(+)-8-Hydroxy-labdan-17-oic Acid

Hanson [1,2] reported a compound with [a]D = -7° and identical IR and NMR spectral data to our compound. He named this compound (-)-8-hydroxy labdan-17-oic acid. By comparison with the spectroscopy data and the specific rotation of the above compound, our results lead to (+)-8-hydroxylabdan-17-oic acid (structure 1). It is a stereoisomer of labdanoic acid. The relative configurations of the carbons from C1 to C10 were deduced by comparison of the ¹³C-NMR resonances with the data for 8-epi-sclareol and sclareol [3]. The configuration at C13 has not yet been established. The HMBC and HMQC spectra confirm the structure 1.

Dried and pulverised leaves ( 1 kg ) of Espeletiopsis muisca were extracted with Petrol ( 69g ) and then

10 g of this extract were subjected to column chromatography on silica gel using Petrol, CH2Cl2 and

AcOEt. The fractions in AcOEt were again chromatographed on silica gel with Petrol: AcOEt and the first fraction yielded the pure title compound 1. White crystals, 90 mg from MeOH. M.p. 68 °C.

[a] D = + 5° (c = 0.025, CHCl3)

IR (l max): 3500, 2700, 3600, 3300, 1690 cm^-1.

¹H-NMR (d, ppm, CDCl3): 0.75, 0.9, 0.96, 0.98, 1.05, 1.19 (CH3), 4.8 (OH) ; 1.4 and 2.5 (m, CH and CH2).

¹³C-NMR (d, ppm, CDCl3): 178.5 (C), 74.9 (C), 55.28 (CH), 44.3 (CH2), 42.1 (CH2), 41.2 (CH2), 41.2 (CH2), 40.8* (CH2), 39.2 (CH2), 33.49 (C), 33.2 (CH3), 30.2 (CH), 23.9* (CH3), 22.1* (CH3), 21.5 (CH3), 20.5 (CH2), 20(CH2), 18.5(CH2), 15.5 (CH3).