Palladium‐Catalyzed Direct Oxidative CH Cross‐Coupling of Azoarenes with Alcohols

Abstract

A palladium-catalyzed cascade oxidative C À H cross-coupling of azoarenes with alcohols was developed using tert-butyl hydroperoxide (TBHP) as oxidant. This reaction provides a convenient access to ortho-acylazoarenes under mild conditions in which readily available alcohols were used as the acyl sources. Results and DiscussionAzobenzene (1a) and benzoyl alcohol (2a) were first used as the model substrates to screen the reaction conditions for the optimization of the catalyst, oxidant, solvent, and temperature under an argon atmosphere (Table 1). We were pleased to find that when the mixture of azobezene (0.15 mmol) and benzoyl alcohol (0.15 mmol) was treated with 4.0 equiv. of

Palladium-catalyzed direct ortho-sulfonylation of azobenzenes with arylsulfonyl chlorides via C–H activation

“…With the optimized reaction conditions in hand, the reactivities of different arylsulfonyl chlorides as the sulfonylation reagents were investigated. The results are revealed in Table 2, the C-H 25 sulfonylation of azobenzene (1a) with arylsulfonyl chlorides could proceed smoothly and furnish the corresponding ortho-substituted products 3a-n in 63-92% yields (Table2, entries [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The substrates with a para-electron-donating group afforded the products 3a , 3g , 3n in excellent yields (92% , 84% 30 and 91%).…”

Acylation of (Hetero)Arenes through CH Activation with Aroyl Surrogates

“…Under similar reaction conditions, moderate to good yields were achieved (Scheme ). In the same year, Lin, Zeng, and co‐workers reported the acylation of azoarenes with alcohols 39b. In the presence of palladium acetate and TBHP, moderate to good yields of the desired products were produced with benzyl alcohols and aliphatic alcohols as the acyl sources (Scheme ).…”

Alternative and Uncommon Acylating Agents – An Alive and Kicking Methodology

“…This cascade oxidative CÀ H crosscoupling was assisted by azo directing group to achieve acylation at ortho-position (Scheme 43e). [91] In 2017, Mandapati et al showed the ortho-acylation of 2-arylpyridines 6 with benzylic alcohol 169 as an acyl source via Pd(II) complex. They used simple recyclable and stable heterogeneous Pd(II) complex for such selective ortho-acylation (Scheme 43f).…”