Chlorination and ortho-acetoxylation of 2-arylbenzoxazoles

Abstract

Efficient and facile catalytic protocols for chlorination and ligand-directed ortho-acetoxylation of 2-arylbenzoxazoles have been developed. The chlorination is not a ligand-directed ortho-functionalization, but an electrophilic substitution process in the benzo ring of the benzoxazole moiety. Meanwhile, the acetoxylation exhibited high regioselectivity for the substrates containing a meta-substituent and occurred at the less sterically hindered ortho-C-H bond of the directing group.

Gold nanoparticles supported on titanium dioxide: an efficient catalyst for highly selective synthesis of benzoxazoles and benzimidazoles

“…From these reactions, we can know that a was the coupled product and a lot of a can be observed during the dehydrogenation of benzyl alcohol. But all the yield was based on o-nitrophenols, the possible measured products were c, d, e, f and g. And we did not observed the reaction (5) and (6) under catalysis of heterogeneous Au catalysts. When employing heterogeneous Pd catalysts, we can observe the reaction (5).…”

Transition‐Metal‐Catalyzed Acyloxylation: Activation of C(sp2)–H and C(sp3)–H Bonds

“…Acetoxylation of 51 , each with two potentially active positions for palladation and subsequent C–O bond formation, gave only monosubstituted products 52 , determined by HMBC (heteronuclear multiple bond correlation) . Ac 2 O plays an important role in the oxidative addition step (Scheme ).…”

“…Acetoxylation of 51, each with two potentially active positions for palladation and subsequent C-O bond formation, gave only monosubstituted products 52, determined by HMBC (heteronuclear multiple bond correlation). [42] Ac 2 O plays an important role in the oxidative addition step (Scheme 16). Unlike that of oxygen, the presence of sulfur in heterocyclic cores 53 led to the mono-and disubstituted products in Pdcatalyzed acetoxylation (Scheme 17).…”

A mild convenient ultrasound assisted synthesis of 2-aryl benzoxazoles catalyzed by KCN/MWCNT as an efficient heterogeneous nanocatalyst

“…These results demonstrated that the ultrasound irradiation was an efficient method for the one-pot synthesis of 2-substituted benzoxazoles. The structures of products were completely characterized by spectroscopic data such as IR, 1 H NMR, 13 C NMR and melting point and they were consistent with those of authentic samples [14,[38][39][40][41][42].…”