TCI Practical Example: Suzuki-Miyaura Coupling of Diaminonaphthalene (dan)-Protected Bromophenylboronic Acid

We are proud to introduce the Suzuki-Miyaura coupling of the stable bromophenylboronic acid protected with 1,8-diaminonaphthalene (dan). The dan group can be deprotected by acidic condition and the free boronic acid can be easily obtained.

Used Chemicals

Procedure: To a reaction vessel, 2-(4-bromophenyl)-2,3-dihydro-1H-naphtho[1,8-de][1,3,2]diazaborine (3.0 g, 9.3 mmol), 4-(ethoxycarbonyl)phenylboronic acid (2.7 g, 4.0 mmol), Pd(PPh₃)₄ (0.54 g, 0.47 mmol), potassium carbonate (3.9 g, 28.0 mmol), toluene (30 mL), ion-exchange water (15 mL) were subsequently added and heated at 90 °C. After the consumption of the starting material, the reaction mixture was cooled to room temperature. Dichloromethane was added and aqueous layer was removed. The organic layer was dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated to obtain crude product. The crude product was dissolved in dichloromethane and passed through a pad of silica gel and concentrated. The residue was washed with hexane to give 1 (2.5 g, yield. 69%) as a pale yellow powder.

Experimenter’s Comments: The reaction mixture was monitored by TLC (hexane:ethyl acetate = 4:1, Rf = 0.5).

Analytical Data

Compound 1

¹H NMR (400 MHz, CDCl₃); δ 8.17-8.10 (m, 2H), 7.80-7.65 (m, 6H), 7.16 (dd, 2H, J = 7.3, 8.2 Hz), 7.8 (dd, 2H, J = 7.3, 8.2 Hz), 6.45 (dd, 2H, J = 0.8, 7.3 Hz), 6.08 (brs, 2H), 4.42 (q, 2H, J = 7.2 Hz), 1.43 (t, 3H, J = 7.2 Hz).

Lead Reference