Aust. J. Chem., 1988, 41, 1789-96

New Depsides from Dimelaena Lichens

John A. ~ l i x . ~ Joanne E. ~ v a n s ~ and Thomas H. Nash I I I ~

A Chemistry Department, The Faculties, Australian National University, G.P.O. Box 4, Canberra, A.C.T. 2601.

Department of Botany and Microbiology, Arizona State University, Tempe, AZ 85287, U.S.A.

Abstract

The new depsides 3-chlorostenosporic acid (2), 3-chloroperlatolic acid (3) and subsphaeric acid (24) have been detected in Dimelaena lichens and the structures of the metabolites have been established by unambiguous synthesis. Wrightiin (methyl 3-chloroevernate) (21), a depside from Erioderma wrightii, has also been synthesized by using similar methodology.

Introduction

Total synthesis has provided a definitive method for structural proof of lichen depsides and provides a useful alternative to the classical hydrolytic degradation procedure.' Further, in cases where complex mixtures of homologous depsides or simply lack of lichen material make isolation of the natural depside impractical, chromatographic comparisons of synthetic material with the natural mixtures has enabled the identity of a number of new depsides to be e~ tab l i shed .~~~

In this report we describe the total synthesis of four lichen depsides, 3- chlorostenosporic acid (2), 3-chloroperlatolic acid (3), wrightiin (methyl 3- chloroevernate) (21) and subsphaeric acid (24). The overall procedures for such synthesis are now well e~tablished.~

Depsides in Dimelaena californica

At the commencement of this work 3-chlorodivaricatic acid (1) was the only known monochloro depside where the chlorine atom had substituted position 3. This depside was originally isolated from the lichen Thelomma mammosumS and the structure was elucidated by 'H n.m.r., 13c n.m.r., mass and ultraviolet spectra and confirmed by total synthesis.6 In the course of a chemotaxonomic survey of the American species of Dimelaena we discovered that D. californica routinely produced 3-chlorodivaricatic acid (I), but occasionally this compound was accompanied by two homologous

Elix, J. A., Whitton, A. A., and Sargent, M. V., Fortschr. Chem. Organ. Naturst. 1984, 45, 103. Elix, J. A., Mahadevan, I., Wardlaw, J. H., Arvidsson, L. and J$rgensen, P. M., Aust., J. Chem.,

l987,4O, 1581. Elix, J. A., Wilkins, A. L., and Wardlaw, J. H., Aust. J. Chem., 1987, 40, 2023. Elix, J. A., Aust. J. Chem., 1974, 27, 1767.

* Huneck, S., Sundholm, G., and Follmann, G., Phytochemistry, 1980, 19, 645. Elix, J. A., Parker, J. L., Teame, P. D., and Wardlaw, J. H., Aust. J. Chem., 1985, 38, 1863.

0004-9425/88/111789$03.00

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depsides. Neither of the new depsides were isolated but we tentatively established the respective structures (2), (3) and/or (4) by RF correlations in two-dimensional thin-layer chromatograms and mass spectrometry, and have now confirmed these by synthesis.

The synthetic strategy was to prepare suitably protected benzoic acids and phenols as A- and B-ring precursors respectively, as has been described previously.4*6 3-Chloro- 2-hydroxy-4-methoxy-6-pentylbenzoic acid (16) was prepared in an analogous manner to that described previously for 3-chloro-2-hydroxy-4-methoxy-6-propylbenzoic acid (18) (Scheme I ) . ~

el

(16) R = C5Hll Scheme 1 (17) R = M e

(18) R = Pr

Thus chlorination of ethyl 4-hydroxy-2-oxo-6-pentylcyclohex-3-ene-l-carboxylate (8) with two molar proportions of chlorine effected selective substitution and aromatization to afford ethyl 3-chloro-2,4-dihydroxy-6-pentylbenzoate (10). Methylation of the ester (10) by treatment with dimethyl sulfate and potassium carbonate gave ethyl 3-chloro-2,4-dimethoxy-6-pentylbenzoate (12), and selective demethylation of this compound by treatment with boron trichloride gave ethyl 3-chloro-2-hydroxy-4-methoxy-6-pentylbenzoate (14) in excellent yield. Subsequent

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hydrolysis of the ester (14) afforded the required key intermediate, 3-chloro-2-hydroxy- 4-methoxy-6-pentylbenzoic acid (16).

