A Mild Oxidative Aryl Radical Addition into Alkenes by Aerobic Oxidation of Arylhydrazines

Abstract

A mild and practical oxyarylation of alkenes by oxidative radical addition has been developed by using aerobic oxidation of hydrazine compounds. The use of a catalytic amount of potassium ferrocyanide trihydrate (K(4)[Fe(CN)(6)]⋅3H(2)O) and water accelerated this radical reaction to give peroxides or alcohols from simple alkenes in good yields. The environmentally friendly and economical radical reactions were achieved at room temperature in the presence of iron catalyst, oxygen gas, and water. A method involving aniline as a radical precursor is also described.

Denitrogenative Pd/Cu‐catalyzed Suzuki‐type Cross‐coupling of Aryltrifluoroborates with Arylhydrazine Hydrochlorides in Water under Room Temperature

“…In cross‐coupling arylation. Recent advances in the coupling reactions of arylhydrazine, which is utilized as an effective arylation partner in oxidative radical arylation and Pd‐catalyzed cross‐coupling (Heck‐type, Suzuki‐type, addition, homocoupling, etc …”

Copper(ii)-catalyzed coupling reaction: an efficient and regioselective approach to N′,N′-diaryl acylhydrazines

“…Metal-catalyzed or metal-mediated N-arylation reaction is the most direct method for the preparation of diaryl acylhydrazines. 18 25 Among them, copper-catalyzed Ullmann-type N-arylation of acylhydrazines has already achieved some success. Uno Mäeorg and co-workers have developed several methods, either via copper-catalyzed addition of arylboronic acids (or organobismuth reagents) to azo compounds (Scheme 1a), [19][20] or via the direct 30 addition of organometallic nucleophiles to azo compounds (Scheme 1b).…”

“…Strong base as DBU dramatically inhibited the progress while weak base as DMAP promoted this reaction. The organic weak base might influence both the oxidation of aryl hydrazide and the subsequent 25 coupling reaction via its coordination with copper salt. Inorganic bases, such as K 2 CO 3 and KOH were less effective (entries 9-10), for they might form insoluble precipitates with Cu(OAc) 2 ·H 2 O, hence decreasing the catalytic efficiencies.…”

“…The reaction scope was further expanded to various N-acyl-N'aryl hydrazines. It was found that most substituted aryl acyl groups bearing both electron-rich and electron-deficient 25 substituents provided good to excellent yields (Table 3, entries 20-25). Unprotected hydroxyl substituent was tolerant in this reaction and showed good yield (entry 21).…”

Transition Metal‐Mediated Direct CH Arylation of Heteroarenes Involving Aryl Radicals

“…[77] More recently, Heinrich et al extended the scope of this reaction to the synthesis of 2-aminobiphenyls from arylhydrazines and anilines, by exploiting the strong directing effect of the free unprotected amino group. [78] Finally, the environmentally-friendly oxidative aryl radical addition into alkenes using copper [79] or iron [80] salts was also reported. The first radical C À H arylation of heterocycles with arylhydrazines was described by Hardie and Thomson, who reported two examples of arylation of pyridine and thiophene, respectively by phenyl-and 4-nitrophenylhydrazines, with a stoichiometric amount of silver oxide as oxidant (Scheme 22).…”