Ionic liquid-catalyzed Diels-Alder reaction of levopimaric acid with quinones

Click chemistry on diterpenes: anti-inflammatory activity of the acetylenic derivatives of levopimaric acid and products of their transformations

“…The precipitated naphtholevopimaric acid 1 (NqLpA) is filtered to provide the 93% of the product. 16 The NqLpA amides 4a-e with alkyne substituents were prepared by condensation of NqLpA acid chloride 2 with the library of aminoacetylenes 3a-e (see the SI part). We had used amides as the first set of targets based on our earlier reports of promising anti-inflammatory and anti-ulcer properties of related NqLpA amides.…”

Ionic Liquids Based on the 7‐Azabicyclo[2.2.1]heptane Skeleton: Synthesis and Properties

“…For many years, ionic liquids have attracted a great deal of attention because of their very interesting properties, such as non‐volatility, good thermal and electrochemical stability and high ionic conductivity. This has led to various applications based on some of their unique properties, such as the modification of starch and other carbohydrates,1–4 the electrodeposition of various metals5–7 and their use as electrolytes in Li batteries,8,9 lubricants10,11 and (re‐usable) catalysts in various organic reactions 12–15. The most popular choices for the cations of ionic liquids are based upon imidazolium, ammonium, piperidinium and pyridinium and popular anions are dicyanamide and bis(trifluoromethylsulfonyl)imide.…”

New nitrogen-containing and hydroxy derivatives of quinopimaric acid

“…The coupling constant for the 18-H and 13-H protons, found in the 1 H NMR spectrum (J ≈ 8.1 Hz), indicated their cis orientation with respect to each other and hence cis-junction of the D and E rings, as in other adducts formed by diene I with benzoquinones [2][3][4]. The 1 H-15 N HMBC two-dimensional heteronuclear correlation spectrum revealed vicinal coupling between the nitrogen atom and 18-H (δ 2.77/δ N -54.11 ppm), which confirmed the position of the nitrogen atom at C 17 .…”

“…In continuation of our studies on the synthesis of new quinopimaric acid derivatives [3] in the present work we examined Diels-Alder reaction of pine rosin containing ~30% of levopimaric acid (I) with N-tosyl-1,4-benzoquinone imine and 5-hydroxy-1,4-naphthoquinone (juglone).…”