Mild Synthesis of 3,4-Dihydroisoquinolin-1(2H)-ones via Rh(III)-Catalyzed Tandem C–H-Allylation/N-Alkylation Annulation with 2-Methylidenetrimethylene Carbonate

Abstract

A tandem rhodium(III)-catalyzed system was established to access 3,4-dihydroisoquinolin-1(2H)-one by coupling of N-methoxy-3-methylbenzamide with 2-methylidenetrimethylene carbonate. This one-pot synthesis protocol processed smoothly under mild reaction conditions. Moreover, a total of 28 examples, broad substrate scope, and high functional-group compatibility were observed. Preliminary mechanism studies were also conducted and demonstrated that the rhodium(III) catalyst played a vital role in the C−H-allylation and N-alkylation cyclization process.

Ru(II)‐Catalyzed ortho C—H Allylation of N‐Aryl‐7‐azaindoles with 2‐Methylidene Cyclic Carbonate

“…Although significant progress has been made in the field, [12] the C-H allylation reaction of N-aryl-7-azaindole with 2-methylidene cyclic carbonate has not been reported yet. [13] In 2021, Zhang group reported Rh(III)-catalyzed C-2 C-H allylation of indole derivatives using pyrimidine and N-methoxyformamide as directed groups with 2-methylidene cyclic carbonate (Scheme 1a). [14] However, as a bioisostere of indole, N-aryl-7-azaindole requires an efficient method of C-H allylation with cyclic carbonates using a low-cost transition-metal catalyst to expand the scope of 7-azaindole derivatives.…”

Synthesis of Bridged Cycloisoxazoline Scaffolds via Rhodium-Catalyzed Coupling of Nitrones with Cyclic Carbonate

“…(3S,8S,9S,10R,13S,14S,17S)- 3,4,7,8,9,10,11,12,13,14,15,16,phenanthren-3-yl-2-(tert-butyl)-4-(hydroxymethyl) -1,2,4,5-tetrahydro-1,4-methanobenzo[d] [1,2]oxazepine -7-carboxylate (3ae). Characterizations of substrates: Eluent: PE: EA = 1:1, white solid, the product (28.2 mg) was obtained in 48% yield as an inseparable mixture of two diastereomers (3:2, estimated by HPLC with a Daicel Chiralpak IA−H, n-hexane/2-propanol = 70/30, v = 0.8 mL•min −1 , λ = 210 nm, t 1 = 7.6 min, t 2 = 20.7 min; signals of the two isomers cannot be distinguished by 1 H NMR).…”

“…Whereafter, the Kim group employed Morita−Baylis−Hillman (MBH) carbonate as an allylation reagent to work with nitrones, furnishing the bridged cycloisoxazolines bearing an ester group (Scheme 2a). 10 5-Methylene-1,3-dioxan-2-one is widely utilized in metalcatalyzed coupling reactions for its ability to form intermediates through alkene insertion/β−O elimination. This makes it a promising allylation reagent with potential applications in C−H activation/cyclization tandem reactions.…”