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Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog
Synthesis of tubuphenylalanine and tubuvaline, α-substituted γ-amino acid building blocks for tubulysin family of antimitotic compounds, has been improved using a radical addition reaction in the presence of unprotected hydroxyl functionality. The key carbon–carbon bond construction entails stereose...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
2016
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4924578/ https://www.ncbi.nlm.nih.gov/pubmed/26883395 http://dx.doi.org/10.1038/ja.2016.7 |
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author | Friestad, Gregory K. Banerjee, Koushik Marié, Jean-Charles Mali, Umesh Yao, Lei |
author_facet | Friestad, Gregory K. Banerjee, Koushik Marié, Jean-Charles Mali, Umesh Yao, Lei |
author_sort | Friestad, Gregory K. |
collection | PubMed |
description | Synthesis of tubuphenylalanine and tubuvaline, α-substituted γ-amino acid building blocks for tubulysin family of antimitotic compounds, has been improved using a radical addition reaction in the presence of unprotected hydroxyl functionality. The key carbon–carbon bond construction entails stereoselective Mn-mediated photolytic additions of alkyl iodides to the C=N bond of chiral N-acylhydrazones, and generates the chiral amines in high yield with complete stereocontrol. Reductive N–N bond cleavage and alcohol oxidation converted these amino alcohols into the corresponding γ-amino acids. The route to tubuvaline proceeded via peptide coupling with serine methyl ester, followed by a high-yielding sequence to convert the serine amide to a thiazole. Finally, peptide bond construction established the tubulysin framework in the form of a C-terminal alcohol analog. Attempted oxidation to the C-terminal carboxylate was unsuccessful; control experiments with dipeptide 18 showed a cyclization interfered with the desired oxidation process. |
format | Online Article Text |
id | pubmed-4924578 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
record_format | MEDLINE/PubMed |
spelling | pubmed-49245782016-08-17 Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog Friestad, Gregory K. Banerjee, Koushik Marié, Jean-Charles Mali, Umesh Yao, Lei J Antibiot (Tokyo) Article Synthesis of tubuphenylalanine and tubuvaline, α-substituted γ-amino acid building blocks for tubulysin family of antimitotic compounds, has been improved using a radical addition reaction in the presence of unprotected hydroxyl functionality. The key carbon–carbon bond construction entails stereoselective Mn-mediated photolytic additions of alkyl iodides to the C=N bond of chiral N-acylhydrazones, and generates the chiral amines in high yield with complete stereocontrol. Reductive N–N bond cleavage and alcohol oxidation converted these amino alcohols into the corresponding γ-amino acids. The route to tubuvaline proceeded via peptide coupling with serine methyl ester, followed by a high-yielding sequence to convert the serine amide to a thiazole. Finally, peptide bond construction established the tubulysin framework in the form of a C-terminal alcohol analog. Attempted oxidation to the C-terminal carboxylate was unsuccessful; control experiments with dipeptide 18 showed a cyclization interfered with the desired oxidation process. 2016-02-17 2016-04 /pmc/articles/PMC4924578/ /pubmed/26883395 http://dx.doi.org/10.1038/ja.2016.7 Text en Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: http://www.nature.com/authors/editorial_policies/license.html#terms |
spellingShingle | Article Friestad, Gregory K. Banerjee, Koushik Marié, Jean-Charles Mali, Umesh Yao, Lei Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog |
title | Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog |
title_full | Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog |
title_fullStr | Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog |
title_full_unstemmed | Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog |
title_short | Stereoselective Access to Tubuphenylalanine and Tubuvaline: Improved Mn-Mediated Radical Additions and Assembly of A Tubulysin Tetrapeptide Analog |
title_sort | stereoselective access to tubuphenylalanine and tubuvaline: improved mn-mediated radical additions and assembly of a tubulysin tetrapeptide analog |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4924578/ https://www.ncbi.nlm.nih.gov/pubmed/26883395 http://dx.doi.org/10.1038/ja.2016.7 |
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