Enabling Cyclization Strategies through Carbonyl-Ylide-Mediated Synthesis of Malonate Enol Ethers

Abstract

Malonate enol ethers are afforded in one step by condensation of cyclic ketones with α-diazomalonates under [CpRu­(CH3CN)3]­[BArF] catalysis. The dual reactivity of these 2-vinyloxymalonates can be used to expand the classical range of cyclizations derived from carbonyl ylide intermediates.

Catalytic Synthesis of 1H-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers

“…Formation of 1a in high yields is in fact not trivial at all, as besides formation of 1a′ instead of the expected 6-membered ring product 2a , the instability of the substrate under both acidic and basic conditions (caused by the reactive α-H position of the allylcarbonyl moiety) could have led to a variety of other unwanted side reactions. Ring-closure reactions involving (formal) carbene addition to a ketone group are rare in general, and ring-closure of a carbene precursor onto a ketone group to produce an 8-membered O -heterocycle is unprecedented.…”

“…This method has been properly benchmarked against experimental data for cobalt(II)-porphyrin systems. [16][17][18][19][20][22][23][24]32 The proposed mechanism of 1H-2-benzoxocin generation based on our computational studies and experimental observations is shown in Scheme 2.…”

“…c Substrate 1 (0.1 mmol, 1.0 equiv), the arylsulfonyl hydrazide (0.105 mmol, 1.05 equiv), [Co(TPP)] (0.005 mmol, 0.05 equiv) and base (0.11 mmol, 1.1 equiv) were directly mixed in benzene (1.0 mL) in a one-pot reaction, and the mixture was stirred at 60 °C for 20 h. the synthesis of ring structures, such as cyclopropanes, 14 furans, 15 indenes, 16 indolines, 17 ketenes, 18 dihydronaphthalenes, 19 piperidines, 20 and pyrrolidines. 21 Furthermore, an efficient synthetic protocol for the synthesis of 2H-chromenes has been developed (Figure 2A), 22 and we also successfully applied the intrinsic radical-type reactivity of cobalt(III)carbene radicals to construct two types of new 8-membered carbocyclic compounds: dibenzocyclooctenes 23 and monobenzocyclooctadienes 24 (Figure 2A). Building on these prior results, and in view of our continued interest in cobalt(II)based metallo-radical catalysis, we envisioned that related open-shell catalysis could also uncover new possibilities for the synthesis of 8-membered O-heterocyclic compounds (Figure 2C).…”

Three-component acyloxylation of diazo compounds with carboxylic acids and azadienes

“…Diazo compounds have become important building blocks to form complex heterocycles. 1 Among various transformations, O–H insertion reactions of alcohols or water into diazo compounds have been well developed by using transition metal catalysts such as Rh, 2 Ru, 3 Cu, 4 Pd, 5 etc . 6 However, O–H bond insertion reactions of carboxylic acids into acceptor/acceptor (A/A) diazo compounds have not been extensively explored, mainly due to the relatively stable characteristics of diazo compounds.…”

Welcome to Volume 2 of ACS Organic & Inorganic Au

“…Over 2021, our content covered a range of exciting topics in all areas of organic and inorganic chemistry. These included the synthesis of a novel inorganic oxyfluoride, the development of new synthetic methods, − electrochemical transformations, visible-light-driven reactions, , polymerization, the synthesis of interlocked molecules, and the development of fluorescent probes . To celebrate the 2021 Nobel Prize in Chemistry awarded to Benjamin List and David MacMillan, we closed out 2021 by taking part in a joint Virtual Issue, “Asymmetric Organocatalysis: A Nobel Achievement”, with our sister ACS journals: Journal of the American Chemical Society , The Journal of Organic Chemistry , Accounts of Chemical Research , Chemical Reviews , Organic Letters , ACS Catalysis , Organic Process Research & Development , JACS Au , and Organometallics .…”