4H,5H-pyrano[3,4-c][1]benzopyran-2-carboxylic acid, 4a,10b-dihydro-4,4-dimethyl-, methyl ester, (4aR,10bR)- InChI=1/C16H18O4/c1-16(2)12-9-19-13-7-5-4-6-10(13)11(12)8-14(20-16)15(17)18-3/h4-8,11-12H,9H2,1-3H3/t11-,12-/m0/s methyl (4aR,10bR)-4,4-dimethyl-4a,10b-dihydro-4H,5H-pyrano[3,4-c]chromene-2-carboxylate