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In conclusion, a nucleophilic intramolecular ring transformation of 2-pyrone derivatives into 2-pyridone derivatives with a 1,5-diketo motif through a translocative rearrangement has been developed. Keywords: ring transformation; rearrangement; pyrones; pyridones; diketones; medicinal chemistry EN ring transformation rearrangement pyrones pyridones diketones medicinal chemistry 1631 1633 3 07/31/23 20230815 NES 230815 Graph 2-Pyridone derivatives are abundant in natural products, several of which have important pharmaceutical properties such as antimicrobial, antimalarial, antitumor, or cardiotonic activities. Ring transformation, rearrangement, pyrones, pyridones, diketones, medicinal chemistry. [Extracted from the article]

Robinson-type cyclopentannulations of cyclic ß-oxoesters possessing a 1,4-diketone moiety are accomplished under four different Brønsted basic reaction conditions. Using pyrrolidine/acetic acid in DMSO, an oxohexahydrocyclopenta[a]indene (42%) and an N-Boc-protected oxohexahydrocyclopenta[c]pyridine derivative (62%) are obtained with retention of the ester moieties. The latter compound defines an interesting new scaffold for medicinal chemistry with three positions allowing further derivatizations. The use of KOtBu in DMSO or NaH in toluene leads to cyclopentene derivatives with either partial ester saponification and decarboxylation or displacement of the ester moiety within the carbon skeleton. With aqueous KOH, the cyclopentannulations are successful in almost all cases, but with the ester moieties cleaved off. The respective bicyclic and tricyclic products are obtained in good to excellent yields. The 1,4-diketone starting materials are prepared by cerium-catalyzed oxidative coupling of ß-oxoesters with isopropenyl acetate. Alternatively, a two-step sequence consisting of a-propargylation followed by palladium-catalyzed alkyne hydration is used. [ABSTRACT FROM AUTHOR]

An asymmetric organocatalytic Michael addition-cyclization cascade reaction has been developed using cyclopentane-1,2-dione as a Michael donor and α,β-unsaturated aldehydes as Michael acceptors. Bicyclic hemiacetals were obtained in excellent yields and enantioselectivities. On the basis of the results, a one-pot reaction has been developed to obtain chiral 3-substituted cyclopentane-1,2-diones and substituted dihydropyrans in good yields and excellent enantioselectivity. [ABSTRACT FROM AUTHOR]

The selective addition of carbamoylsilane to vicinal dike-tones in toluene solvent at 110 °C affords β-keto-a-siloxyamide derivatives in good yields (54-99%). The steric hindrance is an important factor in the addition reaction. [ABSTRACT FROM AUTHOR]

An unexplored ability of the long-known chemical transformation, Borsche's cyclopentenone synthesis (the construction of a 1,4-diketone with subsequent base-induced cyclization), is reported. Double alkylation of ethyl 4-(het)aryl-3-oxobutanoates with 2-bromo-1-(het)arylethanones, with subsequent alkali treatment, provides access to cyclopentenones substituted with a 2-oxoethyl group at the 5-position. These products might serve as valuable synthons for heterocyclization, and this feature was demonstrated by synthesis of 4 H -cyclopenta[ b ]thiophene derivatives. [ABSTRACT FROM AUTHOR]

We report on a facile synthetic route for the preparation of substituted 1,4-diketones by thulium triflate mediated hydration of substituted 4-alkynones in MeNO2 at 25 °C for five hours. The products were obtained in moderate to high yields. [ABSTRACT FROM AUTHOR]

Manganese dioxide mediated oxidative cleavage of 1,3-disubstituted benzo[c]furans in dichloromethane at room temperature gave good yields of 1,2-di(het)aroylbenzenes [ABSTRACT FROM AUTHOR]

A fascinating oxidation of alkynes mediated by CAN directed by the amide group to synthesize N-[2-(2-oxo-2-phenylacetyl) phenyl]benzamide derivatives under mild conditions is reported. Excellent yields were obtained with various substituents by this method. [ABSTRACT FROM AUTHOR]

A novel and efficient method for the preparation of 1,2- diketones is reported. A series of α-diketones were readily prepared by the nitroxyl-radical-catalyzed oxidation of silyl enol ethers using magnesium monoperoxyphthalate hexahydrate (MMPP.6H2O) as the co-oxidant. [ABSTRACT FROM AUTHOR]

An efficient method for the 2-hydroxylation of 1,3-diketones by using atmospheric oxygen as an oxidant under transition-metal-free condition is described. The protocol has the advantages of using an in-expensive and stable oxidant, producing high yields, and requiring ecofriendly conditions. [ABSTRACT FROM AUTHOR]