The general procedure for the synthesis of 3,3-dimethylcyclobutanecarboxylic acid from the compound (CAS:231303-93-8) was as follows: intermediate 285C (250 mg, 1.452 mmol) was dissolved in pyridine (5 mL) and the reaction was stirred for 16 h at 120 °C. After completion of the reaction, the reaction mixture was cooled to room temperature and the reaction was quenched with 1.5 N HCl aqueous solution. Subsequently, extraction was carried out with ether (2 x 50 mL) at 0 °C. The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to afford intermediate 285D as a viscous liquid (170 mg, 91% yield).1H NMR (400 MHz, DMSO-d6) δ ppm: 2.90-3.02 (m, 1H), 1.84-1.95 (m, 4H), 1.07-1.14 (m, 3H) , 0.99-1.07 (m, 3H).
