Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

Abstract

SummaryCatalytic direct (hetero)arylation of (hetero)arenes is an attractive alternative to traditional Kumada, Stille, Negishi and Suzuki–Miyaura cross-coupling reactions, notably as it avoids the prior preparation and isolation of (hetero)arylmetals. Developments of this methodology in the oxazole series are reviewed in this article. Methodologies, selectivity, mechanism and future aspects are presented.

Widely Exploited, Yet Unreported: Regiocontrolled Synthesis and the Suzuki–Miyaura Reactions of Bromooxazole Building Blocks

“…[45,46] Subsequent electrophilic trapping of the corresponding organolithium intermediate with 1,2-dibromo-1,1,2,2-tetrafluoroethane (DBTFE) resulted in regioselective C-2 bromination and gave the target product 9 in good yield (74 %). First of all, all three isomeric 2-, 4-, and 5-bromooxazoles were prepared.…”

N-heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed C–H bond benzylation of (benzo)oxazoles with benzyl chlorides

“…5 Therefore, based on our results on the NHCePd(II)-Im complex 1 catalyzed direct CeH bond arylation of (benzo)oxazoles with aryl chlorides, 4a we then turned our interest to its application toward direct CeH bond benzylation of (benzo)oxazoles with benzyl chlorides. 6 In addition, to the best of our knowledge, this is the first example of phosphine-free, NHCePd(II) complex catalyzed direct CeH bond benzylation of (benzo)oxazoles with benzyl chlorides. 7 Herein, we report these results in detail.…”

CH Activation in S‐Alkenyl Sulfoximines: An Endo 1,5‐Hydrogen Migration

“…[1] Metal-free processes are also known. It has been studied with a variety of substrates using metal catalysis, and research in this area continues unabated.…”