2-CARBOXYPHENYLBORONIC ACID, PINACOL ESTER

To a round bottom flask containing 2-(4, 4, 5, 5-Tetramethyl-l, 3, 2-dioxaborolan-2-yl)benzoic acid (1.00 g, 4.03 mmol) was added DCM (40 mL), diisopropylethylamine (1.05 mL, 6.04 mmol) and HBTU (2.29 g, 6.04 mmol). The reaction mixture was stirred for 30 min before adding cyclopropylpiperazine-l-ylmethanone (0.86 mL, 6.04 mmol). The reaction was stirred overnight before the excess solvent with removed in vacuo and the crude material purified via flash column chromatography (EtOAc:MeOH 10:1) affording (4- (Cyclopropanecarbonyl)piperazin-l-yl)(2-(4, 4, 5, 5-tetramethyl-l, 3, 2-dioxaborolan-2- yl)phenyl)methanone as a white solid (1.08 g, 2.82 mmol, 70%) in a mixture of rotamers (2:1). The shifts relating to the minor rotamer has been donated with an asterisk.* *H NMR (400 MHz, CDCh) d = 7.81 (d, J = 7.4 Hz, 1H + 1H*), 7.45 (td, J = 7.6, 1.5 Hz, 1H + 1H*), 7.35 (td, / = 7.5, 1.3 Hz, 1H + 1H*), 7.22 (d, J = 7.5 Hz, 1H + 1H*), 3.86 - 3.69 (m, 4H, 4H*), 3.67 - 3.50 (m, 2H, 2H*), 3.34 - 3.07 (m, 2H, 2H*), 1.81 - 1.52 (m, 1H + 1H*), 1.29 (s, 12H + 12H*), 1.04 - 0.95 (m, 2H + 2H*), 0.67 - 0.87 (m, 2H + 2H*); 13C NMR (100 MHz, CDCh) d = 172.3 (1C + 1C*), 171.3 (1C + 1C*), 142.3 (1C + 1C*), 135.7 (1C + 1C*), 131.2 (1C + 1C*), 128.2 (1C + 1C*), 125.4 (1C + 1C*), 84.1 (2C + 2C*), 47.3 (1C*), 47.0, 45.2 (1C*), 44.9, 41.9 (2C), 41.6 (2C*) 24.9 (4C + 4C*), 11.0 (1C + 1C*), 7.65 (2C + 2C*) (the carbon bearing the boron substituent is not observed); IR (v, cm 1): 2970, 1634, 1467, 1213, 1014, 741; HRMS (ESI) for C2iH3o10BN204 [M+H]+ requires 384.2220 found 384.2218; Mp: 85 - 87C.A mixture of 2 (0.15 g, 0.60 mmol), To a solution of anhydrous THF (20 mL) under an atmosphere of argon was added 2- boronobenzoic acid (1.00 g, 6.02 mmol), pinacol (0.71 g, 6.02 mmol) and magnesium sulfate (1.44 g, 12.04 mmol). The reaction was left to stir overnight at room temperature. Upon completion, the reaction was filtered and the excess solvent removed in vacuo affording 2- (4, 4, 5, 5-Tetramethyl-l, 3, 2-dioxaborolan-2-yl)benzoic acid as a white solid (1.49 g, 6.00 mmol, 99%). *H NMR (400 MHz, DMSO-d6) d = 7.83 (dd, / = 7.6, 0.9 Hz, 1H), 7.55 (td, J = 7.3, 1.3 Hz, 1H), 7.46 (td, J = 7.5, 1.4, 1H), 7.43 - 7.39 (m, 1H), 1.29 (s, 12H); 13C NMR (100 MHz, DMSO-de) d = 169.6, 134.7, 132.2, 131.9, 129.2, 128.3, 83.4 (2C), 25.0 (4C) (the carbon bearing the boron substituent is not observed); IR (v, cm 1): 2972, 1679, 1344, 1304, 1141, 754; HRMS (ESI) for Ci3Hi610BO4 [M-H] requires 247.1212 found 247.1215; Mp: 118 - l20C.

Molecular Weight:248.08
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:2
Exact Mass:248.1219892
Monoisotopic Mass:248.1219892
Topological Polar Surface Area:55.8
Heavy Atom Count:18
Complexity:324
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes