dehydration of primary amides to nitriles efficiently proceeds under mild, aqueous conditions via the use of dichloroacetonitrile as a water acceptor. A key to the design of this transfer dehydration catalysis is the identification of an efficient water acceptor, dichloroacetonitrile, that preferentially reacts with amides over other polar functional groups with the aid of the Pd catalyst and makes the desired scheme exergonic, thereby driving the dehydration.
- Okabe, Hiroyuki,Naraoka, Asuka,Isogawa, Takahiro,Oishi, Shunsuke,Naka, Hiroshi
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supporting information
p. 4767 - 4770
(2019/06/17)
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- Peptide ligation by chemoselective aminonitrile coupling in water
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Amide bond formation is one of the most important reactions in both chemistry and biology1–4, but there is currently no chemical method of achieving α-peptide ligation in water that tolerates all of the 20 proteinogenic amino acids at the peptide ligation site. The universal genetic code establishes that the biological role of peptides predates life’s last universal common ancestor and that peptides played an essential part in the origins of life5–9. The essential role of sulfur in the citric acid cycle, non-ribosomal peptide synthesis and polyketide biosynthesis point towards thioester-dependent peptide ligations preceding RNA-dependent protein synthesis during the evolution of life5,9–13. However, a robust mechanism for aminoacyl thioester formation has not been demonstrated13. Here we report a chemoselective, high-yielding α-aminonitrile ligation that exploits only prebiotically plausible molecules—hydrogen sulfide, thioacetate12,14 and ferricyanide12,14–17 or cyanoacetylene8,14—to yield α-peptides in water. The ligation is extremely selective for α-aminonitrile coupling and tolerates all of the 20 proteinogenic amino acid residues. Two essential features enable peptide ligation in water: the reactivity and pKaH of α-aminonitriles makes them compatible with ligation at neutral pH and N-acylation stabilizes the peptide product and activates the peptide precursor to (biomimetic) N-to-C peptide ligation. Our model unites prebiotic aminonitrile synthesis and biological α-peptides, suggesting that short N-acyl peptide nitriles were plausible substrates during early evolution.
- Canavelli, Pierre,Islam, Saidul,Powner, Matthew W.
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p. 546 - 549
(2019/07/18)
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- Peptide ligation by chemoselective aminonitrile coupling in water
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Amide bond formation is one of the most important reactions in both chemistry and biology1–4, but there is currently no chemical method of achieving α-peptide ligation in water that tolerates all of the 20 proteinogenic amino acids at the pepti
- Canavelli, Pierre,Islam, Saidul,Powner, Matthew W.
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p. 546 - 549
(2019/07/31)
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- C(sp3)?H Cyanation Promoted by Visible-Light Photoredox/Phosphate Hybrid Catalysis
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Inspired by the reaction mechanism of photo-induced DNA cleavage in nature, a C(sp3)?H cyanation reaction promoted by visible-light photoredox/phosphate hybrid catalysis was developed. Phosphate radicals, generated by one-electron photooxidation of phosphate salt, functioned as a hydrogen-atom-transfer catalyst to produce nucleophilic carbon radicals from C(sp3)?H bonds with a high bond-dissociation energy. The resulting carbon radicals were trapped by a cyano radical source (TsCN) to produce the C?H cyanation products. Due to the high functional-group tolerance and versatility of the cyano group, the reaction will be useful for realizing streamlined building block syntheses and late-stage functionalization of drug-like molecules.
- Wakaki, Takayuki,Sakai, Kentaro,Enomoto, Takafumi,Kondo, Mio,Masaoka, Shigeyuki,Oisaki, Kounosuke,Kanai, Motomu
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supporting information
p. 8051 - 8055
(2018/06/15)
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