The condensation of the acids (18) and (16) with benzyl 2,4-dihydroxy-6- pentylbenzoate (20)~ and (16) with benzyl 2,4-dihydroxy-6-propylbenzoate (19)~ in the presence of trifluoroacetic anhydride gave rise to benzyl 3-chlorostenosporate ( 9 , benzyl 3-chloroperlatolate (6) and benzyl 3-chloroimbricarate (7) respectively. Hydrogenolysis of the esters ( 9 , (6) and (7) in the presence of palladized carbon and hydrogen produced, in turn, 3-chlorostenosporic acid (2), 3-chloroperlatolic acid (3) and 3-chloroimbricaric acid (4). The thin-layer chromatographic behaviour of compounds (2) and (3) in three independent solvent systems was identical to that of the corresponding unknown lichen depsides present in Dimelaena californica. This was further confirmed by high-performance liquid chromatographic (h.p.1.c.) comparisons of the synthetic and natural compounds.

Synthesis of Wrightiin (Methyl 3-Chloroevernate)

During the course of the above investigation wrightiin (21), a further 3-chloro depside, was isolated from the lichen Erioderma wrightii.' The structure of this depside was elucidated by X-ray crystallography. We have now effected the synthesis of depside (21) starting from ethyl 4-hydroxy-2-oxo-6-methylcyclohexe-3-ene-l-carboxylate (9) in the manner described above for the synthesis of 3-chloro-2-hydroxy-4-methoxy-6- pentylbenzoic acid (16) (Scheme 1). Ultimate condensation of 3-chloro-2-hydroxy-4- methoxy-6-methylbenzoic acid (17) with methyl orsellinate (22) in the presence of trifluoroacetic anhydride afforded wrightiin (21), identical in all respects with the natural materid.

' Maass, W. S. G., and Hamon, A. W., 2. Natui$orsch., Teil B, 1986, 41, 1589.

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Depsides in Dimelaena thysanota

Thin-layer and high-performance liquid chromatographic analysis of the acetone extracts of the lichen Dimelaena thysanota indicated the presence of the known depside sphaerophorin (23) together with a second homologous depside, subsphaeric acid. Given the small quantities of lichen available the new depside was not isolated but the tentative structure (24) was established by RF correlations using the standard t.1.c. methods of Culberson e t a1.8-10 and by mass spectrometry, and subsequently confirmed by synthesis. Thus condensation of 2-benzyloxy-4-methoxy- 6-methylbenzoic acid (26)" with benzyl 2,4-dihydroxy-6-pentylbenzoate (20)~ in the presence of trifluoroacetic anhydride gave rise to benzyl2- 0-benzylsubsphaerate (25). Subsequent hydrogenolysis of the ester (25) produced subsphaeric acid (24). The t.1.c. and h.p.1.c. behaviour of the latter compound was identical to that of the corresponding unknown lichen depside present in Dimelaena thysanota.

Experimental General experimental details have been reported previously.4 Two-dimensional t.1.c. runs were

carried out according to the standard method of Culberson and ~ o h n s o n . ~ Standard RF values were determined in three independent t.1.c. solvent systems: ( A ) ~ tolueneldioxanlacetic acid (180 : 45 : 5); (B)'~ hexanelmethyl t-butyl etherlformic acid (140 : 72 : 18); and (c19 toluenelacetic acid (200 : 30). The h.p.1.c. was camed out on a Perkin-Elmer C-18HS-5 h.p.1.c. column with 10% waterlmethanol containing orthophosphoric acid (80 p11400 ml) at a flow rate of 0 .6 ml min-l. Compounds were detected at 254 nm.

