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To a 1-L flask equipped with a nitrogen inlet, a thermocouple, and a mechanical stirrer were sequentially added isopropanol (IPA, 200 mL), 1,8-diazabicyclo[5,4,0]undec-ene (DBU, 9.8 g, 64.4 mmol, 0.125 equiv), 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (1, 101 g, 520.51 mmol, 1.01 equiv) and tert-butyl 3-(cyanomethylene)azetidine-1-carboxylate (2, 100 g, 514.85 mmol) at ambient temperature to generate a reaction mixture as a suspension. The resulting reaction mixture was heated to reflux in 30 minutes to provide a homogenous solution and the mixture was maintained at reflux for an additional 2-3 hours. After the reaction was complete as monitored by HPLC, n-heptane (400 mL) was gradually added to the reaction mixture in 45 minutes while maintaining the mixture at reflux. Solids were precipitated out during the n-heptane addition. Once n-heptane addition was complete, the mixture was gradually cooled to ambient temperature and stirred at ambient temperature for an additional 1 hour. The solids were collected by filtration, washed with n-heptane (200 mL), and dried under vacuum at 50° C. with nitrogen sweeping to constant weight to afford tert-butyl 3-(cyanomethyl)-3-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl)azetidine-1-carboxylate (3, 181 g, 199.9 g theoretical, 90.5%) as a white to pale yellow solid. For 3: 1H NMR (400 MHz, DMSO-d6) δ 8.31 (s, 1H), 7.74 (s, 1H), 4.45-4.23 (m, 2H), 4.23-4.03 (m, 2H), 3.56 (s, 2H), 1.38 (s, 9H), 1.25 (s, 12H) ppm; 13C NMR (101 MHz, DMSO-d6) δ 155.34, 145.50, 135.88, 116.88, 107.08 (br), 83.15, 79.36, 58.74 (br), 56.28, 27.96, 26.59, 24.63 ppm; C19H29BN4O4 (MW 388.27), LCMS (EI) m/e 389 (M++H).

1. customTo a 1-L flask equipped with a nitrogen inlet
2. customat ambient temperature
3. customThe resulting reaction mixture
4. temperaturewas heated
5. temperatureto reflux in 30 minutes
6. customto provide a homogenous solution
7. temperaturethe mixture was maintained
8. temperatureat reflux for an additional 2-3 hours
9. additionwas gradually added to the reaction mixture in 45 minutes
10. temperaturewhile maintaining the mixture
11. temperatureat reflux
12. customSolids were precipitated out during the n-heptane addition
13. additionOnce n-heptane addition
14. filtrationThe solids were collected by filtration
15. washwashed with n-heptane (200 mL)
16. customdried under vacuum at 50° C. with nitrogen sweeping to constant weight