[N+](=[CH:3][C:4]([O:6][CH2:7][CH3:8])=[O:5])=[N-].[CH:9]([B:11]1[O:19][C:16]([CH3:18])([CH3:17])[C:13]([CH3:15])([CH3:14])[O:12]1)=[CH2:10]>C(OCC)C.C([O-])(=O)C.[Pd+2].C([O-])(=O)C>[CH2:7]([O:6][C:4]([CH:3]1[CH2:10][CH:9]1[B:11]1[O:19][C:16]([CH3:18])([CH3:17])[C:13]([CH3:14])([CH3:15])[O:12]1)=[O:5])[CH3:8]Ethyl diazoacetate (3.49 g, 61.3 mmol) was added over 20 minutes to a stirred suspension of palladium (II) acetate (61 mmol) and vinylboronic acid pinacol ester (1.9 g, 12.26 mmol) in diethyl ether (30 mL) and stirred for 2 hours. The reaction was concentrated in vacuo and the residues distilled under vacuum (100-140° C. at 0.5-1 mbar) to afford 2-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-cyclopropanecarboxylic acid ethyl ester (3.08 g, quant.) as a 4:6 mix of products, cis/trans isomers. 1H NMR 300 MHz (CHCl3-d): δ 4.26-4.25 (0.8H, m), 4.12-4.12 (1.2H, m), 1.83-1.82 (0.4H, m), 1.76-1.75 (0.6H, m), 1.28-1.27 (6H, m), 1.26 (6H, m), 1.22 (3H, m), 1.16-1.05 (0.8H, m), 1.01-1.00 (1.2H, m), 0.58 (0.6H, ddd, J=10.25, 7.44, 5.18 Hz), 0.41-0.41 (0.4H, m)
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