Ethyl 3-Chloro-2,4-dihydroxy-6-pen tylbenzoate (1 0)

A solution of chlorine (7.35 g) in glacial acetic acid (100 ml) was added dropwise to a stirred solution of ethyl 4-hydroxy-2-oxo-6-pentylcyclohex-3-ene-l-carboxylate (8)12 (13.2 g) in glacial acetic acid (50 ml) at room temperature over a period of 45 min. The solution was then stirred at room temperature for a further 3 h and then heated at reflux for 16 h. The reaction mixture was cooled to room temperature, diluted with water and the brown precipitate filtered to give ethyl 3-chloro-2.4-dihydroxy-6-pentylbenzoate (10) (10.7 g, 72%) which crystallized from dichloromethanellight petroleum as colourless needles, m.p. 50-52" (Found: C, 58.7; H, 6 5; C1, 12.6. Cl4HI9C1O4 requires C, 58.6; H, 6.7; C1, 12.4%). 'H n.m.r. (CDC13) S 0.91, bt, (CH2)4CH3; 1.0-1 -9, m, 0CH2CH3 and CH2(CH2)3CH3; 2 72-3.00, bt, ArCHZ; 4 -41, q, J 7 Hz, 0CH2; 6 -01, s, OH; 6.3 1, s, ArH and 12 51, s, bonded OH. Mass spectrum mlz 286 (M, 23%), 240 (100).

Ethyl 3-Chloro-2.4-dimethoxp6-pentylbenzoate (12)

Ethyl 3-chloro-2,4-dihydroxy-6-pentylbenzoate (10) (5.56 g), anhydrous potassium carbonate (15 g) and dimethyl sulfate (4.88 g, 4.0 ml) were stirred and heated under reflux in acetone (100 ml) for 24 h. After cooling, the mixture was poured into dilute cold hydrochloric acid and extracted with ether. The ethereal phase was washed with water, dried (MgS04) and the solvent evaporated. The crude ester (6 -04 g, 99%) was purified by radial chromatography over silica gel with 2.5% ethyl acetatellight petroleum as eluent to give the benzoate (12) as a colourless oil (Found: C, 61.0; H, 7.4; a, 11 -5. C16H23C104 requires C, 61.1; H, 7.4; a, 11.3%). 'H n.m.r. (CDC13) 6 0 - 89, bt, (CH2)4CH3; 1 -25-1 - 33, m, CH2(CH2),CH3; 1.35, t, J 7 Hz, 0CH2CH3; 1.50-1.70, m, ArCH2CH2; 2.58, bt, J 7 Hz, ArCH2; 3 -89, 3 -90, 2s, OMe; 4.38, q, J 7 Hz, 0CH2 and 6.56, s, ArH. Mass spectrum mlz 314 (M, 31%), 225 (100).

Culberson, C. F., and Johnson, A., J. Chromatogr., 1976, 128, 253. Culberson, C. F., J. Chromatogr., 1972, 72, 113.

lo Culberson, C. F., and Johnson, A., J. Chromatogr., 1982, 238, 483. l1 Elix, J. A., and Wardlaw, J. H., Aust. J. Chem., 1987, 40, 425. l2 Anker, R. M., and Cook, A. H., J. Chem. Soc., 1945, 311.

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Ethyl 3-Chloro-2-hydroxy-4-methoxy-6-pentylbenzoate (14)

A solution of boron trichloride (5.52 g) in dichloromethane (40 ml) was added dropwise to a stirred solution of ethyl 3-chloro-2,4-dimethoxy-6-methylbenzoate (12) (4.32 g) in dichloromethane (30 ml) at -80'. After the addition, stirring was continued as the reaction mixture was slowly warmed to room temperature. The reaction mixture was then poured into water, extracted with ether and the ethereal solution washed with water and dried (MgSO4). On removal of the ether the residue was crystallized from dichloromethanellight petroleum to give ethyl 3-chloro-2-hydroxp4-methoxy-6-pentylbenzoate (14) (3.58 g, 86%) as colourless needles, m.p. 38' (Found: C, 60.3; H, 7.3; C1, 12 -0. C15H21C104 requires C, 59.9; H, 7.1; C1, 11 8%). 'H n.m.r. (CDC13) S 0.95, m, (CH2),CH3; 1.30-1.44, m, CH2(CH2)2CH3; 1.46, t, J 7 Hz, 0CH2CH3; 1.75-1 - 85, m, ArCH2CH2; 2 89, bt, J 7 Hz, ArCH2; 3 ~ 9 7 , s, OMe; 4 -46, q, J 7 Hz, 0CH2; 6 37, s, ArH and 12.32, s, OH. Mass spectrum mlz 300 (M, 1 I%), 254 (100).

