- Protecting-Group-Free Amidation of Amino Acids using Lewis Acid Catalysts
-
Amidation of unprotected amino acids has been investigated using a variety of ‘classical“ coupling reagents, stoichiometric or catalytic group(IV) metal salts, and boron Lewis acids. The scope of the reaction was explored through the attempted synthesis of amides derived from twenty natural, and several unnatural, amino acids, as well as a wide selection of primary and secondary amines. The study also examines the synthesis of medicinally relevant compounds, and the scalability of this direct amidation approach. Finally, we provide insight into the chemoselectivity observed in these reactions.
- Sabatini, Marco T.,Karaluka, Valerija,Lanigan, Rachel M.,Boulton, Lee T.,Badland, Matthew,Sheppard, Tom D.
-
p. 7033 - 7043
(2018/05/04)
-
- Direct amidation of unprotected amino acids using B(OCH2CF3)3
-
A commercially available borate ester, B(OCH2CF3)3, can be used to achieve protecting-group free direct amidation of α-amino acids with a range of amines in cyclopentyl methyl ether. The method can be applied to the synthesis of medicinally relevant compounds, and can be scaled up to obtain gram quantities of products.
- Lanigan, Rachel M.,Karaluka, Valerija,Sabatini, Marco T.,Starkov, Pavel,Badland, Matthew,Boulton, Lee,Sheppard, Tom D.
-
supporting information
p. 8846 - 8849
(2016/07/22)
-
- New strategies for the design of folded peptoids revealed by a survey of noncovalent interactions in model systems
-
Controlling the equilibria between backbone cis- and trans-amides in peptoids, or N-substituted glycine oligomers, constitutes a significant challenge in the construction of discretely folded peptoid structures. Through the analysis of a set of monomeric peptoid model systems, we have developed new and general strategies for controlling peptoid conformation that utilize local noncovalent interactions to regulate backbone amide rotameric equilibria, including n→π*, steric, and hydrogen bonding interactions. The chemical functionalities required to implement these strategies are typically confined to the peptoid side chains, preserve chirality at the side chain N-α-carbon known to engender peptoid structure, and are fully compatible with standard peptoid synthesis techniques. Our examinations of peptoid model systems have also elucidated how solvents affect various side chain-backbone interactions, revealing fundamental aspects of these noncovalent interactions in peptoids that were largely uncharacterized previously. As validation of our monomeric model systems, we extended the scope of this study to include peptoid oligomers and have now demonstrated the importance of local steric and n→π* interactions in dictating the structures of larger, folded peptoids. This new, modular design strategy has guided the construction of peptoids containing 1-naphthylethyl side chains, which we show can be utilized to effectively eliminate trans-amide rotamers from the peptoid backbone, yielding the most conformationally homogeneous class of peptoid structures yet reported in terms of amide rotamerism. Overall, this research has afforded a valuable and expansive set of design tools for the construction of both discretely folded peptoids and structurally biased peptoid libraries and should shape our understanding of peptoid folding.
- Gorske, Benjamin C.,Stringer, Joseph R.,Bastian, Brent L.,Fowler, Sarah A.,Blackwell, Helen E.
-
scheme or table
p. 16555 - 16567
(2010/02/15)
-