A solution of 7-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydro-2H-benzo[b][1,4]oxazine (0.488 g, 1.774 mmol, prepared according to the procedures outlined for related compounds in Ref. WO20100130034) and K2CO3 (0.490 g, 3.55 mmol) in dry DMF (5 mL) was sparged with N2 for 5 min, treated with allyl bromide (0.773 mL, 8.87 mmol), then heated (70° C.) for 22 h. The reaction was diluted with water (50 mL) and extracted into EtOAc (50 mL) and washed with water, brine and then dried (Na2SO4), filtered, and concentrated. The crude was purified by biotage column chromatography (12 g SiO2, 0% (3 CV), 0-40% (10 CV), 40% (2 CV), EtOAc in hexanes). Product rich fractions were re-purified by biotage (0% (3 CV), 0-40% (15 CV), 40% (2 CV), EtOAc in hexanes) to afford the desired product (0.345 g, 0.938 mmol, 52.9% yield), as a colorless viscous oil. 1H NMR (500 MHz, CDCl3) δ 7.20 (s, 1H), 6.62 (d, J=0.5 Hz, 1H), 5.92 (ddt, J=16.9, 10.4, 5.9 Hz, 1H), 5.29 (dq, J=17.2, 1.6 Hz, 1H), 5.23 (dq, J=10.2, 1.4 Hz, 1H), 4.30-4.24 (m, 2H), 3.89 (dt, J=5.9, 1.3 Hz, 2H), 3.27-3.18 (m, 2H), 2.43 (s, 3H), 1.33 (s, 12H).
