As is known, pine galipot contains a large number of biologically active substances [1]. One of the main components of this resin is levopimaric acid (I), the derivatives of which were reported to possess antibacterial activity and antifungal activity [2]. Acid I readily forms adducts of diene synthesis with benzo-, acetamido-, thienonaphtho-, -, and -quinones and naphthazarin [3 – 6]. We have synthesized a series of derivatives of quinopimaric acid (IIa) and studied their antiinflammatory activity. Quinopimaric acid, together with chloroquinopimaric acid (IIb), were isolated from pine galipot as described in [4]. Compound IIb was found to form regiospecifically with a yield of 50%. The structure of diterpenoid IIb was established using the data of H NMR spectroscopy. According to these, H-12 proton ( = 2.85 ppm) is characterized by two trans coupling constants, with H-11 (axial) and H-1a protons (J 1 = J 2 = 13.6 Hz), and one cis constant with H-11 (equatorial) proton (J = 4.5 Hz). The signals from H-1a and H-4a protons, observed at = 2.40 ppm (dd) and 2.48 ppm (d), respectively, are characterized by the cis constant (J = 9 Hz). Calculations performed by the additive schemes with increments showed that the chemical shifts of H-1a and H-4a protons correspond to a chlorine atom in the C-3 position. In an alternative structure with chlorine at C-2, the chemical shift of H-1a would be greater than that of H-14a [7]. It should be noted that the spectrum of adduct IIb exhibits a weak-field shift of the signal of the H-4a proton ( = 2.48 ppm) relative to the analogous signal in the spectrum of IIa ( = 1.93 ppm) [4]. The above spin – spin coupling constants of IIb indicate that the E cycle is cis to the C cycle and syn to the D cycle, as manifested by a shift of the signal of the H-4 proton toward stronger field (from = 5.68 ppm in IIa to 5.47 ppm in IIb). The aforementioned regiospecificity of the interaction between chlorobenzoquinone and acid I is related to the influence of chlorine – an electron acceptor favoring the formation of a transition state by closing a hydrogen bond between carboxy group and carbonyl oxygen in the C-1 position [4, 8]. This leads to a product containing a substituent at C-3.