Synthesis of Unnatural α-Amino Acid Derivatives via Light-Mediated Radical Decarboxylative Processes
Unnatural amino acids (UAAs) are key building blocks with widespread application across several scientific fields. Therefore, it is highly attractive to develop straightforward and simple methodologies capable of granting quick access to these species. Herein we report a light-mediated protocol for the synthesis of UAA via radical decarboxylative processes. This methodology, which employs readily available and abundant starting materials – such as carboxylic and α-keto acids – proceeds under very mild reaction conditions and shows a high functional group tolerance. In addition, the products of the radical reaction can be readily derivatized to grant rapid access to complex UAAs. (Figure presented.).
Merkens, Kay,Aguilar Troyano, Francisco José,Djossou, Jonas,Gómez-Suárez, Adrián
Synthesis of β-silyl α-amino acids via visible-light-mediated hydrosilylation
An expedient synthesis of β-silyl α-amino acids is reported via the application of visible-light-mediated hydrosilylation. The reaction utilizes readily accessible and structurally diverse hydrosilanes to provide radicals for conjugate addition to dehydroalanine ester and analogues. Notably, the use of chiral methyleneoxazolidinone as the substrate and chiral inducer enabled the highly stereoselective synthesis. Furthermore, the reaction could also be performed in a continuous flow fashion and scaled up to the gram scale.
Synthesis of Enantioenriched α-Deuterated α-Amino Acids Enabled by an Organophotocatalytic Radical Approach
A mild, versatile organophotoredox protocol has been developed for the preparation of diverse, enantioenriched α-deuterated α-amino acids. Distinct from the well-established two-electron transformations, this radical-based strategy offers the unrivaled ca
Derivatization of Amino Acids and Peptides via Photoredox-Mediated Conjugate Addition
Unnatural amino acids are key building blocks in therapeutically relevant peptides. Thus, the development of novel methods to increase the structural diversity of the unnatural amino acid pool is needed. Herein, a photoredox-mediated decarboxylative radical conjugate addition to dehydroalanine derivatives is disclosed. Mild, robust, and general conditions were identified and applied to the diastereoselective synthesis of unnatural amino acids and the late-stage derivatization of a tripeptide.
Decarboxylative Radical Addition to Methylideneoxazolidinones for Stereocontrolled Synthesis of Selectively Protected Diamino Diacids
Syntheses of stereochemically pure and selectively protected diamino diacids can be achieved by redox decarboxylation of distal N-hydroxyphthalimide esters of protected aspartic, glutamic or α-aminoadipic acids via radical addition to methylideneoxazolidinones. The products are useful for solid-supported syntheses of robust bioactive carbocyclic peptide analogs. Yields of reactive primary radical addition are superior to those of more stabilized radicals, and the reaction fails if the alkylideneoxazolidinone has a methyl substituent on its terminus (i.e., 13a/13b).
Annadate, Ritesh,Beadle, Jonathan,Hsiao, Yu-Ting,Pascoe, Cameron,Vederas, John C.
p. 7270 - 7273
(2021/10/01)
Biocompatible Photoinduced Alkylation of Dehydroalanine for the Synthesis of Unnatural α-Amino Acids
A site-selective alkylation of dehydroalanine to access protected unnatural amino acids is described. The protocol is characterized by the wide nature of alkyl radicals employed, mild conditions, and functional group compatibility. This protocol is further extended to access peptides, late-stage functionalization of pharmaceuticals, and enantioenriched amino acids.
Delgado, José A. C.,Correia, José T. M.,Pissinati, Emanuele F.,Paix?o, Márcio W.
p. 5251 - 5255
(2021/07/20)
Rapid Syntheses of (?)-FR901483 and (+)-TAN1251C Enabled by Complexity-Generating Photocatalytic Olefin Hydroaminoalkylation
We report a common strategy to facilitate the syntheses of the polycyclic alkaloids (?)-FR901483 (1) and (+)-TAN1251C (2). A divergent synthetic strategy provides access to both natural products through a pivotal spirolactam intermediate (3), which can be accessed on a gram-scale. A photocatalytic olefin hydroaminoalkylation brings together three readily available building blocks and forges the majority of the carbon framework present in 1 and 2 in a single operation, leading to concise total syntheses. The complexity-generating photocatalytic process also provides direct access to novel non-racemic spirolactam scaffolds that are likely to be of interest to early-stage drug discovery programs.
Reich, Dominik,Trowbridge, Aaron,Gaunt, Matthew J.
p. 2256 - 2261
(2020/01/24)
Rhodium-catalysed conjugate addition of arylboronic acids to enantiopure dehydroamino acid derivatives
The rhodium-catalysed conjugate addition of arylboronic acids to an enantiopure acceptor derived from (R)-S-methylcysteine proceeds under substrate control to provide a range of functionalised phenylalanine derivatives with excellent stereocontrol via a highly diastereoselective protonation.
Hargrave, Jonathan D.,Bish, Gerwyn,Koehn, Gabriele Kociok,Frost, Christopher G.
experimental part
p. 5120 - 5125
(2010/12/25)
Synthesis by conjugate radical addition of new heterocyclic amino acids with nucleic acid bases in their side chains
N-(2-Iodoethyl) and N-(3-iodopropyl)pyrimidines and purines undergo stereoselective conjugate radical addition with an optically active oxazolidinone acceptor to give syn-adducts that can be converted into pyrimidine and purine amino acids.
Jones,Berthelot,Iley
p. 2131 - 2132
(2007/10/03)
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