Acetamidoarenediazonium Salts: Opportunities for Multiple Arene Functionali­zation

Abstract

Unlike their ortho counterparts, meta-and para-acetamidoanilines can be converted into the corresponding acetamidoarenediazonium salts. These offer various opportuni-

Styrylsulfonates and ‐Sulfonamides through Pd‐Catalysed Matsuda–Heck Reactions of Vinylsulfonic Acid Derivatives and Arenediazonium Salts

“…The reasons might be, as mentioned above, the comparatively high reaction temperatures and the occasionally reported high loadings of Pd precatalysts and expensive ligands. Based on our own and others' positive experiences with arene diazonium salts as electrophilic coupling partners in Pd‐catalysed coupling reactions, we investigated these reagents in the Heck reactions of vinylsulfonates and vinylsulfonamides. Heck reactions using arene diazonium salts were pioneered by Matsuda and coworkers in the late 1970's, and are therefore referred to as Matsuda–Heck reactions .…”

A Solid‐Phase Assisted Flow Approach to In Situ Wittig‐Type Olefination Coupling

“…Of these, olefins 2 , 15 – 19 (entries 1–6) have been previously synthesised using resin 1 , [2c,e,f,17] while 20 – 24 (entries 7–11) have been reported using a solution‐phase PPh 3 approach [18] . We also highlight that acetamidostilbene 25 (entry 12) has not been previously synthesised using a Wittig reaction but through a reported Matsuda‐Heck coupling procedure [19] …”

“…[18] We also highlight that acetamidostilbene 25 (entry 12) has not been previously synthesised using a Wittig reaction but through a reported Matsuda-Heck coupling procedure. [19] The flow protocol proved amenable across the scope of substrates employed, enabling near-quantitative conversions (> 99 %) to the desired olefins 2, 15-25 in high yields and purities (> 95 %, entries 1-12). In comparison to the corresponding batch methods, which typically required lengthy reaction times, the flow protocol within minutes afforded the target olefins in equal, and in some cases, substantially higher yields (> 95 %, entries 6-9, 11).…”

Pd‐Catalyzed Oxidative Sulfoalkenylation of Acetanilides and Traceless Removal of the Catalyst Directing Group

“…The tremendous progress on the field has been covered in several comprehensive or focused reviews. [7][8][9][10] We became interested in Pd-(II)-catalyzed orthoalkenylations [6,11] and other CÀ H-activation reactions directed and accelerated by acetamide groups [12] when we investigated the deacetylation-diazotation-coupling-(DDC)-sequence [13] as a method for the traceless removal of the CDG. [14][15] The DDC sequence [13] is a one-pot Lewis-acid promoted deacetylation of an acetanilide, the in situ diazotation of the aniline and a Pdcatalyzed Matsuda-Heck [16][17][18] or cross-coupling reaction [19] of the resulting arene diazonium salt.…”

“…When combined with a directed oxidative coupling, the acetamide group is used twice: first as a catalyst directing group and subsequently as a leaving group in a Pd(0)-catalyzed coupling (Scheme 2). [6,[11][12] We planned to expand the oxidative ortho-alkenylation of acetanilides by investigating vinylsulfonyl compounds as olefinic coupling partners with a view towards exploring the removal of the acetamide CDG in the products via a DDC sequence. Importantly, the alkenesulfonyl moiety must remain intact under DDC-conditions, because the products, functionalized 2-arylsulfonyl compounds, are interesting from a medicinal chemistry perspective.…”