ABSTRACT
A novel class of reagents, thioester isocyanides, have been prepared and applied in the synthesis of peptide macrocycles. The isocyanide part of the molecule is deployed in a multicomponent macrocyclization step. This step is followed by chemoselective peptide ligation at the thioester part of the macrocycle. Our method can now be used for rapid assembly and evaluation of cycle-tail peptides.
Subject(s)
Cyanides/chemistry , Esters/chemistry , Peptides, Cyclic/chemical synthesis , Sulfhydryl Compounds/chemistry , Cyclization , Propanols/chemistry , Solvents/chemistryABSTRACT
Copper(II) acetate catalyzes the coupling of pinacol vinylboronates with silanols producing enol silyl ethers. This represents a novel enol silyl ether synthesis via formation of the C-O bond instead of the conventional Si-O bond. This also constitutes the first transition-metal-catalyzed oxidative cross-coupling with silanols.
ABSTRACT
Simple alkenes and alkynes, with 3-hexyne in particular, are found to be important pi ligands for oxidative copper-based coupling (modern Ullmann) reactions. This enabled syntheses of various alkoxydienes with removable protecting groups that are valuable substrates for Diels-Alder reactions from alcohols and vinyl boronate esters. In addition to demonstrating that 3-hexyne is a ligand for copper in both stoichiometric and catalytic reactions, the reaction atmosphere was found to play a critical role.
