1-Ethyl-3-(3'-dimethylaminopropyl)carbodiimide → 5,7-Dimethyl-1,3-benzoxazol-2-amine

A mixture of 1-bromo-4-isothiocyanatobenzene (63.92 g, 0.298 mol) and THF (1200 mL) was treated with 2-amino-4,6-dimethylphenol (41.8 g, 0.304 mol), stirred at room temperature for 3 hours, treated with EDCI (68.46 g, 0.358 mol), warmed to 40° C. for 16 hours, cooled to room temperature, and filtered. The filtrate was concentrated at 50° C. to a final volume of about 300 mL, treated with acetonitrile (800 mL), concentrated to a volume of about 200 mL, treated with acetonitrile (800 mL), and again concentrated to a volume of about 200 mL. The mixture was treated with acetonitrile (800 mL), cooled to room temperature, and filtered. The filter cake was washed with acetonitrile (100 mL) and dried to constant weight in a vacuum oven at 45° C. over 24 hours to provide 85.8 g (85%) of 5,7-dimethyl-1,3-benzoxazol-2-amine. A mixture of 5,7-dimethyl-1,3-benzoxazol-2-amine (76.4 g, 0.230 mol), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane (73.9 g, 0.292 mol), potassium acetate (71.5 g, 0.730 mol), and DMF (760 mL) was cycled three times through vacuum degassing and nitrogen purging, treated with Pd(dppf)Cl2.CH2Cl2 (19.9 g, 0.024 mol), sealed, cycled three times through vacuum degassing and N2 purging, heated to 80° C. for 5 hours, and distilled on high vacuum (0.2 mm Hg) at 40° C. to 80° C. to remove DMF. The residue was treated with CH2Cl2 (1300 mL), stirred for 10 minutes, and filtered. The filter cake was washed with CH2Cl2 (300 mL) and the filtrate was concentrated to a volume of about 800 mL. The solution was treated with SiO2 (509 g), stirred for 10 minutes, poured onto a bed of SiO2 (790 g) in a 4 L coarse glass fritted funnel. The SiO2 was washed with 16 L of 15% ethyl acetate and the solution was concentrated at 50° C. The concentrate was treated with heptane (800 mL), concentrated, treated with heptane (900 mL), stirred at 50° C. for 30 minutes, cooled to room temperature over 2 hours, and filtered. The filter cake was washed with 100 mL heptane and dried to constant weight in a vacuum oven at 45° C. over 24 hours to provide 68.3 g (77%) of the desired product. The final product was determined to be 98.2% potency (vs. analytical standard) by HPLC. Rt=6.5 min. HPLC conditions: Zorbax SB-C8 Rapid Resolution (4.6 mm×75 mm, 3.5 um); flow 1.5 mL/min; 5:95 to 95:5 acetonitrile:water (0.1% H3PO4) over 7 minutes.