3-Chloro-2-hydroxy-4-methoxy-6-pentylbenzoic Acid (16)

A solution of ethyl 3-chloro-2-hydroxy-4-methoxy-6-pentylbenzoate (14) (1 - 1 g), dimethyl sulfoxide (50 ml), potassium hydroxide (0.5 g) and water (3.0 ml) was stirred and heated at 90-100" for 8 h. The mixture was diluted with water and then washed with ether to remove any unchanged starting material. The basic aqueous layer was poured into cold dilute hydrochloric acid and extracted with ether. This ethereal solution was washed with water, brine and dried (MgSO4). The solvent was evaporated and the residue crystallized from dichloromethanellight petroleum to give 3-chloro-2-hydroxy-4-methoxp6-pentylbenzoic acid (16) (0 9 1 g, 90%) as colourless needles, m.p. 140' (Found: C, 57 ~ 4 ; H, 6 -6; C1, 12.8. C13H17C104 requires C, 57 3; H, 6 3; C1, 13.0%). 'H n.m.r. (CDC13) S 0.90, bt, (CH2)4CH3; 1.30-1.55, m, CH2(CH2),CH3; 1.75-1 -85, m, ArCH2CH2; 2-95, bt, J 7 Hz, ArCH2; 3.95, s, OMe; 6.39, s, ArH and 12.2, bs, OH and C02H. Mass spectrum mlz 272 (M, 0.5%), 228 (17), 172 (100).

Ethyl 3-Chloro-2,4-dihydroxy-6-methylbenzoate (I I)

This compound was prepared from ethyl 4-hydroxy-6-methyl-2-oxocyclohex-3-ene-1- carboxylate (9)12 in the manner described above for the synthesis of ethyl 3-chloro-2,4- dihydroxy-6-pentylbenzoate (10). l3 Ethyl 3-chloro-2,4-dihydroxy-6-methylbenzoate (1 1) (8 3 g, 71%) crystallized from ethanol in colourless prisms, m.p. 146-148' (Found: C, 52 94; H, 4 6. ClOHl1ClO4 requires C, 52.1; H, 4.8%). 'H n.m.r. (CDC13) S 1.34, t, J 7 Hz, 0CH2CH3; 2.34, s, ArMe; 4.17, q, J 7 Hz, 0CH2; 6.03, s, OH; 6 - 84, s, ArH and 12 ~ 0 2 , s, bonded OH.

Ethyl 3-Chloro-2,4-dimethoxp6-methylbenzoate (13)

This compound was prepared by methylation of ethyl 3-chloro-2,4-dihydroxy-6-methylbenzoate (11) in the manner described above for the synthesis of ethyl 3-chloro-2,4-dimethoxy-6- pentylbenzoate (12). The crude ester was obtained as a yellow oil (4 - 0 g, 94%). A portion was purified by radial chromatography with 5% ethyl acetatellight petroleum as eluent to give the ester (13) as a colourless oil (Found: C, 55 5; H, 5 -9; C1, 13 -7. C12H15C104 requires C, 55.7; H, 5.8; Cl, 13.7%). 'H n.m.r. (CDC13) S 1.28, t, J 7 Hz, 0CH2CH3; 2.13, s, ArMe; 3.59, s, OMe; 4.08, q, J 7 Hz, 0CH2 and 6.11, s, ArH. Mass spectrum mlz 258 (M, 39%), 213 (100).

Ethyl 3-Chloro-2-hydroxp4-methoxy-6-methylbenzoate (IS)

This compound was synthesized by demethylation of ethyl 3-chloro-2,4-dimethoxy-6- methylbenzoate (13) in the manner described above for the preparation of ethyl 3- chloro-2-hydroxy-4-methoxy-6-pentylbenzoate (14). Ethyl 3-chloro-2-hydroxy-4-methoxy-6- methylbenzoate (1 5) (2.3 g, 64%) crystallized from dichlorornethanellight petroleum as colourless needles, m.p. 146-148" (Found: C, 54.3; H, 5 -4; C1, 14.6. CllH13C104 requires C, 54.0; H, 5.4; Cl, 14.5%). 'H n.m.r. (CDC13) S 1 -43, t, J 7 Hz, 0CH2CH3; 2.56, s, ArMe; 3.95, s, OMe; 4 -42, q, J 7 Hz, 0CH2; 6.36, s, ArH and 12 -22, s, OH. Mass spectrum mlz 244 (M, 17%), 198 (100).

l3 Grossman, J. D., and Light, K. K., U.S. Pat. 3,701,801 (Chem. Abstr., 1973, 78, 3807q).

