Barbatolic acid

CH2OH R = H, CHj. Most D. are didepsides, such as, e.g., atranorin, chloroatranorin, gyrophoric acid, and lecanoric acid. In some D. (e. g., alectorialic acid and barbatolic acid) the acid part (S) is linked with a benzylic hydroxy group of the A part. The structures of about 100 D. isolated from lichens have been elucidated by hydrolysis and alcoholysis to the corresponding carboxylic acids or esters (S part) and to the phenols (A part), respectively. 

C Barbatolic acid aggregates of small rod-shaped crystals... 

Fig. 20. A Barbatic acid, oT. Bar 100 im. B Barbatic acid, Py. Bar 100 j m. C Barbatolic acid, Py. Bar lOjiLm. D Boninic acid, GE. Bar lOjim...

Deriv Methyl barbatolate, needles (AcOH), mp 193 °C, from barbatolic acid with CHjNj StL Bryoria capillaris (Ach.) Brodo et D. Hawksw. 

Elix JA, Jayanthi VK (1987a) Synthetic confirmation of the structure of the lichen benzyl esters alectorialic and barbatolic acids. Aust J Chem 40 1841-1850 Elix JA, Jayanthi VK (1987b) The isolation and synthesis of the lichen depside 4-0-demethylmicrophyllinic acid. Aust J Chem 40 1851-1859... 

T.l.c. comparisons indicated that both the phthalide (113) and 5,7-dihydroxy-6-formylphthalide (114) occur in extracts of Alectoria capillaris together with the cogeneric benzyl esters, alectorialic acid (115) and barbatolic acid (116). It seems highly probable that these phthalides are artefacts of the isolation procedure rather than metabolites of the lichens (303). 

PD+,K+ Depsides alectorialic acid, atranorin, baeomycesic acid, barbatolic acid, chloroatranorin, decarboxythamnolic acid, haemathamno-lic acid, nephroarctin, thamnolic acid, Depsidones constictic acid, fumarprotocetraric acid, norstictic acid, physodalic acid, proto-cetraric acid, salazinic acid, stictic acid, virensic acid... 

Elix JA, Jayanthi VK (1987) Synthetic Confirmation of the Structure of the Lidien Benzyl Esters Alectoiialic and Barbatolic Acids. Aust J Chem 40 1841... 

Methods to synthesize elephantorrhizol (35) and barbatol (67), two flavan-3-ols with highly oxygenated A-rings that were isolated from Elephantorrhiza goetze and Campanula barbata, respectively, were recently developed. ° ° Catechin (2) was efficiently converted into the potential electrophilic 2,3-rr r-3,4-rrtf j -flavan-3,4-diol (68) via a seven-step procedure. The authors, however, did not elaborate on their handling of this very sensitive and reactive flavan-3,4-diol, especially under mild acidic conditions. 

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