title: Improved simplicity and practicability in copper-catalyzed alkynylation of tetrahydroisoquinoline.
abstract: Alkynylation reactions of N-protected tetrahydroisoquinolines have been performed using several different protocols of cross dehydrogenative coupling. Initially, a CuCl-catalyzed method was investigated, which worked well with three different N-protecting groups, namely phenyl, PMP, and benzyl andt-BuOOH as oxidant in acetonitrile as solvent. The peroxide could then be replaced by simple air and acetonitrile for water, leading to an overall very environmentally friendly protocol. Finally, a decarboxylative alkynylation protocol starting from alkynoic acids was also developed using again air as oxidant. This avoids the use of gaseous alkynes in the introduction of short-chained alkyne substituents.
authors.affiliation: Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Gröll
authors.affiliation: Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Vienna, Austria.
authors.forename: Patricia
authors.initials: P
authors.lastname: Schaaf
authors.affiliation: Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Vienna, Austria.
authors.forename: Michael
authors.identifier: 0000-0003-2946-9294
authors.initials: M
authors.lastname: Schnürch
keywords: Alkynes; Catalysis; Copper catalysis; Cross dehydrogenative coupling; Oxidative coupling