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3-Chloro-2-hydroxy-4-methoxy-6-methylbenzoic Acid (1 7)

This acid was prepared by hydrolysis of ethyl 3-chloro-2-hydroxy-4-methoxy-6-methylbenzoate (15) (0.90g) as described above for the synthesis of 3-chloro-2-hydroxy-4-methoxy-6- pentylbenzoic acid (16). 3-Chloro-2-hydroxy-4-methoxy-6-methylbenzoic acid (17) (0.74 g, 94%) formed colourless crystals from acetone, m.p. 230-233' (Found: C, 49.5; H, 4.1; Cl, 16.2. C9H9C104 requires C, 49.9; H, 4 2; C1, 16.4%). ' H n.m.r. (CDC13) S 2 - 32, s, ArMe; 3.90, s, OMe; 6.64, s, ArH and 3.35, bs, OH and C02H. Mass spectrum mlz 216 (M, 16%) 198 (100).

Synthesis of Depsides-General Procedure

The appropriate carboxylic acid, i.e. (16), (17), (IS), (26) (1 mmol), and benzyl ester, i.e. (19), (20) or methyl ester (22) (1 mmol) were dissolved in a solution of anhydrous toluene (4 ml) and trifluoroacetic anhydride (2 ml) and stirred at room temperature for 2-6 h. The solvent was then removed under reduced pressure and the residue applied to a silica gel Chromatotron plate. Radial chromatography by using 5% ethyl acetatellight petroleum developed a major, faster moving depside ester band and a minor slower band containing unchanged benzyl ester. The depside ester, i.e. (5), (6), (7), (25) (0.5 mmol), was dissolved in ethyl acetate (5 ml) containing 10% palladium-on-carbon (25 mg) and the suspension stirred in an atmosphere of hydrogen for 2-22 h. The catalyst was then filtered and the solvent evaporated. The depside so obtained was crystallized from an appropriate solvent.

4-(3' -Chloro-2' -hydroxy-4' -methoxy-6' -propylbenzoyloxy)-2-h ydroxy-6-pen tylbenzoic Acid (3-Chlorostenosporic Acid) (2)

Benzyl 3-chlorostenosporate (5) (67%) crystallized from ethyl acetatellight petroleum as colourless crystals, m.p. 82-84' (Found: C, 66.2; H, 5.9; Cl, 6.7. C30H33C107 requires C, 66.6; H, 6 2; C1, 6 6%). 'H n.m.r. (CDC13) S 0.80-0.97, m, (CH2)4CH3 and CH2CH2CH3; 1.00-1 80, m, CH2(CH2)3CH3 and CH2CH2CH3; 2 85, 2 -97, 2bt, ArCH2; 3 -99, s, OMe; 5.41, s, 0CH2; 6.44, s, H5; 6.55, 6.75, 2d, J 2.5 Hz, H3', H5'; 7.44, m, C6H5 and 11-55, 11 $65, 29, OH. Mass spectrum mlz 91 (100).

3-Chlorostenosporic acid (2) (84%) crystallized from dichlorornethanellight petroleum as colourless crystals, m.p. 138' (Found: C, 6 1 4; H, 6.2; C1,7.8. C23H27C107 requires C, 61 -2; H, 6.0; C1,7.8%). 'H n.m.r. (CDC13) S 0 9 92-1.10, m, (CH2)4CH3 and CH2CH2CH3; 1.20-1.80, m, CH2(CH2)3CH3 and CH2CH2CH3; 3.02,3.00,2bt, ArCH2; 4-00, s, OMe; 6.46, s, H 5; 6.55, 6 76, 2d, J 2 5 Hz, H 3', H 5'; and 11.45-1 1.80, bs, OH and C02H. Mass spectrum mlz 244 (14%), 228 (32), 226 (loo), 224 (8), 206 (14), 169 (27), 150 (22), 124 (22). Standard RF values: RF (A) 44; RF (B) 61; RF (c) 49. The t.1.c. and h.p.1.c. behaviour of synthetic (2) was identical with that of a major metabolite of Dimelaena cf. calijornica (Magnusson) Sheard-collected on basalt, Punto Santo Tomas, Baja California del Norte, 31' 34' N, 116' 39' W, Mexico, i? H. Nash No. 12,951 (Arizona State University).*

