4.2.1. 2-[Carboxy(4-chlorophenyl)methyl]benzoic Acid (**10a**)

Prepared according to the general procedure GP1 from 3-(4-chlorophenyl)-2,3-dihydro-1*H*-inden-1-one[21]. Yield 2.344 g, 84%. Colorless amorphous solid. 1H NMR (400 MHz, DMSO-*d*6) *δ* 12.89 (s, 2H), 8.02–7.80 (m, 1H), 7.55–7.48 (m, 1H), 7.46–7.34 (m, 3H), 7.31–7.23 (m, 2H), 7.15–7.10 (m, 1H), 5.99 (s, 1H). 13C NMR (101 MHz, DMSO-*d*6) *δ* 173.6, 169.0, 140.1, 138.5, 132.3, 132.1, 131.4, 131.0, 130.9, 130.2, 128.9, 127.5, 52.9. HRMS (ESI/Q-TOF) *m/z*: [M + Na+] <sup>+</sup> Calcd for C15H11ClO4Na<sup>+</sup> 313.0238; Found 313.0234.
