Room-temperature palladium-catalyzed direct 2-alkenylation of azole derivatives with alkenyl bromides

Recent Developments in Transition-Metal Catalyzed Direct C–H Alkenylation, Alkylation, and Alkynylation of Azoles

“…Molecules 2020, 25, x FOR PEER REVIEW 6 of 33 10) [33]. These modified reaction conditions presented a moderate scope for C2-alkenylation.…”

“…In 2019, Liang and coworkers followed Doucet's Pd-catalytic approach for C2-alkenylation of a variety of azole-based heterocycles by using a more efficient Ni-xantphos catalytic system (Scheme 10) [33]. These modified reaction conditions presented a moderate scope for C2-alkenylation.…”

Palladium-Catalyzed Dehydrogenative C-2 Alkenylation of 5-Arylimidazoles and Related Azoles with Styrenes

“…Although this reaction was first reported in 1967 [12], and thus historically precedes the development of the Mizoroki-Heck alkenylation [18,19], problems related to poor regioselectivity and the need to use oxidants have in the past limited its application in favor of both the aforementioned Mizoroki-Heck alkenylation and the traditional cross-coupling procedures, and also the most recent direct alkenylation of aromatic C-H bonds, also catalyzed by transition metals, involving alkenyl halides [20][21][22][23][24][25][26]. If problems associated with the use of oxidants in stoichiometric quantities can be overcome by the latest electrochemical approaches [27][28][29][30], the achievement of high regioselectivity is still often an issue to be solved.…”

Palladium-Catalyzed Dehydrogenative C-2 Alkenylation of 5-Arylimidazoles and Related Azoles with Styrenes

“…[2-4, 6, 11, 15-17] Although this reaction was first reported in 1967, [12] and thus historically precedes the development of the Mizoroki-Heck alkenylation, [18,19] problems related to poor regioselectivity and the need to use oxidants have in the past limited its application in favor of both the aforementioned Mizoroki-Heck alkenylation and the traditional cross-coupling procedures, and also the most recent direct alkenylation of aromatic C-H bonds, also catalyzed by transition metals, involving alkenyl halides. [20][21][22][23][24][25][26] If problems associated with the use of oxidants in stoichiometric quantities can be overcome by the latest electrochemical approaches, [27][28][29][30] the achievement of high regioselectivity is still often an issue to be solved. In this regard, however, it is important to note that when the reaction is conducted using a heteroarene as a partner, the presence of one or more heteroatoms leads to an innate distinction among the different C-H bonds, thus allowing with appropriate optimization of the reaction conditions the selective involvement of a specific Csp2-H bond.…”