Reactions of cyanoacetic acid with 2,6-diphenyl-4-pyrone

Six‐Membered Rings with One Oxygen: Pyrylium Ion, Related Systems and Benzo‐Derivatives

“…Scheme 18.76 shows two representative examples that describe this regioselectivity. Thus, 1,2-addition followed by double bond formation is observed in the reaction of the reactive methylene group of the cyanoacetamide (238) and c-pyrone 237 [144]. On the other hand, c-pyrone 239 has been transformed into the pyridone 240 by a nucleophilic 1,4-addition upon ammonium hydroxide treatment [145].…”

The reactions of 4‐dicyanomethylene‐2‐phenyl‐4H‐1‐benzopyran and some benzologs with nucleophiles

“…The nmr spectrum in DMSOd6 shows absorption for CH3CH2CH2 at 6 0.6-1.75 (M, 7H), for NCH2 at 6 3.95 (T, 2H), for proton in 1-position at 6 6.47 (S, lH), aromatic protons at 6 7.2-8.7 (M, 9H), and NH at 6 9.5 (S, 1H) (exchanges with deuterium oxide). The nmr spectrum in DMSOd6 shows absorption for C-CH3 at 6 0.73 (M, 6H), for CCHzCHzMe at 6 1.33 (M, 8H), for NCH2Pr at 6 3.28 (M, 4H), for aromatic protons at 6 6.94-8.06 (M, lOH), and for NH at 6 9.9 (M, 1H).…”

“…Compound 1 was prepared from 4-flavone and malononitrile or from 4-methoxyflavylium perchlorate and malononitrile by the procedures which have been described previously for 4pyrones (6). Compound 1 melted at 175-176' (reported (7), m.p.…”

“…Found: C,80.2; H, 4.1; N, 11.3. The nmr spectrum in DMSOd, shows absorption for the methyl protons at 6 3.3 (S, 6H), for the proton in the 1-position at 6 6.2 (S, 1 H ) and for the aromatic protons at 6 6.9-8.0 ppm (M, 9H).…”

Biomimetic syntheses of polyketide aromatics from pyrylium salts

“…The ether solution was shaken with water, dried over sodium sulphate and evaporated under reduced pressure to give the triketone (0.81 g), which was purified by sublimation to give pale yellow crystals, (9).-1-@ Methoxyphenyl)hexane-1,3,5-trione (100 mg, 0.43 mmol) was dissolved in trifluoroacetic acid (2 ml) at -15 "C. The solution was stirred at -15 "C, and after 10 min trifluoroacetic anhydride (0.5 ml) was added. The solution was stirred at -15 "C and trityl-lithium solution added to just maintain the red colour.…”