Rhodium(III)-Catalyzed C–H Activation/Annulation with Vinyl Esters as an Acetylene Equivalent

Abstract

The behavior of electron-rich alkenes in rhodium-catalyzed C–H activation/annulation reactions is investigated. Vinyl acetate emerges as a convenient acetylene equivalent, facilitating the synthesis of sixteen 3,4-unsubstituted isoquinolones, as well as select heteroaryl-fused pyridones. The complementary regiochemical preferences of enol ethers versus enol esters/enamides is discussed.

Synthesis of Isoquinolinones via Regioselective Palladium-Catalyzed C–H Activation/Annulation

“…CF 3 -and Cl-substituted N-methoxybenzamides reacted with 2,3-allenoic acid esters to afford hydroisoquinolinones in relatively poor yields (3q-3s, 53-61%); no products could be isolated from the reactions when para-F-, para-NO 2 -, meta-NO 2 -, para-CH 3 CO-substituted substrates were used. This observation was remarkably different from the previous reports by other researchers [46,50,60], where rhodium was adopted as catalyst for the annulations, which indicates the limitation of this reaction.…”

“…For example, Wang reported Rh(III)-catalyzed C-H allylation/Pd-catalyzed N-allyation to synthesize vinyl substituted dihydroisoquinolinones [49]. Marsden developed a Rh(III)-catalyzed C-H activation/annulation with vinyl esters as an acetylene equivalent [50]. In 2016, Niu developed a Cocatalyzed decarboxylative C-H activation/annulation cascade to get access to isoquinolines and isoindolinones [45].…”

Rhodium(III)‐Catalyzed Cyclative Capture Approach to Diverse 1‐Aminoindoline Derivatives at Room Temperature

“…To confirm the structure, we further converted the oily 3 a to the corresponding 1-aminoindole which formed single crystals suitable for X-ray analysis (see the Supporting Information). [11] Subsequently, the scope of the aryl-substituted diazenecarboxylate substrates was investigated. A series of 1-aminoindolines bearing substituents at the 5-, 6-, and/or 7-positions were synthesized in good yields (Scheme 1; 3 a-l).…”

“…Interestingly, when we switched the substrate to vinyl acetate, we could directly access the aminoindole product 4 p in excellent yield; this reaction might involve an elimination of acetic acid after cyclization. [13] To date, synthetic approaches to 1-aminoindoles, which also display very important pharmacological properties, [14] have been quite limited. [15] We wondered if we could utilize the present transformation for the straightforward synthesis of 1-aminoindoles by introducing an additional oxidant.…”

Rh(III)- and Ir(III)-Catalyzed C–C Bond Cross Couplings from C–H Bonds

“…Marsden and coworkers endeavored to design a catalytic cycle compatible with electron-rich vinyl esters as novel coupling partners [75]. Gratifyingly, a targeted C-H activation/annulation sequence could be achieved when reacting benzoyl hydroxamate (an "internal-oxidant-containing" C-H substrate) with either vinyl acetate or enol ether and enamide (Scheme 4a).…”