RESUMO
The synthesis of rare macrocyclic alkynediyl sulfides by a Cu-catalyzed Csp -S cross-coupling is presented. The catalytic protocol (Cu(MeCN)4 PF6 /dtbbpy) promotes macrocyclization of peptides, dipeptides and tripeptides at ambient temperature (14â examples, 23â73 % yields) via thiols and bromoalkynes, and is chemoselective with regards to terminal alkynes. Importantly, the underexplored alkynediyl sulfide functionality incorporates a rigidifying structural element and opens new opportunities for diversification of macrocyclic frameworks through S oxidation, halide addition and azide-alkyne cycloaddition chemistries to integrate sulfones, halides or valuable fluorophores (7â examples, 37â92 % yields).
Assuntos
Azidas , Complexos de Coordenação/química , Cobre , Peptídeos/química , Sulfetos/química , Alcinos/química , Catálise , Estrutura MolecularRESUMO
Continuous flow chemistry has improved efficiency in the Heumann indole process. 3-Substituted indoles were prepared by three flow steps performed in succession in better overall yield and shorter reaction times relative to their batch counterparts. Novel 3-alkyl and 3-methoxyindoles were synthesized from their corresponding amino ketone and ester precursors by flow sequences featuring base-free alkylation with methyl bromoacetate in DMF, saponification, and cyclization with acetic anhydride and Et3N.
