3,6-Dihydro-2H-pyran-4-boronic acid pinacol ester

A 250 ml_ round bottom flask containing trifluoro-methanesulfonic acid 3, 6- dihydro-2H-pyran-4-yl ester (2.7 g, 11.6 mmol), PdCIUnder an atmosphere of nitrogen, a solution of 3, 6-dihydro-2H-pyran-4-yl trifluoromethanesulfonate (0.7 g, 3.0 mmol), 4, 4, 4', 4', 5, 5, 5', 5'-octamethyl-2, 2'-bi(1, 3, 2-dioxaborolane) (CAN 3183-34-3, 0.84 g, 3.3 mmol), 1, 1'-bis(diphenylphosphino) ferrocene-palladium(II)dichloride methylene chloride complex (CAN 95464-05-4, 0.05 g, 0.06 mmol) and potassium acetate (0.89 g, 9.0 mmol) in DMSO (10 mL) was heated to 80° C. overnight. Water (50 mL) was added to the reaction mixture which then was extracted with ethyl acetate (3.x.30 mL). The combined organic extracts were washed with brine, dried over anhydrous sodium sulfate and evaporated. The residue was purified by column chromatography (silica gel, 9 g, 1percent ethyl acetate in petroleum ether) to yield the title compound (0.32 g, 2 mmol, 50.5percent) as colorless oil. Under an atmosphere of nitrogen, a solution of 3, 6-dihydro-2H-pyran-4-yltrifluoromethanesulfonate (0.7 g, 3.0 mmol), 4, 4, 4', 4', 5, 5, 5', 5'-octamethyl-2, 2'- bi(l, 3, 2- dioxaborolane) (CAN 3183-34-3, 0.84 g, 3.3 mmol), 1, 1A mixture of 3, 6-dihydro-2H-pyran-4-yl trifluoromethanesulfonate (250 mg, 1.1 mmol), bis(pinacolato)diboron (410 mg, 1.6 mmol), and KOAc (323 mg, 3.3 mmol) dioxane (3 mL) was sparged with Ar for 5 min. Then PdClTo a solution of 4.4, 4', 4', 5.5, 5', 5'-octamethyl-2.2'-bi(1.3, 2-dioxaborolane) (993 mg, 3.91 mmol) in DMSO (5 mL) under NWas added to the kettle 5L of toluene, 1.2kg of potassium acetate, 2.0kg boronic acid pinacol ester, 20g [1, 1'- bis (diphenylphosphino) ferrocene] dichloropalladium and b 1.0kg4- bromo-3, 6-dihydro -2H- pyran, under nitrogen, with stirring heated to 80°C, stirring was continued for 4 hours. The reaction mixture was filtered through Celite, evaporated under reduced pressure to give a crude product, obtained after recrystallization 1.1kg3, 6- dihydro -2H- pyran-4-boronic acid pinacol ester (purity greater than 95percent), the yield 80percent.Add Grubbs Catalyst, 2nd Generation (benzylidene-[l, 3-bis(2, 4, 6- trimethylphenyl)imidazolidin-2-ylidene]-dichloro(tricyclohexylphosphine)ruthenium, 2.58 g, 0.03 eq) to a solution of 2-(3-allyloxy-l-methylene-propyl)-4, 4, 5, 5-tetramethyl- 1, 3, 2-dioxaborolane (23.4 g, 98.26 mmol) in dichloromethane (280 mL) and stir for 16 hours. Concentrate in vacuo and add hexanes (120 mL) to the residue. Stir for one hour and filter. Concentrate the filtrate in vacuo to give 2-(3, 6-dihydro-2H-pyran-4-yl)-4, 4, 5, 5- tetramethyl-l, 3, 2-dioxaborolane as a tan solid (20.4 g, 99percent). Step two: adding magnesium metal (1.9 g, 78mmol) and 10 ml of tetrahydrofuran, add 2-3 drop iodine methane initiating the dropwise 11.9 g 3, 6-dihydro -2H-pyran-4-polybromide dissolved in 60 ml tetrahydrofuran solution, reagent cheng Geshi preparing reflux reaction is omitted, then drop by adding trimethoxy-in (9.1 g, 87mmol), after the reaction is complete, by adding 15percent hydrochloric acid solution to adjust PH= 3-4, organic layer by adding 90 ml of ethyl acetate and pinacone (10.3 g, 87mmol), stirring at room temperature until the reaction is complete. After laminating, an organic layer saturated salt water washing, solvent after evaporation to dryness, by adding normal heptane, cooling to -10 °C, filtering to obtain 9.7 g of white solid: 3, 6-dihydro -2H-pyran-4-boronic acid pinacone ester, GC: 99.2percent, HNMR > 98percent, the yield is 63percent.Under an atmosphere of nitrogen, a solution of 4-bromo-3, 6-dihydro-2H-pyran 10 (24.5 g, 0.15 mol), bis(pinacolato)diboron (42.0 g, 0.15 mol), 1, 1’-bis(diphenylphosphino)ferrocene-palladium(II) dichloride methylene chloride complex (1.25 g, 1.5mmol) and potassium acetate (44.5 g, 0.45 mol) in dioxane (350 mL) was heated to 80

Molecular Weight:210.08
Hydrogen Bond Acceptor Count:3
Rotatable Bond Count:1
Exact Mass:210.1427246
Monoisotopic Mass:210.1427246
Topological Polar Surface Area:27.7
Heavy Atom Count:15
Complexity:268
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes