Cu(ii)-catalyzed cyclization of α-diazo-β-oxoamides with amines leading to pyrrol-3(2H)-ones

Abstract

A novel Cu(II)-catalyzed cyclization of α-diazo-β-oxoamides with amines has been developed, constituting a straightforward method to construct pyrrol-3(2H)-one rings. The intramolecular hydrogen bonding effect in α-diazo-β-oxoamides plays an essential role in this reaction. A plausible reaction mechanism involving divergent generation and subsequent [2 + 3] cyclization of ketene and α-diazoimine intermediates was proposed.

Silver‐Catalyzed Cross‐Coupling of Isocyanides and Active Methylene Compounds by a Radical Process

“…Interestingly, acetoacetamides ( 1 h and 1 i ) resulted in the products 3 h and 3 i in the Z ‐isomeric form. This unusual behavior is probably a result of the propensity of the amide group to form hydrogen bonds 18. It is worth noting that, in addition to the acyclic active methylene compounds, cyclic substrates were also capable reacting using this protocol, and afforded the corresponding products ( 3 p – r ) in nearly quantitative yields.…”

“…was obtained in 86 %y ield with ah igh degree of 18 Oincorporation [Eq. (4)].F urthermore,t he yield of 5a was sharply decreased to 23 %( when the reaction was run under an N 2 atmosphere), thus confirming the participation of oxygen in the reaction.…”

“…This unusual behavior is probably aresult of the propensity of the amide group to form hydrogen bonds. [18] It is worth noting that, in addition to the acyclic active methylene compounds,c yclic substrates were also capable reacting using this protocol, and afforded the corresponding products (3p-r)i nn early quantitative yields.A lthough it is al ittle discouraging that the benzyl cyanide,acompound successfully utilized in Hongs work, [17] did not result in the desired product 3s (benzyl cyanide was recovered), this result clearly suggested ad ifferent mechanism is operative in the 3 30 mol %1 ,4-dioxane 92 6A g 2 CO 3 10 mol %1 ,4-dioxane 48 (52) [c] 7P d(OAc) 2 30 mol %1 ,4-dioxane 0 [d] 8C uI 30 mol %1 ,4-dioxane 0 [d] 9M n(OAc) 3 30 mol %1 ,4-Dioxane 0 [ Angewandte current silver-catalyzed reaction. Later, the substrate scope of this reaction was extended to other aromatic isocyanides without difficulty.T he electronic properties of the aromatic rings had no influence on either the stereoselectivities or yields of the products 3aa-ak,although use of 2-isocyano-9Hfluorene resulted in as light decrease in the yield of corresponding product (3ak).…”

Silver‐Catalyzed Cross‐Coupling of Isocyanides and Active Methylene Compounds by a Radical Process

“…[18] It is worth noting that, in addition to the acyclic active methylene compounds,c yclic substrates were also capable reacting using this protocol, and afforded the corresponding products (3p-r)i nn early quantitative yields.A lthough it is al ittle discouraging that the benzyl cyanide,acompound successfully utilized in Hongs work, [17] did not result in the desired product 3s (benzyl cyanide was recovered), this result clearly suggested ad ifferent mechanism is operative in the Delightfully,t he substrate scope is quite general, and aw ide variety of active methylene compounds,h aving various electron-withdrawing groups (EWGs), and aryl isonitriles can be applied to this protocol, thus affording the corresponding b-aminoenones in good to excellent yields.A ll the reactions proceeded smoothly when open to air and were completed within 3-5hours.For example,when 1areacted with avariety of active methylene compounds,i nw hich the methylene moiety is activated with two EWGs which are either the same or different (carbonyl, nitro,c yano,a nd sulfonyl) groups, participated in the coupling reactions smoothly to afford the target N-aryl-b-aminoenones (3b-o)i n4 6-96 %y ields.T he structure and stereochemistry of 3h and 3r were unequivocally resolved by X-ray crystallographic analysis (see the Supporting Information for details).…”

Asymmetric synthesis of 1H-pyrrol-3(2H)-ones from 2,3-diketoesters by combination of aldol condensation with benzilic acid rearrangement

“…Cycloaddition strategies are among the most efficient ways used to access the key 1 H -pyrrol-3(2 H )-ones. 3 However, general highly enantioselective addition methods are rare:one begins with chiral starting materials, 4 and the other employs catalytic asymmetric cycloaddition. 5 Although progress is being made in this area, the narrow substrate scope of reported methods suggests the need for more general enantioselective processes.…”