4.2.4. 2-[Carboxy(phenyl)methyl]-5-methylbenzoic Acid (**10d**)

Prepared according to the general procedure GP1 from 6-methyl-3-phenyl-2,3-dihydro-1*H*-inden-1-one [16]. Yield 1.167 g, 45%. Colorless amorphous solid. 1H NMR (400 MHz, DMSO-*d*6) *δ* 12.71 (s, 2H), 7.71–7.65 (m, 1H), 7.38–7.32 (m, 2H), 7.30–7.26 (m, 2H), 7.25–7.19 (m, 2H), 7.05–6.89 (m, 1H), 5.91 (s, 1H), 2.31 (s, 3H). 13C NMR (101 MHz, DMSO-*d*6) *δ* 174.00, 169.17, 161.41, 139.66, 137.68, 136.58, 132.61, 131.11, 130.88, 130.24, 129.44, 128.92, 127.30, 53.20, 20.78. 13C NMR (101 MHz, DMSO-*d*6) *δ* 174.0, 169.2, 161.4, 139.7, 137.7, 136.6, 132.6, 131.1, 130.9, 130.2, 129.4, 128.9, 127.3, 53.2, 20.8. HRMS (ESI/Q-TOF) *m*/*z*: [M + Na]+ Calcd for C16H14O4Na+ 293.0784; Found 293.0785.
