Oxidative Dehydrogenation of Hydrazobenzenes toward Azo Compounds Catalyzed by tert-Butyl Nitrite in EtOH

Abstract

We describe a tert-butyl nitrite-catalyzed oxidative dehydrogenation of hydrazobenzenes for producing azobenzenes. This method proceeds at ambient temperature and under an atmospheric environment by employing eco-friendly EtOH as the medium, representing a mild, general route to the synthesis of various symmetrical and nonsymmetrical azobenzenes in excellent yields with broad functional group tolerance.

Synthesis and Investigations of Building Blocks with Dibenzo[b,f] Oxepine for Use in Photopharmacology

“…[12,50] Firstly, we explored the various synthetic methods to obtain the azo compounds (2a-2h). We focused on one-step methods because of the short reaction time, although different varieties of azo-product reduction (two-step from the amino group) are also currently under investigation [51][52][53][54][55]. The results are summarized in Table 2.…”

Organocatalytic Reduction of Aromatic Nitro Compounds: The Use of Solid-Supported Phenyl(2-quinolyl)methanol

“…On the whole, these results appear quite interesting because the oxidation of hydrazobenzenes to azo compounds is generally performed with transition metal reagents (as stoichiometric oxidants or catalysts), and only recently, good outcomes were reported via metal-free strategies. For instance, reduced graphene oxide/air, 22 tert -BuOK/air, 23 TEMPO/air, 24 NO x /O 2 , 25 TCCA, 26 TBN/air, 27 molecular iodine/air, 28 and HBr/H 2 O 2 29 were efficiently applied while the simple use of oxygen in MeCN was ineffective. 27 …”

“…For instance, reduced graphene oxide/air, 22 tert -BuOK/air, 23 TEMPO/air, 24 NO x /O 2 , 25 TCCA, 26 TBN/air, 27 molecular iodine/air, 28 and HBr/H 2 O 2 29 were efficiently applied while the simple use of oxygen in MeCN was ineffective. 27 …”

Emerging trends in the sustainable synthesis of N–N bond bearing organic scaffolds

“…Following this, an equal amount of HNO 2 is removed yielding the azo product (Scheme 31). 64 Through a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) mediated direct oxidative dehydrogenation method, Fan and co-workers showed the effective transformation of hydrazobenzene to azobenzene without the use of metal additives. The proposed approach makes use of aerobic oxygen and an eco-friendly catalyst, which is considered an advantage.…”