4-(3' -Chloro-2' -hydroxy-4' -methoxy-6' -pentylbenzoyloxy)-2-hydroxp6-pentylben Acid (3-Chloroperlatolic Acid) (3)

Benzyl 3-chloroperlatolate (6) (91%) crystallized from dichloromethane/light petroleum as colourless needles, m.p. 82-84' (Found: C, 67 1; H, 6.7; Cl, 6 4. C32H37C107 requires C, 67.5; H, 6.6; Cl, 6.2%). 'H n.m.r. (CDC13) 6 0.75-1.10, m, (CH2)4CH3; 1.15-1.85, m, CH2(CH2)3CH3; 2.62, 3 08, 2bt, ArCH,; 3.98, s, OMe; 5.33, s, 0CH2; 6.32, s, H 5; 6.54, 6.63, 2d, J 2.5 Hz, H 3', H 5'; 7.30, m, C6H5 and 11.42, 11.62, 29, OH. Mass spectrum mlz 223 (6.8%), 91 (100).

3-Chloroperlatolic acid (3) (84%) crystallized from ethyl acetatellight petroleum as colourless crystals, m.p. 128' (Found: C, 63.0; H, 6.8; Cl, 7.6. C2sH3i C107 requires C, 62.7; H, 6 5; Cl, 7.4%). 'H n.m.r. (CDC13) S 0.70-1.00, m, (CH2)4CH3; 1 10-1.79, m, CH2(CH2)3CH3;

* Note that in the trivial names of the depsides the atoms on the 'left' side of the molecule are left unprimed, whereas in systematic names they are primed. Trivial nomenclature has been followed for H n.m.r. assignments.

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2.87, 3.12, 2bt, ArCH2; 3.99, s, OMe; 6.44, s, H 5; 6.61, 6.73, 2d, J 2.5 Hz, H 3', H 5'; and 11.56-11.82, be, OH and C02H. Mass spectrum mlz 272 (5 3%), 256 (13), 254 (40), 230 (7), 228 (22), 206 (1 I), 174 (31), 172 (100). Standard RF values: RF (A) 47; RF (B) 66; RF (c) 51. The t.1.c. and h.p.1.c. behaviour of synthetic (3) was identical with that of a minor metabolite of Dimelaena cf. califonica (Magnusson) Shead-collected on basalt, Punto Santo Tomas, Baja California del Norte, 31" 34' N, 116' 39' W, Mexico, T. H. Nash No. 12,951 (Arizona State University).

4-(3' -Ch loro-2' -hydroxp4' -methoxp6' -pentylbenzoyloxy)-2-h ydroxy-6-propylbenzoic Acid (3-Ch loroim bricaric Acid) (4)

Benzyl 3shloroimbricarate (7) (81%) crystallized from dichloromethanellight petroleum as colourless crystals, m.p. 50' (Found: C, 66.2; H, 6.4; C1, 6.8. C30H33C107 requires C, 66 6; H, 6.2; Cl, 6.6%). 'H n.m.r. (CDC13) 6 0.75-1.10, m, (CH2)4CH3 and CH2CH2CH3; 1.20-1.80, m, CH2(CH2)3CH3 and CH2CH2CH3; 2.82, 3.00, 2bt, ArCH2; 3.97, s, OMe; 5 42, s, 0CH2; 6.42,s,H5;6.48,6.63,2d, J 2 . 5 H z , H 3 ' , H 5 ' ; 7 . 4 3 , m , C 6 H 5 a n d 11.53, l l*73,2s ,OH. Mass spectrum mlz 254 (51%), 91 (100).

3-Chloroimbricaric acid (4) (97%) crystallized from ethyl acetatellight petroleum as colourless crystals, m.p. 128-130' (Found: C, 60.7; H, 5.9; C1, 7 8. C23H27C107 requires C, 61 92; H, 6.0; C1,7.9%). 'H n.m.r. (CDC13) 6 0.74-1 11, m, (CH2)4CH3 and CH2CH2CH3; 1.20-1.81, m, CH2(CH2)3CH3 and CH2CH2CH3; 2.85, 3 15, 2bt, ArCH2; 3 ~ 9 8 , s, OMe; 6.40, s, H 5; 6-59, 6.72, 2d, J 2 5 Hz, H 3', H 5'; and 11.60-1 1 80, bs, OH and C02H. Mass spectrum mlz 272 (2%), 256 (4), 254 (13), 230 (6), 228 (20), 196 (2), 178 (9), 174 (32), 172 (loo), 150 (5). Standard RF values: RF (A) 42; RF (B) 62; RF (c) 47. The t.1.c. and h.p.1.c. behaviour of synthetic (4) was dissimilar to that of the metabolites present in Dimelaena cf. cal$ornica (Magnusson) Sheard.

