1978 1271 18-Hydroxyballonigrin, a New Diterpenoid from Ba//ota acetobdosa By Giuseppe Savona and Franco Piozzi,' lstituto di Chimica Organica, Universita di Palermo, Via Archirafi, Palermo, Italy James R. Hanson and Michael Siverns, School of Molecular Sciences, University of Sussex, Brighton, Sussex BN1 9QJ The structure of 18-hydroxyballonigrin (1). isolated from Ballota acerobulosa. has been established by a combin-ation of spectroscopic measurements and an inter-relationship with ballonigrin (3). A NUMBER of furanoid diterpenoids of the labdane series have been isolated from Ballota (Labiatae) species. We have previously examined B. nigra and B. rztpestris.2 In continuation of this work, we have studied a Greek species, B. acetobulosa and isolated a new diterpenoid, C,H,,O,, (1).The i.r. and lH n.m.r. spectra showed that the oxygen functions were a primary alcohol, a y-lactone, an ap-unsaturated ketone and a p-substituted furan ring. In addition the 1H n.m.r. spectrum (Table 1) itself showed no further coupling. This data suggested that the compound was 18-hydroxyballonigrin (1). The alcohol readily gave a mono-acetate (2). The 13C n.m.r. data of (1) and (2) (Table 2) were in accord with the relationship with ballonigrin and permitted the location of the primary alcohol at C-18. In particular when compared to ballonigrin the C-4 singlet resonance had a downfield shift (AS 6.8) whilst both C-3 and C-5 showed an upfield y-shift (A6 5.3 and 3.8 respectively). The chemical shift of the H-5 and H-6 resonances also TABLE1 displayed a downfield shift. ..18 CO-0 19 (1) 12) (3) (4) (5) (6) R R R R R R = = = = = = OH OAc H Cl OTs I lH N.m.r. signals (in CDC1,: p.p.m. from Me,Si) 6-Ha 14-H 15-H 16-H 4.95 6.28 7.23 7.34 4.80 6.28 7.23 7.3Sb 4.75 6.28 7.23 7.35 4.73 6.28 7.25 7.30 4.64 6.28 7.25 7.35 Com-pound 20-H (1) 1.08 (2) 1.10 (4) 1.10 (5) 1.08 (6) 1.08 a Ja+6 Hz. 18-H 17-H 6-H * 3.73 1.80 2.56 4.14 1.83 2.41 3.56c 1.82 2.60 3.95 1.82 2.60 3.20d 1.83 2.48 3.42 d b OCOCH, 2.08. contained signals which were C J 14 Hz. J 12 Hz. assigned to a tertiary The relationship with ballonigrin was confirmed chemically. Treatment of 18-hydroxyballonigrin, under mild conditions with triphenylphosphine in carbon tetra~hloride,~gave the 18-chloro-compound (4).How-ever, reduction of this with tributyltin hydride afforded a complex mixture of products. 18-Hydroxyballonigrin formed an 18-monotoluene-p-sulphonate (5). Reduc-tion of this with zinc and sodium iodide4 gave ballo- nigrin (3) together with an 18-iodo-compound (6). EXPERIMENTAL General experimental details have been described previ- ous1y.l lH N.m.r. spectra were determined at 90 MHz on a Perkin-Elmer R 32 spectrometer. Extraction of Ballota acetobu1osa.-B. acetobulosa was collected on Mount Hymettus, Kaessariani, Athens, and identified in the Institute of General Botany, University of Athens. Air-dried leaves (0.5 kg) were powdered and extracted at room temperature with acetone (2 1) for 1 month.The extract was concentrated in vacuo, re-dissolved in ethyl acetate, washed with aqueous 10 sodium carbonate, dilute hydrochloric acid, and water, and then dried and evaporated. The crude residue (approx. 