Microwave-promoted iminyl radical cyclizations can be terminated by trapping with TEMPO, affording functionalized adducts. The use of alkynes as radical acceptors delivers a range of 2-acylpyrroles in good yields. Toxic and hazardous reagents, which are frequently employed in radical reactions, are not required. The O-phenyl oxime ether substrates are constructed in a single step from readily available ketones.

The bulky dehydroamino acids dehydrovaline (ΔVal) and dehydroethylnorvaline (ΔEnv) can be inserted into the turn regions of β-hairpin peptides without altering their secondary structures. These residues increase proteolytic stability, with ΔVal at the (i + 1) position having the most substantial impact. Additionally, a bulky dehydroamino acid can be paired with a D-amino acid (i.e., D-Pro) to synergistically enhance resistance to proteolysis. A link between proteolytic stability and peptide structure is established by the finding that a stabilized ΔVal-containing β-hairpin is more highly folded than its Asn-containing congener.

Total synthesis of the anticancer peptide natural product yakuamide A is reported. Its b-tert-hydroxy amino acids were prepared by regioselective aminohydroxylation involving a chiral mesyloxycarbamate reagent. Stereospecific construction of the E-and Z-DIle residues was accomplished through a one-pot reaction featuring anti dehydration, azide reduction, and O!N acyl transfer. Alkene isomerization was negligible during this process. These methods enabled a highly convergent and efficient synthetic route to the natural product.

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Total synthesis of the anticancer peptide natural product yakuamide A is reported. Its b-tert-hydroxy amino acids were prepared by regioselective aminohydroxylation involving a chiral mesyloxycarbamate reagent. Stereospecific construction of the E-and Z-DIle residues was accomplished through a one-pot reaction featuring anti dehydration, azide reduction, and O!N acyl transfer. Alkene isomerization was negligible during this process. These methods enabled a highly convergent and efficient synthetic route to the natural product.