Preparative synthesis of ethyl 5-acyl-4-pyrone-2-carboxylates and 6-aryl-, 6-alkyl-, and 5-acylcomanic acids on their basis

Synthesis of novel polycarbonyl Schiff bases by ring-opening reaction of ethyl 5-acyl-4-pyrone-2-carboxylates with primary mono- and diamines

“…Pyrones 1 were prepared according the literature procedure. 24 General approach for the preparation of enaminodiones 3 Pyrone 1 (1.11 mmol) was added to EtOH (6 mL) containing amine 2 (1.11 mmol) (for 3m -2.22 mmol) under cooling on an ice bath. The resulted mixture was stirred at 0 C for 1 h (for 3kat 20 C for 2 h, or 3mat 20 C for 1 day).…”

Direct Synthesis of 5-Acyl-3-oxy-4-pyrones Based On Acid-­Catalyzed Acylation of Enaminodiones with Acylbenzotriazoles via Soft Enolization

“…1 H NMR (400 MHz, CDCl 3 ):  = 4.66 (d, J = 11.2 Hz, 1 H, CHH), 4.71 (d, J = 11.2 Hz, 1 H, CHH), 6.13 (s, 1 H, OCH), 6.52 (dd, J = 3.7, 1.7 Hz, 1 H, H-4 furyl), 7.02 (d, J = 8.1 Hz, 2 H, H-2, H-6 NPh), 7.19 (tt, J = 7.4, 0.7 Hz, 1 H, H-4 NPh), 7.23-7.40 (m, 8 H, NPh, CH 2 Ph, H-3 furyl), 7.44 (dd, J = 7.6, 7.3 Hz, 2 H, H-3, H-5 Ph), 7.53 (tt, J = 7.3, 1.2 Hz, 1 H, H-4 Ph), 7.59 (dd, J = 1.7, 0.3 Hz, 1 H, H-5 furyl), 7.63 (dd, J = 8.0, 1.2 Hz, 2 H, H-2, H-6 Ph), 7.96 (d, J = 13.2 Hz, 1 H, =CH), 12.52 (d,J = 13.2 Hz,1 H,NH). 13 C NMR (126 MHz, CDCl 3 ):  = 73. 7, 83.8, 110.9, 112.3, 117.8, 118.8, 126.1, 127.9, 128.2, 128.4, 128.5, 129.0, 129.9, 131.6, 137.2, 138.5, 139.4, 147.0, 151.6, 153.8, 183.0, 194.6, 195.9. Anal.…”

Self-Condensation of Enaminodiones as a Method for Benzene Ring Construction: Synthesis of Diacyl-Substituted Phenols and Catechols

“…12d The application of enaminodiones as 1,4-ambiphiles has been actively developed in recent years to obtain highly reactive 3-acyl-4pyrones. 13 To the best of our knowledge, in the chemistry of enaminodiones, there is only one example of benzene formation as a byproduct based on ethyl 2-[(dimethylamino)methylene]-3-oxobutanoate. 14 It should also be noted that aminomethylidene derivatives of 4-hydroxyacetoacetic esters are the starting molecules for the preparation of modern HIV integrase inhibitors, such as dolutegravir and bictegravir.…”

“…16 Having a number of enaminodiones 4 in hand, we tried to carry out the condensation of enaminodione 4a with diethyl oxalate to prepare 5-acyl-3-hydroxy-4-pyrone 5 according to the known methods (Table 1). 13 To our surprise, diaroylbenzene 6a as a self-condensation product was obtained in the presence of NaH and LiH in 15% and 55% yields, respectively (entries 1 and 2, respectively). Interestingly, when we decided to carry out this transformation without diethyl oxalate using LiH as the base of choice in various solvents (entries 3−5), product 6a was obtained in extremely low yields.…”

“…The structure of the products 6 was assigned on the basis of 1 H and 13 C NMR spectra and the data of elemental analysis. In the 1 H NMR spectra of benzophenones 6 in CDCl 3 , a characteristic downfield doublet of the H-2 proton of the benzene ring was observed at δ 7.68−8.42 with J = 1.6−2.0 Hz, and the OH group appeared at δ 12.19−12.74 as a result of the formation of the intramolecular hydrogen bond.…”