2 g) was chromatographed on a dry silica gel column (Merck, deactivated with 15 water). Elution with 30 ethyl G. Savona, F. Piozzi, J. R. Hanson, and M. Siverns, J.C.S. Perkin I, 1977, 322. J. B. Lee and I. M. Downie, Tetrahedron, 1967, 23, 359.* Y. Fujimoto and T. Tatsuno, Tetrahedron Letters, 1976, 3326. methyl group and an olefinic methyl group. Spin de- coupling experiments established that a doublet (6 4.95, TABLE2 13C N.m.r. signals (in CDC1,; p.p.m.from Me,Si) Carbon Compound atom (1) 1 30.2 2 17.7 3 22.5 4 48.8 5 45.6 6 77.3 7 193.5 8 131.2 9 166.6 10 36.4 11 29.4 12 24.2 13 123.8 14 110.6 15 143.2 16 138.8 17 29.0 18 67.5 19 180.1 20 12.1 0-COCH, (2) 30.2 17.5 23.1 46.6 45.7 76.7 192.6 131.4 166.2 36.3 29.4 24.2 123.7 110.6 143.2 138.9 28.8 67.5 177.6 12.1 20.9 and 170.4 J 6 Hz) assigned to the proton attached to the y-lactone ring, was coupled to a methine proton (6 2.56) which G. Savona, F. Piozzi, J. R. Hanson, and M. Siverns, J.C.S. Perkin I, 1976, 1607; 1977, 497. acetate-light petroleum gave 18-hydroxyballonigrin (1) (500 mg), m.p. 171 "C, a, -2.4" (c 0.2 in CHCl,) (Found: C, 70.1; H, 7.0.C2,H2405 requires C, 69.9; H, 6.9), v,, 3 480, 1 765, 1 655, 1 595, and 875 cm-l; A,, 259 nm (E 9 400); mass spec. m/e 344, 329, 316, 301, 203, 192, 175, 161, 105, 95, and 81 (base peak). The acetate (2), prepared with acetic anhydride in pyridine, was an oil (Found: M+ m/e 386.173. C22H2806 requires 386.173), mass spec. m/e 386, 371, 343, 311, 298, 279, 231, 203 (base peak), 167, 161, 107, 105, 95, 82, and 81; vmZ 1 770, 1 745, 1670, 1595, and 875 cm-l. Reaction with Triphenylphosphine and Carbon Tetra-chloride.-1 8-Hydroxyballonigrin (30 mg) in carbon tetra- chloride (20 ml) was heated under reflux with triphenyl- phosphine (50 mg) for 16 h. Chromatography on silica gave 18-chZorobaZZonigrin (4) as needles, m.p. 125 "C (Found: M+ m/e 362.128.Cz,H233SC104requires 362.128), mass spec. m/e 362, 347, 319, 297, 203 (base peak), 191, 161, 105, 95, 82, and 81;v,, 1 778, 1666, 1604, and 876 cm-'. Re-J.C.S. Perkin I action with tributyltin hydride in hexane gave a complex mixture of products (t.1.c.). Conversion into Ballonigrin (3) .--18-Hydroxyballonigrin (50 mg) in pyridine (2 ml) was treated with an excess of toluene-fi-sulphonyl chloride overnight to afford the 18-mono-toluene-p-sulfihonate (5) as an oil (Found: M+, 498.170. C2,H,,S0, requires M, 498.171), mass spec. 498, 483, 470, 455, 417, 326, 311, 298, 295, 270, 231, 217, 203, 189, 161, 95, and 81. The oil (40 mg) in dioxan (10 ml) was heated under reflux with sodium iodide (500 mg) and zinc dust (500 mg) for 72 h. Chromatography on silica afforded 18-iodoballonigrin (6) (8 mg) as an oil (Found: Ill+, 454.064. C2,H2,041 requires M, 454.064) and ballonigrin (3) (10 mg) which was identified by its n.m.r. spectrum. We thank Dr. S. Diamantoglou for the collection and identification of the plant material and NATO for a research grant. 8/014 Received, 4th January, 19781 0 Copyright 1978 by The Chemical Society
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