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N‐Heterocyclic Carbene Copper(I) Rotaxanes Mediate Sequential Click Ligations with All Reagents Premixed
Author(s) -
Hsueh FangChe,
Tsai ChiYou,
Lai ChienChen,
Liu YiHung,
Peng ShieMing,
Chiu ShengHsien
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202001398
Subject(s) - azide , steric effects , alkyne , chemistry , rotaxane , click chemistry , carbene , reagent , combinatorial chemistry , catalysis , photochemistry , polymer chemistry , copper , stereochemistry , organic chemistry , molecule , supramolecular chemistry
Abstract We have prepared NHC‐Cu I complexes with a rotaxane structure and used them as sterically sensitive catalysts for one‐pot sequential copper‐catalyzed azide/alkyne cycloadditions in solutions containing all of the coupling partners premixed in unprotected form. Most notably, a photolabile and sterically encumbered complex first catalyzed the coupling of a less bulky azide/alkyne pair; after removing the protective macrocyclic component from the rotaxane structure, through irradiation with light, the exposed dumbbell‐shaped NHC‐Cu I complex catalyzed the second click reaction of a bulkier azide/alkyne pair. Using this approach, we obtained predominantly, from a single sealed pot, a bis‐triazole product (84 %) from a mixture of two sterically distinct azides and a diyne.