tert-Butyl 5-(4,4,5,5-tetraMethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroisoquinoline-2(1H)-carboxylate

Synthesis

Using N-Boc-5-bromo-1,2,3,4-tetrahydroisoquinoline (2.7 g, 8.7 mmol) and pinacol ester of bisboronic acid (4.39 g, 17 mmol) as the starting material, the reactants were mixed with potassium acetate (2.55 g, 26 mmol) and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (0.63 g, 0.87 mmol) under the protection of nitrogen. 0.87 mmol) were mixed in 1,4-dioxane (40 mL). The reaction mixture was stirred at 80 °C for 2 h and then cooled to room temperature. Water (30 mL) was added and extracted with ethyl acetate (3 x 20 mL). The organic phases were combined and concentrated under reduced pressure. The residue was purified by fast chromatography (eluent: cyclohexane/ethyl acetate=85:15) to afford the target product tert-butyl 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroisoquinoline-2(1H)-carboxylate as a clear gel (3.25 g, 105% yield).LCMS (formate method) : Retention time 1.51 min, [M+H]+=360.

References

[1] Patent: WO2010/146105, 2010, A1. Location in patent: Page/Page column 86-87
[2] Patent: WO2016/65222, 2016, A1. Location in patent: Page/Page column 57
[3] Patent: WO2010/145202, 2010, A1. Location in patent: Page/Page column 38
[4] Patent: WO2013/134518, 2013, A1. Location in patent: Page/Page column 39
[5] Patent: WO2016/44666, 2016, A1. Location in patent: Paragraph 0589; 0591