One-pot synthesis of 1,5-diketones catalyzed by barium isopropoxide

Enantioselective [3 + 3] Annulation-Deoxalation Strategy for Rapid Access to δ-Oxoesters via N-Heterocyclic Carbene Catalysis

A new and unprecedented stereoselective synthetic approach to δ-oxoesters derivatives from readily available starting materials has been developed. This method, catalyzed by N-heterocyclic carbene, involves an annulation-deoxalation reaction of alkynyl aldehydes with 2,4-diketoesters and proceeds via the chiral α,β-unsaturated acylazolium intermediates. The annulation includes the in situ formation of dihydropyranones, which undergo ring-opening methanolysis with Lewis acid activation, followed by deoxalation to afford chiral 1,5-ketoesters in moderate to good yields.

Cobalt(II)porphyrin-Mediated Selective Synthesis of 1,5-Diketones via an Interrupted-Borrowing Hydrogen Strategy Using Methanol as a C1 Source

A novel cobalt(II)porphyrin-mediated acceptorless dehydrogenation of methanol is reported for the first time. This methodology has been applied for the coupling of a variety of ketones with methanol to produce 1,5-diketones along with H₂ and H₂O as the environment friendly byproducts. This paradigm was also demonstrated for a one-pot synthesis of substituted pyridines using a sequential addition protocol where the 1,5-diketones were generated in situ. From many experiments including those involving deuterium labeling, it is proposed that protonated cobalt(II)porphyrin methoxide complex acts as an intermediate to generate formaldehyde along with a metal hydride.

One-Pot Synthesis of 1,5-Diketones under a Transition-Metal-Free Condition: Application in the Synthesis of 2,4,6-Triaryl Pyridine Derivatives

We developed a facile and green one-pot synthetic method for substituted 1,3,5-triaryl-1,5-diketones by Claisen-Schmidt condensation following Michael addition reaction of aryl ketones and aryl aldehydes under a transition-metal-free condition. This convenient one-pot synthetic strategy has several advantages, including being transition-metal-free, having no extra additives or reagents, having a broad substrate scope, having a high isolated yield, having a minimum amount of base employment, having a shorter reaction time, use of cheap starting materials, cost-effectiveness, and being environment friendly. Some of the chemical structures of 1,5-diketones were confirmed by X-ray single-crystal diffraction analysis. The application of 1,5-diketones was demonstrated in the preparation of 2,4,6-triaryl pyridine derivatives under a catalyst-free system using ammonium acetate as a nitrogen source.

Biotransformation of Hydroxychalcones as a Method of Obtaining Novel and Unpredictable Products Using Whole Cells of Bacteria

The aim of our study was the evaluation of the biotransformation capacity of hydroxychalcones—2-hydroxy-4′-methylchalcone (1) and 4-hydroxy-4′-methylchalcone (4) using two strains of aerobic bacteria. The microbial reduction of the α,β-unsaturated bond of 2-hydroxy-4′-methylchalcone (1) in Gordonia sp. DSM 44456 and Rhodococcus sp. DSM 364 cultures resulted in isolation the 2-hydroxy-4′-methyldihydrochalcone (2) as a main product with yields of up to 35%. Additionally, both bacterial strains transformed compound 1 to the second, unexpected product of reduction and simultaneous hydroxylation at C-4 position—2,4-dihydroxy-4′-methyldihydrochalcone (3) (isolated yields 12.7–16.4%). During biotransformation of 4-hydroxy-4′-methylchalcone (4) we observed the formation of three products: reduction of C=C bond—4-hydroxy-4′-methyldihydrochalcone (5), reduction of C=C bond and carbonyl group—3-(4-hydroxyphenyl)-1-(4-methylphenyl)propan-1-ol (6) and also unpredictable 3-(4-hydroxyphenyl)-1,5-di-(4-methylphenyl)pentane-1,5-dione (7). As far as our knowledge is concerned, compounds 3, 6 and 7 have never been described in the scientific literature.

In situ formed acetals facilitated direct Michael addition of unactivated ketones

A facile Michael addition of unactivated ketones under Brønsted acid conditions for the synthesis of 1,5-diketones.

Copper-catalyzed synthesis of 1,3,5-triarylpentane-1,5-diones from α,β-unsaturated ketones

An efficient method for copper catalyzed synthesis of 1,3,5-triarylpentane-1,5-diones using α,β-unsaturated ketones as a unique starting material is described.

A green synthesis of highly substituted 1,5-diketones

The advantages of the aqueous reactions over the conventional ones were demonstrated in the synthesis of highly substituted 1,5-diketones.

TiO2 nano crystallites catalyzed water mediated microwave assisted regioselective three component domino hydrolysis/aldol condensation/Michael addition reaction of 3-(1,5-dioxo-1,5-diphenylpentan-3-yl)quinolin-2(1H)-one

Microwave supported, water intervened, nano crystalline TiO₂ catalyzed synthesis of 3-(1,5-dioxo-1,5-diphenylpentan-3-yl)quinolin-2(1H)-ones, is described.

Diastereoselective synthesis of cyclopentanediols by InCl 3/Al mediated intramolecular pinacol coupling reaction in aqueous media

A “green” and practical intramolecular pinacol coupling reaction promoted by InCl₃/Al catalysts in aqueous media has been developed. Under mild conditions, a novel class of polysubstituted cyclopentane-1,2-diols have been obtained with excellent diastereoselectivity.