2-Methylconfluentic acid

Elix JA, Ferguson BA (1977) Synthesis of the lichen depside 2-0-methylconfluentic acid. Aust J Chem 30 373-385... 

Chemically, the procedure of hydrolytic degradation of depsides and identification of the hydrolysis products remains a general and definitive procedure. For example the new depside 2-O-methylconfluentic acid (237) has been isolated from the lichen Lecidea fuscoatra and the structure deduced from spectroscopic data 190). Hydrolysis of the corresponding methyl ester, methyl 2-0-methylconfluentate (238) with methanolic potassium hydroxide gave 2,4-dimethoxy-6-(2-oxoheptyl)benzoic acid (239) and methyl 4-hydroxy-2-methoxy-6-pentylbenzoate (240) thus establishing the structure of this depside (Scheme 27). 

The structural elucidation of the new depside 2-O-methylconfluentic acid (237) 190) via the nature of the hydrolysis products has been mentioned previously (Scheme 27). The total synthesis of this compound has also been reported 119) and was the first instance where a depside containing an oxidized side chain had been synthesized. Here additional difficulties arise because of the close proximity of the reactive benzyl ketone... 

Deriv Methyl 2-0-methylconfluentate, needles (MeOH-HjO), mp 81-82°C, from 2-0-meth-ylconfluentic acid with excessive CHjNj in EtjO in 12 h at 20 °C... 

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