Isomurolic acid

Deriv Isomurolic acid, mp 115-116 °C (MeOH), by heating of murolic acid in dimethyl-formamide at 150 °C for 30 min StL Lecanora muralis (Schreb.) Rabenh. 

The relative configuration of (+ )-neodihydromurolic acid (54) similarly followed from the H-n.m.r. spectrum and was shown to be trans, trans ( 3 2 = 11 Hz, /3 4 = 9Hz). Catalytic hydrogenation of ( + )-murolic acid (53) gave a mixture of isomurolic acid (65) and dihydromurolic acid (66). Subsequent esterification and equilibration with sodium methoxide gave methyl neodihydromurolate (67) thus confirming that (53) and (54) must have the same configuration at C-18, C-4 and C-3 (Scheme 8). 

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See also in sourсe #XX -- [ ]

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