2,6-Dimethoxypyridine-3-boronic acid

To a solution of 2, 6-dimethoxypyridine (10 g, 71.84 mmol) and N, N-diisopropylamine (0.50 mL, 3.59 mmol) in THF (200 mL, dist. Na) at -40°C under nitrogen was added -BuLi (43.10 mL, 86.21 mmol) dropwise. The resultant solution was stirred at -40°C for 5 min, and then warmed to 0 °C and stirred at this temperature for a further 3 hours. The solution was then again cooled to -40 °C, and triisopropylborate (24.87 mL, 107.76 mmol) was added dropwise, and the mixture stirred at r.t. for another 1 hour. Water (50 mL) was added and the solvent was removed in vacuo. To the residue was added 1M NaOH (100 mL) and the aqueous layer washed with EtOAc (2 x 100 mL). The aqueous layer was then acidified to pH 3 and a solid precipitated. This solid was filtered and dried to afford the product 56. Yield = 8.10 g, 61percent. 1H NMR (0334) (DMSO-dGeneral procedure: Methyl 3, 5-diamino-6-chloropyrazine-2-carboxylate 2 (1 eq.) was combined with K2CO3 (10 eq.), the appropriate (het)aryl boronic acid (1.5 eq.) and Pd(PPh3)4 (5 mol%) in a two-neck round bottom flask. The flask was connected to a condenser and purged with nitrogen. A 4:1 mixture of anhydrous toluene: MeOH (60 mL) was added via syringe and the reaction mixture was heated at reflux for 0.5-18 h. The mixture was allowed to cool to room temperature and filtered through Celite (10 x 3 cm, eluting with 3 x 20 mL EtOAc). The filtrate was evaporated to dryness and the residue purified by silica gel flash column chromatography using EtOAc/pet spirit.

May contain a variable amount of acid anhydride.

Molecular Weight:182.97
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:3
Exact Mass:183.0702880
Monoisotopic Mass:183.0702880
Topological Polar Surface Area:71.8
Heavy Atom Count:13
Complexity:157
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes