2.4- Dimethoxy-6-methylbenzoic acid

Di-O-methylorsellinic acid, 2,4-Dimethoxy-6-methylbenzoic acid (2,4-Di-O-methylorsellinsaure, 2,4-Dimethoxy-6-methylbenzoesaure)... 

Hydroxy-4-0-methylum-bilicaric acid 184 168-169 By condensation of 3-benzyloxy-2,4-dimethoxy-6-methylbenzoic acid and benzyl lecanorate with TFAA and subsequent debenzylation (223)... 

Crystals (EtOH-HjO), mp 157-158 °C Deriv Methyl 2,6-dimethoxy-3-chloro-4-meth-ylbenzoate, mp 71-72 °C, from 2,6-dimethoxy-3-chloro-4-methylbenzoic acid with CH2N2 Lit Roller and Popl 1934a... 

Di-0-methyl-3,5-diehloroorsellinic acid, 2,4-Dimethoxy-3,5-dichloro-6-methylbenzoic acid... 

Preparation by hydrogenolysis of 2, 2 -bis (benzyloxy)-3,5,5 -trichloro-4, 4 -dimethoxy-6,6 -dimethylbenzo-phenone (SM) with hydrogen in the presence of 10% Pd/C in ethyl acetate containing concentrated hydrochloric acid (5 drops) (>90%) [1339]. SM was obtained by Friedel-Crafts acylation of 5-(benzyloxy)-2-chloro-3-methoxy-toluene with 2-(benzyloxy)-3,5-dichloro-4-methoxy-6-methylbenzoic acid in the presence of trifluoroacetic anhydride in refluxing ethylene dichloride for 5 h (28%). 

Obtained by addition of 4-acetoxy-2-methoxy-6-methylbenzoic acid to 2-fluoro-3,5-dimethoxy-phenol in the presence of trifluoroacetic anhydride, first at 0°, then at 20-25° for 20 h (21%) [1191]. 

Preparation by hydrogenolysis of 4,6, 6 -tris-(benzyloxy)-3,3 -dichloro-2, 4 -dimethoxy-2-methyl-benzophenone (SM) in ethyl acetate/tetrahydrofuran in the presence of 10% Pd/C at 25° (29%). SM was obtained by condensation of 4,6-bis(benzyloxy)-3-chloro-2-methylbenzoic acid with 4-chloro-3,5-dime-thoxyphenol benzyl ether in the presence of trifluoroacetic anhydride in methylene chloride under nitrogen for 20 min [1179]. m.p. 217-219° [1179] H NMR [1179], IR [1179], MS [1179]. 

Demethoxykanugin. 3,7-Dimethoxy-3 4 -methylenedioxyflavone, 1324 Derrustone. 5,7-Dimethoxy-3, 4 -methylenedioxyisojlavone, 1493 Diacetylorcinol. 2,4-Diacetyl-3,5-dihydroxytoluene, 1570 3,5-Diacetyl-o-orsellinic acid. 3,5-Diacetyl-2,4-dihydroxy-6-methylbenzoic acid, 1573... 

From 2,4-dimethoxy-6- -pentylbenzoic acid and 4-benzyloxy-2,3-dihydroxy-6- -propylbenzoate withTFAA and subsequent debenzylation From 2,4-dibenzyloxy-6-methylbenzoic acid and benzyl 2,4-dihydroxy-3,6-di-methylbenzoate with TFAA and subsequent debenzylation 101... 

The use of open-chain precursors for obtaining the benzenoid ring in anacardic and orsellinic acids has proved a fruitful approach. Ethyl 2-methoxy-6-methylbenzoate (synthesised through the Michael addition of ethyl acetoacetate virith but-2-en-al, followed by cyclisation and aromatisation), has been alkylated in an aprotic solvent after formation of the carbanion with lithium di-isopropylamide (refs. 113,114) to give the anacardic after hydrolysis and demethylation (a). In a similar way ethyl 2,4-dimethoxy-6-methylbenzoate (ethyl orsellinate), (formed from ethyl acetoacetate and ethyl crotonate followed by cyclisation aromatisation and methylation (ref. 115)), has been alkylated (ref. 116, 117). In this way the C.,5 orsellinic acid precursor [R = C14H29 in route (b)] of the component phenols in Anacardium occidentale has been synthesised (ref. 118) and the method indirectly affords another route to the cardol series. 

Preparation by reduction of the 2, 6-dimethoxy-4,6 -dimethylspiro[81574-67-6]-3(2H),4 -dione (SM) with zinc dust in acetic acid for 1 h (83%). SM was obtained from methyl 4-methoxy-2-(2,4-dimethoxy-6-methyl-phenoxy)-6-methylbenzoate by treatment with titanium tetrachloride and hydrogen chloride for 40 h (65%, m.p. 190-192°) [1184]. 

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