Click reactions and intramolecular condensation reactions on azido-adamantyl-functionalized tin sulfide clusters

Abstract

Herein, we present the synthesis of peptide-decorated organotin sulfide clusters via strain-promoted azide–alkyne cycloaddition. Overall, the target compounds are accessed in three major steps. The first step represents the synthesis of azide-terminated organotin sulfide clusters of the general type [(RSn)₃S₄Cl]. In the second step, these are reacted with a complementary cyclooctyne that exhibits terminal amine functionality. According to electrospray-ionization mass spectrometry, the terminal amino group at the alkyne undergoes an intramolecular condensation reaction. The product of this reaction was modelled by means of DFT calculations, which indicate the product to be a minimum on the energy hypersurface. Protection of the terminal amino group inhibits this intramolecular condensation reaction, as verified by mass spectrometry for a cluster with terminal boc-protected dipeptide moieties.