Sodium Hydroxide → 1-(Cyanomethyl)cyclobutane-1-carboxylic acid

To a stirred solution of Intermediate 220B (0.110 g, 0.658 mmol) in ethanol (3.5 mL), THF (3.5 mL) and water (3 mL) was added NaOH (0.079 g, 1.974 mmol) and the reaction mixture was stirred at RT for 16 h. The reaction mixture was concentrated and the residue was diluted with water (3 mL) and extracted with EtOAc (3×20 mL) The pH of the aqueous layer was adjusted to 3 using a 1.5N aqueous solution of HCl and extracted with EtOAc (3×10 mL). The combined organic layer was washed with water, dried over Na2SO4, filtered and the filtrate concentrated. The residual mass was then azeotroped with toluene to obtain the Intermediate 220C as a brown oil (0.06 g, 66% yield). 1H NMR (400 MHz, DMSO-d6) δ ppm 12.65 (br. s., 1H), 3.04-2.79 (m, 2H), 2.42-2.17 (m, 2H), 2.09-1.67 (m, 4H).