Methyl 4-(3' -Chloro-2' -hydroxp4' -methoxy-6' -methylbenzoyloxy)-2-h ydroxp6-meth ylbenzoate (Wrightiin) (21)

Wrightiin (21) (54%) was obtained as colourless crystals from ethyl acetate, m.p. 216" (lit.7 216.5")ound: C, 55 -9; H, 4.6; Cl, 9.6. Calc. for C18H17C107: C, 56 7; H, 4.5; C1, 9.3%). 'H n.m.r. S 2.59, 2.70, 2s, ArMe; 4.00, s, OMe; 6.45, s, H5; 6.62, 6.72, 2d, J 2.5 Hz, H3', H 5'; and 11 -61, 11 .79,2s, OH. Mass spectrum mlz 380 (M, 0.55%), 396 (0.64), 199 (87), 198 (SO), 182 (39), 150 (100). Standard RF values: RF (A) 70; RF (B) 55; RF (c) 74. The t.1.c. and h.p.1.c. behaviour of synthetic (21) was identical with that of a major metabolite of Erioderma wrightii Tuck.--collected in Ecuador, L. Arvidsson (BG).

4-(2'-Hydroxp4'-methoxp6'-methylbenzoyloxy)-2-hydroxp6-pentylbenzoic Acid (Subsphaeric Acid) (24)

Benzyl2-0- benzylsubsphaerate (25) (90%) crystallized from ethyl acetatellight petroleum as colourless crystals, m.p. 88' (Found: C, 73 -7; H, 6 -7. C35H3607 requires C, 73 -9; H, 6 -4%). 'H n.m.r. (CDC13) S 0.73-1 ~ 6 3 , m, CH2(CH2)3CH3; 2.37, s, ArMe; 2.50-2-70, bt, ArCH2; 3.82, s, OMe; 5 -07, s, 0CH2Ph; 5.33, s, C02CH2; 6.37, s, H 3, H 5; 6.60,6.67, 2d, J 2 5 Hz, H 3', H 5'; 7.30, 7 -40, 29, C6H5 and 11 -42, s, OH. Mass spectrum mlz 223 (9%), 206 (5), 91 (100).

Subsphaeric acid (24) (97%) crystallized from ethyl acetatellight petroleum as colourless crystals, m.p. 120' (Found: C, 64.7; H, 6 -4. C21H2407 requires C, 64.9; H, 6 -2%). 'H n.m.r. (CDC13) S 0 - 90, t, (CH2),CH3; 1.14-1.82, m, CH2(CH2)3CH1; 2 63, s, ArMe; 2 86-3 -09, bt, ArCH2; 3.82, s, OMe; 6.38, s, H 3, H 5; 6.66, 6.76, 2d, J 2 - 5 Hz, H 3', H 5'; 11.30, bs, OH and C02H. Mass spectrum mlz 224 (6.7%), 206 (14), 182 (30), 164 (78), 150 (27), 138 (49), 124 (100). Standard RF values: RF (A) 50; RF (B) 67; RF (c) 50. The t.1.c. and h.p.1.c. behaviour of synthetic (24) was identical with that of a major metabolite of Dimelaena thysanota (Tuck.) Hale & W. Cu1b.--collected on basalt, 'Juniper Wayside', 7 miles north of Sisters, Deschutes County, Oregon, U.S.A., W: A. Weber L-64575 (COLO); on rock outcrops, 4 miles east of Osoyoos along Highway 3, British Columbia, Canada, C M. Wetmore 18835 (COLO).

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Acknowledgments

We thank Professor P. M. Jgrgensen, Bergen, for the specimen of Erioderma wrightii, Dr W. A. Weber (COLO) for the loan of specimens, and the Australian National University for a National Undergraduate Scholarship to J.E.E.

Manuscript received 1 1 February 1988